A couple of buddies had non-working MS290's.
Number 0ne had someone pull the muffler (breaking the studs in the process) and they saw some scratches on the piston, and told him it was junk. Although I had never done a 290, I figured how bad can it be, so he bought a Hyway 390 kit to rebuild it with. Taking it apart, the piston had only the finest carbon scratches on it, no aluminum transfer, but the ignition module did have a broken wire - obviously the reason it didn't start.
I put it all back together with the new jug, piston and seals, and pin bearing, checked all of the rubber - it was fine, no breaks or cracks, and put on the carb. Now, this one had come partly disassembled, and had no outside retainer plate or nuts on it for the carb, I just retained it with the air filter.
It starts and runs at high speed just great, but won't idle at any speed that won't stop the chain from turning. I even went so far as putting a new carb kit in it as the metering diaphragm was questionable, all to no avail.
This then gives way to Number Two:
Since the piston and cylinder from One was is good shape, and Two had no compression, I asked One's owner if I could just slap it on Two's saw. They're friends, so of course he said OK.
All went together well, compression was just a bit low for my liking - the pull the cord test, I didn't bother to put a gauge on it - but it ran well and idled well. This carb had the retainer plate and nuts on the outside.
Sooooo..... I swapped carbs, even putting on the plate and nuts on ONE. Since this carb had the limiter caps, I didn't bother to try adjusting it. I runs fine at high speed, but won't idle.
This leads me to think that something other than the carb is the culprit, and I'm missing it. Seals not seating? I have no vac pump, is there another way to test this?
Anyone have any other ideas?
TIA,
Dusty
Number 0ne had someone pull the muffler (breaking the studs in the process) and they saw some scratches on the piston, and told him it was junk. Although I had never done a 290, I figured how bad can it be, so he bought a Hyway 390 kit to rebuild it with. Taking it apart, the piston had only the finest carbon scratches on it, no aluminum transfer, but the ignition module did have a broken wire - obviously the reason it didn't start.
I put it all back together with the new jug, piston and seals, and pin bearing, checked all of the rubber - it was fine, no breaks or cracks, and put on the carb. Now, this one had come partly disassembled, and had no outside retainer plate or nuts on it for the carb, I just retained it with the air filter.
It starts and runs at high speed just great, but won't idle at any speed that won't stop the chain from turning. I even went so far as putting a new carb kit in it as the metering diaphragm was questionable, all to no avail.
This then gives way to Number Two:
Since the piston and cylinder from One was is good shape, and Two had no compression, I asked One's owner if I could just slap it on Two's saw. They're friends, so of course he said OK.
All went together well, compression was just a bit low for my liking - the pull the cord test, I didn't bother to put a gauge on it - but it ran well and idled well. This carb had the retainer plate and nuts on the outside.
Sooooo..... I swapped carbs, even putting on the plate and nuts on ONE. Since this carb had the limiter caps, I didn't bother to try adjusting it. I runs fine at high speed, but won't idle.
This leads me to think that something other than the carb is the culprit, and I'm missing it. Seals not seating? I have no vac pump, is there another way to test this?
Anyone have any other ideas?
TIA,
Dusty
