Recent force 125 rebuild odd findings.

[NEKFORCE]

I recently rebuilt a force 125 that had one cylinder overbore, that cylinder failed for some reason. I don't believe setting all the carbs as normal manual spec would cause a .20 over overbore to run too lean. I don't believe it was sucking air anywhere, so I am not sure what caused it. I stripped the block and had it sent out and is now re sleeved to the factory bore to match the others I also replaced the rings in the other cylinders. The only thing that I found off during the rebuild was that two of the cylinder drain check valves screens were missing and the check valves had become dislodged. However from the way it looks this would be to an un damaged / unrelated cylinder. anyway I corrected that as well with all new gaskets.

does anyone here believe that the factor carb settings set by someone that did not know that one cylinder was a overbore could have caused the problem?

It honestly doesn't even look so much like a lean condition, it looked more like a cold seizure, but why would that be on just one cylinder?

 

[jerryjerry05]

One cylinder bad? #1 or #3 or 2/4?
​I know you posted about the parts coming loose but can't locate that post.

​The cylinder can go bad because of: reeds, carb set wrong, sucking air somewhere on the intake side.(intake side includes the port covers and fuel pump fittings,
​timing off, overheating, head gasket, recirc system???????

​I've rebuilt a bunch of 125's with just 1 cyl. and .020 is nothing to worry about.
.030 and more is when the jets start messing with things.

 

[pnwboat]

Improper break-in procedure, improper tolerance (too tight), not doubling oil mixture for break in, are a few of the things that can also cause cylinder failure after a fresh re-build.

 

[NEKFORCE]

One cylinder bad? #1 or #3 or 2/4?
​I know you posted about the parts coming loose but can't locate that post.

​The cylinder can go bad because of: reeds, carb set wrong, sucking air somewhere on the intake side.(intake side includes the port covers and fuel pump fittings,
​timing off, overheating, head gasket, recirc system???????

​I've rebuilt a bunch of 125's with just 1 cyl. and .020 is nothing to worry about.
.030 and more is when the jets start messing with things.

cyl #3 actually. I know how air leaks can cause this, but it did not look like lean condition. Anyway i have it all back together, but having a hard time starting / runnnng.