Jonsered 630 S idle question

[hersnsh#590]

I have an older J'Red 630 S that I like and use regularly.  It has developed a quirk of idling very fast when it gets warm.  I've had the carb ultra sound cleaned, the saw runs better, but still idles fast when warm/hot.  I have run it with the high idle for awhile to see if the problem goes away, and it sometimes does.  Allowed to cool, and it idles fine again until I work it hard, and it high idles again.

The high idle isn't safe, and I'm frustrated I can't fix it.  I've backed the idle screw way out, and cut down on the high carb set screw to no avail.  I'm at the point of thinking of a new carb.  Any thoughts?

Thanks
Dale

[sawguy21]

It is developing an air leak downstream from the carb as it heats up. Ensure the gaskets are in good shape and the insulator is not cracked.

[hersnsh#590]

SawGuy:  Thank you, I'll head in that direction.

Dale

[sablatnic]

Most likely the crankshaft seals, a known defect on those saws. And replace the two thin o-rings too. And make sure not to lose the x-ring on the oil pump.

[sablatnic]

I just grabbed a Partner S55 today to do a bit of cutting - it showed the same symptoms, so I will try to get parts for it. Will tell how it goes. 

[sablatnic]

Ok, it wasn't the crankshaft seals on my saw. I found a cracked fuel line and replaced it, but that didn't help. I cleaned the carburettor, that didn't help either. Then I went to the shed, and found another S55, and with the carburettor from that I got my "good" S55 running. 
Don't know if that can help you, but it helped me.