Engine Backfire

[ACsam]

I have a 312D in sad shape. I just got it running today after 5 years of sitting. couldn't have more than 10 hours after previous rebuild. The cylinder wall is perfect. I thoroughly cleaned the carb. Here's the problem: Go to throttle up and it starts to die out. When i push the throttle further, it revs up as normal, but starts to backfire like crazy. It is very strange, I've never seen anything like it. I did let it warm up too. Any suggestions?? Thanks, Sam

[sammiefish]

Is yours a black & white sticker hood with the electronic breakerless ignition or do you have points?? Im guessing breakerless

[ACsam]

Nope, it has points, adjusted to 6 thous.

[sammiefish]

Well, I have a strange backfire on one of my breakerless. well, maybe its valve timing.. easy to adjust. BUT, how confident are you that your carb isnt gummed up etc... ? I play with my carb and things seemed to get better but not completely... I was thinking my timing from breakerless.. but maybe same valve issue I did rings valves 4 or 5 years ago.. and this ... similar

[ACsam]

The tractor was actually my grandpa's. I completly tore down the carb and THOURGHLY cleaned it. put the jets on the wire brush to clean them up. I didnt put in a carb kit because it didnt seem like it needed one. Could it be somthing in the wiring?? I should go through and re-wire it.

[ACsam]

Well I went out to check the spark and it seems intermittent. It seems like somtimes it misses a compression stroke. Ill have to check the spark plug lead and coil?

[PeppyDan]

The points should be set at 20 thousandths not 6. Reset the points and then try it again and you may need to adjust the carb at that time also. If it still doesn't run correctly the condenser could be defective. Good luck Dan

[dentwizz]

Your points and plug should start at a baseline gap of .020" Adjust the gap of the points from there plus or minus but keep in mind the smaller distance is less energy and more advanced fire. Also make sure your mix is proper. Plugged air filtration or running too lean can produce misses and backfires.

[ACsam]

Well I set the points at .02 The aggressive flame out of the exhaust is gone, but there is still a small "pop". Should I adjust them out more?? Also, to me, it sounds like the engine is running very fast at not even half throttle. IS this normal?? Thanks again, Sam

[gearhead19]

It sounds like your governor is out of adjustment, max rpm should be 3600. Consult your kohler engine manual for baseline governor adjustment. You will either need a mechanical, or single cylinder electronic tachometer to tweek to the 3600 rpm setting at full throttle.... Dan

[robob]

Almost allways when a engine backfires it,s runing LEAN if you have good ingnition and fuel supply, probably pluged up carb ( no fuel stabalizer installed during hibernation)