Benjo
Some Guy
- Local time
- 9:09 PM
- User ID
- 1088
- Joined
- Mar 27, 2016
- Messages
- 86
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- Location
- New England
Running out of ideas on this one, any help is welcomed!
This is only the second 261 v2 I've worked on, and also the second Stihl mtronic, so forgive any basics I've missed! I liked the first 261 I worked on, and ended up buying this one for myself to see if it would unseat my 550 as most-used in my collection.
Saw ran when I got it but didn't 4 stroke at WOT and when hot had an erratic idle. Eventually found the flywheel side bearing had spun on the crank and had a bit of play, so I split her and put in new:
Did another pressure/vac test (sealed between carb and boot if that's important). It's very tight, held 8psi for 2 hours with no drop including rotating crank by hand, left it with 15in/hg and it held unchanged for 2 hours, then after rotating the crank both by hand and with a drill(!) trying to get it to leak somewhere, then leaving it for 24 hours, it dropped to about 14. Even dunked the whole thing in water thinking there might be a super small leak somewhere that opens when warm...nada.
Opening the tank does nothing (and the vent is new), fuel filter is new and fuel flows easily...spraying carb cleaner at various points while running offered nothing notable.
My instinct is to target the coil/harness next, but that's fully into guessing/throwing part$ at it.
Anyone experienced anything similar? Any new ideas that are better than my idiotic "replace every part until it works" campaign?
Thanks again for any help!
This is only the second 261 v2 I've worked on, and also the second Stihl mtronic, so forgive any basics I've missed! I liked the first 261 I worked on, and ended up buying this one for myself to see if it would unseat my 550 as most-used in my collection.
Saw ran when I got it but didn't 4 stroke at WOT and when hot had an erratic idle. Eventually found the flywheel side bearing had spun on the crank and had a bit of play, so I split her and put in new:
- Crank bearings
- Seal kit (crank seals, case gasket, base gasket, aluminum case bolts)
- Crank (old one was pretty loose on the new bearing)
- Fuel filter
- plugged the decomp
- P/C look good, piston has some common wear but makes 155lbs compression and when put in the bore without rings it provides plenty of resistance pushing it in and out
- tank vent
- solenoid
- when that didn't work, an entire new carb (getting desperate...)
Did another pressure/vac test (sealed between carb and boot if that's important). It's very tight, held 8psi for 2 hours with no drop including rotating crank by hand, left it with 15in/hg and it held unchanged for 2 hours, then after rotating the crank both by hand and with a drill(!) trying to get it to leak somewhere, then leaving it for 24 hours, it dropped to about 14. Even dunked the whole thing in water thinking there might be a super small leak somewhere that opens when warm...nada.
Opening the tank does nothing (and the vent is new), fuel filter is new and fuel flows easily...spraying carb cleaner at various points while running offered nothing notable.
My instinct is to target the coil/harness next, but that's fully into guessing/throwing part$ at it.
Anyone experienced anything similar? Any new ideas that are better than my idiotic "replace every part until it works" campaign?
Thanks again for any help!