Carb adjustment after muffler mod

[chevy]

So I did a mild muffler mod on my climbing saw today. The saw is a ms250 with a 14inch bar and runs 104octane fule. It runs Great! So after the mod I gave the High side adjustment on the carb an extra 1/4 turn so it would not run lean. Ran great throught mid range but missed a little wide open. so I leaned it out a bit and the miss almost went away. I'm still a bit fater the factory setting. Has anyone had this happen to them or have some insite?? Just would like to understand what happened.

Thanks Mike

 

[BostonBull]

Carb adjustments are sensitive things. Anywhere from 1/8 turn to 1/2 turn usually does the trick. Listen for when it begins to 4 stroke. Thats the perfect adjustment.

 

[chevy]

Thanks That is what I was thinking.

 

[Shawn Chamness]

I was think of doing the muffler mod to see if I could get my ms 250 to run better. Never did it before. Any help. Thanks.

 

[SixGun]

Some 250's don't have a high or low adjustment, only an idle screw.
Before modding the muffler, check your carb for adjustment screws.
You will want to back out the high a little for more fuel

 

[blsnelling]

That is not uncommon, contrary to popular belief. You're moving more air, but that air brings with it additional fuel as it comes through the carb.

 

[Steve Connally]

so open up the high?

 

[SixGun]

Yes open counter-clockwise the high screw after doing a muffler mod. Most likely only a small amount, listen to the saw for four-stroking while cutting or check RPM with a Tachometer.
This will give you more fuel at high end to compensate for added air flow .