K301 rebuild

[mgonitzke]

tim, you could leave the cover off points,fire it up and watch for regular pattern spark.If they are working correctly it will be obvious,might have to cover a little to get brightness.I would ask ,how can it blow out carb if valves are sealing correctly??

If the timing is too far advanced, it will backfire through the carb before the intake valve closes.

Timing needs to be set right before any further troubleshooting or this will be a lot more difficult.

 

[HKCooper44]

It's hard diagnosing engine problems "over the phone", but is it possible that someone had this engine apart in the past, then just stored it, possibly because they couldn't get it to run? The reason I ask is that if the ignition points break when the timing mark is centered in the timing inspection hole, if you know you are getting spark, and if you had lapped the vales and are sure they aren't leaking, then maybe....just maybe...someone had the camshaft out and didn't properly index it when reinstalling it. No amount of carburetor or ignition timing fiddling can compensate for that!

 

[Tim Bowman]

Thats why I'm puzzled! I lapped the valves until I had a good pattern on the seat and valve. Everything looked great sitting on the bench.

 

[lpalma]

Maybe you have a bad coil, It will do that, idle fine but run like crap when you throttle up. New condenser? wired correctly?

 

[HKCooper44]

If you had a good, unbroken concentric frosted appearance on both the seat and valve face, you should be good. Be sure the cold tappet clearance on the intake is .008/.010", with .017/.019" on the exhaust. Also ensure you rotate yhe crankshaft so the involved tappet is in its lowest position when you check and adjust these clearances.
Note: check to see the valve spring tappets are fully seated in the retainer too!

 

[gary noblit]

Tim, all of the above will get you there..good advice..

 

[jdrong]

tim, you could leave the cover off points,fire it up and watch for regular pattern spark.If they are working correctly it will be obvious,might have to cover a little to get brightness.I would ask ,how can it blow out carb if valves are sealing correctly??

If one of the valves (probably the intake valve) is set too tight and not closing all the way, then compression will be lost through a slightly open valve on the upwards compression stroke of the piston through the carb. Over the years I've run across that problem more than once, especially when someone rebuilds an engine. I once bought an atv cheap, that kept fouling plugs, the engine was "rebuilt". They had replaced everything ignition related, rebuilt the carb and still it didn't run quite right and kept fouling plugs. Then one day when I had the air box off, I noticed the carb was making an unusual sound, upon closer inspection I found that I could feel a slight pulse coming out of the carb. I checked the valves, and one was too tight, so the valve stayed slightly open all the time. I adjusted it and there was no more pulse or gas coming out of the carb, the engine ran much better, and it never fouled another plug with black soot.

 

[HKCooper44]

Doing a differential compression test would show this, and other faults as well, but most people don't have the necessary equipment.

 

[jpaulus]

Doing a differential compression test would show this, and other faults as well, but most people don't have the necessary equipment.

Most folks don't. But if you put compressed air in the cylinder with the piston at TDC on the compression stroke if the valves are leaking you will hear air at the carb and or muffler. OR the dip stick if you have a lot of blow-by.

 

[Tim Bowman]

If one of the valves (probably the intake valve) is set too tight and not closing all the way, then compression will be lost through a slightly open valve on the upwards compression stroke of the piston through the carb. Over the years I've run across that problem more than once, especially when someone rebuilds an engine. I once bought an atv cheap, that kept fouling plugs, the engine was "rebuilt". They had replaced everything ignition related, rebuilt the carb and still it didn't run quite right and kept fouling plugs. Then one day when I had the air box off, I noticed the carb was making an unusual sound, upon closer inspection I found that I could feel a slight pulse coming out of the carb. I checked the valves, and one was too tight, so the valve stayed slightly open all the time. I adjusted it and there was no more pulse or gas coming out of the carb, the engine ran much better, and it never fouled another plug with black soot.

Thank you for the advice> I reset the lash on the valves and reset the float in the carb! Made a world of difference improving throttle response. It seems to be searching some up and down! Someone had posted tutorial on gapping the points to change the timing but I can't seem to locate it now?

 

[HKCooper44]

Just set the points to .020", so you have a slight drag on the gauge blade.

