660 clone carb? vacuum? problem.

[huskyboy]

I know, they are crap and you have a 50/50 chance of them working right but one of the carbs I tried came off a good running saw. If I have to I'll by an OEM one but I really don't want to put another $70 into this kit saw.

https://www.hlsproparts.com/Stihl-066-MS650-MS660-OEM-Tillotson-carburetor-p/hs-320a.htm

 

[Ronie]

I took the pre filter off and put the carb on without it and the sprayed some brake cleaner at the back of the carb, it was leaking. It turned out that the OEM support ring is very soft and was deforming under the pressure of the boot, replaced it with an aftermarket one and the leak behind the carb it fixed. When it cools down outside I'll see how it acts.

 

[BuckthornBonnie]

I’ve had 1125s with problems there. Sometimes it’s a tiny leak that doesn’t affect much.

 

[Ronie]

Fixing the leak at the carb fixed the jump in RPM. I'll try putting a couple of disc under the needle spring to increase the pop off and try and fix the burbling after the cut.

 

[Maintenance Chief]

Really the only problem I encountered with that aftermarket carburetor was the throttle plate not sealing and a constant high idle.
I bought 2 used oem carburetors for my 066 for less then 70.00 and rebuilt them .
Did you use the Chinese impluse line?

 

[Ronie]

@srcarr52 you were right on the money with the pop off pressure, now I have a little to much I think but it's not burbling after the cut anymore, I'll get it just right tomorrow, thanks.

 

[Maintenance Chief]

Nice , did you shim the spring or stretch it?

 

[srcarr52]

@srcarr52 you were right on the money with the pop off pressure, now I have a little to much I think but it's not burbling after the cut anymore, I'll get it just right tomorrow, thanks.

That's why I normally don't worry about the surging after a cut. Raising the pop off to get rid of that may cause issues feeding at WOT or odd idle issues. You really need a spring with a higher pop off (seat pressure), but a different stiffness so it has the same force at full open (a little like over the nose on a valve spring). All of which is pretty much impossible to measure on these tiny springs.

 

[Ronie]

Nice , did you shim the spring or stretch it?

I shimmed it with some aluminum foil.