failure...grrr...


13 replies to this topic
  • slopoke

Posted April 23, 2006 - 09:58 AM

#1

so, i was riding the other night on my motard in the middle of freakin' nowhere and the 426 (sm) takes a crap...well, i get it home and here's the prognosis....cam chain tensioner broke, intake cam skipped some teeth and bent all three valves, the piston doesn't look bad, but i figure the bore looks pretty worn so i might as well just replace it all....how's the wiseco high comp piston?? anyone make decent and halfway inexpensive big bores? is it possible to just buy a big bore piston and have the cylinder bored and replated? has anyone replace the ti valves with stainless ones? who makes the valves other than yamaha? anyone make a manual cam chain tensioner?
thanks for all the help,
-Kinda unhappy..lol..
Matt

  • kid on a 426

Posted April 23, 2006 - 10:30 AM

#2

Ice cube big bores are the cheapest that I've seen.

  • slopoke

Posted April 23, 2006 - 10:34 AM

#3

Ice cube big bores are the cheapest that I've seen.

i don't see an application for the ice cube big bore for a 426...i only see them for the 450...

  • grayracer513

Posted April 23, 2006 - 01:45 PM

#4

If you believe that the chain tensioner failed, I'd like to see it. I'll pay you to ship it to me, but you can't disassemble it in any way. PM me.

  • 642MX

Posted April 23, 2006 - 03:08 PM

#5

I doubt it was caused by a broken tensioner. How about some pictures?

  • 00YZ426FMRCD

Posted April 23, 2006 - 03:24 PM

#6

Things that make you go hmmmm....

  • slopoke

Posted April 23, 2006 - 07:03 PM

#7

i'll probably be up @ the shop tomorrow...here's what i can tell you so far...
the cam chain tensioner was collapsed, all three intake valves were bent, and the middle cam follower was crushed (broken into about five or six pieces...

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  • slopoke

Posted April 24, 2006 - 09:22 AM

#8

any info on yz400 valves?

  • 642MX

Posted April 24, 2006 - 09:32 AM

#9

any info on yz400 valves?



I would use the Ti valves (OEM). Don't forget to get all new springs. The springs where out twice as fast as the valve. 12,000 RPM is alot of work for an $8 part. A broken or worn spring might have been the start of your problems. Bring on the pictures.

  • slopoke

Posted April 24, 2006 - 03:42 PM

#10

I would use the Ti valves (OEM). Don't forget to get all new springs. The springs where out twice as fast as the valve. 12,000 RPM is alot of work for an $8 part. A broken or worn spring might have been the start of your problems. Bring on the pictures.


i have to replace at least one guide and will replace the springs as well, however, none were broken....all the retainers were good as well...i'll take some pics tomorrow, but like i said, everything was intact (cam chain, springs, (the intake valves were bent, but intact..lol..), all the valve springs were good, the cams and cam caps were good....sooo...i can really only come to one conclusion..but i'll take pics tomorrow...
also, why necessarily, would you use ti valves opposed to stainless?? they wear out quicker and are around 400 for all five opposed to 100 for all the parts i need including guides and springs for the stainless...

  • 642MX

Posted April 24, 2006 - 05:19 PM

#11

why necessarily, would you use ti valves opposed to stainless?? they wear out quicker and are around 400 for all five opposed to 100 for all the parts i need including guides and springs for the stainless...




Properly adjusted Ti valves will have a very long service life. You can use SS, but the Kibblewhite stuff is almost as expensive as Ti.

  • slopoke

Posted April 24, 2006 - 05:23 PM

#12

Properly adjusted Ti valves will have a very long service life. You can use SS, but the Kibblewhite stuff is almost as expensive as Ti.


lol...ya, i was going to call them tomorrow...lol..oh well, i did however get a chance to price out the yz400 stuff, i heard that it does work as well, and it was cheap???

  • Butta

Posted April 24, 2006 - 07:10 PM

#13

I am wondering if the cam's slipped on the cam gears.

Yes...pictures...please

  • slopoke

Posted April 24, 2006 - 07:20 PM

#14

I am wondering if the cam's slipped on the cam gears.

Yes...pictures...please


this is exactly what i think happenned, post the cam chain tensioner failing...but, like i said, i'll post pics tomorrow..





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