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post #46 of 56 Old 03-22-2015, 09:54 PM Thread Starter
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Re: The Mikuni to $14 Honda Carb Swap

Sorry to hear you haven't gotten the swap working.

Make very sure the throttle linkages are not binding, I do recall a few opportunities for this. When running--Try moving the throttle lever on the governor manually and make sure the governor fights you, not the carb.

It looks like I used the 'far' hole on the carbs throttle.

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post #47 of 56 Old 03-23-2015, 09:21 AM
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Re: The Mikuni to $14 Honda Carb Swap

Quote:
Originally Posted by atomix View Post
Sorry to hear you haven't gotten the swap working.

Make very sure the throttle linkages are not binding, I do recall a few opportunities for this. When running--Try moving the throttle lever on the governor manually and make sure the governor fights you, not the carb.

It looks like I used the 'far' hole on the carbs throttle.
Thanks, I used the "inner" hole, that's probably (hopefully) the problem. It makes sense. I'll try and move it this evening. The linkage doesn't appear to be binding. When the engine is running I tried to move the governor arm as far clockwise as possible. The engine did throttle down when I moved the arm but it was still running at high revs. I'm just not in the mood to split the case again. It's still going to be a small PITA to remove the tank, recoil, muffler, shroud and still have to fiddle fart with the carb, linkages and springs.

Thanks for your interest - Mark
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post #48 of 56 Old 03-23-2015, 10:50 AM Thread Starter
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Re: The Mikuni to $14 Honda Carb Swap

I don't blame you for not wanting to split the case, I've done a rebuild on one of these Suzukis.

If you still had high revs with the governor all the way to the right (clockwise,) then it sounds like the carb is still giving you too much fuel! I remember screwing around with the idle adjustment too...but I thought I raised the idle...maybe I lowered it. Turn that screw out!

Of course, if the governor was working correctly, it sounds like it should have been all the way to the right already.

Also, check for air leaks (spray carb cleaner), my Mikuni would make this guy SCREAM once it was all heated up and the governor couldn't seem to throttle it down.

Several LawnBoys, 1D, 1E, 2F's
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Snapper Wisconsin Robin
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post #49 of 56 Old 03-23-2015, 08:49 PM
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Re: The Mikuni to $14 Honda Carb Swap

Okay, I found one of the problems. I got a new governor shaft and seal since I am almost positive that I had air leaking between the shaft and seal so I installed a new shaft and seal. I didn't realize that the new governor shaft was slightly smaller than the old governor arm, so the shaft slipped on the arm. Not matter how much I tightened the nut on the arm it would not hold tight. That explains the very high rev problem.

So I opened up the bottom part of the governor arm and ground a little of the surfaces away (to allow me to torque down on the governor more and "clinch" the shaft to the arm).

That kept the RPMs way down (and I know that the governor dogs are working okay). But the problem I am having now is that the engine seems to be running lean, (hunting for a good idle speed symptom) and only runs when choked (fully to partially). I checked with starter fluid spray to make sure that I don't have any other air leaks and everything seems okay.

Do you think that I should remove the plastic limiter on the carb to make the AF ratio more rich?

Also, what purpose does that small spring on the governor to throttle linkage do? It's a small PITA to get the linkage and spring in one hole.

Again, thanks for the assistance.

Mark

Last edited by KidSheleen; 03-23-2015 at 09:29 PM.
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post #50 of 56 Old 03-24-2015, 08:58 AM Thread Starter
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Re: The Mikuni to $14 Honda Carb Swap

I keep the spring in there, I think it helps overall governor speed and reaction.

Your symptoms sound like mine early on in this thread. Did you drill a hole in the airbox & gasket to align with the Honda carb's idle circuit? You shouldn't have to richen up the idle mixture.

Sounds like you're doing a great job on the rebuild!

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Snapper Wisconsin Robin
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post #51 of 56 Old 03-24-2015, 09:47 AM
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Re: The Mikuni to $14 Honda Carb Swap

Yes, I did drill out a hole on the air box and metal plate. however, I ran the engine without the air box. I just put the two nuts on to hold the carb tight against the crankcase.

Hmmmm....

I'll put the airbox on and check for air leaks this afternoon.

Thanks
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post #52 of 56 Old 03-24-2015, 11:59 PM
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Re: The Mikuni to $14 Honda Carb Swap

All I did today was to move the carb - governor linkage to the outer hole and remove the A/F stop and move it 1/2 turn to rich. The engine again ran at high revs.

When I manually moved the governor linkage by hand the engine behaved like it should.

