anybody familiar with a yz 426?

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Sebastian F7

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So I'm working on a yz 426. It just had a top end done (not by me) I just got into it this morning with the expectation of rebuilding accelerator pump and firing it up.
First I had to fight the carb, the o ring on the seat was shot.
Then I got it to fire but as soon as you turn off the choke or touch the throttle it dies. Been thru the carb 2 times. I'm pretty sure its not carb related.
Is it possible the woodruff key was put in backwards and it's retarding the timing too much.
I don't think it's out of time because I have compression and it will run.
 
Did you run a wire through the jets? My granddaughter's TTR wouldn't stay running and the idle wasn't there. Had to have half-choke all the time. I took it all apart and ran a thin wire through all the possible places and found a clear spec of silica sand jammed in the secondary jet. Put it back together and it runs absolutely perfect now.
 
FZ1inNH said:
Did you run a wire through the jets? My granddaughter's TTR wouldn't stay running and the idle wasn't there. Had to have half-choke all the time. I took it all apart and ran a thin wire through all the possible places and found a clear spec of silica sand jammed in the secondary jet. Put it back together and it runs absolutely perfect now.
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I didn't wire them because it had been cleaned and wired before I got into it. I tore it all apart to see if anything was wrong. Blew everything out with air. I'm really thinking it's timing related. I think it's a 00 and uses a timing key which was switched out due to key failures. Phhh my leg and foot hurt from kicking that pig over.
I got my a** kicked by that bike today.
 
Already checked float level. I didn't take the slide out myself but that doesn't mean the tech before me didn't or the owner... The bike came to us in pieces...

Update: went thru carb again, wired all jets re-checked float height ran for a minute till I turned choke off. Died no restart. Checked timing it's dead on. I'm at a freaking loss. Ready to just bolt a new carb on.
 
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Sebastian F7 said:
wired all jets re-checked float height ran for a minute till I turned choke off. Died no restart. Checked timing it's dead on..
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Has to be the carb. Running fine with choke on? like damn near perfect? If so, then you are not getting enough fuel as when you turn choke off (more air let in) it dies. Did you change out any jets or anything?

Sounds like you messed with the Accelerator pump, what did you do?

Have you adjust air/fuel at all?


I have a similar bike (WR450) and I know a little on the carb so I can try to help
 
JMundy said:
I have a similar bike (WR450) and I know a little on the carb so I can try to help
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I need help! I want your WR 450.... :D How is that bike on the street? Do you have street AND off-road tires on it?

Back on topic... I agree that this is still a carb issue. If the jets are clear, have you tried resetting all the mixture screws to the default turns and starting adjustments from there?
 
I love my WR450. No street, dirt only. I got the R1 for the street. I would get too crazy on the street with the 450.





I have recently removed those FUGLY hand guards. I got them when I bought my FZ1 and tried them on the bike, didn't like them so back to no guards.

The WR450 rips when setup properly. 4th gear wheelies on dirt, so I would kill myself on the street with rear traction. :)

Bike has some amazing power and does everything and more I want it to on the trails. Had my suspension done and now it really rips on the trails
 
FZ1inNH said:
I agree that this is still a carb issue. If the jets are clear, have you tried resetting all the mixture screws to the default turns and starting adjustments from there?
Click to expand...

^^X2

Gotta be mixture screw or if the main jet has a clip setting for fuel delivery check that it is in stock position
 
Finally figured it out it's leaking air behind the throttle cable assembly. Apparently this part is not replaceable.
I managed to get it to run long enough to spray some starting fluid around it ( I would've opted for something different but it was the boss's call)
Looks like it may need a new carb.


Not sure whrere we are gonna go with it.
Next week I get to tear down a brand new GasGas that's never been ridden and put a new frame on it.
 
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Turns out there is a non replaceable o ring style gasket in the middle of the carb that can and did go bad. I split the carb and sealed it with permatex gasket maker, threw the carb on the bike and it runs fine now.
It was a chore getting the permatex in all the grooves and not in the ports.

Too bad I lost my A** time wise in the thing.
 
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