Carb adjustment on 064

[t_andersen]

Hi Guys,

I finally got my 064 running after having changed the carb. I have now adjusted it. The well-known madsen1 link on carb adjustment says that the high speed fuel adjustment screw of a 066 should simply be set to give 13000 rpm at full throttle. However, the Stihl service manual says (because of the electronic rpm limiter) to first turn the high screw two turns counterclockwize, and then slowly turn the screw clockwise until an rpm of 12000 is reached, and then give it yet another 1/2 turn.

I guess that this must be done with the bar and chain on the saw? I only have a 32" bar and with a setting of 1 1/4 turn it runs 11400 rpm. If I would take it all the way to 12000 and give it yet another half turn as the service manual says, it seems to me that it would be too lean.

Does it make sense to adjust it to 11400 with a 32" bar and leave it there?

Thanks
Tom

 

[Lakeside53]

Yes, with bar and chain.

First though : Exactly what coil do you have? is it the electroniclly limited verison or not... it makes a big diffence in how you approach the problem. Also, exactly what carb do you have? 1/2 turn on an OLD carb is NOT the same as 1/2 turn on some of the newer carbs that start 2 turns out.

If it is the limiting type, yes, it makes sense to do as you suggest. I also have the same misgiving with the recommended adjustment even with the correct carb... It makes assumptions about the overall carb condition that could get you in trouble.

I'd set it to about 11,500 WOT, and then do some timed cuts with minor adjustments to the lean side until you are happy The problem with just trying to set it to 13,000 is that the coil will start to skip and you definitely be too lean...

 

[t_andersen]

Thanks lakeside53. It's the electronically limiting type, and the carb is a 1-turn Walbro.

 

[Lakeside53]

Thanks lakeside53. It's the electronically limiting type, and the carb is a 1-turn Walbro.

Do you know the exact Walbro carb number?

 

[t_andersen]

It's a Walbro WJ67, Stihl no 1122 120 0621

I appreciate your help!

 

[Lakeside53]

So, do you have an 066 or and 064? That carb was released on the 66, but your thread title says 064.

I have a very good technical contact inside of Stihl. I'll call him on Monday and discuss their 'recommended" tuning method... It's been bugging me for a while, and I haven't been following it. I've been using a combination of tach and "ear", and erring on the conservative side.

 

[t_andersen]

I have a 064 with "digital ignition". The carb tuning instruction at the Madsen1 web-site covers only 066 and not 064. My service manual is for 064.

It seems to me that the rpm limiter of the "digital ignition" may screw up carb tuning if one follows the procedure of the Madsen site.

I've been using the saw for ripping over the weekend with the setting described above. Works fine but that's of course not a guarantee that it's correctly adjusted.

 

[Lakeside53]

I didn't get very good answers from my Stihl contact... but they will get back to me in a few days. The digital ignition is gone (I think from about 2000), and it is difficult to know what is the "best" adjustment. Best could be "power" or "longevity". Would be great to have both, but you may need to err on the side on "rich" to be safe. If you've been running it, check the plug for a nice light brown color; white means very lean, and black means too rich. The problem with plug color on saws with the limiting ignition is that IF you limit (over rev in or out of the wood) the spark skips, a lot of unburnt fuel enrichens the mixture, and , and this will blacken the plug.

I'm emailing you a great Flywheel/coil chart for 064/066. Please let me know exactly (use the names from the chart) which flywheel and you have.