Jonsered 625II Piston

[bama]

I took the jug off my 625 and the ring is stuck. There is no scoring and the cylinder looks great, but the piston is pitted on top. The compression was less than 100 psi. so I was thinking about a new piston from Baileys. The piston is really black even halfway down the skirt. Is this from being too rich/too much oil in the mix?

Can I clean that crap off and just get a ring or should I spend a few extra $$ and get the 2 ring version?

 

[spike60]

You would be better off to go with the piston assembly, especially if the pitting is anywhere near the edge of the piston.

 

[bama]

I tried to get it off and that carbon is pretty baked on. I set it in some oil and will check back on it in a week. $30 isn't bad for a piston and I needed a new face shield for my helmet, anyway. I will just get the piston. Thanks, Spike.

 

[motosierra]

I tried to get it off and that carbon is pretty baked on. I set it in some oil and will check back on it in a week. $30 isn't bad for a piston and I needed a new face shield for my helmet, anyway. I will just get the piston. Thanks, Spike.

You could soak it in household ammonia for about 5-10 minutes... scrub with scotch brite and repeat process if necessary. ....this also loosens up the chite in the ring grove and it comes out easier when scraping with the edge of a broken ring thorough the grove. Clean it all up with a stiff, small bristled plastic brush and hot water. Don't forget to clean the underside of the piston too. Your piston will come out looking like new... well almost new...

 

[bama]

You could soak it in household ammonia for about 5-10 minutes... scrub with scotch brite and repeat process if necessary. ....this also loosens up the chite in the ring grove and it comes out easier when scraping with the edge of a broken ring thorough the grove. Clean it all up with a stiff, small bristled plastic brush and hot water. Don't forget to clean the underside of the piston too. Your piston will come out looking like new... well almost new...

I will give that a try. Thanks.

 

[motosierra]

If you leave the aluminum piston in the household ammonia to long (overnight or so)...when you remove it... it will be perfectly clean but it will be perfectly black.... aluminum oxide?... I don't know... but it can be removed with a brass brush ...brushing horizontally to create scratchers in the aluminum that will catch oil during operation and provide lubrication

 

[bama]

I was going to try it tonight, but I was missing one thing... Ammonia!

 

[motosierra]

Most grocery stores carry it. It is a household cleaner and will be in that section. One-half gallon would cost 2-3 dollars but you do not need that much but it is handy to have around for other cleaning jobs, like cleaning spark plugs. I use a little yogurt cup... less than 6 oz and can just throw it away when I am done. The whole process should take between 5-15 min's.

 

[motosierra]

Getting back to the original problem.."The piston is really black even halfway down the skirt"...you should be using a high quality 2 stroke oil...like "Husqvarna" ....at a 50:1 ratio... give this a try. And while you have your piston out... put a new ring on it... you can get one from "Cutter's Choice" for about 3 bucks.

 

[bama]

Getting back to the original problem.."The piston is really black even halfway down the skirt"...you should be using a high quality 2 stroke oil...like "Husqvarna" ....at a 50:1 ratio... give this a try. And while you have your piston out... put a new ring on it... you can get one from "Cutter's Choice" for about 3 bucks.

This was a saw I traded for, so the mix problem should be solved with me. I plan to re-ring it once it is cleaned up.