Maybe check the intake joint at the carb? Sounds like it could be getting too much air and you’re having to counter it with more throttle to keep it going. You can try (carefully) spraying some brake clean around the carb joint while its running and see if the idle/running condition changes drastically then you’ll know it’s has a vacuum leak causing a lean running condition.
Need help please
I have a 2007 yfz450
I just did a full rebuild, problem I'm having is it won't idle and to start it I have to press throttle just a little. Once started it runs fine but soon as I let off throttle it just stalls.
I've already tried adjusting throttle cable at both ends as well as idle adjuster. No matter what I do it's still the same.
This is what's been done to it,
Ct racing national kit with 480 big bore, full port and polish on head bigger valves, web cams, full dasa exhaust, fuel customs intake and kn filter(lid off), dynatek cdi
Carb was complete tear down and rebuild.
Carb settings,
170 main jet
50 pilot
Fuel screw 2 1/2 turns
Qs3 1 3/4 turns
Needle ncvq 4th from top.
Tors bypassed
Any ideas on what to change or check?
Thanks in advance
I just did a full rebuild, problem I'm having is it won't idle and to start it I have to press throttle just a little. Once started it runs fine but soon as I let off throttle it just stalls.
I've already tried adjusting throttle cable at both ends as well as idle adjuster. No matter what I do it's still the same.
This is what's been done to it,
Ct racing national kit with 480 big bore, full port and polish on head bigger valves, web cams, full dasa exhaust, fuel customs intake and kn filter(lid off), dynatek cdi
Carb was complete tear down and rebuild.
Carb settings,
170 main jet
50 pilot
Fuel screw 2 1/2 turns
Qs3 1 3/4 turns
Needle ncvq 4th from top.
Tors bypassed
Any ideas on what to change or check?
Thanks in advance
1 - 8 of 8 Posts
I'll give that a try, if that does nothing what else would you recommend?
Check your valves. Tight valves can cause engine stalling as well. You have a pretty healthy list of mods to this atv so you’re gonna have to run back through some of them possibly to double check.
Your problem is in the intake / fuel delivery ..... probably not enough restriction to properly draw fuel through the carb .... So many " mods " do more harm than good ...
Everything needs to be matched and properly balanced to work right ....
Everything needs to be matched and properly balanced to work right ....
Well I have an update,
I belive the problem is in the tors system. I have the plug disconnected at the carb and the jumper installed.
I took the cover off the throttle and was watching while I started it. When mechanism releases the switch it will start and runs fine. If I slowly ease off the throttle the second it pushes the switch in the motor dies.
I tried unplugging the switch and it would even start. If I reconnect it at the carb if won't start and back fires.
My question is if I buy a new switch do you think it would solve the no idling issue? Seems like it's related..
Would a faulty switch cause it not to start unless the switch is released?
I've pulled the carb rejetted it made sure everything was on tight, checked for air leaks, adjusted the idle screw all the way and I just can't get it to idle.
I belive the problem is in the tors system. I have the plug disconnected at the carb and the jumper installed.
I took the cover off the throttle and was watching while I started it. When mechanism releases the switch it will start and runs fine. If I slowly ease off the throttle the second it pushes the switch in the motor dies.
I tried unplugging the switch and it would even start. If I reconnect it at the carb if won't start and back fires.
My question is if I buy a new switch do you think it would solve the no idling issue? Seems like it's related..
Would a faulty switch cause it not to start unless the switch is released?
I've pulled the carb rejetted it made sure everything was on tight, checked for air leaks, adjusted the idle screw all the way and I just can't get it to idle.
so it was connected then it just would idle. Now you connected it and it won't even run?Well I have an update,
I belive the problem is in the tors system. I have the plug disconnected at the carb and the jumper installed.
I took the cover off the throttle and was watching while I started it. When mechanism releases the switch it will start and runs fine. If I slowly ease off the throttle the second it pushes the switch in the motor dies.
I tried unplugging the switch and it would even start. If I reconnect it at the carb if won't start and back fires.
My question is if I buy a new switch do you think it would solve the no idling issue? Seems like it's related..
Would a faulty switch cause it not to start unless the switch is released?
I've pulled the carb rejetted it made sure everything was on tight, checked for air leaks, adjusted the idle screw all the way and I just can't get it to idle.
There is a switch in the throttle too. They must match what you are doing (idling or not) I think I would try shorting the wires at the carb and see it it idles. If so replace the carb switch.
The correct way to diagnose would be to check the throttle switch and carb switch with an ohm meter to see that they both work.
Problem solved, it was the switch in the throttle. I bypassed it and it idles fine.
Thanks for the help
Thanks for the help
1 - 8 of 8 Posts
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