Stihl 076 AV Super Limiter Problem?

[badbackjack]

I am working on a 076 that I think is a bit of a Frankensaw, mash of parts to make a complete saw. I got the saw with a box of parts 051/076. I have the saw working, it idles great and reves up fine but it cuts out at 3/4 throttle like a rev limiter is kicking in, it will not stall but the way it is running it would be useless for milling logs. It is an electronic ignition, could it have a wrong coil or could the coil be pooched? I am fine with buying a new coil but do not want to spend money on an old saw unless I know that is the problem. The saw clearly does not have a lot of hours on it by the condition of the piston and cylinder. Any replies are appreciated, thanks

 

[alexcagle]

I am working on a 076 that I think is a bit of a Frankensaw, mash of parts to make a complete saw. I got the saw with a box of parts 051/076. I have the saw working, it idles great and reves up fine but it cuts out at 3/4 throttle like a rev limiter is kicking in, it will not stall but the way it is running it would be useless for milling logs. It is an electronic ignition, could it have a wrong coil or could the coil be pooched? I am fine with buying a new coil but do not want to spend money on an old saw unless I know that is the problem. The saw clearly does not have a lot of hours on it by the condition of the piston and cylinder. Any replies are appreciated, thanks

Sounds like you have a cutoff saw (all in one) coil. They make them start limiting at 9.2k rpm to prevent overspeeding the wheels.
If you give a normal running 076S 3/4 throttle, it will probably hit the limiter when out of the cut.
As you cut, it probably will not hit the limiter. (Unless you're @Snellerized)

 

[alexcagle]

Those saws are torque monsters, not high revers. Long stroke = torque

 

[alexcagle]

Me

 

[grizz55chev]

I am working on a 076 that I think is a bit of a Frankensaw, mash of parts to make a complete saw. I got the saw with a box of parts 051/076. I have the saw working, it idles great and reves up fine but it cuts out at 3/4 throttle like a rev limiter is kicking in, it will not stall but the way it is running it would be useless for milling logs. It is an electronic ignition, could it have a wrong coil or could the coil be pooched? I am fine with buying a new coil but do not want to spend money on an old saw unless I know that is the problem. The saw clearly does not have a lot of hours on it by the condition of the piston and cylinder. Any replies are appreciated, thanks

Check the carb for a governor, not sure it has one, but the symtoms sound like it's got one.

 

[alexcagle]

They have a "flooder" valve behind the large flat-head screw head on the side of the carb.
It is basically designed to defeat over-reving by creating an over-rich mixture above a certain RPM.

 

[badbackjack]

Thanks for the replies, nice photo alexcagle!. Yes the saw has a governor in the carb but would that cause the rev limiting? it feels like ignition not mixture. I have a another carb (proline) for the saw but I put it on and could not get the saw to idle. I tried the low jet from 1 turn up to 2 turns and it still would not idle so I put the original (Tillitson) governed carb back on. Any way to delete the governor or should I not mess with it?
It sounds like the advice is to try the saw in a big log and see how it behaves.
Clearly an new chainsaw coil should clear up the problem if I choose to spend the money.

Thanks again

 

[stihltech]

Yes rev limiter built in to carburetor. The fix is NOT authorized by Stihl but plenty of the have been modified.
Unscrewed brass jet on side of carburetor. Using a paper punch cut a circle that will fit in the hole. Reinstall brass governor.
DO NOT! Set this carb lean! You will have garbage. These are a tractor,not a hot rod!
Have you tried this in the wood with a sharp chain first? You might find it leans out nicely in the cut.