CR80 hi idle

[DRZ_Dad]

the bike idles hi, then settles down to a low idle after 20 seconds or so, everytime it go's from on gas to idle......
I have cleaned the carb, set air screw, it has a 48 slow jet and I can't recall the main, seems like it was a 125
needle in the 3rd position.

It makes no difference if the bike is hot or cold,
Could it be the float height?

another thing, should you have to physicaly hold the choke plunger up? although it starts fine without the choke ,just thought I would throw that in also

 

[tshs1997]

check the carburetor return spring and make sure the slide is moving easily (not scored or dirty) make sure the throttle cable isnt worn out or freyed.
also may check the carburetor boot for splits or looseness. and make sure the air filter is clean.

 

[DRZ_Dad]

The throttle is working fine, i just rebuilt the top end a few days ago, it was doing this before the rebuild too. the boot is good also,

it doesnt make a sudden jump from high to low its a gradual change, it's not a crazy high idle, but higher than normal, then when it settles down it goes lower than it should be

 

[tshs1997]

did you also replace the reed valve?

i didnt think of it before, but my wife rides a kx 80 with had a similar problem, when i checked the reed valve one of them was warped and wasnt sealing properly.

worth a shot anyway.

 

[DRZ_Dad]

Thanks, I don't think it is the reeds, i can take the reed block out and hold it up to the light and cannot see light around the edge, they are not lifted off the block........

 

[wasted]

maybe its got an air leak...

 

[tshs1997]

back to your original post. it could be the float is set too low. does it ever lose power when your riding hard?

is there a fuel restriction from the tank to the carburetor?

as wasted asked, about an air leak. it could be crank seals letting air by.

 

[DRZ_Dad]

This is my sons ride, but no it never looses power or act like its starving for fuel, I will check the seals but I would think if it were the seals it would not settle down, but I dunno,

Thanks again for your help, I'll check the float height

 

[Devourment 138]

what year, and what condition is the bike in...most importantly what does the plug look like...has it ever been torn down before?...could be and airleak around the cylinder, or airboot, or even the crank seals.

 

[fastbygaff]

It is your crank seals, very common on this bike. If you don't address it you will have crank problems soon.

I replace the crank seals on our 01 model when I replace pistons.

I had this same problem and chaced it in every darection untill it ate up a crank and clutch basket.

Just remove the fly wheel and clutch basket and you will see them