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Adventures with a 1986 KTM MXC 500 Widowmaker

18K views 73 replies 22 participants last post by  Ingersoll444 
#1 · (Edited)

This thread is devoted to my 1986 KTM MXC 500 2-stroke dirt bike. The thread includes everything in chronological order from the time I purchased it to upgrades that I've done to it and my adventures with it out in the mountains. My hope is that you'll get a small view into what life it is like to own a 1980's "widowmaker" open class 2-stroke dirt bike.

Enjoy!

______________________________________________________________________________________________________________________________________________________

The old girl arrived safe and sound have been spending the past couple of days getting acquainted with it in the garage. I finally fired it up and took it for my first ride today. If you'd like to get a firsthand experience of what it's like, then you can read my review below after the pics.

I used UShip to have it transported up from California. Found a shipper with good feedback and had it shipped for less than what it would've costed in me in fuel to go pick it up myself.

























The Basics
When you first throw a leg over it you realize how light it is. Really light. If you're used to riding two strokes and the weight wasn't so noticeable, the hard and unforgiving seat instead will catch your attention. It is probably partly this way due to its age. The gas tank is large and sits up high in front of you, but is unusually quite narrow and slim on the sides like an MX bike. Flick the kick stand up and you wonder if you almost broke it because it feels very light by the way it went up. You definitely feel like you're on something that's retro by the lines of the tank and style of the plastics, but the ergonomics are not so far vintage that you feel like you're on something from the early 70's.

You work the controls a bit to get a acquainted with their positions. The bar is nice and flat (it's actually an aftermarket bar) with a very comfortable reach that doesn't feel anything out of the ordinary. The Magura throttle system is quite heavy in feel with strong return spring pressure. Magazine editors back in the day had complains that it and the front brake lever required too much muscle to operate and could cause fatigue after a while. The clutch lever on the other hand (literally) is light. You then attempt to work the rear brake but you find that your boot rolls off the peg instead as if the brake lever isn't even there. What? The rear brake lever is somewhat oddly mounted inboard with the bike so you have to actually position your boot up and to the left in order to fully activate it smoothly. It's not mounted directly in front of the peg like most bikes so you realize you better work it several times to become comfortable with its orientation.

Starting it
This is where it gets fun. Kicking this thing over is downright scary; plain and simple. The good news is that it does seem to want to start (some bikes just plain don't and will fight you until the end) but it seems to actually be working on your side to do so which is good. If the bike is dead cold, lean it all the way over to its side for a couple seconds until fuel drips out the bottom of the carb. The original Bing carb that had a tickler was replaced with a Keihin PWK flatside so this procedure is the alternative to priming the cylinder. You can either use your left leg, unnaturally, to kick while on the seat, or, kick it with your right leg standing off the bike which I've found is most comfortable. Whatever nonconformist style you chose produces a low and fierce sounding "glug glug" as you turn it over that growls through the exhaust like the echoes the clown in the movie "IT" makes in the sewer pipes. Stories you read of folks having their calves shattered in half or legs broken quickly dance in your mind. You ask yourself "what if" and question if the risk is worth the reward. You press on the lever about 1/4 of the revolution down just until it goes over compression. The feeling is like the kick starter all of a sudden engages what feels like a stuck rock that simply won't budge any further. I use the analogy of a rock because that's exactly what it feels like once the lever comes into compression. When you kick over a big 4 stroke and you reach compression stroke, it will still often feel somewhat "rubbery" with a tiny bit of give at that point. This... notta. Nothing. Zilch. The motor might as well be locked up solid. Even when you put your entire body weight onto the lever it still will not even budge a millimeter or give you any indication that it will. At this point you say a prayer, and jump on it as if your life depended on it with the hope that the lever doesn't spring back up with enough force that could land you on the moon. If your best Hulk impression still did not move the lever one or both of two things will have happened; you either put a nice gouge in the tread of your boot and/or the bike almost fell over.

If you think bump starting this thing is a second option, think again. I initially tried this but unless you are a heavy weight, it wants lock up the tire when you let the clutch out... even in 5th gear.

