2 Stroke cr85 motor help!

TheMotoFamily

TheMotoFamily

Hey guys, I'm looking at getting a 2003 cr85 for my son! The bike is going for cheap cuz of a problem! The guy says that every time you start the bike you have to use a new plug! He says that oil or something is getting up past the ring and killing the plug! And when he took the piston out he says that it looked like the ring was kind of jammed into the piston! His guess is that the head may be warped! This is all the info I got! Even if I have to buy a whole top end it's worth it for me! Was hoping to get some thoughts on this before I get it!
Cheers!
 
SRAD97750

SRAD97750

Moderator
Staff member
Sounds like you need a top end, possible cylinder work, and crank seals.
The fouling every ride says either the float is way off or you're sucking trans fluid into the crankcase.
The only way to find out is to take it apart!-BIG DAN:thumb:
 
TheMotoFamily

TheMotoFamily

Ok thx! I have done all kinds of motor work but I have never split the cases! I guess I'm gonna have to at some point! Lol





SRAD97750:
Sounds like you need a top end, possible cylinder work, and crank seals.
The fouling every ride says either the float is way off or you're sucking trans fluid into the crankcase.
The only way to find out is to take it apart!-BIG DAN:thumb:
Click to expand...
 
P

PawPaw

It sounds like the previous owners kid may have not run the engine hard enough to keep from building up unburnt fuel mix from collecting in the crank cavity. It may just need to be run hard to clean it out. If the kid just putted around on it, this will happen as these little engines need to be run fairly hard to keep the build up from happening.

Paw Paw
 
TheMotoFamily

TheMotoFamily

This would be nice!





PawPaw:
It sounds like the previous owners kid may have not run the engine hard enough to keep from building up unburnt fuel mix from collecting in the crank cavity. It may just need to be run hard to clean it out. If the kid just putted around on it, this will happen as these little engines need to be run fairly hard to keep the build up from happening.

Paw Paw
Click to expand...
 
SRAD97750

SRAD97750

Moderator
Staff member
TheMotoFamily:
Ok thx! I have done all kinds of motor work but I have never split the cases! I guess I'm gonna have to at some point! Lol
Click to expand...
Doesn't look like the seals are captive on this motor. No splitting of cases should be necessary for crank seal replacement. -BIG DAN:thumb:
 
SRAD97750

SRAD97750

Moderator
Staff member
TheMotoFamily:
Really? Even if it cost me $500 to fix it I could sell this bike immediately for $1800!
Click to expand...
I have picked up MANY 2000s 85cc bikes.
Never for more than $400 and never resold for more than $800 with fresh motors/registered.
Very different markets if you can get $1800 for a 12 year old bike in Canada.
-BIG DAN:thumb:
 
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