I'll split the crankcase apart since I don't think that I have the dogs and/or the governor pin in correctly.

Stay tuned if you are interested.
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post #53 of 56 Old 03-28-2015, 06:02 PM
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Re: The Mikuni to $14 Honda Carb Swap

I split the case and everything seemed okay.

I finally got the engine to work as expected. I used the inner hole on the carburetor throttle linkage and the upper hole on the governor arm shaft for the governor spring. I also had to remove the mixture screw tab and turn the mixture to about one (1) turn rich (counter clock wise) to keep the engine from hunting due to a probably too lean mixture.

This application is a little different from a normal mower application. I am trying to use the engine for a GenSet (alternator - inverter) system to charge some 12V deep cycle batteries (to cover our frequent power outage situations).

I still need to put a cast iron flywheel on the crankshaft to make it easier to start (without extreme whiplash and screwing up the recoil mechanism (which I have done)) and maintain torque but that should not be a problem (hopefully, except for figuring out electrical wiring going from a three foot inductor coil to a 2 foot inductor coil).

Again, thanks for your help and assistance.

Mark

Last edited by KidSheleen; 03-28-2015 at 06:10 PM.
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post #54 of 56 Old 03-29-2015, 07:29 AM Thread Starter
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Re: The Mikuni to $14 Honda Carb Swap

Mark, great to hear you have it running. Sorry to hear you had to split the case again. Good to know for others that the mixture may need to be richened, but surprising given my experience.

Then again, if you're running with very light rotating mass, the governor may have a hard time keeping up and compensating.

Cool application, good luck! Do you have any pictures of that project ?

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2 Toro/Suzuki 2 strokes
Snapper Wisconsin Robin
A few others...
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post #55 of 56 Old 03-29-2015, 10:58 AM
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Re: The Mikuni to $14 Honda Carb Swap

Again, thanks for your help.

As of now, I don't have any photos. But I just ordered a cast iron flywheel and ignition coil from a CCR 2000 snow thrower, so when I cobble this together I'll take some photos as I go along. I also purchased a Mega Fire Ii Ignition Module just in case I need it. Hopefully my three legged ignition coil will work with the cast iron flywheel, but I kind of doubt it.

I got the idea for a genset from The Epicenter Convert a Lawn Mower into a Generator. I purchased the steel mounting bracket plate that they have which holds the engine and alternator. I had a "prototype" running earlier but I could never get the Mikuni to work well, so that's why I looked at the Honda swap.

The other problems I had were: I had a too large pulley on the Suzuki. Under a high amp load the engine really, really struggled so I had to go with a much smaller pulley on the Suzuki. Also, once the alternator gets up to the correct RPMs, it would short on the steel plate and cause the Suzuki to ground out. I tried to insulate the alternator from the steel plate with nylon washers but that was a fail. I just simply removed the kill wire from the throttle linkage. I'll put a small single throw switch on the kill wire so I can still stop the engine when I want to.

I'll be out of town for a week or so but I'll start taking photos and maybe put enough effort for a new thread on this subject when I get back and switch the flywheel (and other stuff).

Mark
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post #56 of 56 Old 04-11-2015, 09:10 PM
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Re: The Mikuni to $14 Honda Carb Swap

Well...

I put on the flywheel from the CCR-2000 snowthrower (non electric start) and I didn't get a spark. The CCR-2000 flywheel has only one magnet where the OEM mower aluminum flywheel has two magnets. So I removed the three legged ignition coil and put on the two legged coil that I got with the flywheel. I also installed the Mega Spark II ignition module (whatever ?) (negative ground). When I spun the flywheel (and engine) I got a nice thick blue spark.

I put all of the blower housing, fuel tank and etc. parts back on (again) and gave it a crank. It started on the third pull (alibi: I did use about a 1/2 second of starting spray). First, the mass from the cast iron flywheel made a HUGE difference, not only when running but when pulling the recoil. No more fighting back and a nice smooth pull.

I'm still running a little rich. I was getting some exhaust smoke (even using Stihl Ultra) and when I was done for the day the spark plug looked between charcoal and tan. I turned the mixture screw in about another 1/2 turn and tried to start the engine. Then... the recoil rope broke. I should have known better and replaced the recoil rope when I had everything apart. But, getting the spring tension on the recoil rope correct does take a little effort and time. I'll work on the recoil tomorrow.

As I promised before, I'll start a thread for my genset / inverter. It has been quite a challenge but I have learned a lot from this experience.

Thanks for your assistance,

- Mark

Last edited by KidSheleen; 04-11-2015 at 09:50 PM.
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