Acceptable rpm variance at idle

[Trigger-Time]

What is a acceptable (recommended) rpm variance at idle after saw is warmed up? (not from day to day)

Some days I wish I had never bought a tach, it has made me almost anal about setting the L & H speed. I try to leave the tach at home when I cut wood............but some how it finds a way to go!

 

[THALL10326]

What is a acceptable (recommended) rpm variance at idle after saw is warmed up? (not from day to day)

Some days I wish I had never bought a tach, it has made me almost anal about setting the L & H speed. I try to leave the tach at home when I cut wood............but some how it finds a way to go!

Hmmmmmmmmmm do you have some variance or do you have some unstable idle. I've never seen a two stroke motor hold a exactly on the money idle, they all vary slightly up or down. Usually if all if fine you will still get a 100 rpm variance up or down. How much is your saw varying?

 

[Trigger-Time]

Hmmmmmmmmmm do you have some variance or do you have some unstable idle. I've never seen a two stroke motor hold a exactly on the money idle, they all vary slightly up or down. Usually if all if fine you will still get a 100 rpm variance up or down. How much is your saw varying?

Most are good as you say + or - 100 rpm or less, one maybe + or - 200 rpm
but one is very wild +350 or - 600 rpm, it runs good never bog's when I crack
the throttle, High speed is very stable, (It's a 026) I guess it's sucking air
some where. I quit running it, until I can find the trouble.

I was just wondering though...........Anal! :bang:

 

[timberwolf]

More highly modified saws and larger muffler openings make the idle drift a fair bit.

 

[Lakeside53]

I never tach the low end... and some do vary day to day, hot to cold etc etc.. As Timber says, plus if it's slightly too rich it will load up, and stagger.. My 361 isn't the smoothest idler... but my 066 and MS 200can tick over all day. A worn piston skirt can play havoc with some idles - like on a 200T..

As for your tired 026... a quick pressure/vac test will show all. Or, just replace the flywheel side seal.. 5-10 minutes...

 

[Trigger-Time]

More highly modified saws and larger muffler openings make the idle drift a fair bit.

timberwolf, I have read the thread you did about 026/260 muffler
mod (enjoyed it very much) I also have a 260 and as you said,
when I done the cover, made a diff. in the idle "drift"

 

[Trigger-Time]

I never tach the low end... and some do vary day to day, hot to cold etc etc.. As Timber says, plus if it's slightly too rich it will load up, and stagger.. My 361 isn't the smoothest idler... but my 066 and MS 200can tick over all day. A worn piston skirt can play havoc with some idles - like on a 200T..

As for your tired 026... a quick pressure/vac test will show all. Or, just replace the flywheel side seal.. 5-10 minutes...

My 361 idles very good.........but let it idle 30 sec or more it will
hesitate when I crack the throttle the first time from a idle
I can not adjust it out..........so I live with it.

 

[timberwolf]

On the 026 I have noticed this tendancy to hesitate when hitting the throttle after a period of idle. I think the cause of this is in the corrigations and shape of the boot. At iddle there is not enough air flow to keep fuel from settling in the carb boot, then as soon as the throttle is opened and flow increases, that pooled fuel is picked up throwing the mixture rich for an instant.

Like you say it is hard to tune this out, doing so puts it on the edge of being lean on the LS and the saw tends to rev up when sitting at idle and is slow to come down from WOT.

 

[windthrown]

Idle, and flywheel side seal

I never tach the low end... and some do vary day to day, hot to cold etc etc.. As Timber says, plus if it's slightly too rich it will load up, and stagger.. My 361 isn't the smoothest idler... but my 066 and MS 200can tick over all day. A worn piston skirt can play havoc with some idles - like on a 200T..

As for your tired 026... a quick pressure/vac test will show all. Or, just replace the flywheel side seal.. 5-10 minutes...

I just raise or lower the idle until the chain does not spin and the saw does not stall out when I set it down for a while. The idle speeds seem to drift around on all my saws.

Lake: if a flywheel side seal is blown, does that cause the black gunk to load up in the flywheel cover? I noticed a lot of black gunk on the inside of the flywheel cover on the 460 after I tested it. I could not figure out where else it could come from, and I did not spend much time debugging it.

 

[Trigger-Time]

I just raise or lower the idle until the chain does not spin and the saw does not stall out when I set it down for a while. The idle speeds seem to drift around on all my saws.

Lake: if a flywheel side seal is blown, does that cause the black gunk to load up in the flywheel cover? I noticed a lot of black gunk on the inside of the flywheel cover on the 460 after I tested it. I could not figure out where else it could come from, and I did not spend much time debugging it.

I know you ask, Lake......and I don't know..........But is the gunk, on the back side of the flywheel also?

 

[Lakeside53]

Lake: if a flywheel side seal is blown, does that cause the black gunk to load up in the flywheel cover? I noticed a lot of black gunk on the inside of the flywheel cover on the 460 after I tested it. I could not figure out where else it could come from, and I did not spend much time debugging it.

It can... but often you won't see anything, unless it's REALLY bad... Often the black gunk you see is just sawdust junk that's been mashed by the flywheel fins and sprayed back. If it's behind the flywheel near the seal, then it's likely.