help me out cr 80 please

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brentoncole

Member
Feb 17, 2010
103
0
okay i have just bought a frankenstein bike of sorts it is a 1999 cr 80 with a 1981 cr 80 motor in it and the engine barely fits so it is hard to work on anything

- the carb, bike wont start and when it does it is revving extremely high and the slide + needle appear to be in idle position?

- the front brake is hydraulic and doesnt work the guy said it needs to be bled and i assume refilled will car brake fluid work and how do i do this?

- the air box+hose isnt even close to the carb so i have no air filter?

what makes it revv so high and when i take the carb apart what should i look for is something clogged or could it be the idle screw
 
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brentoncole

Member
Feb 17, 2010
103
0
carb issue

hi i just got a cr 80 and it will not run i don't know what the issue could be i just cleaned the carb out and it will not run unless i spray gas in the carb and it will only run off the gas i sprayed and if i give it throttle it wont do any thing untill i am about half throttle or wot and then it either boggs down or it revs higher i am going to soak the carb sum more and if it doesnt work i am going to be POed :bang:
 
K

kx2502009

Member
Nov 1, 2009
51
0
the reving up high is from it running to lean either your pilot jet is clogged or your left side crank seal is leaking take stator cover off and see if there is some oil residue inside (there was in mine)
 
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dmaegan

Member
Feb 7, 2010
25
0
1-gp reasons change gas
2-check fuel filter on the petcock and the inline
3-check float height
4-clean out pilot circuit(might as well do pilot,needle and main)

bog means lean aka no gas if pilot circuit is cloged the bike will not start or be extremely difficult.

dmaegan
 
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brentoncole

Member
Feb 17, 2010
103
0
i have done/ checked all of those except check float height how do i do that and i have 2 carbs that i am assuming are from the 1999 and 1981 the 81 needs the slide and cap but the 99 is all there (being soaked) will the year affect it? can i order the slide and cap from keihin
 

ellandoh

dismount art student
~SPONSOR~
Mi. Trail Riders
Aug 29, 2004
2,958
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take supply line off carb to see if anything is getting through
 
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dmaegan

Member
Feb 7, 2010
25
0
well the year could cause some jetting problems and some possibly some throttle cable issues.I am not sure the jetting thats is in either of those 2 carbs.I suggest you get a manual on the 81 and set the jetting specs to that year if they are not correct in the carb you have now and then if you use the 99 carb set the float height to the 99 specs.You can get the slide and cap from the honda dealer but make sure you find out the year of the carb and make sure what style and size carb it acutally is.

run the numbers with keihin
 
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brentoncole

Member
Feb 17, 2010
103
0
ok i will try and do that my carb is nice and clean and ready to put back on now but could my problem have been the rubber boot that attaches to the reeds if my carb wasn't sealed good would that have been the issue and also i think u may be on to something with the float height if the boot wasn't the prob how do i adjust that
 
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brentoncole

Member
Feb 17, 2010
103
0
i dont understand the pilot jet clearly is not clogged and niether is my main the only possibilty is the rubber thing or my engine has low compression... will a bike run at all with low compression... my bike sounds alright but it wont start or stay running
 
J

_JOE_

~SPONSOR~
May 10, 2007
4,697
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You need a good seal between the carb and reed block or it'll suck air and go lean.

You need compression of about 120 psi for the bike to start. You also need spark and fuel in the combustion chamber. Sounds like you have good advice to eliminate the fuel supply issue. If you've got compression, the correct amount of fuel, spark and the timing is right it has to start.
 
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brentoncole

Member
Feb 17, 2010
103
0
it has compression the plug just hadn't been tightened now its got a nice hard kick but it still wont run by itself, i got it to start for like a second on its own but it died shortly after.... any one have ideas on how to seal the carb to the rubber piece the frame is pushing on the carb and might be messing with the seal and also could it be the carb itself because one way or another it is not sucking gas
 
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brentoncole

Member
Feb 17, 2010
103
0
okay guys i just messed with the float and now my bike starts on like the first kick but it idles at super high right below the power band so i have to use the kill switch to shift i was hauling though this baby goes i was about 50 up hill
 
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dmaegan

Member
Feb 7, 2010
25
0
it idles at super high right below the powerband?????
where 1/4 throttle , 1/4 throttle through 3/4 throttle or wide open?
does it rev high and then slowly creep back down to normal idle?
you said frame is pushing on the carb is the carb on the motor straight or could the frame be holding the carb on an angle?anywhere throught the throttle range is the acceleration normal?

and yes the boot to carb must be a sealed tight fit there should be a hose lamp around the boot to seal it up.
 
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brentoncole

Member
Feb 17, 2010
103
0
the frame is pushing on it slightly but its not extreme enough to cause anything and i would say it is idling about 3/4 because when i was riding it was just going by itself right below the power band and i would give it throttle and it would go straight into the band... it was idling high enough that i think it would have done a wheelie in first gear and if i tilted the bike way far over to the left it sounded like about 1/2 throttle
 
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brentoncole

Member
Feb 17, 2010
103
0
ok thanks so much guys my bike runs awesome, turns out the float was part of it but the slide wasn't going down far enough so i had to modify the cap and now she hauls but is loud as heck.

i am going to make a new thread now i need more bottom end,a quieter exhaust, and a way to connect the carb to the air box
 

Patman

Pantless Wonder
LIFETIME SPONSOR
Dec 26, 1999
19,765
1
How many threads on this do you really need?
 
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