031 Stihl

[tomdcoker]

I have followed this site for a year and a half and learned a tremendous amount about chainsaws. Nothing can replace the experience of using a piece of equipment and learning it's quirks and problems and being knowable enough to fix the problem. I have not got to the top of that hill. That being said, now for my problem.. I have an 031 Stihl that will crank and run, but it backfires. I feel that the problem is electrical, but I do not know if it is the condenser, module, or points bouncing, points not set correct or module gap has incorrect setting. I have several electronic modules and have put two on other 031's, but I am not sure it will work on this one, because I do not know which component is faulty. Any help would be appreciated. Tom

 

[Justsaws]

Back firing can be caused by a saw ignition being out of time. It can also be caused by carb issues.

When you say back fire do you mean that it rips the starter cord out of your hand with a loud bang? If so that is most likely timing.

Does it start easily and when you rev it back fire a few times but stay running? That is most likely carb issues.

The 031 electrical system has lots of areas for adjustment. Stihl manuals talk of things like edge gap.

My first suggestion is to figure out if the cylinder is loading up with fuel and then igniting. A well tuned 031 should fire cold choked on the third pull, no more than five. After that change the gap on the sparkplug =/- .004 and see if one or the other makes it better. Assuming the saw has a good new Bosch WSRF-6(I think, not positive).

 

[Lakeside53]

This is often associated with a bad condenser, which also means your points would need cleaning and adjusting after condenser replacement.

 

[retoocs555]

I've seen several 031s where the point gap was so far off, it caused the saw to be out of time and backfire.

 

[tomdcoker]

Thanks for all the replies. The saw cranks O.K., but while it is running it periodically makes spitting noises. I will check the plug first. I had a saw recently that was not running as it should and it was the plug gap. Thanks Tom