Top End Rebuild Questions

[jlsparky7]

So we rebuilt the blaster a couple years back 2006 I believe. And it ran fine till this year. It was bored 20 over with a wiseco piston. I had lakes motosport do the boring here in michigan and bought it on flebay. The blaster is no longer getting compression. All it is getting is like 60-70psi. There looks to be VERY little damage to the wall and the piston looks like it shoud be ok.
Can I just get a new set of 20 over rings and see if that works?
Should I get the wall honed not bored and get new 20 over rings?
or should i just get it bored 40 over with a new piston and rings?
I have a local cylinder head shop that i know does good work. i dont know if lakes did bad work or why it lost compression. should i just take it to them and see what they say? they mainly do cars but i know they do atv stuff too.

Does anyone have the specs so we can mic out the cylinder and the rings and stuff to see what the measurements are and what they should be?

I can post pics if i need to so that you guys can see what the piston rings and cylinder look like
Thanks for the Help!

 

[Awk08]

see if this helps ya, straight outta the manual, shows 1st qnd 2nd overbore dimensions, my buds sometimes just do re-ring jobs on their gncc kx's, if caught in time, like it sounds you did, imo
or get a set of rings and "end gap"< measure it, if within specs, go for it

 

[2smoker85]

has it been ridden hard? it sounds like you have blow by, your rings could be warped, i would start with new 20 over rings and go from there. did you make sure when you put the top end back together that the gaps were 180 apart on the rings. also the rings need to be aligned with the pin on the piston. if you had a picture i could explain it better to you.

 

[xjma]

Is the scratch right in line with a port?? Sometimes when people bore the cylinder they forget to re-chamfer the port edges, which make it likely for the edge of the ring to get caught and scrape the cylinder or worse.

I would bring the cylinder to where you want to have it bored/honed....and have them mic it, try and just hone it, and if that doesn't work they'll bore it out to the next size that will work.

 

[jlsparky7]

ok so I got some pictures of the piston and jug....here they are. i am pretty sure both ring gaps were 180 deg apart and on the ends where the wrist pin goes through. If i get just the rings should i get the bore honed? Im gonna try to mic it tonight or tomm.






let me know what you think!
Thanks for the help.

 

[yb200]

id just get it bored the next size up and get a new piston and rings that way you know it'll be good for years to come

 

[03blasteryfs03]

it looks to me like a cold seize

 

[gonzo]

take it back to lakes and talk to Mike (owner) he will set you straight good people, and yep a nice 4 corner seize, you need to get it warmed up a little better.

 

[ROCKSTAR]

thats probly not gonna hone out. you need a bore, son. have it bored, and all new top end parts. as soon as i saw the piston i said...oooh thats not good. then i saw the cyilinder matched the piston....talk to your local machine shop and ask them. but to me it looks like a bore/topend. and yes...warm it up better before you ride.

 

[jlsparky7]

thanks for all the quick replies...since it wasnt really lakes motorsports fault i think ill just take it to the local shop down the street...i know they do good work and ill just get the .40 over piston online...and ill be sure to let it warm up alot more!

 

[gonzo]

ok just sayin that Mike is a top notch guy