 

[jstorma]

Thank you for the advice> I reset the lash on the valves and reset the float in the carb! Made a world of difference improving throttle response. It seems to be searching some up and down! Someone had posted tutorial on gapping the points to change the timing but I can't seem to locate it now?

3rd page 9th post down. Matts link. If you set the gap to .020" and it is still running good at idle but not with more throttle reset to .018" I found .020" on some of mine makes it run good at idle but misses and back fires when when I give it more throttle. Setting to .018" solved my problem. Just make sure the carb needles are adjusted to the proper recommended settings for starting out. Follow the manual for needle adjustments once you get it running.

 

[jdrong]

Thank you for the advice> I reset the lash on the valves and reset the float in the carb! Made a world of difference improving throttle response. It seems to be searching some up and down! Someone had posted tutorial on gapping the points to change the timing but I can't seem to locate it now?

Good to hear that there has been some improvement. Searching or surging may be solved with a simple carb adjustment or there may be small piece of foreign material partially blocking gas or air flow. Carbs can be difficult to get adjusted, it can be a learning process to get the high speed and low idle adjustments to work well together. An out of adjustment carb can cause hesitation to throttle response, back firing. even surging.

 

[mgonitzke]

To get the carb adjusted, start the tractor and let it warm up, get the governor set correctly for wide open throttle, then with the throttle set wide open, enrich the main needle until the engine starts to run rough and cough black smoke, then slowly lean it. The RPMs will rise, then fall again, and if you keep leaning it it will stumble and try to die. The point where you want it set is where the RPMs peak, then enrich it just a tiny bit more. Then, slow the engine down to idle and set low idle speed adjustment, then set the idle mixture so it idles smoothly.

With that done, slam the throttle to wide open. The engine should respond with minimal hesitation. If it stumbles and blows black or gray smoke, it is too rich. If it stumbles and you get a lean pop, it is too lean.

I'll say it again though, static time the points first before you do this, using the link I previously posted, as if the timing is off, you will be chasing your tail trying to figure out why there is poor throttle response.

 

[HKCooper44]

A maladjusted governor can easily cause surging or hunting for speed, too. The Cadet owner's manual or Kohlrr engine manual shows the proper hook-up and adjustment.

 

[Tim Bowman]

To get the carb adjusted, start the tractor and let it warm up, get the governor set correctly for wide open throttle, then with the throttle set wide open, enrich the main needle until the engine starts to run rough and cough black smoke, then slowly lean it. The RPMs will rise, then fall again, and if you keep leaning it it will stumble and try to die. The point where you want it set is where the RPMs peak, then enrich it just a tiny bit more. Then, slow the engine down to idle and set low idle speed adjustment, then set the idle mixture so it idles smoothly.

With that done, slam the throttle to wide open. The engine should respond with minimal hesitation. If it stumbles and blows black or gray smoke, it is too rich. If it stumbles and you get a lean pop, it is too lean.

I'll say it again though, static time the points first before you do this, using the link I previously posted, as if the timing is off, you will be chasing your tail trying to figure out why there is poor throttle response.

Thank you for your knowledge and advice! Sorry for the slow response but I must be getting pretty close to having the carb adjusted!! Running much better and throttle response has improved greatly!

 

[Tim Bowman]

I'm needing help with a wiring diagram for the headlites on my 128? They were present when I bought it but have never been complete! There is a rotating switch beside the ignition but I haven't traced what wires are attached to it. I'm still not adept at navigating this site so all help is greatly appreciated.

 

[mgonitzke]

http://www.cubfaq.com/wiringdiagrams/128lights.jpg

 

[tkhoffman]

I'm needing help with a wiring diagram for the headlites on my 128? They were present when I bought it but have never been complete! There is a rotating switch beside the ignition but I haven't traced what wires are attached to it. I'm still not adept at navigating this site so all help is greatly appreciated.

It sounds like you have the diagram but need help reading it..
Looking at the diagram, it appears the power comes from the AMP gauge with a yellow wire. From there it runs to a fuse (I don't know where it's located) it exits Fuse with yellow wire to switch.. unsure of style or location. It leaves switch with a violet and violet/white wire. The violet/white goes to rear lights. The Violet gets connected to a yellow wire. From there, yellow wire to front lights

 

[dschwandt]

Lights were optional and there should be a bundled breakout in the OEM harness for the, if they are not originally installed.