[kyavion]

Today I was able to successfully remove all 12 head bolts from my C-8. I’ve been spraying them with a little PB Blaster from time to time, and decided to attempt removal today. I started by attempting to tighten each one just a touch, and then loosen each one just a touch before tightening again. After that, all the bolts unthreaded easily.

Before replacing the gasket, any recommendations besides cleaning up the cylinder head? Also, what is the best way to clean up the head? How about the piston and valve heads?

 

[charles g]

easiest is a block of 2x4 wood warped with Emery cloth or 320 and finer sandpaper, hope your going to take a closer look at that bore scoreing?

 

[kyavion]

What would you recommend doing with the scoring seen in the close up?

 

[charles g]

remove the piston and hone it lightly to see if a simple rering would be ok , than i could very well run for years withy a issue as is
from the color of the carbon i would also be concerned about it running lean

 

[kyavion]

I got this machine a few months ago and it runs fine. Since it’s winter and I’m not using it, I thought I’d just go ahead and replace the head gasket along with a few other simple things (e.g., spark plug, fuel filter, etc). So I really was hoping to just replace the gasket. Had I not taken off the head and just left things as they are, what would the outcome likely have been? That is, if I don’t address the scoring in the pic, then what’s likely to occur?

 

[Bodjick L]

Good job on the head bolts. I find it difficult to be patient. Lubing good with penetrating oil and time does make a difference though. Cleanup doesn’t look like it will take much and be sure to vacuum, blow out, and wipe with a rag and solvent to get all the residue. I agree with Charles g - you’ve got something going on with the scoring that you should check out.
I started loosening and retorquing my head bolts every couple years many years agne by one and it only takes a few minutes. New no-seize as needed and they all come easy the next time.

 

[kyavion]

I hate hearing that about the scoring. Not long ago I rebuilt the CCKA on my 816, and while it was fun, I’m really not wanting to break this engine down and dig into.

 

[Bodjick L]

remove the piston and hone it lightly to see if a simple rering would be ok , than i could very well run for years withy a issue as is
from the color of the carbon i would also be concerned about it running lean

I thought maybe too lean, but I zoomed in on the spark plug. Then I thought maybe not.

 

[Bodjick L]

I hate hearing that about the scoring. Not long ago I rebuilt the CCKA on my 816, and while it was fun, I’m really not wanting to break this engine down and dig into.

This is way easier to do.

 

[kyavion]

Compared to putting a NOS crank in the ccka, I imagine this won’t come close. I just don’t have a ton of spare time right now. I guess if it’s got to be done, then it’s got to be done though. However, I’ll need some tips on what I need to get to hone the cylinder, and how to do it if you all don’t mind walking me through it.

I imagine a new cylinder pan gasket and rings are in order too. Anything else?

 

[jrd]

The scoring doesn't look too terrible. But agreed, since you've opened it, you want to investigate further.

I suspect charles is right, a bit of honing and new rings will serve you well.

It's a piece of cake, a zillion times easier than your CCKA. You've already got the head off, so all you need to do is remove the 4 3/8-NF nuts at the bottom of the jug, and it will lift right off, leaving the piston attached to the rod. If you haven't removed the carb, do that first. Also, have some rags handy, and be careful when lifting the jug, not to knock dirt down into the case. Stuff the rags around the rod.

Hone it a bit, new rings, and reassemble. You may want to replace the base gasket while you're at it. Note that you can't use a standard ring compressor, because there would be no way to get it off. I use a scrap of aluminum flashing and a band clamp. Then pop the head etc back on. Piece of cake.

 

[jrd]

However, I’ll need some tips on what I need to get to hone the cylinder, and how to do it if you all don’t mind walking me through it.

Do you have a cylinder hone? Something like

4 in. Engine Cylinder Hone

Amazing deals on this 4In Engine Cylinder Hone at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Chuck it in a drill, stick the business end in the jug, and spin it, while pulling it up and down. You want to end up with a cross-hatch pattern.

You should be able to feel the scoring with a fingernail. Something like 5-15 minutes honing should reduce the scoring some. You don't need it pristine, just knock down any edges and smooth it out some.

I imagine a new oil pan gasket and rings are in order too. Anything else?

You probably mean the base gasket between the jug and the case. There's no oil pan on this engine.

 

[kyavion]

Sounds easy enough. I just ordered a hone similar to the one you posted. Thanks!

You’re right about my meaning the base gasket. I had corrected that in my post, but you got to it before I had saved it.

 

[kyavion]

I had a little time today so I removed the carb, muffler, and dropped the starter and removed the rear shield that holds the fan so I could access the two bolts at the rear of the jug. Before the cylinder pulled all the way out I panicked for a moment since I thought it had a crack in it, but then realized that break is suppose to be there.

As far as cleaning things—to clarify, use Emory cloth or 320 or finer sandpaper to clean the cylinder head and piston head? What about the valves? Should I lightly clean them with Emory cloth too? And of course, I’ll gently wipe the piston down with a clean rag prior to installing new rings.

While I’ve got things apart, I thought now might be a good time to free up that fan blade nut so the pulley can slide up and down like it’s suppose to after loosing the large nut behind the pulley. Any tips? In the past I tried loosening the nut with the fan wrench from gtgravely, but the wrench just stripped out since that nut is on so tight.

 

[Bodjick L]

I got mine off the first time (before I got the flat wrench) when it was really stuck by jamming the fan blade with a piece of wood and hitting the nut with an air impact. It came right off. Probably just luck, but can possibly try it if you have an impact.
I also thought about buying a cheap wrench and grinding it until it was thin enough to fit.
A little heat could help too, but be careful could toast the bearing and need to change it -unless it’s bad already.

 

[Bodjick L]

Forgot- how does the side of the piston look where the scoring was?

 

[jrd]

If you've got the shroud off, just take the fan off, then you can get at the 1-1/2" inch nut easily. There are flats milled in the sides of the barrel, so you can probably get a crescent wrench on there as well.

The scoring on the piston is medium ugly. I'd replace it.

I don't recommend emery cloth (or sandpaper) anywhere in there. You'll never be able to keep it flat. For head and top of barrel, use some solvent and a wire brush. Ignore the top of the piston. If you think the valves need anything, get some valve grinding compound. If you're careful about it, you can spin the valves with a flat screwdriver bit chucked in a drill.

Based on what you posted earlier, I would do this:

Mic the jug. See if you're still close to one of the standard sizes. It didn't look bad, I'm guessing you are.
Hone the jug as above. You're not trying to make it pristine, just remove the worst of that scoring.
Replace the piston and rings.
Clean everything.
Reassemble with new base gasket and head gasket.

That should be good for another 20 years

 

[kyavion]

Thanks for the tips from you both.

How do I determine if the valves need anything?

I’ll clean up the piston and get better pics. Assuming I need a new piston, is gtgravely the best place?

 

[MARK (LI)]

@kyavion ..after the work you did on that last engine I thought you were an expert...you did so much work and did a great job...I am pretty sure this will come out like that, ...good luck

 

[kyavion]

Thanks, Mark. I appreciate that. However, I couldn’t have done it without you all guiding me!