Chainsaw

[caterpillar guy]

Have not done a pressure or vacuum test at this time. Might be the next option after swapping carb from a different running saw.

 

[kevinj54]

If it does not fire on gas squirted into cylinder I doubt a carb change will help.

 

[buickanddeere]

Non resistor plugs are more durable

 

[BarnyardEngineering]

Well now an update on the saw. New coil and gas through the filter and straight in the carb and no start key is not sheared nor gas in the plug hole still not start. Compression is at about 50-55 by gauge. Should still start though. Gas is not as pristine as I might like but is working fine in 3 other saws. All start and run fine with it so I'm ruling out the gas also tried some different gas and still no start. Spark is fine with both just an arc and through a spark tester. Only thing I can think of is either the carb or the line.Gas will spew out of the line at the carb when carb is removed so I'm thinking that should rule out lack of fuel to the carb. Also would think it would rule out a hole in fuel line and pulse line. Vent is open and can blow or suck air through it both ways. At a loss at this point.

Sorry, but 50-55 is roasted. Pull the carb and muffler and look for a scored piston.

 

[caterpillar guy]

I believe the scored cylinder would affect startinf and compression but a scratch i don't think would make a death knell for it. If here is one and why would it just stop running if not out of fuel and then not even pop or attempt to start. It will push pressure into the fuel tank and cause fuel to spew from the vent line if the check valve deal is pulled out of the line end. IF a saw engine is only going to run for 20 years or there about they need to come down a lot in price or parts need to come down a lot to fix them then. with mid range saws in the 500+ range they need to last more than 20ish years.

 

[504]

I think I need a coil for my MS290 saw. I was sawing the other day and it died/ran out of fuel. It was out or close to it on fuel so filled it back up. Have not been able to start it since. Used the other saw to finish up that day. IT would not spark when I tried it so disconnected the kill wire from the tab on the coil. IT then would spark. Spark seemed even and regular not sporadic. Cleaned it up some pulled the plug and scrapped it off with a very small screw driver to clean any debris on the plug. After disassembly of the saw today and cleaning better cleaning all connections except behind the flywheel. Looking at the wires I did not find any bare or frayed wires. I now have good looking spark on a regular interval is a bright blue one has gas/fuel and seems to smell in the plug hole when checking for spark. Still no start. Thinking maybe the coil or plug is going bad or is bad.

My spark plug story is a good friend and I went to pick up his new 400 cc Yamaha. Loaded it in my truck and drove 20 miles home and it would not start. The plug failed from the dealer to home. Put in on from my 250 and it started with the first kick.

 

[kevinj54]

It sounds like your tank vent is shot, they are a one way duck bill type.

The carb should suck fuel, not push into the tank. Are you saying there is a check valve in your filter?

 

[caterpillar guy]

Well I found the problem. The bearings are shot on the rod and letting the piston touch the bottom to the crank counter balance of the crank and also has hit something in the top so the rings are stuck in the ring lands. SO now it is a parts saw or get a new engine for it. Looking at engines I can get an aftermarket Farmtec for less than 40.00 complete just have to install and connect the pieces with the new engine in it. Can supposedly upgrade to a 310or 390 engine in it. Ant information on engines aftermarket or OEM are welcome. Would the upgrade in engine size be worth it?

 

[bweb]

Well I found the problem. The bearings are shot on the rod and letting the piston touch the bottom to the crank counter balance of the crank and also has hit something in the top so the rings are stuck in the ring lands. SO now it is a parts saw or get a new engine for it. Looking at engines I can get an aftermarket Farmtec for less than 40.00 complete just have to install and connect the pieces with the new engine in it. Can supposedly upgrade to a 310or 390 engine in it. Ant information on engines aftermarket or OEM are welcome. Would the upgrade in engine size be worth it?

My 290 shot craps after someone who borrowed it put straight gas in it "accidently". I bought a 390 cylinder and piston and used that. I did put a compression release plunger on it too. Works great.

 

[kevinj54]

So did it get straight gassed or suck in a bunch of dirt???

 

[caterpillar guy]

Well I could not say. I've not put straight gas in it and I have kept the air filter on it at all times except to wash it out dry and put back on. So if anything got in there it had to be while the filter was off or somehow got in the exhaust somewhere. Think I'm going to chance one of those cheap knock offs for it . Would not be out much if it ran a year or so and might have the world change in that time.

 

[caterpillar guy]

Current and probably conclusion to saw is the rod and bearings are shot from some rust that I don't know how got in there since it sets in the house at all times except when going out to use even in summer. Rod and mains are shot so would need a complete engine and not seeing what I think is probably a best option with those cheap $50-80.00 engines for it. Seems just s bit scary .I was thinking of them but further looking left me with some doubts for now. thanks all for input and ideas.

 

[kevinj54]

How long did it sit between use?? What oil were you using???

Last year I redone an old homelite that sat for 20 years in an unheated garage and no rust.

That saw was fed 32 -1 mix and cut a lot of wood before being parked. The insides still had a lite coating of oil.

 

[T.R.K.]

Unless you can declare you never used gas in your mix with ethanol in it, I would expect that to be the cause. Ethanol attracts water out of the atmosphere, when it gets enough water, the water and ethanol separate from the gas. The oil stays with the gasoline. Then when you run it, it runs fine on the Ethanol/water but is not getting any lubrication.

 

[caterpillar guy]

It might set from spring to fall or till I needed it to trim trees along fence rows in summer some years. I don't see how the fuel issue would not let the oil stick to the bearings and in the last couple years I had the engine housing off the bottom and while working on it I oiled the bearings and had no rust on them at that time so the rust got on them in that short of time . I also had to drain the oil out of it after having reassembled the engine housing to the engine with new seals on the crank. I suppose having touched the bearings could cause that though would not think so with the oil needing to be drained off to start. If the gas was the problem why has not all the other saws not been affected by it yet and some have been here longer with less run time or longer times between running. Like dad's 056 is only used when we need to cut larger trees with. Like over 30 inch. Some of this does not seem quite right to me .But stranger things happen.