Tuning advice

[S&S_Work_Saws]

I just finished up another dolmar 7910. I can't for the life of me get it tuned just right. I've encountered this issue before and cant remember what fixed it. Hoping one of you fine gents with a little more carb knowledge can save me a bunch of time.

It starts, idles, and runs AMAZING...until you finish the cut. As soon as I let off the throttle after the cut it will die every time. I can keep it running if I feather the throttle and take off cutting again. Once I stop it from stalling it will idle on its own again also. Thinking it might be a little lean but going richer feels like it's to much fuel in the cut.


The saw is all OEM parts, except a meteor piston. Muffler mod. Timing is still stock on the flywheel. Cut the Squish and base and landed at .023" squish. final port timing is at...
EX- 96
Trans-130
Int-80

Saw has no air leaks with vacuum or pressure testing.

 

[huskihl]

I’m guessing the H is rich. It wets the inside of the case throughout the cut and it’s too rich to idle.

With the ex at 96, it probably wants tuned about 1-1.25 turns out, which is about 1/2 turn in from the limiter

 

[S&S_Work_Saws]

I’m guessing the H is rich. It wets the inside of the case throughout the cut and it’s too rich to idle.

With the ex at 96, it probably wants tuned about 1-1.25 turns out, which is about 1/2 turn in from the limit learned doing these dolmars

These dolmars sure like to be at about 95 or 96 on the exhaust though.
I'll try to lean it out a little and see what I get.
Thanks

 

[EFSM]

These dolmars sure like to be at about 95 or 96 on the exhaust though.
I'll try to lean it out a little and see what I get.
Thanks

How did you make out on this?

 

[S&S_Work_Saws]

How did you make out on this?

Its been a while since I fixed it. If I recall correctly I pulled the carb, cleaned everything again, and started over again on the tuning and it was fixed. Used the tach when I retuned it. Still running great.

 

[Catfishclark89]

I’ve fixed this problem by richening the low screw a little.
Get the saw good and warmed up. Leave it running and let it idle for at least a minute and a half. No blipping the throttle or anything just idling. Then after the minute and a half is up grab the throttle. If it stumbles and dies then it needs more fuel on the bottom.
This may not fix the problem but try this first before taking it apart.

 

[Catfishclark89]

Well shoot. Just seen this was from back in May.

 

[EFSM]

I had a similar situation on a totally different saw. It was a nearly-new Echo CS-355t. The customer complained of it dying at idle, and it acted really weird. The problem totally went away after putting a high-flow mesh filter on like the new style saws have. In that case, it was starving for air (the original filter design on them is really stupid--it has a big spit-back plate that blocks off nearly half the surface area of the flat filter. The nylon are peaked, so there is much more flow.)