426 stalls and no start

15 replies to this topic
  • jsmith4816

Posted May 11, 2013 - 06:02 AM


Hello all, Friday, buddy and I went trail riding and rode fine for about an hour. Went back to the trailer to grab some water and bike wouldn't kick back over. Its a 2001 426 stock bike. Piston and rings are 2 years old. Seems like I've lost compression. I tried pulling the spark plug and it was really hard to get out. After I got it out, it looked like it took some of the threads with it. :thumbsdn: Was going to break it down today to try and find the culprit, but haven't decided where to start. I'm thinking valve clearances?

  • mpmoto

Posted May 11, 2013 - 06:41 AM


start with valve clearances, most likely be the problem I'd say

  • jsmith4816

Posted May 27, 2013 - 06:27 PM


Thats what I was thinking too. I would have done the job a few weeks ago but didnt have as much time as I would like. I have an owners manual but have never done the job itself. Anything to be extremely cautious about?

  • grayracer513

Posted May 28, 2013 - 07:10 AM


Anything to be extremely cautious about?

Assembling and retorquing the cam caps. Seat the caps before you tighten them (don't pull them down with the bolts) and torque them in the correct sequence and in 3-4 small steps. Stop at 75 inch pounds instead of 86.

  • jsmith4816

Posted May 28, 2013 - 12:49 PM


Was taking the cover off and when the bike was at TDC this is what I found.
Mobile Uploads 5-17-13 032.jpg
Are my cams lined up correctly with the cylinder? The bike is at TDC but it looks like the dots are a little off. The cam lobs should be facing opposite of each other right?

Mobile Uploads 5-17-13 033.jpg

As noted before, I have not checked valves on a bike before so I am just making sure everything looks right before I start to take apart/put back together

Edited by jsmith4816, May 28, 2013 - 12:58 PM.

  • grayracer513

Posted May 28, 2013 - 12:58 PM


You're on the wrong TDC. Go around one more revolution and then check it.

  • jsmith4816

Posted May 31, 2013 - 10:24 AM


Rotated another rotation, and now the lobs are facing away from each other. Thanks guys

  • jsmith4816

Posted June 01, 2013 - 04:55 AM


Check clearances and my exhaust spec is .25-.30mm, I measured .127. Intake spec is .15-.20mm and I got .074. Both seem low to me and now worried that its time to get new valves. Is this normal or have a encountered a big problem?

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  • grayracer513

Posted June 01, 2013 - 06:07 AM


If you actually have a 2001 model, you have Ti valves, and your correct valve clearance is .10-.15mm (.004-.006") intake, and .20-.25mm (.008-.010") exhausts. The 2000 model with stainless valves uses the specs you cite.

Adjust them to spec and then recheck them after the next couple of rides. If they have not tightened up again, you should be OK. If they close up farther in that time, it's a bad sign.

  • jsmith4816

Posted June 01, 2013 - 06:26 AM


It's a 2001 and I will double check the title to verify. My manual gave me the specs that I listed.

Again. Thanks for the help

  • jsmith4816

Posted June 11, 2013 - 11:58 AM


Your right grayracer. Thanks for pointing that out. I would have had no odea. Well I got the shims out this weekend and it looks like they are the pretty old. I am thinking they are the original because the previous owner said he never changed anything. Heres a pic
Mobile Uploads 5-17-13 019.jpg

Mobile Uploads 5-17-13 020.jpg

  • jsmith4816

Posted June 24, 2013 - 10:23 AM


Got her all put back together but shes still hard to start. When I get it warmed up, it starts first kick. When I kick it cold, it feels like the kick-starter is getting stuck half way and then it goes down. I am doing the manual decompression right, but it feels like that may be the problem. I am not getting a good enough kick to make it start when cold. Gonna try and look at it again this week. Thanks for all the help.

  • jsmith4816

Posted September 29, 2013 - 12:26 PM


So I road a few times and bike was running great. Went to the track the following day and couldn't get her started. Finally got it running but noticed my radiator hose wasn't connected. Turned the bike off and reconnected tbe hose and she wouldn't start back up. Was pretty ticked since it was running great the previous day. Took it apart and almost all of my clearances are off. When finding TDC this what happened.



Is this normal? Like noted before, im new to valve jobs. It feels like it catches with every turn. I know grayracer was saying if the clearances are off after a few rides, then its time for a valve job. I'll accept that, bikes old, but also want to know if it may be something more.

Edited by jsmith4816, September 29, 2013 - 12:40 PM.

  • jsmith4816

Posted October 02, 2013 - 09:33 PM


Anyone have an idea? I might just have the valves re-seated and go from there.

  • grayracer513

Posted October 03, 2013 - 07:09 AM


"this is what happened"


OK, what? Didn't see anything unusual.

  • jsmith4816

Posted October 03, 2013 - 09:30 AM


That was my question. If there was anything unsual about they way it turned. Like I said before, I am new to working on own bike thing and didn't know if that was normal or not. Thanks for the help.

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