yz426 problems

i have a 2000 yz426 with the 450 hot cams installed. i was riding it around last saturday and it was running like a champ, no bogging and started right up on the first kick. so i was on the way back to the truck to put more gas in it, it had about half a gallon left in the tank, when it suddenly started to sputter and then died and locked up. so i put it gear and rocked it back and forth, loosened it up and now the thing wont start.

i have checked and changed these items:

replaced spark plug and there is a white ish blue spark

valve clearence is good

timing is dead on

cleaned out the carb, it was pretty dirty and verified it has fuel flow

air filter is clean

the fuel vent cap works and there is good fuel flow coming from the tank to the carb

i have been trying to figure out what the problem is, i can kick the shit out of it, and it may start once or twice that night, but only run for a split second then it dies.any help would be appreciated, i don't feel like paying 75 bux an hour for some shop to diagnose it.

now that i double checked the timing, it may be the culprate. i counted 13 pins between the 12 o clock marks

now that i double checked the timing, it may be the culprate. i counted 13 pins between the 12 o clock marks
A) That's correct.

:doh: That's not how you check the timing.

With the crank at TDC, and the cam lobes up and out, the "E" mark on the exhaust cam and the "I" mark on the intake should align with the cam cover gasket surface on the head.

well,then the timing is dead nuts on. so what could be causing this?

well, i stand corrected about the timing. when the crank is at TDC the intake cam timing mark is below (roughly 1/8 of an inch) the head surface and the exhaust is above (1/8 inch) the head surface. so i thought maybe the crank jumped a tooth on the chain. so i repositioned the chain on the crank gear and all it did was reverse the position of the marks on the cam gears. so i am thinking i am due a new chain. what are your thought all mighty grayracer. i would hate to waste the money on a new chain if it isn't the trouble maker.and is there an easier way to remove the chain guides, i feel like i am damaging them when i remove them. thanks for the help everyone.

Well, you do need the chain, by the sound of things, but that's not going to cause your symptoms unless it's farther off than that.

Do you know for sure what exhaust cam your bike has? If it is a 450 type Hot Cams for a 426, the timing marks are correct. But if it's a Hot Cams for a 450, you have to use the alternate timing instructions from the DCM thread. OEM 450 cams don't have an "E" stamped on them.

Really sounds more like electrical to me, though.

it could be, but when i was kicking it over it would backfire out the exhaust. just a quick loud pop noise. so thats got me thinking it is the timing. it's pretty sad when the b-1b that i work on is more maintaner friendly than my dirt bike.

well, i talked to the previouse owner of the bike, and he said it has 450 exhaust cam in it. so that explains why the timing marks don't line up. so to just see if i got the timing procedure correct. set the fly wheel at TDC, line the intake cam up by setting the dimple on the gear level with the cylinder head surface, then line up the exhaust cam by ensuring there is 14 pins between the 12 oclock marks on the gears. then do some voodoo magic to start it.

well, i talked to the previouse owner of the bike, and he said it has 450 exhaust cam in it. so that explains why the timing marks don't line up. so to just see if i got the timing procedure correct. set the fly wheel at TDC, line the intake cam up by setting the "I" mark on the gear level with the cylinder head surface, then line up the exhaust cam by ensuring there is 14 pins between the 12 oclock marks on the gears. then do some voodoo magic to start it.
Correction in bold/red.

well i couldn't figure out why my bike wont start, so i dropped it off at mechanics. and he already thinks he knows what the problem is. he said when the engine peetered out at the speed i was going it may have caused the cam gear to shift just a little bit on the cam. if this is so, it would explain why it was popping thru the exhaust. well, hopefully they wont rape me too bad on the cost of fixing it, atleast he is only charging 40$ an hour

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