my 670 runs like crap

paroughneck · Jan 18, 2012

I bought this 670 on ebay awhile back, and i have a post about clogging the air filter. I found the problem, solved it but now I am back to the drawing board. I was cutting up the last dozen or so logs I had left from my load, it was running good, but then started to back off. I figured maybe the filter was clogged, I emptied the sawdust from the chamber and the longer I ran it the worse it got. It was so bad my 46cc poulan pro smoked it on a log. This is a 68cc all out motor beast. A poulan shouldnt even come close to it. I wasnt even cutting with it and ran it wide open, it didnt seem to come up all the way, it would peak rpms, but it was intermittent. I put it to cutting and it by the end of the log(less than 25 inches around) it was so bogged down it barely cut. 2:30 to 3 mins to cut this thing when normally its thru in less than 30. I did pull the air filter off, and there was some really fine dust in the intake for the carb. I will take it to the shop, but my guess was it didnt have a good seal and sucked in lot of dust. I am going to have my jonsered dealer take care of it, and probably pick up a 2171. I was looking into making it a hotsaw, and I really love it when its running good. Any ideas?

LD1 · Jan 20, 2012

I dont think I remember the post about your air filter issue.

But if it is as bad as you are describing, and having sawdust in the intake, the saw may suffer from sawdust poisoning. If it were mine, I'd pull it appart and see what the piston and cylinder looks like. And if it isnt scored up clean everything, carb included, and fix the sawdust issue.

Chilly807 · Jan 20, 2012

If it starts and idles ok, the cylinder and piston are fine. I had a problem with a Jonsered once that the spark arrestor screen was clogged with fine carbon, the saw couldn't get rid of the exhaust gas and refused to rev.

Another example was a Husky 242 that would idle forever but refused to rev, that one was cured by running a new wire to the ignition coil (old one was pinched nearly off), and replacing the spark plug.

If the saw is set too lean on the high speed screw they won't rev freely or accelerate either.

Sean