R6 rear shock conversion...Race set up! HELP !!

Wheels, shocks, forks, frame
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andy b
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R6 rear shock conversion...Race set up! HELP !!

Post by andy b »

Well after lots of reading on here and a few hours in the workshop my trusty Kr1s has done its 1st race and many test days.
I was just about getting somewhere with the suspension when i decided to change the tyres for some 17" Dunlop 209 gp race tyres which i must say grip like Shit to a Blancket!with hardly any side wall movement which translates= you can feel the drive forwards rather than a slite side slide when the bike is on its side at high speed for a long time which is what i got when running Pirelli Supercorsa Diablos, there a great tyre which takes all the play out of your suspension(soft side wall on tyres).So know i have a very irratic bike which chatters in the corners at high speed which the Zxr 250 forks cant handle, you need a fully adjustable front forks (sp version with compression).This has highlighted a even bigger problem!The R6 shock is 15mm longer than the standard kr1s which means the rear on the bike is a lot higher which helps me with ground clearence but now i have 15mm of weight transfer on the front which does'nt need to be there and is making the bike impossible to turn in high speed corners.
My question to you Guru's is:- who has done this zxr front/r6 rear shock conversion and raced it ? because at the moment i have found it isnt working, i am working with a Ohlins technician on the track and seem to be going in circles...Doh! :( i am considering gettting the old shock revalved /serviced with a better spring so at least the bike will sit right
Last edited by andy b on Sat Oct 09, 2010 11:02 am, edited 1 time in total.
Bikemike
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Post by Bikemike »

I think Scooble had her R6 shock shortened to make it the same length as standard. It might be worth dropping her a P.m.
Hope this helps,
Mike


Edited due to poor spilleng.
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JanBros
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Post by JanBros »

allthough quite a few people are happy with there R6 shock, in my opinion it is just too long to use as is.
either use some longer dog bones to drop the rear a bit, or have it shortenned.
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ScottaKR
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Post by ScottaKR »

Have you tried raising the front of the bike up by dropping the forks down through the yokes further (if there's any left that is) to compensate fot the extra hieght in the rear. That should hopefully bring the balance back.

You say youve "decided to change the tyres for some 17" Dunlop 209 gp race tyres". Is that 17" front and rear, meaning RGV (or similar) rear wheel swap? If so, then that will bring the rear of the bike back down close to the origional hieght (maybe a little taller than stock still), and if you were to fit the stock shock back in without getting shorter dog bone links made up it'll be too low in the rear.

Edit: Just had a look at your pics i the project page, and it seems to me youve got plenty of fork to drop through the yokes to get the balance right. You may want to measure the height of your rear end compared to a standard bike to see exactly how much difference there is, and how much you need to raise the front to get back your weight balance.
It seems to me though, that your problem is more the forks not being valved/sprung right than the rear being too high, but then again, I'm not an expert by any stretch of the imagination. Just my thoughts on the matter.
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andy b
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suspension

Post by andy b »

Well after sleeping on it i have come up with a solution!
Firstly i have a 17" Rgv rim in the back so i am down 25mm from the stock Kr1s rim, i had the front stock forks poking through 15mm and it ran just fine so if the front fork standard measurement is 10mm poking through the front top yolks i make a calculation of for every 5mm of adjustment on the rear you adjust the front by 1mm 5:1 ratio.
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scooble
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Post by scooble »

I posted some setup specs on here some time ago for a ZXR400 front/R6 rear settings from a trackday at Brands once, if you look through some of my post you should be able to find it.
however, the settings were not ideal, and a bit of a compromise.
if you need it re-valved, speak to Russ at Mick Gardner racing, good service, good prices too
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