ring job

[125pb]

just looking to make sure im on the right track. my blaster is putting out about 115-120 psi. it was about 135 when it was rebuilt, i know that it has been dropping off over a period of time whitch is normal for a 2 stroke motor. im wanting to do some rings in it to get it back up to 135-140. i know it still has cross hatching in the cylinder. anyways i just want to make sure i do this right with out over looking something. i know i need to measure the bore first but cant remember exactly the piston to cylinder wall clearence (.003mm?) and i think i measure the middle of the piston? and the last time i checked the OEM base gasket was the best right? so if the cyinder is in spec i should be able to put some rings in and do a proper break in and have a fresher engine. any tips or advise is welcome.

 

[brandoz28]

you will need to run a hone through the cylinder, even if there is cross hatching, to be sure that the new rings will seal up, otherwise you may end up just where you are now.

to properly measure the bore, you need an inside bore gauge, then you will need a micrometer to measure the piston. you measure the piston at the skirt.

 

[125pb]

does the hone take away some mm on the cyl. wall? and how should a proper hone be preformed? do the ports need chamford?

 

[blasterdemon7]

you will need to run a hone through the cylinder, even if there is cross hatching, to be sure that the new rings will seal up, otherwise you may end up just where you are now.

to properly measure the bore, you need an inside bore gauge, then you will need a micrometer to measure the piston. you measure the piston at the skirt.

I second that input. .I:I

 

[brandoz28]

it will take a small amount of material, you simply want to take enough to provide a fresh cross-hatch on the walls so that the new rings have something to grab on to.


have you noticed a decrease in performance? if not, I would simply run it until you do. and then I would worry about it

 

[125pb]

no noticible loss in power, i just want my baby to be at the top of her game. i want to do it now then when its to late. so do i need to worry about any chamfering of ports?

 

[brandoz28]

personally, I would leave it alone until you start getting piston slap or it's just flat worn out.


so long as there is still a good chamfer on the port, you will be fine

 

[michaelbell85]

wow no way id tear that thing apart at that psi.The spare blaster i got on trade had 85psi and still starts on second kick.You most definately are to worried about that kinda stuff.

 

[125pb]

^^^ i plan to, ive read that .03mm is the clearence needed but also read that ken o conner prefers .06mm because in his opion oem spec is a little tight. any one have some insight?

 

[125pb]

http://www.blasterforum.com/general-support-17/piston-clearance-28153/ so if i let it drop to 100psi and everything is in spec with .03mm clearence????? some new rings will be fine?

 

[125pb]

but when i convert .0025 inches to mm i get .06mm.

 

[Awk08]

but when i convert .0025 inches to mm i get .06mm.

my bad, i thought all along we were talking thousandths

 

[vspec]

^^^ i plan to, ive read that .03mm is the clearence needed but also read that ken o conner prefers .06mm because in his opion oem spec is a little tight. any one have some insight?

I'm running with a clearance of .02

zero problems yet.

 

[Budget_Blaster]

Send it to ken.he does such a good and thorough job i dont even bother with my own machine work or even cross hatch.he does such a good job he can actually make you lazy!im a die hard gear head and do all my own work from body work to engines and everything in between and hes got me where its just easier and safer to box it up and send it to ken when hes done it looks new and he gives it a good inspection and tells you exactly whats going on without trying to undersale or upsale you on stupid sh*t you dont need.


Send it to ken you wont be sorry and you will have an engine you can trust and rely on.

 

[sicivicdude]

^^^^^^ really?

Stock piston to cylinder clearance is ~1.5 thousandths or ~.03mm. For a cast piston in a stock heat load engine, that's a fine spec and will make sure that the top end lasts longer. Cast pistons don't expand as much as forged pistons do when they're heated so there's less risk of a 4 point seizure.

Wiseco recommends between .002" and .003" (I've even seen .0025" printed on some boxes) but anywhere between 2 thousandths and 3 thousandths (or .06mm - .075mm) is A ok. The increased strength of the forged pistons comes at a cost. The closer you get out towards about .005" clearance, the closer you are to pistons slap. Because the cylinder wears slightly over time, the "looser" you run it, the less time it will last but the faster it will be....

 

[125pb]

excellent anwser^ just what i was looking for