04 yz450f Timing chain jumping!!!!!

[purepolaris88]

Hey

i have a 04 YZ450F, just did exhaust valves on the bike, set timing up, took it out riding, and i was riding like a old lady,

last couple of days the timing has jumped on the bike, than will not start,

i reset the timing than runs, timing jumps again after riding it for about an hour, reset the timing and goes again,

i have not replaced timing chain,tensioner and guides,

has anyone had problems with the chains stretching, or a faulty tensioner?

do the cranks crack on these bikes or bottom timing gear worn,

i am lost, please help

[Fletch 2]

If the bike was running fine before you pulled it apart more than likely it has not gone back together correctly. Strip it back down, start again and follow the manual, be thorough. Thats just what i would start with.

When you take the cylinder head cover off, is the timing chain loose?

[grayracer513]

There are 4 basic things that cause the timing chain to skip.

> The most usual cause is camshaft seizure, usually the intake. This in turn is brought about either by oiling problems, or more often, incorrect retorque of the cam caps. Look for evidence of this on the camshaft, head and caps.

> The chain either very worn out, or kinked. Kinking is generally associated with a weak tensioner.

> Worn crank sprocket. Caused by running a worn out chain too long. If this is the culprit, both cams will be out by the same amount.

> Weak or worn tensioner. This is fairly rare, but occasionally, a tensioner will feel as if it has little or no spring tension. Even more rarely, they can be made to skip back in by pushing on the plunger. By design, the housing should break before that happens.

[Aka.Goose]

We keep saying it's extremely rare, but the "faulty cam tensioner" issue sure seems to keep popping up...Please let us know what it turns out to be...

[grayracer513]

We keep saying it's extremely rare, but the "faulty cam tensioner" issue sure seems to keep popping up...

It's been more common since the '06 models came out. There was a redesign of the part at that point. The earlier tensioners were very robust. If anyone has one that has actually failed, I would like to see it.

[Aka.Goose]

I had mine replaced, didn't hang onto the old one though...I did inspect it (well didn't really inpsect it carefully, but checked it out) and it was just wierd, there was just no "spring" to it...The top mech, Pat, at Del Amo (used to work for Factory Honda) couldn't explain why it was like that or what caused it...Didn't appear to be broken or anything just had hardly any tension...I was thinking it's just crappy springs, or ones that lose springyness if overheated...?

[grayracer513]

Yours is an '07, which is a part of the '06 and later group I mentioned, and that is the same problem that's been reported with that design. I tend to believe that the springs in them either break at the point where they are anchored, or otherwise become disengaged from the anchor point, not that the springs loose any tension.

But here again, I've never seen an older one do that.

[purepolaris88]

yea who knows, i personally am discusted with this bike, i wish i had never bought it to begin with, 2 strokes are way better, atleast they run,

yea im gonna pull that thing apart again,

im just gonna order tensioner, guide & chain , fix it and let anotehr man have the head ache later on

too high maintainence for me, rather ride than push my yamaha everywhere

do i have to pull the head?

the tensioner seems to be fine, i twisted it back and holds, than releases and cant move by pushing on it

thanks for the info everyone

[grayracer513]

do i have to pull the head?

...to replace the chain? No.

https://www.thumpertalk.com/forum/showthread.php?p=3150405#post3150405

One reason you might have to is if you improperly torqued the cam caps (too much torque, torqued out of sequence, torqued unevenly), and caused a cam to seize. In that event, the head may be damaged and need repairs. They almost always are repairable, though. The cam will likely need replacement if that happened.

[desert-rat660]

i had the same problem on my 450, the chain had stretched i compared the old with the new and the old one was 1/4 inch longer than the new one, i replaced it and the tensioner and everything has been great

[Dillon Sola]

Anyone have a diagram or know how to set the timing on a04 yz450f?

[wetneck]

Get a manual, manualslib.com

[bikedude987]

On 9/22/2008 at 1:45 PM, grayracer513 said:

Yours is an '07, which is a part of the '06 and later group I mentioned, and that is the same problem that's been reported with that design. I tend to believe that the springs in them either break at the point where they are anchored, or otherwise become disengaged from the anchor point, not that the springs loose any tension.

But here again, I've never seen an older one do that.

Are the older tensioners a retrofitable part as an upgrade?

