2 Stroke 1998 CR80R

Trfsrfr

Trfsrfr

We just installed the new cylinder and piston.
Had to re-use the wrist pin from the old (stock?) piston that it had in it before I put in the HotRods rebuild kit (Vertex piston) cuz the Hot Rods pin was too long for the OE piston.
Installed the stock 125MJ, and 50PJ, and ran it about 10 minutes.
No leaks, water pump is working.
 
SRAD97750

SRAD97750

Moderator
Staff member
Please tell me you have a new piston pin and pin bearing installed. Please also tell me you measured the Cylinder to Piston clearance and piston ring end gap at least in 2 places?
I'm afraid without these above things, I can't guarantee your engine past initial startup.
-BIG DAN:thumb:
 
Trfsrfr

Trfsrfr

SRAD97750:
Please tell me you have a new piston pin and pin bearing installed. Please also tell me you measured the Cylinder to Piston clearance and piston ring end gap at least in 2 places?
I'm afraid without these above things, I can't guarantee your engine past initial startup.
-BIG DAN:thumb:
Click to expand...
The piston, cylinder, and ring are OE.
I measured ring end gap at .012, (.011-.017 spec) torqued it all down, and fired it up.
 
O

ossagp

you end up trusting a lot. if i am using oe i like to know if i got an a or b cylinder. either one is happy the first go around with either piston, i just like to know. i measure anyway, always imagining that it will tell me how to break it in. I like to torque the studs and use blue locktite on them. Just keeps them in place when I have to take the head off again, a little better. Most of my favorite tuners don't put anything on the studs. Some like me like to reuse them since we imagine the aged ones have already stretched all they are going to.
 
Trfsrfr

Trfsrfr

Update:
1st off, two questions - which way should the curved half-moon part (the part that sits in the air stream) in the jet needle holder face? toward the piston, or towards the air filter? And can it be installed backward?

We took it out to the dez today, and it still sputtered in the low to mid range. Plug was black.
So I dropped the needle to the lowest position, and it ran much better, but seemed to have a slight bog in the middle of revving up. Plug was brownish/greyish.
Afraid to burn it down again, I tried something else; I put the needle clip back to 2nd position, but dropped the PJ down one size to a 48.
Zach said it felt similar to the lowest needle setting, maybe a bit better, but I wasn't able to ride it to verify because when he pulled in it died. When I pulled the plug it was wet fouled and wouldn't restart.

It seems like the only time either this CR or my YZ run well is when I am way off the factory recommended positions.
Thats why I'm starting to wonder about the half-moon thing. My manual doesn't address it, and I can't find anything in the parts fiches.
 
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PALMER84ONE

PALMER84ONE

Trfsrfr:
Update:
1st off, two questions - which way should the curved half-moon part (the part that sits in the air stream) in the jet needle holder face? toward the piston, or towards the air filter? And can it be installed backward? Should have a slot and not be able to go in backwards. Otherwise the curve is to AF.

We took it out to the dez today, and it still sputtered in the low to mid range. Plug was black.
So I dropped the needle to the lowest position, and it ran much better, but seemed to have a slight bog in the middle of revving up. Plug was brownish/greyish.
Afraid to burn it down again, I tried something else; I put the needle clip back to 2nd position, but dropped the PJ down one size to a 48.
Zach said it felt similar to the lowest needle setting, maybe a bit better, but I wasn't able to ride it to verify because when he pulled in it died. When I pulled the plug it was wet fouled and wouldn't restart.

It seems like the only time either this CR or my YZ run well is when I am way off the factory recommended positions.
Thats why I'm starting to wonder about the half-moon thing. My manual doesn't address it, and I can't find anything in the parts fiches.
Click to expand...
 
Mihylo33

Mihylo33

Trfsrfr:
Update:
1st off, two questions - which way should the curved half-moon part (the part that sits in the air stream) in the jet needle holder face? toward the piston, or towards the air filter? And can it be installed backward?

We took it out to the dez today, and it still sputtered in the low to mid range. Plug was black.
So I dropped the needle to the lowest position, and it ran much better, but seemed to have a slight bog in the middle of revving up. Plug was brownish/greyish.
Afraid to burn it down again, I tried something else; I put the needle clip back to 2nd position, but dropped the PJ down one size to a 48.
Zach said it felt similar to the lowest needle setting, maybe a bit better, but I wasn't able to ride it to verify because when he pulled in it died. When I pulled the plug it was wet fouled and wouldn't restart.

It seems like the only time either this CR or my YZ run well is when I am way off the factory recommended positions.
Thats why I'm starting to wonder about the half-moon thing. My manual doesn't address it, and I can't find anything in the parts fiches.
Click to expand...


Just because the plug was black doesn't really mean anything. Ive seen plenty of black plugs but the burn rings were perfect on the porcelain base. Pic of the plugs as you see them would help. I don't like grey looking plugs. Reminds me of coolant leaks or gear oil burning.
 
O

ossagp

I would make sure that you really are getting the enrichenor valve shutoff. It would help me if you would look in manual or look online at a parts schematic and name the parts you are asking about.
 
supercrossman4

supercrossman4

Can someone help me, my kids cr 80,I used a low end off of a cr 85 and top off a cr 80,wich was perfict,but when I shut it down I hear somthing rattle,I don't own special tools so was wondering can it be that the fly wheel just didn't get torqued enough,tighten it the best I could.

Sent from my SM-G900V using Tapatalk
 
Trfsrfr

Trfsrfr

To be nice (he PM'd me and I responded nicely), he is new and using Tapatalk and not used to it.
I can see that using a PC is much better than a phone here...
No worries!
Welcome supercrossman4!
 
Mihylo33

Mihylo33

supercrossman4:
Can someone help me, my kids cr 80,I used a low end off of a cr 85 and top off a cr 80,wich was perfict,but when I shut it down I hear somthing rattle,I don't own special tools so was wondering can it be that the fly wheel just didn't get torqued enough,tighten it the best I could.

Sent from my SM-G900V using Tapatalk
Click to expand...


Welcome!!!
Start a new thread and also be more detailed and provide pics of everything.
Thanks:thumb:
 
Trfsrfr

Trfsrfr

Went riding 2 weekends ago with the bambino. He fouled 2 plugs in 4 hours, spooge everywhere, said it still sputtered at off-idle to mid-range.
Were going riding again this weekend.
Pulled the carb off and checked the float. I thought I had it set at factory spec of 19mm, but it looked like it was at 18mm.
Is 1mm difference enough to produce these symptoms?
I set it at 19 and took it for a rip.
Seems to go pretty good, but I didn't hit the pipe much, residential asphalt, and I've already crashed 2 bikes out in my street so I didn't get on it.
 
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