Husqvarna 450 no power in cut

[tankgijohn72]

Have husqvarna 450 rancher and need some help with it. It starts and runs fine. Maybe a little sluggish when pulling the trigger, but not bad. TAC shows idle around 3000rpm and full throttle is 9500-10,000. Problem is there is absolutely no power if trying to cut. Will barely pull the chain on a 4" piece of ash. New carb, spent some time trying to adjust it to no avail. Replaced fuel filter. Fuel is new and runs fine in my other Husq 450. Checked exaust and spark arrester, completely clean. Just about out of ideas before i take it to someone else to fix. Any ideas? thanks in advance.

 

[svk]

How does the piston look through the exhaust port?

 

[tankgijohn72]

Looked nice and clean. Couldnt see any scoring on the wall or anything like that.

 

[svk]

Still could be carb adjustments? I worked on two saws today that were set way lean from the factory.

 

[Vintage Engine Repairs]

Check that the clutch is all good, the clutch drum is all good and that there isn’t a heap of oil in the area maybe?

 

[tankgijohn72]

Didnt see anything in the clutch area. It very well could be the carb adjustment. Spent quite a bit of time with two different carbs and basically achieved the same results. To be fair it is my first time adjusting the carbs. One thing i read online, but havent gotten to mess with yet is it possible that the fuel vent is clogged and not allowing proper fuel flow?

 

[svk]

If the vent was plugged it would run normal then die. Then run normal again once you opened the cap.

 

[svk]

Did this saw run good for you before? Or did you acquire it with this issue?

 

[tankgijohn72]

It ran good when i bought it. Was a factory refurb. Ran for a couple years. Had an issue with the ignition coil and sat for maybe 9 months before I got around to replacing it. Anything i could have screwed up there? Dont see how that could affect the power since it is clearly firing.

 

[svk]

I’m still leaning towards tuning. Have you tried turning main jet out at WOT until it burbles?

 

[tankgijohn72]

I think i had the High jet turned out approx 3 turns and that seemed to be running well. will give it another shot and see if i can get it tuned.

 

[rupedoggy]

Rebuild the carburetor and use ultra-sonic and fresh diaphragms. 3 turns out is not right. Also check the flywheel for a sheared key (part of the flywheel) then reset with a business card.

 

[rupedoggy]

My 435 has the same problem. I switched to skip chain but still no power. Do you think I should go to 3/8 instead of .404.

 

[irhunter]

I would: (1) check compression, (2) set carb to factory setting, (3) report back with test results.

 

[Bob Hedgecutter]

The new carb- what country did it come from?

If it were me, I would be cleaning/kitting the original carb as Rupedoggy suggested above and taking off the inlet manifold, intake block to check for leaks.
3 turns out is way rich.

 

[Saw Fixr]

The max power speed for that saw is noted as about 9,000 rpm, but I would think that you’d need a higher max rpm in free air (piss rev’d), so that when it gets in the wood, it’ll drop down into the 9k range... sounds like you’re H adjustment is too rich??? Can you adjust it the carb leaner?

 

[Huskitoter]

Check the linkage between the carb and upper flap. Is the flap working right?

 

[tankgijohn72]

Carb adjustments did it. Finally got it to cut through a good sized piece of ash without too much of an issue. Still needs some fine tuning. What no load speed at wide open throttle should it be set at? im at 11,000. Husqvarna shows max power speed of 9,000 rpm on their website. Is that under load? If so, im way to lean. If i open up the H jet i just dont get the power needed to keep the chain moving in the cut. Thoughts?

 

[Saw Fixr]

Do you have a manual? Sometimes it seems harder to find the published max engine speeds for Huskys than for Stihl, as Husky advertises max power/rpm, and you’ve seen. I’ll bet it’s around 12,000-12,500, just guessing though...
If you’re aware of what “4 stroking” is, you can probably adjust it that way, and I’d bet you’d end up around the 12-12.5k...
Good luck.

 

[Old2stroke]

You can get nowhere by trying to correct tuning errors by relying on tach numbers. Learn to tune the saw by ear and save yourself at lot of grief.