Husky 61 9.5K RPM Maximum

[Termite]

I have been working on this Husqvarna61 white top for awhile and it has me stumped. It will not rev beyond 9.5 K rpms. When I lean out the high side it just starts sputtering and will eventually die. Now, what I have done to it. Pressure and vacuum tested, passed, Tilitson kit in Tilitson carb, aftermarket carb, three ignition modules two factory one aftermarket, new fuel line and filter. The Tilitson carb I cleaned twice in ultrasonic cleaner. The flywheel key was partly sheared, it now has a different flywheel and key from a white top 61. Module to flywheel is set at .008 inch. Compression is around 135psi. The saw starts easily but just won't rev up. It kinda feels like a rev limiter but at 9.5k ? What am I missing? Thank You for all suggestions in advance.

 

[Westboastfaller]

does it have plugged muffler screens or something in muffler? anyway the 61 sure responds well to MM
Or it's a contact issue somewhere?
Saw runs and tunes the same with both carbs?

 

[Termite]

Westboast, muffler is an empty can and yes it runs and tunes the same with both carbs.

 

[Totembear]

Fuel line ok? Not mushy? Check fuel filter. Might have an obstruction somewhere in the fuel system.

 

[Westboastfaller]

Runs same with air filter off? No restrictions to the air box
right choke on it? unclip it and try maunally

 

[TLG]

I would try to verify flywheel and coil combinations used. Most times your issue is due to a single or dual coil style mismatch with the same scenario of flywheels. There are differences in key locations on wheels.

 

[Termite]

The fuel line and filter are new OEM. I have only ran it with no air filter. TLG, the parts saw I have is the same vintage, that is white top, with what looks to be the same two part ignition. However. your theory has merit. How could I test it? I already have three sets of ignition coils. I don't have a good running 61 to experiment with. My local dealer is helpful, I will ask if they can check part numbers.

 

[TLG]

The fuel line and filter are new OEM. I have only ran it with no air filter. TLG, the parts saw I have is the same vintage, that is white top, with what looks to be the same two part ignition. However. your theory has merit. How could I test it? I already have three sets of ignition coils. I don't have a good running 61 to experiment with. My local dealer is helpful, I will ask if they can check part numbers.

If you could post front and rear pics of all the flywheels you have. Put the key slot at 12:00 and make a note on magnet locations would be a good start. Did you check spark arrestor for blockage as mentioned by the other members?

 

[Termite]

No spark arrestor, the muffler is an empty can. I will get on this tomorrow thanks.

 

[J D]

Are you sure your tach is accurate?What does it act like tuned by ear?Tried a new plug?
135PSI is getting low

 

[Termite]

Are you sure your tach is accurate?What does it act like tuned by ear?Tried a new plug?
135PSI is getting low

Tach seems correct on other saws, for example, 7900 hits the rev limiter at about 13.2K. Tuning by ear it sounds slow and it cuts slow. I have tried several different plugs. Spark will jump a good tenth of an inch. I ordered Caber rings I plan on installing soon. But wouldn't you think 135psi would rev past 9.5K.

 

[SteveSr]

Tach seems correct on other saws, for example, 7900 hits the rev limiter at about 13.2K. Tuning by ear it sounds slow and it cuts slow. I have tried several different plugs. Spark will jump a good tenth of an inch. I ordered Caber rings I plan on installing soon. But wouldn't you think 135psi would rev past 9.5K.

Is the P & C OEM or aftermarket?

 

[Bob Hedgecutter]

Okay, we have a kind of confirmed correct left hand side of the saw (ignition) , confirmed correct back side of the saw (fuel delivery and mixing), in my mind that leaves the right hand side of the saw (PTO and oiler) and the bottom middle (crank bearings).

Remove the clutch and oiler (or one at a time), start the saw and see if the top end speed increases.
Could also be main crank bearings with enough cage damage they spin at low speed, but bind up at high speed. I have a crank out of a saw sitting in front of me that would start and run, main bearings can hardly be turned by hand out of the case.

 

[Termite]

P&C is OEM. I will try the clutch oiler thing.

 

[frank_]

The flywheel key was partly sheared,

my guess is the crank is twisted from a previous repair, and its thrown the spark timing out

 

[Huskvarna hotellgäst]

Left-field suggestion time.
When you changed the ignition modules, did you check that the screw in the white plastic insert connecting the wires from each unit, is not too long so that it's close to the metal crankcase?

 

[Termite]

my guess is the crank is twisted from a previous repair, and its thrown the spark timing out

Interesting, never thought of that.

 

[Termite]

Left-field suggestion time.
When you changed the ignition modules, did you check that the screw in the white plastic insert connecting the wires from each unit, is not too long so that it's close to the metal crankcase?

Each screw in the two saws are the same and really couldn't be any shorter.

 

[J D]

How freely does it spin with the plug out?
If you bring the piston up to TDC how far away are the magnets from the pickups? (Can reference one of your other saws for comparison)
Do the magnets feel as strong as the original flywheel?
You could try increasing the gap a few thou to see if that makes a difference... or refitting the original flywheel by just lining up the keyways & tightening the nut up

 

[J D]

Do you know what originally sheared the key?
Have a real good look inside the cylinder & check squish too... It's possible your low compression is due to piston stop damage or excessive squish