'94 YZ80F Carb help

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carter76112

Member
Aug 7, 2008
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I just brought a '94 YZ80 home from my sister's farm. It was her son's. She said he took it apart to work on, got distracted and interested in other stuff, and never worked on it again. She said it was running the last time he worked on it. I have never worked on a bike before, but I have worked on cars so I got it home and started with what I figured was the basics. Removed carb and cleaned it good. Drained and replaced gear oil. Replaced the chain, the old one was all rusted. Replaced air filter. Removed small critter nesting materials from exhaust system. Drained old fuel from tank, rinsed tank with plain gas, filled tank with fresh mix 32:1. I got it back together, and when I turn on the fuel, it pours out the pilot overflow at the float bowl of the carb. I don't know what to do from here. I don't have any manuals, don't know what the initial settings should be on the carb jets, etc. I don't know if my nephew jacked with the jets when he tinkered with it. The jets all looked good when I had the carb apart. Could it be the float setting, the pilot jet not adjusted right? I just don't know. I'm thinking float level, but want to hear the voice of experience, and see pictures if at all possible! What do I do? Thanks!

P.S. I am a Mom fixing this bike up for her son's 17th b-day.
 
Last edited:

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
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Merrillville,Indiana
Take the carb back apart. Remove all the jets, spray and poke a fine wire through the jets and orifices. Remove the float, and float valve. Clean it and inspect it, or better, just replace the float valve/seat if applicable. Sounds like the float got installed wrong. It may be bent, now. Check the float height. Goggle any online shops micro fiche. If you look carefully, it will tell you the stock jet sizes. Float height, you are going to really need a manual.
 
C

carter76112

Member
Aug 7, 2008
10
0
I cleaned the jets when I had it off the first time, but I will clean it all again. Can anyone tell me the best settings (turns) to start out with on the Idle Adjusting Screw and Air Pilot Screw? I realize I will probable have to fine tune it, but when I got it they were both screwed in all the way. I know that's probably not right. Also, the pilot jet screws into position. Is there a default number of turns for it? Hopefully I will have an answer to this by the time I get the carb off, clean it again, and get ready to try again. Thanks!
 
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Blink-182

Member
Feb 2, 2008
127
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its not the pilot jet you adjust you snug that up in the carb not to tight either, its the air screw for the pilot jet that you adjust that is on the outside of the carb should be close to the idle screw

is it not starting?
 
C

carter76112

Member
Aug 7, 2008
10
0
Well, it wouldn't last time I tried. Right now I have the carb back off making sure there is nothing impeding the float. It wouldn't stop filling the float bowl and fuel was pouring from the overflow. Will also check that the flote valve is seated properly. All the guys I have asked locally just tell me to bring it in for repair, but I'm a smart girl and have worked on lots of cars. I just usually have a book for reference and they want to charge me $80 bucks for a manual. I checked the library, and someone stole their copy. I'd really like to get this bike running for my son, he turns 17 tomorrow. Any suggestions? I'll take all the help I can get!
 
J

_JOE_

~SPONSOR~
May 10, 2007
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Is there liquid in the floats? Make sure the valve isn't deteriorated where it contacts the seat. Set the pilot at 1 and a half turns out from closed. Set the idle screw so it picks the slide up about a 16th of an inch or so. That should get it started.
 
J

_JOE_

~SPONSOR~
May 10, 2007
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Also the part about nesting material in the exhaust makes me nervous. How far apart was it when you got it?
 
C

carter76112

Member
Aug 7, 2008
10
0
The main parts were all connected together, but the connections were loose, hoses disconnected, etc. It turns over when I kick it, but doesn't catch. I'm sure part of that has to do with the flooding. Regarding the idle screw. If it is fully seated now, and the carb is together, how will I know when it picks up the slide? Is it by feel?
 
J

_JOE_

~SPONSOR~
May 10, 2007
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Back it out first. If you can see the slide, watch for it to stop dropping.
 
C

carter76112

Member
Aug 7, 2008
10
0
Ok, I did that. Will it hurt anything for me to turn the petcock before I hook up the intake or try to start it, just to see if it is going to overflow again?
 
C

carter76112

Member
Aug 7, 2008
10
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OK, Good news! It started. but won't idle. I figure that's just a matter of setting the screws right. But now I have another problem. It won't go into gear. Arrrgh! Does that mean I need a new clutch? Could it just be sticking?
 
J

_JOE_

~SPONSOR~
May 10, 2007
4,697
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Try turning the idle screw in, it should idle. It may not idle long though. Some bikes don't idle well. Is there resistance when you pull the clutch lever in? How about if it's not running, will it go into gear then?
 
C

carter76112

Member
Aug 7, 2008
10
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Yes, it goes into gear when it is not running. I know it does because I have it up on a stand, when I move the shift lever, the rear wheel will stop turning. I have to pull the clutch lever in.
 
J

_JOE_

~SPONSOR~
May 10, 2007
4,697
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Does the lever go down when you push on it while it's running? Have you ried shifting up into second with it running?
 

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
2
Merrillville,Indiana
What did the oil look like that came out? If any? Try going through all the gears by rocking the wheel back and forth and shifting. Does the clutch work?
 
D

Dylan19302

Member
Jun 27, 2008
111
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when you said it wouldnt idle how long have you let it run. you have to let it warm up first for about 1 min. With my bike I have to hold the choke up for about 1 min then it will idle without it.
 
C

carter76112

Member
Aug 7, 2008
10
0
Hey ya'll, Susan here. Gosh this last week has been busy. I just got back to the bike today. I got it running good, idle set, shifts up & down through the gears. There is one problem that keeps me from allowing my son to learn to ride . . . the front brake doesn't work The master cylinder is good, but the line is totally plugged with something. I've tried squirting brake cleaner down the line, forcing the obstruction out with pressure from the cylinder, blowing it out with compressed air, and running a nylon guitar string down the line to try to push the obstruction out. I have done this from both ends of the line. No one will be riding it without front brakes, but I'd rather not buy any new parts right now if I can help it. Does any one have any suggestions? I have been thinking of trying to rig up some sort of roto-rooter snake with my dremel tool. I figure, I can't hurt anything, as the line is off the bike right now, and it doesn't work anyway.
Suggestions?
 
J

_JOE_

~SPONSOR~
May 10, 2007
4,697
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Hmmm. I've never heard of any tricks for clearing a restricted brake hose. I would think if you could hook the line up backwards and force it out with the pressure from the master that would be your best chance. Can you actually feel something in the line with the guitar string?
 
C

carter76112

Member
Aug 7, 2008
10
0
I have hooked it up backwards and tried forcing it through that way. It feels like the obstruction is exactly where there is a line coupler (not sure if that's the correct term here). The "coupler" is where the line clamps to the front forks before looping under to connect to the brake caliper, and it is heavy metal, not flexible like the rest of the line. The line comes manufactured with this coupler in place about 9-12 inches from the end of the brake line. My snake becomes stuck at this point, regardless of which end I enter the brake line from. I have attached a picture of the "coupler" in the line.
 

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J

_JOE_

~SPONSOR~
May 10, 2007
4,697
3
Honestly, you're probly going to have to replace it. I've seen plenty of automotive brake hoses "collapse" and cut off flow, though I have never actually cut one apart to see what went wrong. The automotive hoses are similar to bike hoses. Check Flea-Bay? Let us know if you end up getting it working.
 
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