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08 common problem?

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I have an issue with my 08 that started yesterday at a local track. The first lap I went very slow, rolled every jump to make sure nothing changed since the last time I was there...beginning of the 2nd lap at about 1/8 throttle, I hadn't nailed the throttle yet at all it makes a aweful noise...kind of like the front sprocket slipped off or broken chain slapping the case..."NOT GOOD SOUND" and engine died. I fired it back and slowly headed back to the truck. At the truck, it lost compression.

My riding buddy, who is a national pro said maybe it jumped time. His mechanical dad pulled the valve cover off and the cam chain appeared fine. When he turned it over by hand, it would lock up at a point in the stroke.

Another rider at the track said his 08 CRF450 did the same thing with 5 hrs on it because the crank gear sheered the key...major damage.Honda paid to replace everything. I was wondering if this problem has happen to anyone else or just he and I. We bought them at different dealerships. I service the bike regularly and take overall great care of my bikes...I'm 36.

I have a 07 CRF250 with zero problems. The valves are still in spec after a year and half. I hope Honda pays for my 450 and this is not the beginning of future problems. Thanks

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Have not heard about that one, but will keep an ear out! Good luck on the repair cost with honda.

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If it did in fact jump time -- that would be the auto cam chain tensioner failing. That is why it is a good idea to mod the stock one to essentially become a manual tensoiner - Kelstr has a process on this... Or get an aftermarket MCCT such as the TT one.

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What actually happens to the chain tensioner to cause problems? Do they bend, break, or what? Thanks for the input.

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where can I get an aftermarket one ?

What one do you use ?

thanks

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The stock spring tension tensioners on these bikes can fail/loose tension. Can be as simple as casing a jump or landing hard, etc... Or have heard of them failing by being on the gas, then off, then on again hard. (such as a jump)

I have the Thumpertalk manual cam chain tensioner, you can get it from the TT store for $47 -- and I think you get free shipping in the continental USA, or something like that.

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The stock spring tension tensioners on these bikes can fail/loose tension. Can be as simple as casing a jump or landing hard, etc... Or have heard of them failing by being on the gas, then off, then on again hard. (such as a jump)

It makes sense that if they are going to fail it will be on sharp application of the throttle/closing of the throttle. Since F=ma the biggest force imparted on the tensioner spring will be when the acceleration of that chain is at its highest, probably on landing from a jump when you open it up again.

I have never heard of one failing in the UK though.

mechanical dad

couldn't resist, does he have to WD40 him now and then and keep him out of the rain?

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Did you try draining the transmission/clutch oil? My 2007 did this and i thought it was the clutch, turned out to be a transmisison case full of metal shavings, have not taken it apart yet to see where the metal came from.

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couldn't resist, does he have to WD40 him now and then and keep him out of the rain?

No, he got the stainless steel...one of those "pro perks". With a moto win, he gets the ti version:thumbsup:

Bike - I'm taking it back to the dealership tomorrow and will keep everyone posted.

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