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Discussion Starter · #1 ·
I had a K321 rebored to .010 over and the cranckshaft miced down .010 under, ground the valves and seats all cleaned up at machine shop (cost me $180). It has a starter /generator, no balance gears, its on a 1977 -444, owner told me all was original (tractor and engine). Kohler spec #60313d (sn 8240867). I installed a new piston and new connecting rod that matched the rebored and miced crankshaft. The engine idels fine but misses at higher RPM's. (3600 RPMs when it ran ok at higer RPMs) I had to adjust the valve to tappet clearence twice since rebuild, they were way off from specs (.009 I, .018 E) I think this is what is causing it to run sluggish / miss at higher RPM's. A guy who repairs small engines told me that I need to get the camshaft resized (don't know what that means) to match the change in the rod/crankshaft. Is this true, I can not re-use the same camshaft and lifters with a rebored cylinder and miced crankshaft?? Could the cam lifter lobes or the compression release tangs be in bad condition? Any help here would be greatly appreciated, I dont want to keep taking this engine apart.......
 

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There seems to be some confusion here with a heavy dose of misunderstanding.

Based on what you posted, you did everything correct when it comes to rebuilding the engine. I think that the small engine guy is saying that you should have had the camshaft "profiled". Profiling a camshaft is a process whereby the lobes of the camshaft (which are subject to wear) are checked to make sure that the "lift" and the "duration" aspects of the lobes are within the factory specifications. They also check to make sure that the camshaft is not twisted. The camshaft must lift the valves off the valve seat to a certain height and it must also hold that valve open for a certain length of time (duration) or the performance of the engine suffers. A twisted camshaft won't open the valves at the correct time and there are timing marks on the cam and crank gears that are there to synchronize the opening and closing of the valves in relationship to the position of the piston in the cylinder.

The fact that the cylinder was bored oversize or that the crank journal was cut 10 thou undersize, plays no part in the valve timing. Do you own a tachometer of some kind that will tell you for sure what your engine is turning at wide open throttle? If not, then you are just guessing and guessing is never a good thing. For sure, valve timing is affected by valve clearance but I have to wonder if this "miss" you are complaining about is not related to something else such as a carb or electrical problem.
 

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If you have an old ignition switch in it then get it replaced. Mine was a major headache. Just plain old worn out. At times it would start and run fine and others no spark or start at all. Sometimes the thing spat and sputtered while running and finally got ticked off enough get rid of it. Runs fine now.
 

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Discussion Starter · #6 ·
Re: Camshaft and valve lifter question;It seems to be electr

Hey all - I got the generator field stud and armature studs in the gen/starter, even replaced the brushes. Tried to start up the 77-444 and needed to jump start it with car. Started right up - and she ran fine at idle and at full open throtle. Have 3600 RPM high and 1260 idle. Heres the problem - no lights???? so I wiggled the light connection / wire on the back side of the ignition swith and then I saw the fuse blow. The tab on the back of the ignitino switch is loose, so it looks like Rockdog hit it the nail on the head. Does anyone have an ignition switch for sale?? Its the 4 prong switch for the 400 series tractor.
 
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