Stihl 066 Redlight Rebuild Help

[emf123]

Hey guys, I've been working on an 066 Magnum red light version and need some help. I picked it up at an auction, so I don't have any history on it, but it's got good compression at 150+ psi. It would pop but not run so I figured I'd rebuild the carb and go from there. I also pulled the muffler, piston looks great, and did a muffler mod to it, I'll post pics shortly.
Anyway, onto the carb. It's got a Walbro WJ41 so I got carb kit K15-WJ. Installation was straightforward, one thing that I thought was a little unusual was that fulcrum lever has the fork to attach to the diaphragm but the diaphragm doesn't have the notch to hook it to. I put it together anyways because that's the way the original was. When I first went to fire it up, it popped after a couple of pulls with the choke on. Set it to half choke, pull and it fires right off, then as I pull the trigger, it just dies. Ok, I try this a few more times, same result. I got the high and low speed needles at 1 1/4 turns out, tried turning the low out, no effect.
So I set it aside, and came back to it later, which was tonight. I pulled the carb, checked the fulcrum height, it was good, got the gasket/diaphragm order correct, pulled the needle out and made sure it was clear and alright. I also put the new welch plug in since I didn't do it originally. Tried starting it again, and same result. Pulled the carb again, this time I changed the fuel pump diaphragm to the black one that was it the kit. Same result.
I'm out of ideas at this point, any help would be appreciated!
Thanks,
Eric

 

[Full Chisel]

Did you replace the fuel lines?

 

[Laslabjohn]

Also when you rebuilt it did you replace the metering inlet needle? If so put the old one back in. Alot of times the new needle will not seal.. I have had this happen on several saws. Item a in this pic.

 

[jmssaws]

Gasket on first then the diaphragm?
Pump on first then the gasket?

 

[jmssaws]

When it's running lean the low side and see if it gets better.
I bet it's fat and not lean

 

[emf123]

I didn't change the fuel line yet. It really sounds like it's going to run but as soon as I hit the trigger it just dies, can't feather it or anything. I did replace the inlet needle with the new one. The fulcrum lever is in the right way, the spring seated into the dimple. The gasket/diaphragm is correct. I didn't try leaning the low side, that seemed opposite of what I normally have to do. That's a couple more things I could try I guess! Anyways, here's some pics.

 

[Laslabjohn]

Put old needle back in and try it.

 

[jmssaws]

It's either fat or has a big airleak
How long will it idle?

What style boot flange? 2 metal rings or a metal plate and gasket?

Turn them to 1 and 1 or 3/4 and 1

 

[emf123]

It won't idle at all, as soon I touch the trigger it dies. I don't see any cracks in the intake boot but I haven't had it off. There's no gasket between the carb and flange. I'll give it another go tonight and see what happens.

 

[jmssaws]

Sounds like your metering arm is off

 

[emf123]

Yeah, I know what you mean. The carb diaphragm don't have the notch to attach to the arm though! Why do they send the arm with the notch in it for the lever if the diaphragm won't hook to it?

 

[jmssaws]

Did it run like this before you rebuilt the carb? Why did you rebuild it?

 

[emf123]

Well, switching the needle back to the original didn't have an effect and neither did having the L side at 1 turn. I'm onto replacing the carb boot and impulse line. I'm sure I'm going to need some help getting things put back together!

 

[earlthegoat2]

I think you need to do a full fuel system overhaul. Clean the tank out and replace the fuel filter. Replace the fuel lines and impulse line. Intake boot as well. New mix with non ethanol gas or motomix.

When you took the needle out, did you blow down the hole with air? If that passage has an obstruction that will clear it out. Did you take out the jet/nozzle and clean that good?

 

[Thr0_NChiPz]

If you're still needing help troubleshooting your problems with the Saw just let me know. Thanks

 

[emf123]

I finally got back to this project. Put new intake boot, impulse line, and fuel line on. Re assembly went pretty good, it was seriously filthy so it needed a good cleaning. Went to fire it up, and it did the same thing. Fires off, then as as soon as you hit the trigger it just dies. So, going to blow some air through the needle inlet and try it again, but I'm not optimistic. Are the aftermarket replacement carbs on ebay any good or should I go with the Tillotson for $50?
Thanks,
Eric

 

[jmssaws]

Have you changed the coil?
Grab the flywheel and wiggle,same with the clutch and see if there's any play.

Under the carb is there 2 metal rings or 1 flat plate and a gasket?

There's 2 different carb housings and each takes there own boot and hardware.

I still think the metering arm is to high.

You need a carb off a running 066 064 660 so you can eliminate some what ifs

 

[ZeroJunk]

Might want to make sure somebody hasn't gotten the coil and flywheel mixed up.

 

[emf123]

OK, got a new Tillotson carb and more of the same problems, maybe a little better but I had to open the low side needle way, way out to get it to idle. Then it was almost running like that, but it still sounded like it needed more low side, like it would bog when I pulled the trigger fast but I could ease into it and get it to rev up. Then it just quit altogether and wouldn't restart and I was tired of it, and I knew it wasn't right so I figured I'd better do something else for awhile.

 

[windthrown]

As mentioned above, the original coils on these had issues with the limiters (which is what set off the LED). They can also fade badly and drop off with time. I would replace the coil with the generic one that was not limited. Its the coil that is shown dropped down in the list of 066 coils in the file attached. They were used on many pro saws from the 026 on up. Also check for shorts in the wiring. If the LED leads are still there (if it has the original coil) they may be cracked or grounding out someplace.

As for the bearings, they can and do go out on these. As said above, yank on and try to wiggle the clutch and flywheel to see if there is ~any~ bearing play. My red light 066 blew the clutch side bearings because the arbor company that I bought it from over-tightened the bars when the chains were hot.