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Spring advice - CR250R

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I will be working with a local suspension guy (Moto-Pro) to dial in my springs. I'm not here to doubt Moto-Pro's advice, but thought getting some advise on here might be helpfull. Following are my current suspension details.

Rider - 232lbs (no clothes), I'm roughly 10 pounds heavy after the holiday

Gear - 28lbs (includes tool pack, and 64oz water)

Terrain - Woods/Desert (faster trails, not into tight single track, no MX)

Rider Class / Type - Fast "B" rider, usually running a gear up and carrying speed through corners

Current Springs Front - 48kg

Current Spring Rear - 5.3kg

Rear sag measurements:

Race Sag - 4" / 101.6mm (with gear on)

Static Sag - 1/2" / 12.7mm

The spring is also compressed to 9.5" for the above numbers, the Honda manual states 9.8" as a minumum (this may not be valid for an aftermarket spring). Obviously I need a stiffer spring in the rear, but by how much? I'm guessing a 5.6kg, but I'm not really sure. My suspension guy seems in favor of lighter springs in the front to get the bike to compress more through corners. He mentions I may be giving up some bottoming resistance in the whoops, which I like to hit very hard. I was tempted to try a used CRF450R spring, which is 5.5kg, but my suspension guy advised against using a progressive spring for link bikes.

Thanks

Edited by Redlined

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what year ? my chart says 5.8 rear and 0.47 forks

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I was tempted to try a used CRF450R spring, which is 5.5kg, but my suspension guy advised against using a progressive spring for link bikes.

Thanks

A stock 5.5kg CRF spring isn't progressive, it's linear. A CRF is a linkage bike, just like your CR.

Edited by Ed2006CRF450R

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what year ? my chart says 5.8 rear and 0.47 forks

Sorry, the bike is an '02. Thanks for your input on spring rates

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A stock 5.5kg CRF spring isn't progressive, it's linear. A CRF is a linkage bike, just like your CR.

I've heard it mentioned that the CRF450R springs are progressive, on this forum and by Moto-Pro, who has run them on his spring tester.

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the first inch of travel is different than the second, and third. the true, or claimed rate by the factory will be noticed in the second/third inch of testing. the fork springs if too soft, will have more of a negative effect in the whoops than the stock 5.5kg shock spring. if you like the whoops, go with heavier fork springs to keep the front up. if the front dives in the whoops, you've got trouble. also, don't disable the midvalve. you're going to want the front to stay up in the stroke through those suckers.

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the first inch of travel is different than the second, and third. the true, or claimed rate by the factory will be noticed in the second/third inch of testing. the fork springs if too soft, will have more of a negative effect in the whoops than the stock 5.5kg shock spring. if you like the whoops, go with heavier fork springs to keep the front up. if the front dives in the whoops, you've got trouble. also, don't disable the midvalve. you're going to want the front to stay up in the stroke through those suckers.

Thanks for the advice, any input on optimum spring rates for my application?

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Honda don't claim to have fitted a progressive spring and progressive springs are wound tighter at the end , you can see it clearly by liking at a ktm progressive spring , we need to know how the spring was tested as springs are linear after the first few inches as Marc said , you must ignore the first few inches reading and then average the other readings to get a true rate

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Honda don't claim to have fitted a progressive spring and progressive springs are wound tighter at the end , you can see it clearly by liking at a ktm progressive spring , we need to know how the spring was tested as springs are linear after the first few inches as Marc said , you must ignore the first few inches reading and then average the other readings to get a true rate

So if I understand correctly, an aftermarket spring would show similar results as the OEM Honda spring in the first few inches. Thanks for clearing that up.

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all springs are off on the first inch or so , but that's fine as you expect to preload it to get correct sags , what are progressive was the ti range of springs on the yzf , but that's is down to how hard it is to make a ti spring accurately

the range from 5 to 5.5 is a little more than I would expect from a oem spring but again it maybe linear in all but the first inch

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Also, Moto-Pro should have plenty used 5.5s off CR450s he could let you try. Used springs are still good unless they have 35,000,000 hrs on them. Or a trip to your local MX track should get you one cheap. Good luck. Hope you have better luck than I have.

Edited by YHGEORGE

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