Replacing timing chain?


10 replies to this topic
  • rzr33

Posted September 01, 2014 - 06:35 PM

#1

Have a 2012 yz 450 that has less than 20 hours on it. The dealer says timing chain has stretched and is a tooth off. It won't even start. What all needs to be don't replace timing chain. Trying to figure out if I want to do myself. Anyone else have this problem??

  • WoodsRidinYZ01

Posted September 01, 2014 - 07:13 PM

#2

I'll have to look in a manual tomorrow but it will either pull out of the generator side or you have to split the cases. This of course also meaning you have to pull the tensioner and remove the cams on both scenario's.

Edited by WoodsRidinYZ01, September 01, 2014 - 07:15 PM.


  • billygildark5007

Posted September 01, 2014 - 07:14 PM

#3

I find that really strange for a chain to go in 20 hours under normal conditions. You should pull the valve cover yourself and check the timing marks to verify. If you do replace the chain a tensioner is a good idea.

  • WoodsRidinYZ01

Posted September 01, 2014 - 07:16 PM

#4

I find that really strange for a chain to go in 20 hours under normal conditions. You should pull the valve cover yourself and check the timing marks to verify. If you do replace the chain a tensioner is a good idea.

Second that on replacing the tensioner as well!

  • billygildark5007

Posted September 01, 2014 - 07:18 PM

#5

No need to split the cases. You can remove the stator cover, flywheel, and valve cover to remove/install the timing chain

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  • WoodsRidinYZ01

Posted September 01, 2014 - 07:23 PM

#6

I couldn't remember! Lol it's been awhile since I have been in a 450 and that was in a quad were they won't keep the thing on four wheels! Oil starvation to the crank!

  • rzr33

Posted September 01, 2014 - 08:40 PM

#7

Thinking it's odd also. The bike just died. We verified it's getting spark and fuel. But it will not start. The dealer said it's off one tooth and the exhaust valve is open when suppose to be closed. Any chance this could of damaged any valves.

We also checked all plugs. Dis connected kill switch to make sure it didn't go bad. Ran out of ideas. Of coarse only has 30 day warranty and that's up by a few weeks.

  • WoodsRidinYZ01

Posted September 02, 2014 - 04:38 AM

#8

Any good reputable shop would help you out somewhat with the labor or parts. Just gotta talk to them and feel them out.

  • rzr33

Posted September 02, 2014 - 06:09 PM

#9

Turns out bent two valves. Dealer saying enough shavings have got in that it has scarred the cylinder. They are recommending new piston and cylinder and also replace Rod bearing. Keep mind only has 20 hours or less. Any thoughts???

  • WoodsRidinYZ01

Posted September 02, 2014 - 06:11 PM

#10

How did it die wide open?

  • grayracer513

Posted September 03, 2014 - 10:59 AM

#11

If it bent two valves, it was the impact that probably caused the damage to the piston, and then that damaged the bore.  There may be nothing detectable wrong with the crank, but that same impact may have also "stamped" the crank pin with marks from the bearing rollers, something which may cause problems right a way, or some down the road.  The tech has to recommend that because you want him to stand behind his work, and he wants you to take the gamble, not he himself.







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