Installed New Piston, Rings And Honed Cylinder

[Nitroman]

I took the comp on my 394xp and it was 135 psi on the nose. I thought that was low so I pulled the jug, honed it lightly, crossed-hatched it and slapped in the new piston and rings. Didn't get a chance to fire it up since it was around 9:00 p.m. when I was done and didn't want to disturb the neighbors new baby. I'll do it today after work.

Question: do you do a long warm up and cool-down a few times before getting into some wood, or do you just fire it up and make chips?

 

[blsnelling]

Question: do you do a long warm up and cool-down a few times before getting into some wood, or do you just fire it up and make chips?

I like to but don't always. It's the piston itself that it's more important for. The rings do take time to seat, but it the first few thermal cycles of the piston that is more critical. I would not work it real hard for an extended period of time the first few times. However, I'm sure it would do just fine if thrown right into service. It all depends how picky of a person you are.

 

[timberwolf]

Just cut wood, either it's right or it's not. But if anything does not sound or feel right, stop check and it out.

 

[stihl025]

On that note, what type of compression increases do you typical see after new rings and cylinder honing? I know that there are a lot of factors involved, but lets say he started out with 135 PSI with a good cylinder (no scoring)... What should he expect to see after that first initial start up? Just trying to get an idea of a baseline...

 

[timberwolf]

I would like to see a saw like that come up to at least 150 psi and expect to see another 5 to10 psi once the ring seats.

 

[pops21]

I would be VERY carefull honing the cylinder. If its chrome plated there is a chance you could wear through the chrome. Niksil also. If there is no scoring, a maroon scotch pad and a good wash with detergent will do fine.

 

[Nitroman]

I have an AMMCO hone I use on snowmachine cylinders since you cannot use a ball type hone on them. I was going to use that, but never read it mentioned in all the posts I've read, so used the ball-type from Bailey's.

The cylinder was pristine, no scoring whatsoever on the piston or jug, and was amazed I tell you. When I first received the saw from the eBay seller, it really had been used hard, emphasis on hard. So much so I was kind of surprised when it started up! I was thinking I'd have to buy a jug, or at least see some scoring, but nope.

I didn't wear it out. I was even a good boy and used lots of the special honing oil (mineral oil). Cleaned it up real nice using lots of hot, soapy water and scrubbing to make sure all the bad abrasive was out.

When I pulled in I heard the neighbors kid crying so I think I'll take it over to a buddy's house to start it up, those modded mufflers do not make for happy neighbors ya know? I think I'll do one warm up/cool down and the second I'll blip the throttle a few of times from idle, and the third I'll cut some wood bey-beh!!