What's on your bench today?

[adw]

If as you say any air leak will cause a problem how do you explain the Partner saws with a jet in the clutch side crank journal from inside the crankcase to the out side to lubricate the clutch bearing? this was also used on some Husqvarna machines with no running issues.

[Pint]

On the 266 - may be worth changing the clutch side seal, itis the typical suspect but depends on how much mechanics you do. If you are tempted to run it, give the H screw 1/4 - 1/2 extra turn out but wouldn't recommend running it until a pressure/vac test has been done on it, especially if it currently has good compression!

 

Any air leak will cause a lean mix and at high revs, the saw will over rev, this causes heat and enough to start melting the piston on the exhaust side and this transfers on to the cylinder and POP, the end of your saw running:thumbdown:

 

Thanks Spud for the advice.

Symptoms are it won't idle properly despite tweaking the L and H screws. I do the usual screw both in and then 1 turn out. When you let go the trigger it takes a few seconds to slow down it's like it still wants to race on. Proper dodgy. Hence I'm not using it until I can get the spanners on it

[Eddy_t]

If as you say any air leak will cause a problem how do you explain the Partner saws with a jet in the clutch side crank journal from inside the crankcase to the out side to lubricate the clutch bearing? this was also used on some Husqvarna machines with no running issues.

 

 

Any air leak is a problem, as it draws air into the cylinder and leans out the mixture

[adw]

I know the theory Eddy, but cant explain the Partner thing, if you try to pressure or vacume test them they leak like a seive, but it does not upset the running, i have fitted the same style crank from the 268K into a 266XP and no problems, with the added avantage it lubs the drum bearing from a small amount of the fresh charge in the crankcase.

[Adamam]

B*stard 026 still not sparking!

 

Switched flywheel, switched coil, switched HT lead, detached kill wiring etc. Checked resistance and continuity, switched plugs.

 

Tested against known working set-up and can't find anything that differs.

 

Tested ground from cylinder in case somebody managed to isolate that accidentally.

 

Utterly bizarre. Must be something obvious, albeit less common, but cannot get the ruddy thing sparking!

 

Gah!

 

Grrrr!

 

Etc!

 

[Eddy_t]

I know the theory Eddy, but cant explain the Partner thing, if you try to pressure or vacume test them they leak like a seive, but it does not upset the running, i have fitted the same style crank from the 268K into a 266XP and no problems, with the added avantage it lubs the drum bearing from a small amount of the fresh charge in the crankcase.

 

 

It could be due to the fact that cut-off saws run super rich, being limited to 10k rpm, although I would imagine there's something to stop backfeed or the crank would be filled with dust or slurry

[TGB]

Adamam - are the plugs you're using sound? No tiny cracks in the insulator or inner electrode, the gap correctly set and the thermal nut making good contact.

[spudulike]

I know the theory Eddy, but cant explain the Partner thing, if you try to pressure or vacume test them they leak like a seive, but it does not upset the running, i have fitted the same style crank from the 268K into a 266XP and no problems, with the added avantage it lubs the drum bearing from a small amount of the fresh charge in the crankcase.

 

Sounds like a similar system that is used on the 3120XP, there is a one way valve fitted in the crankshaft that can fail, last 3120 in had the hole plugged as it was leaking!

[Adamam]

Adamam - are the plugs you're using sound? No tiny cracks in the insulator or inner electrode, the gap correctly set and the thermal nut making good contact.

 

Yep. Tested 4 in another saw and no dice from any of them.

 

Am almost certainly being an idiot.

 

Tried all combinations of 2 coils, 2 flywheels, several ht leads.

[adw]

The one way valve was added, but the orginal 268K Partner K650, and 650,550 chainsaws had nothing just a brass jet, never could really understand why it never effected the idle, as air leaks usually increase the idle speed