Husqvarna Rancher 55 - burning up top end

[flattires]

I'm seeming to have trouble keeping the top end from blowing up. Buying it nearly new, I had a problem with a large pine and wound up putting a new Mahle piston/cylinder on it in pretty short order after buying it. Fast forward to owning it for 10 years, but not running it much, and another big 24" pine did it in again. I'm running pump fuel, proper 50:1 mix but with a 20" bar, I know there are times that I push the saw and am not really letting the saw do the work. Its often very hot here in AZ, so I think I am asking too much of it. I'm having good luck with my 16" Husky for smaller trimming.

Its not scoring the cylinder, but it is scoring the piston and the ring becomes one with the piston resulting in no compression.

Ive got a new piston/cylinder lined up, and the new ones have a compression release (mine didnt originally). What advice do you have for keeping it lasting longer? Its almost like it is running too hot.

Let it cool after running it for an hour? 30 mins?

 

[Bubster]

Running too lean,could be carb adjustment issue or air leaks.

 

[Bubster]

just for curiosity,check how far your hi- needle is backed out. Should almost always be at least 1 turn.

 

[flattires]

No doubt a lean setup would cause that, and for sure there is no air leak. I've got some education ahead of me for the "4-stroking" I am reading about for the carb setup.

 

[Bubster]

No doubt a lean setup would cause that, and for sure there is no air leak. I've got some education ahead of me for the "4-stroking" I am reading about for the carb setup.

I can adjust a carb just fine, but some guys on here can explain it to you much better. Crank seals, intake, fuel lines , base gasket can all be culprits and not always noticable at first.

 

[NSEric]

I'm seeming to have trouble keeping the top end from blowing up. Buying it nearly new, I had a problem with a large pine and wound up putting a new Mahle piston/cylinder on it in pretty short order after buying it. Fast forward to owning it for 10 years, but not running it much, and another big 24" pine did it in again. I'm running pump fuel, proper 50:1 mix but with a 20" bar, I know there are times that I push the saw and am not really letting the saw do the work. Its often very hot here in AZ, so I think I am asking too much of it. I'm having good luck with my 16" Husky for smaller trimming.

Its not scoring the cylinder, but it is scoring the piston and the ring becomes one with the piston resulting in no compression.

Ive got a new piston/cylinder lined up, and the new ones have a compression release (mine didnt originally). What advice do you have for keeping it lasting longer? Its almost like it is running too hot.

Let it cool after running it for an hour? 30 mins?

If you're pushing on the saw with a dull chain and 20 inch bar on a hot day for 30 minutes cutting 24 inch wood you're gonna burn it up.
Keep it sharp and take little breaks letting the saw cool after a few big cuts.

I've watched my brother burn up a couple perfectly good saws cutting with a dull chain on a hot day.

 

[flattires]

A few more data points. I just checked, and the carb adjuster screw have the plastic limiters, which I have no intention of removing. I will say that my 4 stroke background would say that I am adjusting the high side (probably when fully warm), but not when running in wood (meaning no load).

The other owner abuse I am now shamefully admitting is a dull blade. I've since perfected my saw sharpening skills where I have corrected my poor knowledge of raker height, and what a proper tooth profile should be. I've graduated from making sawdust to making chips. I'm wearing a dunce cap for my prior mis-steps and my cuts no longer curve wide enough to clear a milk jug.

Letting the saw cool between longer sessions sure makes sense (advice now taken), and the top end damage was clearly on very hot days, and cutting sessions were long. My experience with air cooled motors of the automotive kind somehow failed me in the 2 stroke world. (forehead slap).

 

[furray]

I always check ring gap & piston fit.

 

[cookies]

pull off the limiters and give it more fuel on the H needle to the point it cleans up and runs great under a load. Your piston got so hot it expanded and rubbed the cylinder wall, the fuel keeps it cool under load. When it is adjusted to the edge of lean you will nuke pistons over working and over revving the saw.

 

[Lawless]

I don’t remember but do those saws have the plastic boot clamp that plagued the 359?

 

[Chevboy0167]

^^^^^ No. intake is basically a rubber hose.

https://www.ebay.com/itm/2240412759...ro-Line+Racing&_trksid=p2563228.c101113.m2109

 

[Chevboy0167]

Need to start with a pressure and vacuum test just to rule out seals and such. I find the impulse tubes like rub on the intake pipe and cause a hole in them. Lean condition.

 

[david newbie]

There's also a teeny piece of rubber in the cylinder ( impulse pipe) that can cause an air leak I think, its only about a 1/4 inch long, and sells for a lot of money. Drives me nuts to pay 10-15 for a 1/4 inch of rubber

 

[mountainlake]

You need to pull the limiter caps off and adjust richer, a lot of newer saws come set lean thanks to the EPA. Steve