How exactly do you tune a 4mix?

[FergusonTO35]

Yes, my 91 has a bike handle and support strap. It's awfully big not to. I'll have to ask my Stihl distributor buddy if he thinks a cruise control trigger can be installed. Or, if there is room on the throttle cable, I could just install a cable stop to hold it at my desired RPM.

 

[hacskaroly]

Yes, my 91 has a bike handle and support strap.

I have the 91 without the bike handles (the 91R wasn't an option at that time where I worked). The standard strap is too short for me, so I just free hand the thing. It does get heavy after a while and sometimes the power head hits the underside of my arm, then the muffler wakes me up!!

 

[FergusonTO35]

The strap it came with was laughably short, so I added extra length to it.

 

[bogieboy]

That's my one and only gripe about my FS-91. I use it exclusively with a blade and it bounces off the rev limiter constantly at WOT. It's not only annoying but I can't imagine it's good for the engine. Runs smooth at about 60% throttle and still has plenty of power. I wonder if there is a way to put the cruise control dial on it like some of the bigger ones have.

Tune it just rich enough to not hit the limiter. I run a blade on my fs130, and tune it to just under the limiter

 

[lilspenny]

How would you go about tuning something like a fs110?

How would you go about tuning something like a fs110?

If I can crank it I prefer to dial in the high speed first by running wide open and turning the H screw. Then adjust the L screw .... Consider this the "pick up rpm" screw. Turn this until there is the smoothest/quickest acceleration from idle to top speed. Finally, adjust your throttle wire for idle speed. Adjusting valves is, from my 20 years of ownership, not as likely to be a tuning issue as the carburetor. If the above mentioned carb adjustment does not work start looking for bad gas, fuel filter, fuel lines, impulse line, dirt in carb, or carb replacement. Always check for spark and clean air filter/exhaust pathway prior to carb adjustment. Pull the muffler to make sure exhaust port is clean. The H screw may need adjustment after each change of 2 stroke oil.

 

[SawAddictedFarmer]

If I can crank it I prefer to dial in the high speed first by running wide open and turning the H screw. Then adjust the L screw .... Consider this the "pick up rpm" screw. Turn this until there is the smoothest/quickest acceleration from idle to top speed. Finally, adjust your throttle wire for idle speed. Adjusting valves is, from my 20 years of ownership, not as likely to be a tuning issue as the carburetor. If the above mentioned carb adjustment does not work start looking for bad gas, fuel filter, fuel lines, impulse line, dirt in carb, or carb replacement. Always check for spark and clean air filter/exhaust pathway prior to carb adjustment. Pull the muffler to make sure exhaust port is clean. The H screw may need adjustment after each change of 2 stroke oil.

It's working just fine I've just never tuned it. I understand everything but how to set the high speed currently.

 

[SawAddictedFarmer]

Is just under the limiter fine or is that going to be too rich?

 

[lilspenny]

It's working just fine I've just never tuned it. I understand everything but how to set the high speed currently.
[/QUO
Do you have the correct tool? If not, let me know. If so, turn it until it at max rpm. You can hear it.

 

[SawAddictedFarmer]

Thanks! I have a Dremel and a screwdriver.

 

[lilspenny]

Thanks! I have a Dremel and a screwdriver.

Not good. Genuine OEM Stihl 5910 890 2307 4MM Specialty Carburetor Screwdriver... Or possibly Genuine Stihl Screwdriver Adjust Tool - 5910 890 2314 if newer size. Ebay... As Stihl dealers usually will not sell them.

 

[SawAddictedFarmer]

Not good. Genuine OEM Stihl 5910 890 2307 4MM Specialty Carburetor Screwdriver... Or possibly Genuine Stihl Screwdriver Adjust Tool - 5910 890 2314 if newer size.

I already slotted the screws with a super thin cut off wheel. There's plenty of metal left and the screwdriver fits nicely. I do have a kit of specialty tuneing screwdrivers if I need them.

 

[lilspenny]

I already slotted the screws with a super thin cut off wheel. There's plenty of metal left and the screwdriver fits nicely. I do have a kit of specialty tuneing screwdrivers if I need them.

10-4

 

[lilspenny]

I already slotted the screws with a super thin cut off wheel. There's plenty of metal left and the screwdriver fits nicely. I do have a kit of specialty tuneing screwdrivers if I need them.

Gotcha ..... There are so many varieties of screws that many times the correct driver will not be in the kit.

 

[bogieboy]

Is just under the limiter fine or is that going to be too rich?

I ha e been running my fs130 there for 8 yrs now, and have yet to foul/replace a spark plug, running hp ultra mixed at 40:1

 

[lilspenny]

I ha e been running my fs130 there for 8 yrs now, and have yet to foul/replace a spark plug, running hp ultra mixed at 40:1

Is just under the limiter fine or is that going to be too rich?

Run out the max (with guard) string length then wide open. That should not trigger the rev limiter.

 

[lilspenny]

I ha e been running my fs130 there for 8 yrs now, and have yet to foul/replace a spark plug, running hp ultra mixed at 40:1

Same plug for 8 years?

 

[EFSM]

Is just under the limiter fine or is that going to be too rich?

Depends on the line style, diameter, and length.

 

[bogieboy]

Same plug for 8 years?

Yep... if it runs it stays LOL it gets checked for wear about 2x a year and still looks good.... in that time i have had to adjust the valves about 4 times...

 

[lilspenny]

Yep... if it runs it stays LOL it gets checked for wear about 2x a year and still looks good.... in that time i have had to adjust the valves about 4 times...

What was the reason you had to adjust the valves?