Still (not stihl) backfiring !

japfpe · Apr 3, 2004

Hey folks,

I posted a thread sometime back about one of my older John Deere saws (1980 +/- 60V) backfiring thru the muffler after it warms-up. I rebuilt the carb yesterday and there was only a marginal improvement. A local saw shop guy (where I just purchased a new Jonny 2159 Turbo...) thought that the saw was running hot and suggested I check the cooling fins for blockage. I cleaned the fins (really wasn't a lot of blockage) and again...still backfires.

I know the saw is somewhat of an antique but there is some sentimental value associated with it since it was my fathers saw.

Any ideas of what to check ?

Thanks,
Joe

JD 60V
JD 50V
Jonsered 2159

Dadatwins · Apr 3, 2004

Make sure you have the right spark for the saw, sounds simple but over the years the wrong plug may have been put in. Make sure you have the right gas mix for your saw. Some older models run on different ratios. I had a few older homelites and they would backfire when the flywheel was bad. Older flwheels not as durable as the ones today and might be warped and through off timing. Also check coil might be failing and missing. hope this helps

Crofter · Apr 3, 2004

Intermittent ignition will do it. Check carb adjustment for possible too lean high sped. Check exhaust port and muffler for carbon buildup.

Frank

stihltech · Apr 3, 2004

60V

I assume(OK ,I know, bad thing to do), that this has points, since it is not a 60 EV. Try points and condersor, or, better yet, an aftermarket ignition module.
If the saw has an electronic ignition, please disregard this post.

Lawn Masters · Apr 3, 2004

If the saw has a points system I would just upgrade to an electronic ignition unit just for peace of mind. and to eliminate the ingnition system from the list of possible causes.