If you were successful with the kicker, the lever will have gone half way down its revolution and your ears all of a sudden begin bleeding with a very rewarding joy. I felt like I had just won a gold in the national Olympics when I fired it for the first time. The sound of it is VERY loud. POP POP POP, BANG BANG BANG, CRACKLE CRACKLE CRACKLE. You almost need ear protection standing next to it when it idles it is that loud.

What is it like to ride?
To be honest, I had naively been wondering just how "powerful" it was going to feel next to modern day machines and thus preparing myself that it may not be just exactly what I had been envisioning. I was just going to enjoy for what it is. Boy, could I have ever been more wrong.






I don't think I could ever post enough of those "yikes" smilies to justify this bike. It is hands down the SCARIEST bike I have EVER ridden in my entire life. I used to review motorcycles for a part time job and have ridden varieties from all over the spectrum. Forget 1000cc+ liter bikes in terms of ferocity. The acceleration this thing has is pure insanity to the tenth degree. Violent. Pure i-n-s-a-n-i-t-y. I was shaking after my first ride on it as if I had just gotten out of a cold shower. I have not even gotten past a 1/4 throttle yet as the bike just wants to explode out from under you. I'd describe it like a stick of dynamite. Again, pure insanity. Insanity! You almost ride the clutch on this thing more than you're on the throttle. As you give it a hair of throttle input it takes off like you're going down a roller coaster. Basically if you give it any throttle it says "oh, you want a piece of me?" You let off the throttle but then you don't slow down at all because it has hardly any engine braking. You reach for the brakes and while the front works, you totally miss the rear because of the awkward positioning that you still haven't mastered yet. You've got a lot other things on your mind at the moment so you can forgive yourself for that.

As you're riding, you quickly begin to notice the heat from the expansion chamber on the left side begin getting hot so you have to swing your leg out to not burn yourself. It's hot, there's no heat shield, and it's easy to bump your leg on it which I seemed to repeatedly do. Eventually I'll get the picture. Surprisingly it is smooth in the low end, then as the revs build the vibes begin to come. Unlike some of the other 500 open classers of the time, this one came with a heavy flywheel which helps mask vibrations.

I go back to the noise because it is a lot louder than I expected it to be. The exhaust has a factory spark arrestor so it's not like it's running an open pipe either. I was even a little concerned this thing might sound a little too plugged up and already considering options of having a custom muffler made. Turns out you need ear plugs to ride it as the "BANG BANG BANG" makes you think there's bottle rockets going off inside your helmet. When it idles it's nearly as loud as a 4 stroke single that is running straight out of the manifold with no exhaust system. It's ridiculous, every part of it!

It is by far the most absurd and scariest machine I have ever experienced in my life. I can only wonder what the heck would happen if you were to fully open the throttle. The bike would probably shoot out from under you doing a zillion backwards somersaults until it eventually crashed into some trees in the next state. I now understand why these are called "widowmakers."

Now for the real question. Will I be able to start it again?
 
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21
#3 ·
Re: The widow maker has arrived

WOW!!

Thanks for that wonderful writeup.
Love the descriptions! Very vivid.
I almost feel like I was riding it!

That reminded me of my first trip on a 2 stroke...
I took my friends modified RZ400 for a quick trip on the highway...
Heading into a ramp I let off the throttle expecting some engine braking, but nothing!!
Hit the brakes and remembered that he told me the rear wasn't hooked up!!:eek:
Made it out ok with the front brakes and some quick downshifting, but what a ride!!

But back to your KTM...

WOW!!

( I was REALLY scared of the clown from "IT" as a child. Matter of fact I still am. Now I'm scared of your bike too. )
 
#4 ·
Re: The widow maker has arrived

Very nice review of the new toy, Austen. Do you still plan to register it for the street?

It sure is is nice condition for it's age, hope you can learn to enjoy it!
 
#7 ·
Re: The widow maker has arrived

nice looking bike, but it is too clean... had an xr 250 was a blast to ride... nice duc too but most of all cool tractor...ride safe.. c falcon
Thanks! I'll bet you have some great memories on that XR.

WOW!!

Thanks for that wonderful writeup.
Love the descriptions! Very vivid.
I almost feel like I was riding it!

