12 hp kohler issues

wj-ihc · #1 02-15-2011, 11:38 PM

Hello, new member here, glad to be part of the group. This past summer/fall I have been working on restoring a 123. I found a worn out 10 horse block, had it bored to a stock 12, had my crank ground 10 under, new rod, had the valves done, starter/generator rebuilt, new coil, points, condensor, wires, etc. Rebuilt the carb. The engine would fire up pretty well but runs horrible off of an idle. It will cut out and act like it just won't go, like it isn't getting fuel. It also seems to idle very rough. The whole tractor just sort of shimmys when it is idling, like it is out of balance a little, worse than what I would expect. I checked to make sure I was getting good fuel flow out of the tank, took the carb back apart, even tried a different carb of a runner, same results. Started looking at timing, hooked a light up to it and varied the gap, this would change the way it ran, but would not completely correct it across the rpm range. On that note, I did not find an S on my flywheel, just a single casted line that passes the sight hole. This line seemed to approximately correspond to the timing light?? I tried differnt points, coils, condensors, plugs, unhooked generator, nothing helps it. Finally had time to pull the engine out of the tractor this weekend and pulled the pan to check timing, line on the crank matches perfectly to dot on cam. Valves are set correctly. I am at a lose at this point. Only thing I can think of is possibly a valve not seating right or haning up in a guide, the ACR sticking, or the lobe on the cam for the points pushrod being worn or the rod its self. Any help on this would be greatly appreciated. I have a short video I took this summer of the engine running if anyone would like to hear it. Thanks.

cubs-n-bxrs · #2 02-15-2011, 11:57 PM

First off wj-ihc welcome to OCC. What pieces did you use from the 2 different motors. The rotating pieces from a 10 and 12 motors are not interchangeable. Different strokes and weighted different also. Probably why it shakes as bad as it does. Just a guess on my part.

wj-ihc · #3 02-16-2011, 08:45 AM

The crank and piston are from a twelve, I believe the cam was from a 10 because the ACR on my twelve was messed up. The flywheel is from a 12 I believe.

wj-ihc · #4 02-16-2011, 11:51 PM

Here are some pictures of it up to this point.
Like I said, I am at a complete loss for new ideas on what could be my problem at this point.

Methos · #5 02-17-2011, 05:17 AM

Quote:

Originally Posted by wj-ihc

Here are some pictures of it up to this point.
Like I said, I am at a complete loss for new ideas on what could be my problem at this point.

Sweet looking 100!

I'm sure one of the engine guys will chime in and try and help you get this figured out.

JOHN SCHUTTE · #6 02-17-2011, 08:47 AM

Wj-ihc, I am with cubs-n-bxrs on the different strokes and weights. What connecting rod was used, a 10hp or 12hp?

wj-ihc · #7 02-17-2011, 09:46 AM

I bought a new .010 under rod for a 12. Like I said, the cam may be out of a 10, and it is possible that the flywheel may have been off a 10. But the crank, rod and pistons are for a 12. Could this have anything to do with it not running correctly.

JOHN SCHUTTE · #8 02-17-2011, 10:36 AM

Quote:

Originally Posted by wj-ihc

I bought a new .010 under rod for a 12. Like I said, the cam may be out of a 10, and it is possible that the flywheel may have been off a 10. But the crank, rod and pistons are for a 12. Could this have anything to do with it not running correctly.

If the rotating assembly is 12hp, you should be in good shape there except for the 10hp flywheel. 12hp is balanced differently than a 10hp. Since you have the motor out, I would remove the head. Rotate the crank by hand and check your valve movment and ARC like you stated previously. If all is good there, I would lean towards timing/ignition.