[Skido]

I just picked up an abused FS 90r for $90 and it needs some TLC. The High and low tabs were pulled off. Does anyone know how many turns out from CLOSED on the H and L is the suggested settings?

Also it starts great if I hold the throttle as I pull but won't start without the throttle being held.

Finally it is reving up while idling and sometimes going into full acceleration.

When I got it idling smooth, it died on acceleration.

So you can see I have some work to do. I did check the plug and made sure the gap is set correctly. I also pulled the air filter and it looked fine.

I guess my first question is:

What should I work on first?

1) Getting it to start with no throttle.
2) Getting it to idle smoothly
3) Getting it to accelerate smoothly and appropriately.

And how would you suggest I tackle each problem?

Thanks in advance!

 

[dutch1]

A few random thoughts:

1. You made no mention of replacing or checking the condition of the intank fuel filter. The filter may allow sufficient fuel to pass for idle conditions but not enough for full throttle.

2. 1 1/4 to 1 1/2 turns open as a starting point. Adjust the low speed needle first then the high speed. If you readjust the low speed, readjust the high speed as the high speed adjustment is dependent upon the low speed.

3. Full throttle is the preferred starting procedure.

4. The FS90R is a four stroker and I believe Stihl has a recommended time interval for valve adjustment. I don't recall the recommended valve clearance but a Stihl tech will likely show up with some specs. Stihl had a feeler gauge for their equipment but I don't recall what the measurement was for certain.

5. Stihl had some problems with their 4 stroke technology. I haven't been around enough of it in the last 2 or 3 years to know if they have solved their problems or not.

A Stihl guy can likely provide more info.