MISteve
ArboristSite Operative
Got a 488 of Ebay, needed new piston/cylinder they said. Got lucky, cylinder cleaned up just fine, only needed a piston. Piston is a Mako unit, but had to mill of some extra stock off the bottom of the piston. It was making contact with the crankshaft. New piston was .260 from the bottom of the wrist pin bore to the bottom of the piston. Old one was .200. Had to do the same thing on my other 488 which needed a piston. Sorry, got of track a little. Fired the saw up, sounds real good. Ran it for a couple of minutes to check for bar oil flow. Shut it off and installed bar and chain. Fired it back up and started to cut. In a minute or so, it starts to go chug-chug-chug, can not accelerate. Than it quits. I can restart it but it still runs like it is flooding. I pull the plug, man is this flooded. Clean out the cylinder. Get it started, same thing again. Runs good for a minute or so. Put in a new plug, same thing. I go through the carb, everything looks good. Clean out the cylinder, runs good till it gets warm. I swap carbs with my other saw, same thing. Ok, not carb related. I was going to swap coil with the other saw, than thought why not see what my friends at AS say about coil issues on 488's. I find a thread on resister spark plugs, says some older saws may not run right with them. I am doubtful, but plugs are easier to change, so I change my BPMR7A for a CJ8Y. I proceeded to run through 2 tanks of gas with no problems. Interesting. Put a new BPMR7A in. Runs good till it gets warm, than starts to go chug-chug-chug again. Same with a WSR6F and a RCJ6Y. Put the CJ8Y back in, all is well. Is it the resister type plug or do I have another issue?
