Husqvarna 61 leans out as it warms up

[jacrawley]

A friend gave me a husky that runs fine when cold then gets leaner and leaner as it warms up. The only way it will idle is with the idle screw turned all the way in. I replaced the carb with the same results. I have pressure tested it and don't see any bubbles. Not sure how I could pressure test when it's hot but that seems like what I need to do.

The saw was purchased used from a guy who put a new top end on it.

Anything obvious I should look at? Base gasket maybe?

Thanks

 

[merc_man]

Spray some carb cleaner around seals and see if it changes. Spray some around intake boot and base gasket. See if idle changes.

Does idle change if you roll saw side to side or upsidedown while idling.

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[MACHINE]

Vac and pressure test saw , my 44 same thing bad seal on chain side

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[pioneerguy600]

Check to see if the fuel line in the tank is soft or gummy.

 

[Huskvarna hotellgäst]

If you think it's leaking on the clutch side, could be the o-ring seal on the oil pump.
Note! You need a taper tool to slide the pump over the lip on the crankshaft when reassembling.
(btw, it's an intake block, not a boot.)

 

[HarleyT]

Check to see if the fuel line in the tank is soft or gummy.

Hey, that was what I usually say!!!

 

[pioneerguy600]

Hey, that was what I usually say!!!

Its yours on the next one.

 

[HarleyT]

Its yours on the next one.

Don't say "soft and gummy" around my squirrel!!

 

[jacrawley]

Vac and pressure test saw , my 44 same thing bad seal on chain side

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I have done both with soapy water. No bubbles nor does a vacuum suck anything in at the crank seals.

 

[jacrawley]

Check to see if the fuel line in the tank is soft or gummy.

Fuel line is new

 

[jacrawley]

I will put it back together and replace the fuel line again which has cracked up while sitting for a year. Not sure what they(Oregon) make this line out of but it is garbage.

I will spray it down and see what happens. Maybe I will use WD40 since it sounds safer than carb cleaner.

 

[jacrawley]

I got it started up and left the clutch and oil pump off. I sprayed here and there. The only place that killed it was on the intake block. This seems odd since the block has no visible cracks in it. All the gaskets are in place between carb and cylinder. Perhaps it's the base gasket on the carb side? I'm at a loss.

 

[MACHINE]

I have done both with soapy water. No bubbles nor does a vacuum suck anything in at the crank seals.

What did the guage read ?

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[Totembear]

Could be the base gasket. Pull the jug and replace. Cheap enough to eliminate one thing. Either that or the cylinder base might be warped or uneven.

 

[jacrawley]

What did the guage read ?

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I pumped to 7 psi. It took about 2 minutes to drop to zero. There were some leaks at the rubber pieces used to block intake and exhaust.

 

[Huskvarna hotellgäst]

On early 61s the carb bolts go right through the block and into the cylinder. On 266s the block is held on with separate bolts. I have no idea if this setup was also used on later 61s.
Anyway, the 266 style blocks were slightly prone to cracking under the bolt heads and around the metal thread inserts for the carb bolts.
61 style blocks were far less likely to crack but if one developed between the intake path and a bolt tube on either side, it may leak pressure along the bolt.

 

[chainmaster]

Have you change the oil seals I am thinking that when the saw is cold the seals are a bit stiff and when saw is hot seals are soft causing the the air leak perhaps I am wrong but seals are not that expensive I would replace them that would eliminate that area

 

[Totembear]

The pressure or vacuum wont do didly if there an air leak at the intake or exhaust blockage points. I just had an 026 that passed a p&v test that when it warmed up it acted like it had an air leak. The pto side seal looked new, the flywheel side looked a little old. Replaced that seal and saw ran fine. Also, replace the fuel line with echo or husqvarna line and dont let mix with ethanol sit in the saw a year.

 

[jacrawley]

Have you change the oil seals I am thinking that when the saw is cold the seals are a bit stiff and when saw is hot seals are soft causing the the air leak perhaps I am wrong but seals are not that expensive I would replace them that would eliminate that area

When it's running I can spray the clutch seal and it has no effect. I have sprayed behind the flywheel but can't be sure any carb cleaner is getting back there.

 

[jacrawley]

I replaced the base gasket and the old one felt very greasy on the surface it also had no rtv. I thought I had it licked but it is doing the exact same thing. I made a pin point straw for my spray can with an old pen to try and be more precise with the carb cleaner. I found a leak between the carb and the intake block but I don't think this is it. It is very slight. I did notice if I spray the base gasket below the intake block the saw will idle for about 30 seconds before stalling. It may be time for me to give up on it. I hate to throw random parts and money at something. That's just bad problem solving.