Jonsered 670 Champ

[kcjones]

Picked a very nice up this week. It seemed it the carb adjusted. Sounded too lean. Smash the throttle and it wots nicely for split second then screams. Sounds too high rpm to me. I adjusted high jet out to 2 turns,didn't change anything. What does everyone think the issue might be.

 

[RED-85-Z51]

Got a tach?

Sent from my LM-G820 using Tapatalk

 

[Bob Hedgecutter]

Air leak.

 

[kcjones]

When I picked it up it started fine, idled fine, oiled fine. At idle it i turned it on both sides, upside down, bar straight up, bar straight down and everywhere in between. Didn't seem to effect anything.

 

[Bob Hedgecutter]

When I picked it up it started fine, idled fine, oiled fine. At idle it i turned it on both sides, upside down, bar straight up, bar straight down and everywhere in between. Didn't seem to effect anything.

So you tried the redneck test and nothing was up- try a mightyvac vacuum test and or a pressure soapy water test.
Could be a carb issue..... maybe...... but need to vac test the powerhead and intake to rule out air leaks from seals, gaskets and manifolds first.
The vintage of that saw lends itself to worn out rubber, paper and plastic bits if it has not been well maintained during its lifetime.

How about popping the muffler off and taking some photos of the exhaust side of the piston for us?
If you keep running it, maybe long enough to get a tach reading and it does have an air leak- you just might make a fairly cheap repair a whole lot more expensive!