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Thermos O flask

'03 WR450 tight spot when turning over...

11 posts in this topic

As the title says my mates '03 WR450 has a tight spot when turning over using the starter motor or the kicker

The engine is just as tight to turn over when the spark plug is removed!

 

I replaced the YZ cam with the stock WR cam (which I put in my WR400 :ride: ) and checked the valve clearances = all good. 

Re set the timing chain tensioner and triple checked the valve timing.

 

The engine starts and idles fine but makes a funny noise when it gets to the tight spot every rotation.

The bottom end was rebuilt a few years ago when 5th gear blew, very little use since then.

 

This bike has always had issue after issue,starter motor problems/ battery's/ stator/ starter clutch / regulator etc.

The clutch was always dragging,I recently replaced the half spring on the inside with a normal plate and the clutch finally fully disengaged.

 

Any ideas where to start looking? I really don't want to have to split the cases. :banghead:

Please help

Cheers

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It's normal for it to do it some of the time, or if the battery is below 12.8 v & the minimum of 9CCA.

 

You really want a 12CCA battery anyway......

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???? How is it normal for an engine to be as hard to turn over with the plug removed or fitted?

There is No compression with the spark plug removed.

What does the battery have to do with that too if you use the kicker??

Sigh...

Edited by Thermos O flask

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Has it been like that ever since the gearbox failure? I've had bikes do that before after similar failures. One had damaged teeth on the clutch basket, and the other on a balancer drive gear which cause a tight spot and a grinding kind of noise when turned over. (Can be caused by wedging primary (crank) and drive(back of clutch) gears with something too hard when undoing the main crank, flywheel or clutch nuts. I.e a screwdriver.

You couldn't tell that they were damaged unless you looked really closely. Some careful filing and wetsanding and all was good again.

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Ok after a lot of swearing and tearing the bike apart it looks like the problem has been identified....

 

See if you can spot the issue from the pictures.

 

wrrcover_zps0ixq4yfw.jpg

 

wrhead_zps8wlvznst.jpg

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Ive seen some pretty bad cam journal damage sucessfully repaired when done by a competant shop.

How did this happen?

Looks like the cams werer not seated far enough back?

Did you use a torque wrench when installing the caps?

I always put a couple drops of rotella on the journals during reassembly then check that the cams move freely once tightened down.

After that you should always run the motor over by hand once the timing is set.

Ive seen this alot and even being really familiar with these engines i always follow the above ritual.

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Yes! cam journals are damaged but caused by a mi$$ing rear dowel!  Allowing the cam so float in the journal slowly wearing into it.

Don't ask how but some where along the line it must have fallen out and was never noticed. 

Everything torqued and lubed and cams will turn fine at first with dowel missing but not after a while when they hammer into the journals.

Edited by Thermos O flask
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