That reminded me of my first trip on a 2 stroke...
I took my friends modified RZ400 for a quick trip on the highway...
Heading into a ramp I let off the throttle expecting some engine braking, but nothing!!
Hit the brakes and remembered that he told me the rear wasn't hooked up!!
Made it out ok with the front brakes and some quick downshifting, but what a ride!!

But back to your KTM...

WOW!!

( I was REALLY scared of the clown from "IT" as a child. Matter of fact I still am. Now I'm scared of your bike too. )
Glad you could get a little sense of what it's like to operate!

It sounds like you know from firsthand experience what big bore 2 stroke engine braking is... none! Thanks for sharing that experience, I'll bet it got your adrenaline going for sure. I can only imagine the heart dropping feeling when you reached for the brake and it wasn't there!

Ha ha, I was definitely the same way about the clown. I usually had to pull the covers over my eyes during his parts in the movie.

Very nice review of the new toy, Austen. Do you still plan to register it for the street?

It sure is is nice condition for it's age, hope you can learn to enjoy it!
Thanks Mike! I'd like to eventually make it legal for times when you need to hit some blacktop in between trail heads. I'm honestly not sure how well it do riding in city traffic due to the character of the engine performance but out in the open would be alright. I'm currently exploring ideas for a headlight and taillight that would look acceptable.

Had a short ride on an Egli street bike in Germany and that ride came back to me as I was reading this! Nice bike hope you get a handle on it so it doesn't stay scary (although that's part of the fun).
I'll bet that was a memorable ride!

It is definitely part of the fun. I'm looking forward to getting it out into its element in the mountains this spring and summer when we get dry weather again to become accustomed to it.

Great write-up. I read your initial thread of the KTM and the Factory sent out a Tech Service Bulletin Warning of just how to start it, You know if it's that dangerous to start it's got to be fun!!
No kidding! It certainly adds to the experience and makes it even more thrilling.
 
#8 ·
Re: The widow maker has arrived

Man, what a great thread to read on a frigid January evening!

The Yamaha RZ400 was a twin, Austen. I don't know much about them but my buddy loved em.
That was the first and last time I rode that thing.
The biggest single 2 stroke I've been on is a 125.
Never been on a BIG bore, I can only imagine...

I had a 400cc single snowmobile engine on a gokart I built long ago, and let me tell you, THAT was scary! (mostly because I built the gokart)
That was the first 2 stroke that really put the fear in me and most likely the reason I went for 4 strokes when I got into dirtbikes.

The engine had been sitting a while before I got it. Brought it to shop class at high school where I was building the gokart.
First time I went to start it up it ran wide open with no throttle control.
Pulled the plug wire off and it wouldn't stop!!:eek:
Gokart was shaking so hard the tack welds were breaking and parts were banging all over the floor.
Sounded like the world was ending.
Half the class cleared out and half the class came over to see what was happening (general level shop class, remember)
Finally died when we pulled the fuel line.
Teacher said the crankseals were leaking and it was firing off compression.
That was the lesson of the day!


But now, the only real bike I own is a 2 stroke. (hope you don't mind me adding a link to my bike thread)

http://www.mytractorforum.com/113-motorcycles/819338-not-tractor-but-has-lo-range.html

:fing32:
 
#9 ·
Re: The widow maker has arrived

Man, what a great thread to read on a frigid January evening!

The Yamaha RZ400 was a twin, Austen. I don't know much about them but my buddy loved em.
That was the first and last time I rode that thing.
The biggest single 2 stroke I've been on is a 125.
Never been on a BIG bore, I can only imagine...

I had a 400cc single snowmobile engine on a gokart I built long ago, and let me tell you, THAT was scary! (mostly because I built the gokart)
That was the first 2 stroke that really put the fear in me and most likely the reason I went for 4 strokes when I got into dirtbikes.

