Husqvarna 455 Rancher - bogging - runs well with choke on

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Ksquared

Ksquared

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Joined
May 22, 2013
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Wisconsin
I picked up a Husqvarna 455 Rancher (2005) that the previous owner ran straight gas in. The problem was no compression. I did a complete tear down with new cylinder & piston, new crankcase seals, new cylinder seals. I put everything back together and it started up well. Put the chain on and it bogged when cutting with throttle. I then attacked the carb - I cleaned it all out - No change bogging under throttle starts only with choke on. I then ordered a complete carb kit - changed fuel filter, fuel line to carb, new primer bulb, new air filter, new spark plug, and new carb - exact same result. The saw will idle nicely with choke on, but when the choke is closed the rpms skyrocket and also throttle bogs. The only line I did not change was the one from the cylinder up into the intake - maybe I should change that one. Anyone have any ideas what to check next? I did add a little bit more 2 cycle oil to the gas for break-in, but is it possible that is the issue? Thank you in advance!
 
Yukon Stihl

Yukon Stihl

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Vacuum and pressure test will save you a bunch of time.
Something i do every time i get a new to me saw that has zero history.
Definitely something to do prior to a tear down and rebuild,otherwise the issue that burnt down the saw the first time can burn down your new rebuilt saw.
Did the previous owner tell you it was straight gassed?
 
Ksquared

Ksquared

New Member
Joined
May 22, 2013
Messages
4
Location
Wisconsin
Vacuum and pressure test will save you a bunch of time.
Something i do every time i get a new to me saw that has zero history.
Definitely something to do prior to a tear down and rebuild,otherwise the issue that burnt down the saw the first time can burn down your new rebuilt saw.
Did the previous owner tell you it was straight gassed?
No - I was assuming straight gas. It had no compression and the ring was basically welded to piston. You make a good point that it could have been the cause of the original failure.
 
Vintage Engine Repairs
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Aug 12, 2019
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3,774
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Australia
Thanks for the reply - I don't have the equipment to do a pressure/vacuum test, but i will wait until I can check. Thanks for the info!
Hi, so many people don’t invest in a vacuum and pressure tester and chase their tails throwing money at new parts and play the guessing game. Save the frustration, spend $50 and get one from Ebay - it’s cheaper, quicker and less frustrating than replacing parts unnecessarily hoping to find the issue.
Best of luck :)
 
Motherboard

Motherboard

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Jan 20, 2019
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Ireland
I dont know what you call it in your area, penetrating or easing oil, with a long straw from the
can, spray around the seals and it should pull the engine down if its pulling in air, spray around
the carb too, the boot area, it should pull the engine down or stall it, but dont spray into the carb,
same as others said, pressure and vac test would be the ideal way to go.
Is there transfere caps on the side of that engine, if so there could be a leak there, they have seals too.
 
cranman1951

cranman1951

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Feb 22, 2020
Messages
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Location
lakeville Mass
I built my pressure vacuum tester from a MitiVac unit I got from Harbor Freight ....cost was about $35. I block off the carb and exhaust ports with some rubber sheeting cut from an old innertube, and pressurize the cylinder through the spark plug hole. I made my own from an old spark plug, but E-bay has the Husqvarna tool that looks like a spark plug, but with a port to pressurize the cylinder.....cost about 9 bucks
 

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