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fastfreshdougie

HELP what to do? top end done for!

12 posts in this topic

hello well here is the nightmare..

first off i have a 06 wr450f that i have changed over to a supermoto. for to and from work and weekend fun time.

i do my oil changes ever 800 miles. and keep the bike mantained very well

only prob i have had is the timming chain tenstioner spring broke and me lucky nothing else was hurt... this was 800 to 1200 miles ago

 

 

i was riding to a buddies house had a very nice wheelie going (on a private roadway ;) )

When i let it down and the front wheel touched down a sound of crunching and baging happen and killed the bike instanly.

 

 after the tear down i found the right intake valve has been destroyed as you see in the pics.

the right exhast vavle dos not shut all the way.

the piston head has pretty big  diggs in it.

the piston walls look fine as well no scratches.

and the front chain dampener was bent near the bottom.

but the chain tenstioner was fine.

 

now the questions

what could of cause this?

how can i prevent it?

 

is the head saveable ?

and cost of the save?

 

anyone have one for sale ?

 

if i have to buy new parts where is the best place .

what years share the same part?

 

i found on most big name websites the assy head for 700$

im i correct to think that does not come with vavles?

 

and as for piston any suggestions? is it salvagable

if not what brand would be best choice?

 

any and all help is welcomed . thank you for reading

 

 

20150319_173127.jpg

20150319_172208-0.jpg

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800 mile oil changes and long wheelies? 

Way too long, and this head does NOT like long wheelies (oil starvation).

This can make the cam sieze, and then the valves bend, etc.

More likely is a jumping cam chain that has stretched.......

 

If you had a tensioner  break, I assume you changed the timing chain at the same time?

 

You can have that head rebuilt.

 

Call BigBoreThumpers.com

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kan

long as in  20 seconds max. oil startvation that quick?

 

i would not have guessed you needed to change the chain same time if the tenstioner sprin breaks..

 

thanks for the refrence

 

800 miles really that long> ? oil is hardly broken down when i change it...

 

and should i look into a manual chain tenstioner?

Edited by fastfreshdougie

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800 miles = ? hours, depending on how fast you are riding

 

At 26 mph, that's 30 hours, which is too long IMHO.

 

At 50 it's 15 which is better.

 

The if the cam chain tensioner fails, usually the chain gets messed up.

 

OEM tensioners are normally very reliable in my experience

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Something let go it could have been a valve. If the chain was old enough it could have slipped. A lot of people don't use stainless steel valves in a WR however I do figuring it's good for the longest haul. If you do run stainless you need to run the stiffer springs and might as well throw in some titanium retainers.

 

I don't let my bike run too long with old oil. About every 400 mi. for me. However from the looks of it you did not have a oil failure.

 

Big bore thumpers has a very large modern machine shop.

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I change the oil every 10 hours.  My bikes last a long time.  If you're into riding really long wheelies, you should check out the wheelie boyz videos on YouTube and see what they're riding.  I see few WRs and many CRFs, I wonder why.  

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I'm calling total BS on the cause of failure. Not an oiling issue! You can wheelie that bike till tomorrow without issue. It's a "Dry Sump" oiling system. The oil in the frame tank feeds the oil pump. You'd have to cycle 80% of capacity and recover none to run short on oil pressure.

Most likely an interference issue. Weak valve springs and high RPM causes contact and valve breakage. Badly worn crank allows piston over travel and contact. There seems no heavy piston scoring, not an overheating issue.

This engine either broke a valve or lost the keepers and dropped a intake valve!

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well after close look its a broken vavle top is still attached.  now looking for new parts.. haha will keep updated and let you guys know of any questions

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I'm calling total BS on the cause of failure. Not an oiling issue! You can wheelie that bike till tomorrow without issue. It's a "Dry Sump" oiling system. The oil in the frame tank feeds the oil pump. You'd have to cycle 80% of capacity and recover none to run short on oil pressure.

Most likely an interference issue. Weak valve springs and high RPM causes contact and valve breakage. Badly worn crank allows piston over travel and contact. There seems no heavy piston scoring, not an overheating issue.

This engine either broke a valve or lost the keepers and dropped a intake valve!

Couldn't it be an oiling issue if it caused the cam to seize? I agree, though, that a dry sump ought to prevent that. 

 

I saw this on FB too. What do people here think of a bigbore? Although I've bought stuff from you and everything worked well.

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I doubt the cam seized. That level of oil starvation would also cause piston seizure and clutch failure, thus no power and no wheelie.

I've built and maintained WR 450s for 10yrs and cannot remember seeing a cam seizure that caused the chain to break. Just check the cam bearing surface, I'll bet it's clean.

FB, what kind of source is that ?

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