The engine had been sitting a while before I got it. Brought it to shop class at high school where I was building the gokart.
First time I went to start it up it ran wide open with no throttle control.
Pulled the plug wire off and it wouldn't stop!!:eek:
Gokart was shaking so hard the tack welds were breaking and parts were banging all over the floor.
Sounded like the world was ending.
Half the class cleared out and half the class came over to see what was happening (general level shop class, remember)
Finally died when we pulled the fuel line.
Teacher said the crankseals were leaking and it was firing off compression.
That was the lesson of the day!


But now, the only real bike I own is a 2 stroke. (hope you don't mind me adding a link to my bike thread)

http://www.mytractorforum.com/113-motorcycles/819338-not-tractor-but-has-lo-range.html

:fing32:
:)

I agree!

What a terrifying story about the go kart project! :eek: I'll bet the world DID sound like it was ending!! Blown cranks seals and running off compression, wow... almost the same thing as a diesel running away. I'll bet you were concerned the engine might explode without any control of the throttle!

I'm like you and mainly have experience with 4 strokes when it comes to motorcycles. My family really never had any 2 strokes bikes, they were all 4. After owning this it kind of makes me wish I had ridden more of them earlier in my life. I think growing up during our father/son trail riding days my dad just thought 2 strokes were too impractical.
 
#13 ·
Re: The widow maker has arrived

Gotta say.......it even looks vicious! Enjoy it and thanks for the write up, Austen.

Oh, and from one "toy" guy to another, you're building quite the arsenal for a man your age. My compliments :fing32:
 
#15 ·
Re: The widow maker has arrived

Nice!! You gotta give it to the guys that rode these things all out in the day!!!
No kidding!!

Awesome old Dirt bike.

I miss my CR250.

Good Luck and safe riding.

MU
Thanks! I'll bet the CR was fun.

I was concerned for the engine, but more so for my life!
I'll bet!!

That was the first time I heard the term "dieseling" which is how the teacher explained it.
That was certainly a great example of it.

Gotta say.......it even looks vicious! Enjoy it and thanks for the write up, Austen.

Oh, and from one "toy" guy to another, you're building quite the arsenal for a man your age. My compliments
Thanks Ellis! I have a problem falling in love with this kind of thing.

You know, hearing that review it reminds me of the guys talking about the old TZ750 from the 70's, and the late 80's 500cc GP bikes. Just WAY over the top HP, that gave rideablity a razor sharp edge that only the best of the best could hope to master! Be safe and learn your limits!
You certainly would need to be pretty fearless to race one of these things. If they are still powerful in a high HP day and age as we are currently, I can't imagine how they felt back then when they were new.

Thanks!
 
#16 ·
Re: The widow maker has arrived

Those big bore 2 stroke singles are a handful, once the revs come up the rider best be hanging on. I started out wrenching in a Suzuki shop, I remember scaring myself silly on a modified RM400. That thing was far more than I could handle.
 
#17 ·
Re: The widow maker has arrived

Nice looking machine you got there. I can imagine the ride. Had a Honda CR480R back in the day. PURE BRUTE POWER. Bike would just stand straight up in any gear at the first crack of the throttle. 1st day on it ended with a week long hospital stay. Did get back on her though. Nowadays it's just my H.D. bagger.
 
#18 ·
Re: The widow maker has arrived

Those big bore 2 stroke singles are a handful, once the revs come up the rider best be hanging on. I started out wrenching in a Suzuki shop, I remember scaring myself silly on a modified RM400. That thing was far more than I could handle.
You're so right! It sounds like the RM left an impression!

Nice looking machine you got there. I can imagine the ride. Had a Honda CR480R back in the day. PURE BRUTE POWER. Bike would just stand straight up in any gear at the first crack of the throttle. 1st day on it ended with a week long hospital stay. Did get back on her though. Nowadays it's just my H.D. bagger.
Thanks!

Ohh, a 480, the precursor to the CR500. I'll bet that was an exciting bike. I'm sure another one will land in the stable at some point and a vintage Honda like yours might be the one. :fing32:

There's nothing like the instant power of a big bore 2 stroke.
 
#19 ·
Re: The widow maker has arrived

You're so right! It sounds like the RM left an impression!



Thanks!

