Stihl 260 Pro & 391 issues after rebuild...

[jiggysmb]

Figured I would condense these. I have rebuilt about a dozen Stihls due to scored pistons, leaking crank seals, etc, so I have some background. I was recently given 2 saws and here are their stories.

Stihl 260 Pro -low compression and broken handle but started and ran ok. I replaced the cylinder/piston, gas line/filter, rebuilt the carb and used an after market (chinese) fuel tank/handle. The carb on this saw was a little different than most. Fixed High screw on carb, and metering diaphram had a little nub to hit the needle lever. This area I was unsure of, with the lever sitting down in a sump, should the lever sit flush with the lip around that area? Either way, the saw wont start unless I dump some fuel mix in the carb and it will run for a couple seconds. Wont start at all pulling. I thought it was a fuel line issue, so I replaced the Chinese fuel line with a stock line and still wont start. Impulse line also came on the handle housing but fits tight. I wasnt sure where the Low screw on the carb should be so I tried 1/4 turn and full turn out with no luck. Any idea where the carb with no H screw should be set on the L side?

Stihl 391 - This saw overheated and needed a complete rebuild. It was a construction company's demolition saw, I dont know how it ran, it only had 2 loose screws holding the cylinder on. It would run for a second then cut out, and had 120 psi. Needed cylinder/piston/seals, fuel line, clutch, sprocket, carb kit, oil pump/worm. The saw will consistently start (150psi) but will only run at low RPMs with throttle held in, as soon as it is released saws cuts off. I am pretty meticulous about keeping parts together, but looking at some pics on ebay I see the carb has a black ring on one side? Mine does not have this. Also, I used the carb turns 1 L & 3/4 H  that are listed on the filter cover, but it seems like a carb issue, so I tried one off a working 391 and the saw acted the same exact way. Any ideas?

[dougand3]

260 - I'd try a fully adjustable Walbro clone for ~$10.
391 - Muffler/Screen is clear? Try real rich - 2.5 L  &  2 H and see if can get a throttle up.

[jiggysmb]

Thanks Dougand3, carb ordered and I will let you know how 2 turns out works on the 391!

[jiggysmb]

Unfortunately 2.5/2 turns out just made fuel come out the exhaust.

[dougand3]

If another known good 391 carb did not allow throttle up - the answer lies elsewhere. Easy start, good idle and boggy/no throttle up is a classic clogged exhaust symptom.
If the known good carb is a red herring - could be needle lever is too high = floody condition even on lean H-L screws.

[Air Lad]

Had a problem seat before on my 039
One minute no fuel. Tiny tweak and she floods
new needle fixed the problem
May not be the answer to you're problem
Good luck