394xp popping in the cut

[srcarr52]

I'm confused... how does it being easier to dump extra fuel make it lean in the cut?

Because it dumps fuel almost like a limited carb, then you lean it out to 4 stroke appropriately and then it's too lean in the cut.

 

[paragonbuilder]

Because it dumps fuel almost like a limited carb, then you lean it out to 4 stroke appropriately and then it's too lean in the cut.

So it only over fuels during free rev, but under load it can't keep up?

 

[Mattyo]

I took the flywheel off. key is not sheared. jason suggested I change the plug and remove the kill wire.

ok, its not popping now. put the kill wire back on. no popping. put the old spark plug back in. no popping. ???????????????????? back to where I started... no popping. now, I got a 28" bar on it in a 20" piece of oak...which is all I have to test. maybe a longer bar would bring out the popping? either way, I can't replicate it and I don't have any more time for the next few weeks to mess with it. ...unless I take it to dads tomorrow and find a tree to cut on lol.

I dunno. it revs fine, runs fine. who knows.

 

[Chainsaw Jim]

Rings needed to seat.

 

[Mattyo]

maybe... interesting idea
.... comp is unchanged at 185-190

 

[Mattyo]

i haven't run it since it was popping a few week ago ..haven't had the time. but I did get it warm today.

and yes, it has very little time on it, so its possible the rings were seating?

 

[mdavlee]

346 coils on the 390.

Fixed for you

 

[Jimmy in NC]

Raise the pop off pressure, the needle is opening to easy and dumping extra fuel. Making your four stroke tune actually to lean in the cut.

Because it dumps fuel almost like a limited carb, then you lean it out to 4 stroke appropriately and then it's too lean in the cut.

Had an 880 doing that the other day. Blubbering like crazy but turning 12,800. Would not pull at all. New 088 carb and it is happy at 12,000-12,200.

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[Duane(Pa)]

Fixed for you

Damn...Only missed it by four...

Guess he has a sh1t ton of 390 coils cause the blue 346 coil makes them go more better...

 

[mdavlee]

390 coil is 13k limiter. 372 13.3k. 346 14.1k

 

[Moparmyway]

Had an 880 doing that the other day. Blubbering like crazy but turning 12,800. Would not pull at all. New 088 carb and it is happy at 12,000-12,200.

Dibbs on that blubbering carb ........

 

[Jimmy in NC]

Dibbs on that blubbering carb ........

Vendor is giving a good credit for the stock 880 carb. The 084 they sent me is going back too... so no extra big carbs floating around.

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[Moparmyway]

Vendor is giving a good credit for the stock 880 carb. The 084 they sent me is going back too... so no extra big carbs floating around.

 

[peter92]

My 94 seems to mill happily at about 8,400-9,000 but very much wide open throttle.
A skip in ignition dumps unburt mix into the ex port and muff... then bang, that's my .02 (or IT).

That RPM , is that in the cut

 

[danimal]

Would think so..

 

[Wolverine]

That RPM , is that in the cut

Yep.

 

[Wood Doctor]

Amazing to me how many "popping" troubles with big saws are electronic failure. Usually it's the IM. Seldom does the plug fail. Wiring shorts or switch failure cause most of the rest. Usually you can leave the engine alone.