140843c rebuild thread (Mod, delete if inappropriate)

[jakedaawg]

This thread is intended to document the rebuild of this engine for my partner in the boat. He wants to follow along while he is away.

Should anyone see anything I am doing wrong feel free to comment.

Well Cap, as you know we had the following compression readings: #1=125 psi, #2=125psi, #3=125 psi, #4=102 psi.

Several methods of decarbing stuck rings were tried. Result was ~ 5 psi gain. still not good enough.

I pulled port head.

 

[jakedaawg]

Well Cap, pic did not come through, I will try to figure that out. There was significant burning and pitting on #4 piston. Some aluminum transfer to sleeve of cylider wall on port side at 270 degrees.

I will begin teardown today.

I will work on getting pics posted tonight.

Any one who can post pics feel free to tell me how, keep in mind that I am computer illiterate and working from an apple laptop.

 

[jakedaawg]

No Title

failed pic post

 

[Bob_VT]

Use photbucket for posting pictures. #4 is only about 10 psi of being out of spec and those numbers are not too bad.

 

[jakedaawg]

it actually looks like I got the pic to work using the edit function.

Well Cap, as I suspected we did have an issue even though the engine pulled well. Think how good it'll do when I am done. What do you think caused the pitting and carbon build up? my guess is ????? who knows. Maybe bad fuel at some point, lean condition causing detonation, aftermarket power packs. I suppose we could have a bad mag in the flywheel being just slightly out of place making improper timing on the #4 hole but that is extremely unlikely.

 

[Bob_VT]

All pistons are timed together. It is a lean condition from a carb that causes that. You could spend the money or just run it. What motor is it? What year?

 

[jakedaawg]

140843c 1978 rude 140. I dont think it will last long in our intended use. We are gonna fix it. Its on a little 14' stuery sidewinder. Will be run at high RPM. We only have $300 into the whole thing so have some $$ to play with. The hull is solid.

 

[Bosunsmate]

put in new rings and hone the walls and it willbe great.
do the top and lower seals too
yeah photo functions crashed on here, but keep trying as it makes all the difference when following along

 

[jakedaawg]

Emdsapmgr-- in another thread you mentioned muriatic acid to remove aluminum transfer and the honing. Could you go into a little more detail of this process? Are you refering to honing at the machine shop?