Stihl 066 run-on

[NPKenny]

This is a recently finished Stihl 066. I’m having trouble tuning out the the run-on as the saw returns to idle and the off-idle bog.

The saw is ported with machine work. Complete rebuild. Meteor piston. 461 coil.

It will idle all day. It seems like it settles into that idle nicely, but only after a lean run-on for 1-2 seconds. Is this carb or coil? Outside chance of a crank issue? Tank vent?

 

[dirter]

Run-on and bog are both signs of lean L screw.

 

[av8or3]

Or clogged/dirty main jet (orifice).

 

[Wonkydonkey]

I'm Just curious as to why fit the 461 coil ? On the 66

Cheers

 

[Stump Shot]

Open up the throttle plate slightly and set your Lo speed properly then reset the throttle plate for proper speed.
Recheck Hi speed operation for possible final adjustment.

 

[NPKenny]

Thank you for the solid responses.

Run-on and bog are both signs of lean L screw.

Good point. I have moved the L screw from 3/4 turns to past 3-turns trying to chase the lean bog. The run-on changed slightly, but was still present. The bog was slightly better at the 3/4 - 1 turn range, but I expect zero bog without a chain on the saw.

Or clogged/dirty main jet (orifice).

Thank you!

I'm Just curious as to why fit the 461 coil ? On the 66

Cheers

The 066 coil was delaminated. It is a somewhat rare post configuration. I had a few new 461 coils and was able to fit it pretty reasonably.

Open up the throttle plate slightly and set your Lo speed properly then reset the throttle plate for proper speed.
Recheck Hi speed operation for possible final adjustment.

Regarding the throttle plate, are you talking about increasing the idle adjustment screw or slightly increasing the cut-out on the plate itself Thank you!

 

[NPKenny]

Stihl 461 coil on 066

The 066 is an early model with an aluminum flywheel. The coil is delaminating and I have these 461 take-off coils I bought just for this. Now I am figuring out the best way to mount the Stihl 461 coil. It looks like the top hole in the coil is the reference to maintain timing. All three bolt...

opeforum.com

 

[ManiacalMark]

Too lean, timing is probably off as well. What rare coil did it have? Also if it’s an 066 you’ve got the wrong starter and flywheel on it.

461 coil is rev limited, if you have a flywheel that’s for a non-limited coil you could have a timing problem for sure.

 

[jacob j.]

The 066 coil was delaminated. It is a somewhat rare post configuration. I had a few new 461 coils and was able to fit it pretty reasonably.

Is the 461 coil limited? I have no experience with them. If so, it may require a slightly different carb tuning curve.

 

[jacob j.]

Too lean, timing is probably off as well. What rare coil did it have? Also if it’s an 066 you’ve got the wrong starter and flywheel on it.

461 coil is rev limited, if you have a flywheel that’s for a non-limited coil you could have a timing problem for sure.

I think he started with a later 064 carcass. Two of the coil mounting holes in the case match the 1122 400 1300 dogleg coil.

 

[farminkarman]

Is the 461 coil limited? I have no experience with them. If so, it may require a slightly different carb tuning curve.

Yes, they are limited.

 

[NPKenny]

I think he started with a later 064 carcass. Two of the coil mounting holes in the case match the 1122 400 1300 dogleg coil.

Yes, it is a short case. Quite different configuration than the 660's I have worked on. This saw is a real resurrection effort.

 

[qurotro]

My plastic flywheel 660 does NOT like 461 coil. I use the 1300 coil and its fine. Dunno why, the timing is different ?

 

[jacob j.]

My plastic flywheel 660 does NOT like 461 coil. I use the 1300 coil and its fine. Dunno why, the timing is different ?

Your plastic flywheel saw would likely run best with the 1122 400 1314 coil. It is specifically made for the plastic flywheel saws.

 

[ManiacalMark]

If you can’t find a coil maybe make a mount for the standard 1300 coil, or swap flywheels. Keyways are in different spots in the metal flywheel saws depending if it’s rev limited or not. I’d bet mix matching the two won’t tune out.

 

[NPKenny]

On the original saw in question, it is an aluminum flywheel saw that originally had the dogleg coil. By the time I ended up with it, there was no external trigger. Would the 046 coil be a more likely candidate?

Is the run-on symptom something that can indeed be coil related?

 

[NPKenny]

If you can’t find a coil maybe make a mount for the standard 1300 coil, or swap flywheels. Keyways are in different spots in the metal flywheel saws depending if it’s rev limited or not. I’d bet mix matching the two won’t tune out.

I have seen the mounting strategies for the 1300 coil. Good idea.

 

[farminkarman]

On the original saw in question, it is an aluminum flywheel saw that originally had the dogleg coil. By the time I ended up with it, there was no external trigger. Would the 046 coil be a more likely candidate?

Is the run-on symptom something that can indeed be coil related?

The run-on is likely being caused by the p&c getting too hot which could be from too much timing advance or being lean. I would take other’s advice and try a different coil.

 

[Stump Shot]

Thank you for the solid responses.
Regarding the throttle plate, are you talking about increasing the idle adjustment screw or slightly increasing the cut-out on the plate itself Thank you!

Turn in the idle speed screw, turn out the Lo screw and find a happy medium.

 

[jacob j.]

On the original saw in question, it is an aluminum flywheel saw that originally had the dogleg coil. By the time I ended up with it, there was no external trigger. Would the 046 coil be a more likely candidate?

Is the run-on symptom something that can indeed be coil related?

An 046 coil has the timing curve for the poly flywheel, so that might not work so great with your setup.

Do you still have the dogleg coil? If so, I would start there. As Mark mentioned, there are different flywheels for the 064/066, depending
on which coils they had originally. If your carcass came with the Dogleg coil, then it's likely timed for the standard (universal) coil as well.