Chainsaw Repair

I'd like to get another one and tweak it a little.  The ones we did on the build off years ago had the 199 and they had tons of power on the top end but ran erratic (lean) on the low side. Ran great after a little carb work!!!

I Think it comes down to really lean factory drill patterns on the Zama and Walbro.  This early generation of saws were some of the first to have to pass much stricter EPA regs and really lean low sides and Cats were used to meet the regs.  The ms200t went though a bunch of carb changes during these years to try and meet the smog regs and still run ok. The shaft actuated accelerator pump on the little zama C1? Was a great example of a crappy fix that usually had issues after a short time of use.

Well I still haven't had a chance to go over the saw. I got it almost for free because it wouldn't start and was making kind of a rattling sound when you pull it over. When I tried to check compression I took the spark plug out and the ground electrode was broke off the spark plug when I pulled it over it locked up. I think the ground electrode is stuck in a port between piston and port. Maybe a parts saw? Why would the ground electrode break off a spark plug unless it hit the piston? I will take it apart tonight.

The EPA carbs had a smaller high speed jet in the floor of the metering valve chamber that ultimately limited how rich you could make the high speed mixture.

The high speed needle merely reduced the mixture the jets (limited) amount to a lesser amount.

To drill this jet would make the high speed needle more sensitive and also make the carb able to meter more fuel. 

I didn't know that.

The non-EPA carbs were the 190 (heated saws) and 198, and likely the 174 before that.

2009 359 E-tech ...  I took it apart finally tonight. That carb is a **** to get off, that throttle rod from the trigger to the carb was almost impossible for me to figure out how to get it off. I ended up pulling the cylinder with the carb on to get it up enough to get that rod off the carb. It had a Zama C3  EL42  8ZD were the numbers on the side of carb. I pulled off the cat muffler, and took the cylinder off. I found the ground electrode that broke off the spark plug sitting on top of the piston. There was no real damage to the cylinder other than some dent marks from the piece of electrode that was causing it to lock up at TDC, and dent marks in the top of the piston, but no scoring on piston or cylinder wall. I noticed the single piston ring is not real free it is a little seized in the piston ring groove opposite the little pin at the ring gap. I think I can clean everything up and slap it back together. The crankshaft looks good the bearings all seem tight. Is there a good way to smooth out all the dent marks in the top of the piston? Or should it work ok with just leave all the little dent marks as is on piston and top of cylinder? What should I do with the cat muffler just toss it and get a new non cat muffler, or is it worth cutting the cat muffler open and gutting it out? Another thing I noticed when I was taking it apart the throttle linkage rod from the trigger to carb seemed like it was not opening the carb all the way to full throttle do you just bend that rod I don't see any other way to get it to go full throttle?