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2003 Crf450r: Manual Timing Chain Tensioner VS Stock Spring Loaded Tensioner

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What is better? I've heard bad things about the stock timing chain tensioners on 2003 Honda CRF450R's are weak and allow the chain to skip. The bike has a manual timing chain tensioner on it right now but it does not have a lock washer so the only way to lock it in place is to screw it in all the way... Doesn't seem right... So I'm gonna replace it with either a stock replacement or a new manual tensioner. Just looking for any insight you guys might have. Thanks

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The main advantage to a manual tensioner is that if keeps the cam timing exact when the engine is running.

You can degree cams in with an auto tensioner, and start the engine and the timing jumps all over the place. The second advantage is that they will not suddenly fail like some auto tensioners do.

There is a reason we sell these to the oem factory race teams.

http://www.bigborethumpers.com/tensioners.html

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The main advantage to a manual tensioner is that if keeps the cam timing exact when the engine is running.

You can degree cams in with an auto tensioner, and start the engine and the timing jumps all over the place. The second advantage is that they will not suddenly fail like some auto tensioners do.

There is a reason we sell these to the oem factory race teams.

http://www.bigborethumpers.com/tensioners.html

I just ordered a stock replacement one... I haven't heard of any of my friends who ride honda 450r's having problems with their stock ones.

The one I have on it now is a manual one and it doesn't have a lock nut.

A stock one has GOT to be better than what's on there now.

ANOTHER question for you since you work for APE...

Are your 2006 crf450r heads with the SS valves ported heads or is the porting left stock and you guys just put the SS valves and heavy duty springs in them?

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We do ported ones, but the ones we sell for less than $600 are not fully ported.

What we do when we get the heads from Honda is put them through our porting dept and match the seat throats to the ports. Sometimes the factory has considerable mismatch in this area.

When you look down the ports of our heads, you can see where we have done this.

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If you can, cancel that OEM tensioner. The things DO fail...not a lot, but enough to have several (read many) companies come out with manual ones.

The 02-03 tensioner was a known problem to the point Honda redesigned it. But even the 04 and up unit fails too.

Find yourself a jam nut for your current manual adjuster. APE Jay was just being nice about the OEM tensioner.

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I've been riding CRF 450's since 2004 and never had one or know anyone in my local area who had an OEM tensioner fail. I bought a manual one 4-5 years ago, then never installed it and just resold it.

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^^^^^^Hey Steve! Kenny Hess had his fail at 408mx. It wiped out his engine.

My neighbor took his chain tensioner on his crf and drilled it out, tapped it, and put in a bolt with a locking nut. Pretty clever...

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Stock tensioner failed in my old -05 crf. Noticed it just in time before chain jumped.👍

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I ride supermoto, sometimes on the big road race tracks. Once I come into the pits and the motor on my 05 450 starts making this ugly screeching noise. I shut it down and start checking things. Oil etc. Take clutch cover off and see what's there, nothing helps. Then I released the (stock) tensioner and let it go again, the sound stopped.

What creeps me out about the aftermarket stuff is how vague the setup instructions are. No deterministic way to know if really got it tensioned up correctly.

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its also twice as expensive.

But...it increases horsepower!

from their site....

The Tokyomods mechanical cam chain tensioner increases horsepower, extends cam chain and cam chain slider life. In addition to eliminating any possibility of the automatic tensioner failing, causing catastrophic engine failure. It can be installed in minutes with no special tools needed.

Can someone explain this one?

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Silly Question: why dont you put a lock nut on the manual tensioner you have now and be done with it?

Because the guy I got the bike from apparently cut the head off the bolt; shortened it to the length he said was "perfect" then welded the head back on the bolt. The thing is I don't trust that the tension is right, and even if it is it will eventually fail as the chain stretches over time.

I don't know what the heck he was thinking

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But...it increases horsepower!

from their site....

Can someone explain this one?

I'm pretty sure it's safe to say that's just a marketing ploy to help them sell more products.

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I would go to the hardware store and find another bolt with the same threads that you could put a lock nut on. Grind the tip down like the original, it doesnt have to be perfect. The directions say to turn the bolt gently in while turning over the engine (easier if spark plug out) until you take up all the slack, just finger tight. Then back bolt out 1/4 turn. Tighten locknut. A manual tensioner puts less stress on the cam chain than the spring loaded and will not fail. A new manual one is about $60 from Thumpertalk. Good luck.

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If the Tokyo mods tensioner indeed provides more stable timing there could be an increase in horsepower. That is based on the assumption the OE tensioner is allowing an erratic timing.

Aloha

Edited by alohajeff

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