Ohh, a 480, the precursor to the CR500. I'll bet that was an exciting bike. I'm sure another one will land in the stable at some point and a vintage Honda like yours might be the one. :fing32:

There's nothing like the instant power of a big bore 2 stroke.
For the time it was the "big dog". Didn't have the power band of the smaller 125's and 250's of the day. The 480 was just all power. I was talking with the owner of a KTM last week. He told me it was a 450 as I was looking at it. I know KTM makes a serious dirt bike. He described the ride as "insane". I'll take his word on that. I would like to jump on one, but at my age now I don't think it would be a wise choice. (still want too!)
 
#20 ·
Re: The widow maker has arrived

Back in the day.... I spent some time with a 505 Maco... And a Husqvarna 450 WR...

Between them, a 1967 Harley Sportster, and a few other wrecked cars, trucks, airplanes, one each gun shot and stabbing... That is why I have limped like this for so long...

That's all I'm going to say about that...
Keep safe... Enjoy...
 
#21 ·
Re: The widow maker has arrived

It's too bad that 'modern' bikes' motors were biased so much to pro-level MX. I worked at a Maico dealer back in the mid 70's and the 400 and 450 Maicos were both tractable and powerful. Plenty of smooth low end grunt and the more you turned the throttle the more you got.
 
#22 · (Edited)
Re: The widowmaker has arrived

Boy, I've caught this "vintage" open class 2 stroke bug hard. It's a totally different breed of bike that I've never owned or experienced before. I think back to riding bikes like modified CBR1000RRs that were complete monsters to ride on the street, 190HP Ducatis, and this is just a whole different level of scary excitement that no kind of bike can offer. I'd love to see it find a CR500 garage partner. I guess there was a reason why a lot of times the teams had to literally help the riders off their bike after race due to complete fatigue.

In proper gearhead fashion, a new set of motorized wheels doesn't remain in its current state as he bought it for long, whether that be dramatic or subtle, after the papers are signed.

There were a few "pressing things" that I wanted to do to get the bike fully ready before I really took it out this summer in the mountains. I've listed them below.

Boysen Rad Valve


vs



The original reed cage was beginning to develop cracks in the rubber intake track. Boyesen fortunately offers one of their rad valves for this motor which has an aluminum track that eliminates the issue of cracking. Reason enough to justify the "need" over "want" for one of these. The Boysen Rad Valve is a dual stage reed valve system, a design Boyesen apparently discovered several decades ago. A stock single stage reed valve system works similar to a powerband in that it works most effectively at a certain RPM range. The dual stage design solves this by incorporating two different style valves with different tensions that react effectively at separate RPM ranges. The carbon reeds (low tension) are lighter and open in the lower rev range and as you increase the throttle, the larger and more heavier (high tension) fiberglass reeds (yellow portion in the photo) open up at higher RPMs. The design is supposed to offer better throttle response and smoother power delivery.

Additionally, the Rad Valve straightens out the angle of airflow from the carb to the reed valve which helps reduce turbulence by smoothing out the airflow which provides a more constant velocity. With the development of the mono-shock, the carburetor was now required to be offset to one side so it no longer had a straight airlow track from the carb to the reeds resulting in the air flow having to change directions.

Differences?

After putting it back together, I was able to get it started on the second kick which was a pretty cool feeling. The carbon fiber reeds are definitely more responsive right off the bat. I could notice it when as soon as I twisted the throttle in neutral by how quickly it revved compared to before. These vintage big bore KTMs have a heavier flywheel and it seems to have made it respond a lot quicker as if it had a lighter weight flywheel. In terms of overall power, it seems the same. I guess the only other thing is that it may have smoothed out the powerband a little bit down low.

Airbox to carburetor boot



vs.






The PO who definitely performed a lot of good in bringing this bike back to life such as installing an upgraded Keihin carburetor also took a few shortcuts along the way I've discovered. An example of this is in the custom airbox- to-carburetor boot that had to be made to accept a CR500 Keihin carb. The problem was that he used an automotive tire inner tube which wasn't holding up well to the heat of the motor. I ended up replacing it with an automotive silicone hose reducer and trimmed it length. It should be a permanent solution.

The other notable shortcut was that he seemed to have a love affair with gasketmaker instead of ordering the correct gaskets (many of which are still available) from a company overseas. I'm slowly addressing this as I go along.

