Normal Ring Blow-by?

[Marshy]

Just for kicks, let us know what you get for end gap on the new ring.

 

[Marshy]

Just for comparison...

This saw ran great too.

 

[bwalker]

Just for kicks, let us know what you get for end gap on the new ring.

Wont yell you much unless you also measured the ring gap when the saw was new.
Regardless, I highly doubt this is a ring or cylinder wear issue. The piston doesn't appear to be worn.

 

[Marshy]

Wont yell you much unless you also measured the ring gap when the saw was new.
Regardless, I highly doubt this is a ring or cylinder wear issue. The piston doesn't appear to be worn.

It might not seem like much but it will tell you if it is more or less than the ring that he plans on removing. If the new ring gap is 0.013" then hes not gaining much. If the new ring gap is 0.005" then it might be worth increasing.

 

[redtractor]

Remember, I didn't pull the jug because of a problem. Since I have it off, I'm changing it so I can run it another decade without worrying about it. I asked the original question as an opportunity to learn something.

 

[bwalker]

Remember, I didn't pull the jug because of a problem. Since I have it off, I'm changing it so I can run it another decade without worrying about it. I asked the original question as an opportunity to learn something.

Best guess is it was ran lean for an extended period of time. Piston wash or lack there of seems suggest this as well.

 

[bwalker]

Just for comparison...
View attachment 23344
This saw ran great too.

Looks almost like it was run on castor.

 

[Marshy]

Looks almost like it was run on castor.

Husqvarna Black bottle low smoke.

 

[smokey7]

The underside of the Piston shows that it got hot that's for sure. The Heat and may be magnified by poor quality oil.

 

[old guy]

I just swapped a used 346oe p&c onto a 351, the old ring gap was .014, I read somebody say the most they would put back together was .013 so it got a new caber ring which was at .007 just above the ex. port.
With a base gasket delete and after one tank of fuel this one is blowing 170.

 

[smokey7]

When breaking in a new ring like that I prefer to bury the bar and push it to the point of almost stall in the clutch work it that way for a full tank of fuel.

 

[bwalker]

It might not seem like much but it will tell you if it is more or less than the ring that he plans on removing. If the new ring gap is 0.013" then hes not gaining much. If the new ring gap is 0.005" then it might be worth increasing.

You are making the assumption that the new rings will have the same clearance as the old ones. They very often do not. The other thing is I much prefer a looser vs tighter ring gap. If you touch the two end together while running it's game over.

 

[bwalker]

When breaking in a new ring like that I prefer to bury the bar and push it to the point of almost stall in the clutch work it that way for a full tank of fuel.

You will never seat the rings until you load the motor. With a cast piston that's properly clearanced I bring them up to operating temp, then run the hell out of them.

 

[Marshy]

You are making the assumption that the new rings will have the same clearance as the old ones. They very often do not. The other thing is I much prefer a looser vs tighter ring gap. If you touch the two end together while running it's game over.

Do you hear yourself? Go re-read my post you quoted.

 

[jake wells]

are caber rings just cast rings or are they chrome moly rings?

 

[Marshy]

They are cast iron

 

[bwalker]

are caber rings just cast rings or are they chrome moly rings?

Personally, I would go OEM.

 

[bwalker]

Do you hear yourself? Go re-read my post you quoted.

I believe I misunderstood where you were going with your post.
Iregardless that piston isn't worn too bad as the oil retention grooves are still present, and the owner claims the cylinder still has cross hatch. Given these two items I woukd use some GM top engine cleaner to remove the carbon, slap a new Husky ring in it, set the carb properly and run it at 32:1 on good oil.

 

[redtractor]

Just for kicks, let us know what you get for end gap on the new ring.

New OEM ring was .003. Gasket delete brought the squish to .025. New compression, a hair under 200.

 

[smokey7]

.003 is too tight imo. I'd recommend to open ring gap up to .006 as a safer starting point.