[glenn robshaw]

Gday fellas ...i have been reading all the input on this site the last few days regarding timing chain isues on yzf 450 bikes an i can understand exactly where you guys are at as i purchased a 2011 yzf 450 3 weeks ago with only 26 hours on her . An after 4 hours use bringing her up to 30 hours ...she jumped a couple of teeth on the chain ....it happend on the kick start up thank God ..an didnt munch the valve on the  piston . The valve did colide with the piston as the kick start locked up but not under running load thankfully ...it had me stumped wondering how this has happened on such low hours ..but there it is on 30 hours from new bike !  bugger!  but a learning proccess to keep ontop of these possible issues with yzf bikes after 2010 with the slanted back cylinder head ....i now have a tottaly differant outlook on Yamaha yzf 450 motorcycles built after 2010 ... an its to change the timing chains before 30 hours or even 25 hours  or run a risc of a high five with your piston on your valves .i havnt heard of another 450 on this site doing this before 50 hours but mine did ...take care guys its not worth the risc 

Edited February 15, 2019 by glenn robshaw

[wetneck]

8 hours ago, glenn robshaw said:

Gday fellas ...i have been reading all the input on this site the last few days regarding timing chain isues on yzf 450 bikes an i can understand exactly where you guys are at as i purchased a 2011 yzf 450 3 weeks ago with only 26 hours on her . An after 4 hours use bringing her up to 30 hours ...she jumped a couple of teeth on the chain ....it happend on the kick start up thank God ..an didnt munch the valve on the  piston . The valve did colide with the piston as the kick start locked up but not under running load thankfully ...it had me stumped wondering how this has happened on such low hours ..but there it is on 30 hours from new bike !  bugger!  but a learning proccess to keep ontop of these possible issues with yzf bikes after 2010 with the slanted back cylinder head ....i now have a tottaly differant outlook on Yamaha yzf 450 motorcycles built after 2010 ... an its to change the timing chains before 30 hours or even 25 hours  or run a risc of a high five with your piston on your valves .i havnt heard of another 450 on this site doing this before 50 hours but mine did ...take care guys its not worth the risc 

How are you confirming your hours ?

Educated guess ?

[tmeyer37]

9 hours ago, glenn robshaw said:

Gday fellas ...i have been reading all the input on this site the last few days regarding timing chain isues on yzf 450 bikes an i can understand exactly where you guys are at as i purchased a 2011 yzf 450 3 weeks ago with only 26 hours on her . An after 4 hours use bringing her up to 30 hours ...she jumped a couple of teeth on the chain ....it happend on the kick start up thank God ..an didnt munch the valve on the  piston . The valve did colide with the piston as the kick start locked up but not under running load thankfully ...it had me stumped wondering how this has happened on such low hours ..but there it is on 30 hours from new bike !  bugger!  but a learning proccess to keep ontop of these possible issues with yzf bikes after 2010 with the slanted back cylinder head ....i now have a tottaly differant outlook on Yamaha yzf 450 motorcycles built after 2010 ... an its to change the timing chains before 30 hours or even 25 hours  or run a risc of a high five with your piston on your valves .i havnt heard of another 450 on this site doing this before 50 hours but mine did ...take care guys its not worth the risc 

Its not all about hours. That bike is 8 years old with that low of hours which means the chain has spent a lot of time sitting not moving. Low hours doesn't mean the bike is still new. I replace my timing chain once a year on my 06 just to be safe. It isn't too hard to do and the timing chain is only like 16 bucks on rocky mountain

[molloyjp]

What is a camshaft cap and how can it be overtorqued? I have a 1981 XT250 with 800 miles and the timing is off by a tooth. What could I have overtightened?

[mlatour]

18 hours ago, molloyjp said:

What is a camshaft cap and how can it be overtorqued? I have a 1981 XT250 with 800 miles and the timing is off by a tooth. What could I have overtightened?

Your 1981 XT250 engine is not of that design,

from what I can guess from the parts fiche images, the cylinder head has a fixed bore that carries the camshaft.

link: https://www.partspitstop.com/oemparts/l/yam/500420c7f8700209bc786fb4/1981-xt250h-parts

 

Skipped timing can be from: installation error, worn chain, worn cam and/or crank chain gears, worn/damaged tensioner.

Edited June 29, 2019 by mlatour

[Floyd James]

 Hey guys thought I would add my 2cents recently purchased a 2014 yzf450 with estimated 40hours on her bikes condition does reflect that so havnt got to much doubt around it, so 1 day I pull the idle up out kick her over she starts fine but ran out of gas as forgot to top it up, toped it up and gave her a thew kicks to prime it nothing to heavy and felt the piston fire under foot so went to give her a start kick and it was completely locked had me stumped, not the most mechanicaly minded person thought the worst, any how took the bike to a mate had a look took the rocker cover of and noticed it had some how jumped a tooth timing was out, chain was mint tensioner very mint no sighn of anything out of place seems it may well just be a Yamaha thing, like the other guy glad it happend under kicking stroke and not limi bash!!

[Rembrand]

I believe that on all these modern four stroke bikes the timing chain is just part of a complete top end job and very low cost peace of mind.