Husqvarna 55 High Speed Jet Adjustment

I am trying to adjust the high speed jet on my Husky 55. I cannot seem to get it to 4-stroke. It runs really rough, but not the usual 4-stroke sound at 12,000 rpm, but smooths out nicely as I lean it out. Right now I am at 13,000 rpm, but hesitate to go any more. I am using an analog tach, so these numbers are not exact. What should the top unloaded RPM be?

Starting and acceleration are good. Saw appeared to be running rich before I made any adjustments. Arrestor screen has been removed. I am running a 20" bar with 3/8" chain. Fuel is 91 octane, non- ethanol. I realize further adjustment might be needed when actually cutting.

I like them to be four stroking or slightly rough sounding running free and then to just smooth out when you get into the cut.

The max rpm question was brought up not to long ago and I believe the manual states it at 13,300. If you continue to have trouble getting the saw tuned I would check for a air leak around the intake area. The intake boot, impluse grommet and plastic intakes are well known issues with these saws.

Thanks for the responses. The carb on this saw bolts directly to the cylinder block, along with a gasket. The impulse port aligns with a hole on the carb flange. There is no impulse line, grommet, or boot. Everything looks tight. I will leave it at 13,000 rpm, and fine tune it the next time I am cutting. It just kinda puzzled me that I could not get it to 4-stroke, but it runs fine otherwise.

Oli said:

Thanks for the responses. The carb on this saw bolts directly to the cylinder block, along with a gasket. The impulse port aligns with a hole on the carb flange. There is no impulse line, grommet, or boot. Everything looks tight. I will leave it at 13,000 rpm, and fine tune it the next time I am cutting. It just kinda puzzled me that I could not get it to 4-stroke, but it runs fine otherwise.

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There is indeed a intake boot and impulse grommet behind the plastic intake, I have worked on to many of these saws.

Roanoker494 said:

There is indeed a intake boot and impulse grommet behind the plastic intake, I have worked on to many of these saws.

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:agree2:

Thanks for the pic's. I stand corrected. I will check further to make sure everything is tight.

Roanoker494 said:

The max rpm question was brought up not to long ago and I believe the manual states it at 13,300. If you continue to have trouble getting the saw tuned I would check for a air leak around the intake area. The intake boot, impluse grommet and plastic intakes are well known issues with these saws.

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Workshop Manual says 12,500 max rpm for 55. I tried to upload WM failed twice.
Shep

Oli said:

Thanks for the pic's. I stand corrected. I will check further to make sure everything is tight.

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They are defiantly hard to see with how the intake wraps the cylinder, so I can see where they are easy to miss. Another weak spot is the intake itself, who ever designed the intake should be shot. If you happen to get the carb bolts a little to tight you will strip the plastic threads out of the intake and cause a air leak.

EDIT:
You may want to run the high speed jet all the way in snug and then readjust it again, that may help break loose any crud that is stuck in the jet. If that does not help then pull the needle completely out and spray some carb cleaner back in there, may have to end up taking the whole carb apart for a good cleaning.

May also want to check or replace the fuel line and filter. The filter may be clogged, the fuel line could have gotten soft and is sucking closed at WOT, the fuel line could have a pin hole or the line has hardened up and restricted the fuel flow.

Thanks for all the helpful information