New front tire & wheel bearings

The original front tire was dry rotted and needed to be replaced. While the wheel was off, I replaced the front wheel bearings as one of the outer was dry and becoming to fall apart. One thing always turns into another!

Odometer:



I wanted a way to track mileage without always having to stop and pull my phone out while on the trail. An odometer was an optional feature on these bikes but not already outfitted on this one. A period correct look is what I was after over the practicality of a modern computer like a Trailtech so I did a little research and happened to find a complete used take off odometer system from an '85 MXC500 on Ebay. The issue was that the meter itself read kilometers instead of miles so I ordered a new, OEM, meter that reads mileage instead. Again, I know this is a very old school system instead of running a small computer that has a lot more features but I wanted the period correct look and want to keep things really simple on this bike.

Also, I've decided for now anyway that I'm not going to make it street legal. I really like the vintage styling and don't like the idea of mucking it up with a headlight, taillight, probably signals, and having to run a computer system with wiring to run the electronics. I may feel differently in the future but I don't picture myself riding this psychopath on the street anytime soon.

An extra touch to the right side panel

Can you spot it?

I think I've mentioned before that a certain recall was performed to eliminate the issue of deadly 18:1 compression kick backs that would more importantly break the starting mech due to timing advancing too far on start up. When the timing advances too high, the engine tries to run in reverse and can if it starts. I've read of one case where this happened and the rider got a chest full of handlebar when the bike unexpectedly went in reverse when he tried to get the holeshot! Note to self; let the clutch out slowly after starting to confirm engine is running in the correct direction.

What's next?

Not too much. After said work I told myself it's just about done. I will have to replace the front number plate with a reproduction because the top mount can no longer be used with the odometer meter and more importantly, it's missing the top straps that wrap around the bar. Right now the top is just secured be a zip tie. I may replace all the plastic with reproduction and put a green number instead of blue like pictured below but we'll see. I'll have a new expansion chamber made sometime in the future.


 
#23 ·
Re: The widowmaker has arrived

Looks really nice Austen. :thThumbsU
Makes me want to get my bike out.
The shed where it rests is still entombed in ice at the moment, but temps are rising...

Is the "extra touch to the side panel" the 3 holes? :dunno:

What's the story there?
I read your entire post, did I miss something, did you explain it?
 
#24 ·
Re: The widowmaker has arrived

Is the "extra touch to the side panel" the 3 holes?

What's the story there?
I read your entire post, did I miss something, did you explain it?
Yesterday 06:25 PM
Thanks,

Yeah, somehow it seemed like it was missing something there and I had this vision in my head. :rolleyes:

Makes me want to get my bike out.
The shed where it rests is still entombed in ice at the moment, but temps are rising...
Good stuff! We're certainly on the downhill stretch now.

Be sure to post some pics once you get her out again. :fing32:
 
#26 ·
Re: The widowmaker has arrived

The bike looks great Austen, I like the new intake and reed valve assemblies. You won't have to deal with that issue again. Nice Odometer as well, OEM is very cool and doesn't look out of place on the bars. Good stuff, enjoy the ride...................and hang on! :D
 
#28 ·
Re: The widowmaker has arrived

Nice fixes. That Reed block should help broaden the powerband at least a little... Maybe 200rpms instead on 100. MAN I love 2 strokes!!!!!
Haha,

I agree. This is kind of a cool documentary of a 1980s dezert race for open class 2 strokes that you might enjoy as well. https://youtu.be/HzyQrNU4d0o?list=LL43sSeLRXDvV0z58NeDJGzA

The bike looks great Austen, I like the new intake and reed valve assemblies. You won't have to deal with that issue again. Nice Odometer as well, OEM is very cool and doesn't look out of place on the bars. Good stuff, enjoy the ride...................and hang on!
Thanks Mike. Glad you can appreciate it.

Now you need to find some vintage clothing to wear when you ride it so you look like old Heinz, there.
Funny you mentioned that as I've kind of thought the same thing. They wore some interesting masks back then around their faces. It's kind of hard to justify it as protection has advanced so far since then but it would certainly provide the right feel for the bike. :fing32:

Thanks guys.
 
