2 Stroke cr85 problems

K

kingster

Ok guys, im just about ready to sell this thing. Here is my problem, new top end only gets 90 psi of compression. It also smokes. The smoke smells like gas. The right crank seal has been replaced. It wont idle and it doesnt sound high pitch when i rev it. Sounds like its choking or something is choking it.
Whats the problem guys. The cylinder is the right size right along with the piston and ring. Also it leaks black spooge out of the exhaust
 
SRAD97750

SRAD97750

Moderator
Staff member
kingster:
The cylinder is the right size right along with the piston and ring.
Click to expand...
jackson409:
Did you check the ring gap with the ring in the cylinder?
Click to expand...
kingster:
No i did not. Is that critical?
Click to expand...
If you didn't do the measurement, then you are not certain of your first statement.
'Ring end gap' shows how well the ring fits the cylinder. If this measurement is off by much, if could be the source of the compression loss.
When this measurement is out of spec and it's a new ring, then the cylinder needs to be bored to the next size, and the next size piston/ring installed. Typically +0.5mm at a time. -BIG DAN:thumb:

https://www.youtube.com/watch?v=ViEjQ7B1uM8
 
M

MikeinFresno

low compression can lead to the spooge out the exhaust, which also could be a rich condition due to jetting or a stuck/too high float level, its hard for us to be 100% accurate from here
 
K

kingster

Float valve it could be. The carb was leaking at one point. Also can i bore a sleeves cylinder? I took it to my local atv shop to have it measured/ mic and he said its the stock bore.
 
SRAD97750

SRAD97750

Moderator
Staff member
kingster:
Float valve it could be. The carb was leaking at one point. Also can i bore a sleeves cylinder? I took it to my local atv shop to have it measured/ mic and he said its the stock bore.
Click to expand...
I suspect the issue to be flooding. Your symptoms are rich, but 90 psi is not good.
If you find it is worn or damaged in some way, a steel sleeve is meant to be bored oversize as the cylinder wears.
Yes, a std piston kit will work then. -BIG DAN:thumb:
 
O

ossagp

If you can't remember when the float was set, it probably happened when the carburetor was built. That would go a long way to explain your smoking and the flooding symptoms. Not knowing how you did your compression test I feel like Mike and would just be guessing there. If you have glazed the cylinder already etc it could be down, or it could have partially seized etc. FYI I put those together with a dry cylinder, particularly if the bore is old. They seat sooner and stay tight longer for me.
 
O

ossagp

I don't know. How did your ring gap measuring come out? you can measure at the bottom of the cylinder, then move it up a half inch at a time and record all the measurements and see how much taper ie wear you have.
 
Top