[Crazykid]

I have a 2003 yz450f with a big bore kit (480cc) and stage 2 cams both intake and exhaust, I have it timed correctly and it has spark I can spray fuel through the carburetor and literally can kick it all day and get maybe one or two pops, anyone know what might be wrong??

I reset the tps and the exhaust isn't plugged and the intake is off, need help!

 

[wameki92]

Oh


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[Crazykid]

Can you help me ?

 

[Thatblueyfz450983]

Have you checked your valves to see if they are adjusted correctly?

 

[Crazykid]

They are I reshimmed one of the intake vales because it was fairly tight and out of spec. I took the stator cover off and the stator was very far away from the magneto, fixed that but it still won't give me anything, it has thrown a fire ball out the exhaust but that's it.

 

[hew]

It kinda sounds like a timing/ valves issue. did you check that the crank is in timing with the valves? Make sure that the crank is at TDC and its line up with the I and the cam lobes are facing away from each other and the dots are even with the top of the head.

 

[Crazykid]

I double checked them and the piston is top dead center and the cam dots line up like they should and the pipes point correctly but I'm wondering if the timing chain is stretched enough to cause it not to start I have learned the hard way on timing correctly. haha

 

[Thatblueyfz450983]

How is the tension on the cam chain? Too tight? Too loose? make sure your chain tensioner works correctly and isn’t busted.

 

[Crazykid]

How is the tension on the cam chain? Too tight? Too loose? make sure your chain tensioner works correctly and isn’t busted.

The chain is not to tight and the tensioner looks good, I have suspicion of the timing chain being stretched and the exhaust valves being tight enough that the decompression hits slightly before it should.

 

[Thatblueyfz450983]

Seems like you have went through everything thing. I would guess too that the timing chain is stretched out and or the woodruff key is possibly sheared. And I’m just throwing this out, is it getting gas from the tank to the carb?

 

[Crazykid]

Seems like you have went through everything thing. I would guess too that the timing chain is stretched out and or the woodruff key is possibly sheared. And I’m just throwing this out, is it getting gas from the tank to the carb?

I need to tear down the stator cover again and check the woodruff key and I'm spray gas thought the carb so the throttles not open but I took the tank off and just sprayed fuel into the intake so that fuel wasn't an issue.

 

[hew]

When you kick it over is it hard too kick over? Have you checked the decompression pin on the exhaust cam and make sure its opening and closing. I would try to pull start it and see if it turns on. I once had a blaster and you can kick it over for days and nun would happen but then we pulled started it and it turned on right away and was running.

 

[Crazykid]

When you kick it over is it hard too kick over? Have you checked the decompression pin on the exhaust cam and make sure its opening and closing. I would try to pull start it and see if it turns on. I once had a blaster and you can kick it over for days and nun would happen but then we pulled started it and it turned on right away and was running.

It's not super hard to kick over I can put almost all my weight (all 145lbs) on the Kickstarter, I have checked to make sure it works and isn't stuck that it's present, I may try to bump start it before I totally tear it down again, thank you everyone for your comments and help.

 

[Crazykid]

UPDATE!

Hello everyone thank you for your help
I took of the valve cover and guess what it's out of time on the exhaust side by ONE tooth(causing fireball). I retimed the cams and now she starts for a little I still have things to work out for fueling as it doesn't what to run off of what the carb is putting out, if you've had a similar issue please help, again thank you for your help, also side note when I shift the bike into gear and try to move the tire back and forth it makes and very hard metal smacking sound not sure if that's normal or not but... To be continued