Revalve question


6 replies to this topic
  • flintlock28

Posted January 23, 2006 - 03:59 PM

#1

I'm thinking of getting my stock forks and possibly rear spring revalved. I have checked out Racetech's site and they list my Yamaha 2004 Yz 450f as measuring .460 kg/mm (My manual states .459 kg/mm) I normally weigh about 186 without gear, although I have put on about 8 or 10 pounds.

My question is: According to Racetech, the stock fork springs are perfect for a 200 lb. rider (without gear), but people on this site have stated that race tech number's tend to be off. I'm going to get my fat Arse back down to 186, so I'm wondering if the stock spring is fine, or do I need to replace it for a 186 pound rider. I'm probably only a "c" rider mainly riding MX , and sometimes I hit the trails, but I want to get the bike set up properly for MX for 186 pounds. Should I use the stock springs and revalve, or replace the springs and revalve??

Let me know....
Thanks

  • mtrdrms

Posted January 23, 2006 - 04:53 PM

#2

Typically when you get your suspension revalved the company that is doing the work will tell you if you need new springs for your weight. I suggest Factory Connection. They are very helpful and my bike was a whole new machine when I bolted up the revalved suspension. And they arent that far away from you (NH).

  • grayracer513

Posted January 23, 2006 - 05:02 PM

#3

Racetech's charts do seem to run to the soft side, but if you're bent on loosing the weight, use the stock springs. If you set the "race sag" ( the rear suspension sag with your weight on the foot pegs) at 100mm, you should have a free sag (the sag with no weight on the bike, sitting on its wheels) of about 1 inch. Less means your spring is too light, and needed to be preloaded too far to support your weight. More free sag than that means the spring was too stiff and didn't need much preload to support your weight.

Keep in mind that an increment of 0.01 KG/mm equates to 1.1 LB/inch (.558 per spring) on the front end for the pair (the front is held up by two springs working together), so the difference between a .46 and a 47 is not likely to be really critical for your purposes, but a .2 margin might. At a full 12" compression, a .48 will put about 25 pounds more rebound force on the fork than a .46, and carries 12 more pounds of weight at half travel.

At the rear, it's harder to visualize the effect. A 5.4 spring is right at 302 LB/in, but the spring is at about a 3:1 disadvantage, so it only puts something like a 100 LB/in force on the axle. (Old timers like me can divide that in half to compare it to the springs they ran back in the day on the twin shock bikes with the shocks mounted near the axle and standing straight up) Going to a 5.5 changes it from 301.7 to 307.3 lb/in, but instead of doubling the difference, like we did in front with two springs, we divide by roughly 3 so that it only changes the effective rate at the axle by about two pounds. That doesn't seem like much at first, but at half travel, that's another 12 pounds the spring will carry that the lighter one wouldn't.

I weigh 180 (currently) and the stock rates work out OK for me.

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  • 642MX

Posted January 23, 2006 - 05:10 PM

#4

Typically when you get your suspension revalved the company that is doing the work will tell you if you need new springs for your weight. I suggest Factory Connection. They are very helpful and my bike was a whole new machine when I bolted up the revalved suspension. And they arent that far away from you (NH).




I don't want to jack the thread, but how much does Factory Connection charge for a revalve front and rear?

  • flintlock28

Posted January 23, 2006 - 05:22 PM

#5

Thanks guys for the info....

My stock suspension works pretty decent for me, but I noticed lately it seems to be a little harsher than normal. I was wondering if my weight gain could be attributing to this, or if it's mainly due to the original oil in the forks (about 80 hours of non raced time) most on trails, about 10% of total time on MX track. Also yesterday, I ran into a guy at the track, whose son I think is near or already at Pro-level status. He recommended a local suspension guy who he said is cheaper than Racetech, and also has given him better results than Racetech. He said they had three bikes done by either Racetech or Factory connection that came out really nice, but he said this local guy did even better work. and a friend of his also said the work was better than the two afermentioned suspension companies. I'll probably give this guy a call.

  • mtrdrms

Posted January 24, 2006 - 08:40 AM

#6

I don't want to jack the thread, but how much does Factory Connection charge for a revalve front and rear?


Just a revalve is 3-400 bucks. With new springs (if you need em) and seals and sliders and stuff about 600. It varys greatly but give em a call, they are always willing to help.

  • 642MX

Posted January 24, 2006 - 04:35 PM

#7

Just a revalve is 3-400 bucks. With new springs (if you need em) and seals and sliders and stuff about 600. It varys greatly but give em a call, they are always willing to help.




Thanks, I think I'll call them.





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