Chainsaw Repair
Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Husqvarna => Topic started by: fatboycowen on December 23, 2012, 05:15:40 pm
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A friend of mine asked me to look at his saw.
It's a 2005 Husqvarna 455 Rancher. The saw looks to be in excellent condition with very low hours. He bought the saw new at half price, because the choke lever was broken off just behind it's exit. He claimed it was easy enough to start without the choke, so he never worried about it. Now, he can't get it started. That was about a year ago.
I began by dumping out the year old fuel. I pulled the muffler and plug. Piston and cylinder are OK, but not as good as i would have expected. I found what i think is some minor pitting in a few spots on the inside of the cylinder wall. Just a few small specs. I couldn't get much of a photo of it.
The fuel lines look good. I stretched them a bit and couldn't find any cracks.
The primer bulb feels a little stiff, but functions and doesn't leak.
I ordered a fuel filter, choke and plug. I installed those, and took the carb apart, cleaned it and re-assembled (also removed limiters). The carb internals looked good. The diaphragm was still soft and supple.
The saw fires in 2 pulls on choke. It then starts, but quickly dies. You can repeat start it with the choke on over and over. Once the saw starts running, it will rev only a little then die. It won't idle properly. I tried everything i could with the carb needles, but no help.
Today i pressure/vacuum tested the saw. It was a ****, but i managed to seal off the intake and exhaust. It held pressure immediately. However, vacuum was strange. With the Mity-vac, i pumped maybe 10 times, and it wouldn't hold (bled out super fast). Pumped several more times and it began to hold, then held steady. I left it at 10 in hg for what must have been 5 minutes, and it didn't budge. I'm not sure if the hose was initially leaking, or what. Repeated tries after, and it held.
Where do i go from here?
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I'd still try new carb diaphragms $3-$5 dia kit and $7-$12 for complete rebuild kit.
I had some you would think were fine but didnt work before.
How about impulse? Shown in this 455 IPL http://s30387.gridserver.com/partsDiagrams/Husqvarna%20455%20Rancher.pdf
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It doesn't take much stiffness and that metering valve or regulator side diaphragm will give you fits when trying to set the needles.
If you don't have a new diaphragm on hand, some brake fluid will soften one up for a little while if you have sometime on your hands and no parts?
Get the diaphragm out and massage it real good with some brake fluid. Dry it off and reassemble.
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I decided to order the carb kit, along with new lines, just for the hell of it.
Does anyone know where i can find the repair manual for this saw? I have the IPL.
Thanks
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Well, you guys were spot on, as usual. I installed the carb kit, and the saw was easy to keep running.
Now the question is tuning. Is it me, or is it much more difficult to tune the strato saws? This is my first shot at tuning one. My 357 was very simple.
I started out with the specs i found on Bills Saw Shop page, which states 2.5 turns out for the H, and 1.5 for the L. I tuned the low side, which was fairly simple, i think. The high side wasnt as simple as my 357. At 2.5 turns out, it seemed to rev to around 13,000. I couldn't hear the 4 stroking, so i turned the screw out 1/2 turn. It went down to 12,500, but i still couldn't hear it distinctly. Turning the screw out beyond that didn't seem to have much affect.
I have heard that these are easier to tune in the wood. Any advice?
Thanks!
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Leave it at 12500 and try it in some good size wood and see what you hear when you lift on it slightly. With it tuned to 12500, I don't think you are going to hurt it?
I don't think the four stroke is a audible on a Strato engine as it would have been on your 357. Part of the theory principle of operation of a Strato would keep it from four stroking unless extremely rich.
I don't have a 455 but have seen them apart over at cut4fun's house. I like the way they are made.
I have a 357 and it will four stroke at 14500 which is too fast even for that saw.
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Ok, i finally got the saw into wood. I set up a 5 foot piece of 15" dia. pine up at waste level.
I tuned the saw. I think i got it right. The saw cuts well. Then, i found a new problem.
The saw runs and idles fine. But when warm (haven't tried it cold), it bogs or dies at idle when tipped forward (bar down).
The first time i noticed it, the saw was idling normally on the ground (running at about 2700 rpm). I lifted it up, tilted it forward a little and it immediately died. Repeated tries, it always does the same thing. Sometimes it will just speed down a bit (noticeable), other times it dies completely.
Ideas?
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Sounds like a puddle of fuel is let loose?
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This can also happen with a fuel filter being trapped high and coming out of the fuel or a hole in the fuel line.
One other item if the lever is wrong height in carburetor or leaking main nozzle. Start with the easy make sure filter is not stuck high in tank and then double check line make sure no hole. Re-adjust carb and then if it is faltering still look at lever height and if that good replace the carb.
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Sounds like a plan. I'm glad no one said leaky bearing seals.
I already told my friend that the saw was running good again. He's not going to be pleased.
FWIW, i replaced the fuel line and filter, so i know i don't have a pinhole.
Would the filter being out of the fuel affect the saw that quickly? When tipped, it instantly reacts. There is no delay whatsoever.
Thanks again.
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No the filter would not allow a reaction that fast would take many seconds of running.
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I ran the saw again. I checked the fuel line (which is new) and it was not kinked. Very straight.
The filter was moving around in the tank just fine. To rule this out, i used a completely full tank. Same problem. I also opened the fuel cap and re-closed just before tipping forward to rule out any vent problems. Same problem.
Then, i started messing with the low side needle. I think i straightened it out. I believe the final settings were richer on the low side than originally. Now, the saw doesn't stall when tipped forward, so i think i fixed the problem. Does this seem possible?
I have to assume the strato design has made tuning a difficult thing for me. I just wish i had another 455 beside it to compare to.
The idle is not perfectly steady. It goes from around 2500 to 2700. It's not really audible, but it shows up on the tach. I let it idle for at least 5 minutes, so i know it won't stall out. It also has no hesitation on throttle even after extended idling.
Any of this sound like a problem?
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The rich idle needle causing fuel to puddle does.
Most of my chainsaws will move the rpm around at little at idle speed.