yz426 problems


9 replies to this topic
  • usaf_yz426

Posted May 15, 2009 - 04:17 PM

#1

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.

  • usaf_yz426

Posted May 15, 2009 - 04:20 PM

#2

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

  • grayracer513

Posted May 15, 2009 - 04:23 PM

#3

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.

  • usaf_yz426

Posted May 15, 2009 - 06:00 PM

#4

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

  • usaf_yz426

Posted May 19, 2009 - 09:02 PM

#5

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.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted May 19, 2009 - 09:16 PM

#6

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.

  • usaf_yz426

Posted May 19, 2009 - 09:25 PM

#7

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.

  • usaf_yz426

Posted May 20, 2009 - 08:32 AM

#8

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.

  • grayracer513

Posted May 20, 2009 - 08:40 AM

#9

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 [COLOR="Red"]"I" mark[/COLOR] 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.

  • usaf_taco

Posted May 22, 2009 - 06:56 AM

#10

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





Related Content

 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.