#29 · (Edited)
Re: Adventures with a 1986 KTM MX 500 Widowmaker

Better get your popcorn out because this installment is two parts in one. The first part consists of a series of more updates to the bike and secondly my first real exploration into the mountains with it.

Recently I took it out on a maiden voyage on some local trails with a co-worker who also rides. It was a good shakedown test to see if there was anything that I wanted to change before I took it on a trip. After the ride, I noticed that a couple of seals had blown where Permatex had been used so I placed an order with "Enduro Klassiker" in Austria that specializes in parts for vintage bikes like this and got an assortment of new gaskets where suspected gasket maker.

1. A nice trickle of smoke was puffing out from where the expansion chamber meets the head and sure enough the gasket maker had failed and blown out. The design of how the expansion chamber attaches to flange is not very good. It made sound weird, but using stretch and seal plumbing tape is what other owners swear by to use to solve the issue so that is what I did. No more leak.

2. Secondly, and more disturbing, I noticed some very small droplets of coolant starting to ooze out from the head "gasket." After I removed the head I found quite a few droplets of coolant scattered inside the cylinder as you can see in the photo below. It must have been losing a fair amount of compression here combined with the air leak in the exhaust; I'm surprised that it ran as well as it did. It most likely was burning some white steam mixed in with the smoke of the exhaust that I didn't notice. In any case, it turns out the head gaskets for these are made out of some extremely thin material, it is basically thinner than a piece of copy paper. This is why I it was tough to identify what was or wasn't in there before other than Permatex. I actually broke the one I bought when I was installing it so I said "forget it" and made my own new head gasket out of some very slightly thicker gasket paper.



3. Something else I came across which I thought was noteworthy. When I ordered all my gaskets for a '1986 KTM 500' the water pump gasket in particular, which I indeed verified is for a 1986, does not fit. After looking at some microfiches I discovered the left side engine/clutch/water pump cover is on my bike is off a later 1988-1996 500/550. I had to re-order a later style gasket so that it would fit. At some point early on in the bike's life, I imagine, the cover was swapped out for a later style. The original may have suffered bad cavitation early on and had to be replaced. When I opened it up, I did find some cavitation inside the waterpump so I did what was recommended to me on the KTM forum and filled it with a coating of JB Weld. The Evans Coolant prevents corrosion but I didn't want to leave the existing cavitation exposed. Someday when replacement covers are available I'll replace it with an aluminum version.

4. While the bike was torn down for a while I decided to change the graphics to green as seen in the photos below. I also purchased new OEM style Acerbis plastics from Andre (Enduor Klassiker) as well. I'll store the original plastics with the blue decals in case I ever want to go back to them but for now I really like the green.






5. I also found a good used four pot rear brake caliper on Ebay from a later year KTM that will swap over. I plan to also install a more modern front master cylinder to provide increased braking power and will do that all at once sometime.


6. I also installed a new front fender brace support which was an option for these bikes originally. I think it adds another little bit of retro bling.


I had modify it slightly to fit.



7. During the same time period in the 80s, some of the smaller CC KTM dirt bikes came with these cool, stylish, magnesium ignition covers. I found one on Ebay and took my chances with it in terms of fitment, however, it seems to have disappeared in the garage!! I don't know where it went and still can't find it.... sooo odd to lose something like this. Anyway, when I actually did have it in my hands I discovered that it has a slightly different mounting bolt pattern than a 500's (of course) which is kind of a shame. It would actually mount if you were to flip it upside down however but that wouldn't look right. Really the only way that I can see to make it work would be to cut the center out of the original cover which would leave you with a mounting ring that you could then glue onto the mounting surface of this cover. Voila. I would also shave off the mounting tabs on this cover if I did go that route. Might give it a try in the future if I'm feeling ambitious. If you have any other ideas in terms of how it make it work before it's too late, let me know!


 
#30 · (Edited)
Re: Adventures with a 1986 KTM MX 500 Widowmaker

2nd part, The Trip!

Let's see if it all paid off.

