06 yz450 carb problem

[gdbarr1976]

The jetting on this bike has been spot on. The problem now is that it will stall right off idle. I was sure I had a clogged pilot jet but after a complete carb cleaning I still have the same problem. I am running a 42 pilot which is on the lean side but it has been running fine. Adjusting the fuel screw makes no difference. Could I be having a excellerator pump problem. How would I check?

While moving it will stall when the throttle is opened in 1st gear. At high and mid rpm it runs fine and it will idle. I am fairly sure it is a fuel problem but I dont think it is a jetting problem. Any ideas?

thks

[YZfamily]

I installed a Boyseen QS 2 and it solved that problem for me.

[todds924]

The jetting on this bike has been spot on. The problem now is that it will stall right off idle. I was sure I had a clogged pilot jet but after a complete carb cleaning I still have the same problem. I am running a 42 pilot which is on the lean side but it has been running fine. Adjusting the fuel screw makes no difference. Could I be having a excellerator pump problem. How would I check?

While moving it will stall when the throttle is opened in 1st gear. At high and mid rpm it runs fine and it will idle. I am fairly sure it is a fuel problem but I dont think it is a jetting problem. Any ideas?

thks

Try pulling your float bowl off and making sure your leak jet is clean..also the passageway the leak jet screws into. Double check your pilot also, even though it looks clean it could be partially clogged.

[gdbarr1976]

Thanks for your replies. I have another 06 450 with a quick shot so I swapped it out. No help. I put a 48 pilot in from a 42 and again blew out all the jets. No help. Finally I swapped complete carbs. No change.

This is what it does. It will run fine till it gets hot. Then it will stall right off idle. It acts lean but only after it gets hot. With the choke on it will run ok but rich. So it is not the ignition and since I swapped carbs with no change it is not the jetting or anything else in the carb.

I am thinking it is a air leak. I tightened the hose clamp on the carb with no change. I am not sure were to go from here. HELP! This is my sons motor and we are heading to a enduro tomorrow.

tks

[1st450]

i have the same bike and it seems to do the same thing if i dont change the oil everyother ride. when was the last time you changed the oil?

[gdbarr1976]

Oil is fresh.

Could tite exaust valves be the problem? I have replaced the intakes but not the exausts. If the exausts were hanging open would that not let in air and would it not get worse as it heats up and they expand?

[gdbarr1976]

The exhaust valve was a little tite, fixed that but no help. Goes lean when it gets hot. Anybody??

[Norman]

You might post in the jetting forum and see if Eddie can offer any advise.

[racegmc]

I had the same problem. Come to find out I had put to much oil on my air filter after I cleaned it.

[todds924]

Thanks for your replies. I have another 06 450 with a quick shot so I swapped it out. No help. I put a 48 pilot in from a 42 and again blew out all the jets. No help. Finally I swapped complete carbs. No change.

This is what it does. It will run fine till it gets hot. Then it will stall right off idle. It acts lean but only after it gets hot. With the choke on it will run ok but rich. So it is not the ignition and since I swapped carbs with no change it is not the jetting or anything else in the carb.

I am thinking it is a air leak. I tightened the hose clamp on the carb with no change. I am not sure were to go from here. HELP! This is my sons motor and we are heading to a enduro tomorrow.

tks

You need to check your VALVE clearance...sounds like a tight valve

[gdbarr1976]

The problem was a bad ignition. After about 5 min it would advance the timing at idle which made it seem that it was running lean. Swapped out the black box, runs perfect.

[grayracer513]

You mean retard? Advancing the timing speeds the engine up. Retarding slows it down and makes it feel flat, much like as if it were lean.

Interesting though. Don't see many CDI's fail.