Ported muffler, adjusting carb??

[parrisw]

I got a ported muffler on the way for me 394xp, and wondering about tuning. Do I set the high end until max rev's, then just back off a bit, thats what I ve done in the past with stock saws.

Thanks

Will

 

[Lakeside53]

No.... That will be way too lean.

Set for the 4-stroking sound" and then check with a tach that you haven't exceeded the max rpm allowed. You could just use a tach, but training your ear is a good tihng.

I'm not sure of the 394 max prm, but someone here will know.

 

[parrisw]

Thanks I will see if I can find max rpm rating, will my auto RPM tach work with a saw, I ve never tried it, I think it may. Its a high end multimeter that does RPM, I think it has a 1 cyl setting.

 

[Lakeside53]

As long as the 1 cyl setting is one spark per revolution, it should work.. Might not go high enough though... you'll likely need to get up to 12-13k or so.

 

[parrisw]

Yes it will, cause it has 2stroke and 4stroke setting, but im not sure how high it will go, I guess Im about to find out.

 

[fishhuntcutwood]

No.... That will be way too lean.

A muffler mod will increase the RPMs, and lean the saw out with no carb adjustments. So if he ran it back at the stock RPMs, and then even backed off from that, wouldn't that be on the rich side?

 

[Lakeside53]

He didn't say that - he said - "Do I set the high end until max rev's, then just back off a bit".

The answer is no... What if the max is 15500, and he backs it to 15K...?

 

[JohnL]

I have trouble with "back it off a bit" if you are reffering to rpm, because you could do that either by making it leaner (clockwise, bad), or richer (counterclockwise, good) which is what you want.

 

[fishhuntcutwood]

He didn't say that - he said - "Do I set the high end until max rev's, then just back off a bit".

The answer is no... What if the max is 15500, and he backs it to 15K...?

OK gotcha. We're on the same page then. I thought we were referring to the factory max rev setting.

 

[parrisw]

Thanks guys, what I meant was get max revs out of it, then (back off) meaning go richer, turn the mix screw out.

 

[Lakeside53]

I was right!
-1 for Jeff...

 

[parrisw]

Ok, I got the muffler on, and HOLY CRAP its loud!!!!!!!

Anyway I adjusted the carb with my multimeter tach and it works fine, the tach reads high enough, so I set it to 12,500rpm, it would go over 13,000 but I didn't push it, madsens says a 394 is max 13,000, so do you guys think that 12,500 will be fine.