In this part I thought it would be fun to sort of document the trip in sort of an ADV Rider style. It gets a little annoying stopping all the time, taking off my backpack to get the camera out so I didn't take a zillion photos but you'll get the idea.

Logistics
I realize most are not located on the west coast so this won't mean much, but the plan was to go riding where my dad and I have gone trail riding a lot back in the day near Lake Chelan. More specifically, over Cooper Mountain. It's about 4-1/2 hour drive from home. I was going to camp where we usually did too.


The plan was to drive to the camp site and stage there. It turns out our old super secretive camp site is now tent city. Definitely un-appealing in many regards. So, I decided I'd find another spot to camp while exploring on the bike so I staged temporarily elsewhere for the interim.


It didn't take long to realize that something had to be done to the tire pressure as traction was just not there, at all. This bike is like riding something that's on nitrous and has 1000HP underneath you. Giving it 1/4 throttle has the same effect as cracking the throttle wide open on a 'normal' bike only without having any lag, RPM build, up whatsoever. The power is just there instantly at any given point. I sound like a broken record here, but you really do almost ride this bike more off the gas than you do on the gas. Anytime you're on the gas you're basically in a full on drift, back tire squirling side-to-side while you're trying to counter steer the heck out of it. I ended up lowering the tire pressures down to single digits where the tires where almost spongy-balloon like; thank God for rim locks. It helped maybe 15-20%.




There were a few of these trails we used to ride that were now either overgrown or had a lot of downed trees. I had already crossed three smaller ones before I had gotten to this point and decided to turn around. The trail was increasingly getting narrower and narrower and I didn't feel like putting a ton of new pinstripes on the plastics and number plates.


This is more like it.



This is what I call the "burnt forest." It was quite an interesting sight. All of a sudden you just enter it. There was another person there taking photos too when I was passing through.







The 'look out.' I had officially made it to Cooper mountain at this point. It was only 13 miles on the odometer but figured it'd be a good time to do a fuel check. I was almost dismayed to see that I was nearly at half a tank already! WHAT!?? If I had been on any of my former 4 stroke dual sports at I would have still had a full tank at this point.

I had a realization that because of the level of performance this thing pumps out, it's really not hard to understand why it goes through fuel so fast and I shouldn't complain about it either. You can't get both. This thing is not a dual sport, but that's not what I was hoping or wanting it to be either. I had kind of always thought it was my imagination when I'd notice a change in the fuel level after a short time running it a bit at home. I wasn't- it just goes through fuel that fast. These bikes came with an even small tank designed for MX tracks. This one has the large 3.1 but still has a limited range. I estimated it gets between 13-15 MPG.


I was feeling hungry and this seemed like a nice spot to stop. It is sure different that riding a four stroke going down hill because there's zero engine braking. I don't like coasting for long distances on 2 strokes without applying any throttle so it was a balance between using lots of brake input with little inputs of the throttle periodically at the same time.


Obligatory food pic.



Some pretty wildflowers.


Helmet hair! Helmet hair!! Nobody gets worse helmet hair then I do. If there was a product that lessened it, I would be the first in line.


Lake Chelan in the distance. The next goal was to find a new camping spot.


I eventually found a good camping spot so I decided to head down into Chelan to the "Lakeview Drive-in" to grab a burger for dinner. It was like spring break in Cancun, the beaches were filled college kids.


Time to head back into the mountains to setup camp. The new camp site was several miles further up a narrow and rough road where I had to go slow with the trailer.




The camp site.


Watched the sun go down.


And watched a movie before bed, haha.

I Didn't encounter any wildlife. There was a noisy owl that I heard at night and there was wind that came through the trees that made a lot of noise. The spookiest part were three different cars that drove past at odd hours of the night. As my dad has always said, you sometimes have to watch out for the people you come across more when you're out here vs. the wildlife.


The next morning I went for a short ride before I packed up and left. I found another trail I had never been on before and this one offered some long stretches that I could open it up a little.

Overall, a great trip! I have another one planned with my dad in Oregon in September. I'm sure in the meantime I'll post some more updates to the bike and maybe another ride report if I do another weekend trip with it.
 
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