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How-to: Adjust your forks for a 70 series tire.

32K views 58 replies 46 participants last post by  dopler 
#1 · (Edited)

This one is pretty simple. It will take you about 30 min tops. I am going to explain how to adjust the front forks to compensate for the larger tire up front, thus keeping the bikes geometry.

You may also need to adjust your front fender, as the tire heats up it will balloon up and scrape the front fender possibly damaging it. On my ’99 I had to move it up (after I damaged it, cause my shop put the 70 without telling me) On my ’04 I took the same chance driving home on the 70 not trying to heat it up too much. I got home without damage and then actually didn’t bother to adjust it and took it out for 6 hours the next day aggressive riding without any damage. You choose.

You will need

4mm hex
5mm hex
6mm hex
Measuring tool
Small jack
An extra set of hands.

Start off by removing your clip-ons there are 4 bolts all together, two of them are located underneath the black plastic covers.




Then remove the 1 blot holding your brake fluid reservoir to you triple tree



Now you should be able to remove you clip-ons by pulling them up over the top of your forks.




Now with your clip-ons off you need to take a measurement. Measure from the top of the upper triple tree to the top edge of the fork tube. You only need to measure one side, they should both be the same anyway. Now add about 8mm to the measurement you just found. This is how high the forks tubes should be when we are done.



Next use a small car jack and place it under your headers and jack you bike up; the jack, your side stand, and the rear tire will support the bike.

Here is a pic provided by AFC (rear stand and wood not required)


Once the front tire is off the ground you need to loosen the lower triple tree bolts, they're 2 for each tube. (located behind my cables in the photo)



Now this is where you might need an extra set of hands to help stabilize the bike and loosen the upper triple tree. Stand in-front of the bike and hold the front tire, it is going to fall through the triple trees if you don’t. Now loosen the upper triple tree.



With the upper triple tree bolts loose push the fork tubes up and measure, once you have them in position tighten the upper triple tree bolts and then re-check the measurement. If they are within spec. then tighten the lower triple tree and put back on the clip-ons.


Now, to add a few more things to this how-to. First off this is what happens when you don’t adjust your front fender on a 1st generation R6.



Second in the how-to I said to adjust to about 8mm higher, this can be different depending on what brand tire you bought, how much tread you have on it, and just how you think the bike feels. I first adjusted my forks to 10mm higher, and then noticed my front end sort of tucking in the corners so I brought them back down to 8mm and they seem great now. This is on my ’04.

On my ’99 I didn’t adjust the forks at all, the bike felt so much for solid with just putting the 70 on there.

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#4 ·
if your jacking up your bike with a car stand...wouldn't it put a dent in it?
 
#10 ·
serpentracer said:
nice ochlocracy, One thing I read someplace is how to know how much to lower.
the article said to measure both tires diameter using a string or one of those tape measures tailors use. use the difference in the two measurements for the amount to raise the forks.
Yea that is on the sport rider site. I thought about including it but they ask you to check you old dia. and your new dia. Well most of us would have already replaced the old tire. Also since we all have the same bike, it will be the same for everyone.
 
#13 ·
what happens if one of the forks is off by like .05 millimeter??
I did my fork adjustment yesterday but i dind't have a cool super height measuring tool like in the picture. I used a ruler and it looks like its level but i have a feeling its not....
so what will happen if its a tiny bit off?
 
#14 ·
what happens if one of the forks is off by like .05 millimeter??
I did my fork adjustment yesterday but i dind't have a cool super height measuring tool like in the picture. I used a ruler and it looks like its level but i have a feeling its not....
so what will happen if its a tiny bit off?
^^^^ditto^^^^

Did mine yesterday too and I had the same result when came to measurement.It was a fraction off,0.5mm exactly and no matter what,could get it to line up.And I also used a regular steel metric ruler.

Took it out for a spin and what a nice improvement.Thanks OCHLOCRACY.
 
#15 ·
here is a conversation regarding the fork set up for a 70 series tire... just some food for thought before you blindly change the geometry on your bike because it seems to make sense... make sure you read it all!!

"with adjusting your ride height... on the 99-02 i have found that it is NOT necessary, the 6 rides better up high. In fact if you go to an aftermarket rear shock that has adj ride height, raise the rear AND the front. It comes from the factory set a little high to begin with so the 70 will put it pretty much where it needs to be (without an adj rear). Myself and a handful of racers have noticed that lowering the font to comp for a 70 series tire causes front end push (ie not good )

Not sure how the 03 differs

just a couple cents of advice from mine and others experiece"

tim


reply... "I dont agree (sorry) I tried to run the 70 series with out adjusting the ride height and the bike was very lazy. As soon as I restored the geometry the bike was itself again. Before I had a/m shocks I would drop the tripples but now that I have adjustable ride hight with my shocks i leave the frt at the stock height and adjust the rear.

I have an 02 and an 03 and they are both set up almost identical.
Quote:
If you use tire warmers, I would almost say it is mandatory you raise your front fender,

I use the tire bakers and with supercorsa's you can snake them in there pretty easy but with the Bt-002 (which is about 3mm taller) it gets really tough. They get hung up alot and it takes quite a bit of work to get them in there. Raising the fender would be a good idea if your warmers wont slip on easy"


response... "thats why bike set suggestions are just that...suggestions. Everyone has different riding styles and height, weight, body positioning that all effect the geometry of the bike once turn in begins. These 2 guys have both won ccs points championships so it works for them. But again this is exactly why there is no "chart" for bike set up. No height+weight=X set up for optimal handling that really works for everyone. Try lowering, if you get front end push...try raising back to where it was. That was all it took for me. (edit... I think this is similiar to what Och experienced)

again just my 2 cents"

that was a brief blurb from Big Deezul and I a day or so ago. The important thing to remember is that everyone has a different style of riding that requires different geometry of the bike for maximum performance. Personally, I have my preload cranked WAY up on the rear (cause stock shocks suck A$$) and I found that leaving the forks alone when going to a 70 series tire is fine, dropping the triples gave me front end push. Make sure your have a solid base line for suspension set up before you go adjusting your triples. (ie sag, comp, reb, damp) Once you know how the bike is handling when it is set up properly, then you can dial her in. If you do this backward you will be chasing the demons FOREVER!!!

tim

ps.. the TYPE of riding that you do may influence how you like the set up to feel as well. For instance, a drag racer, a cruiser, and a racer would all have COMPLETELY different set up. :2cents
 
#16 · (Edited)
Actually I've been riding my 70 series tire on my 04' for about 4 and half months and noticed from day one it was a little stiffer to turn.

Ochlocracy did state in his post on his 2002 he did not do anything or adjusted his when the 70 series was installed.Except for the fender,though.Which I also adjusted from day1 with 70's.

I'm happy with the 8mm added hieght in the forks.

tstruyk said:
Make sure your have a solid base line for suspension set up before you go adjusting your triples. (ie sag, comp, reb, damp) Once you know how the bike is handling when it is set up properly, then you can dial her in. If you do this backward you will be chasing the demons FOREVER!!!
Your probably right,Since this is more trial and error on my part and trying to figure out,it will be awhile before I'm happy with my set up.So far it has improved rasing 8mm on my 04',but still need adjustments sag,comp,reb,damp.

Again,good post and how to.Thanks.
 
#17 ·
ok I have a newb question....does moving the front forks up 8mm make the front faring clear the tire??? Or do you have to move the faring itself???

I plan on going with a D208, up front but I want to go 70 series. How do you just adjust the fender, do you oval out the bolt holes and move it.

Thanks for any info.



And great how to by the way. :D
 
#19 ·
Is the HOW TO for raising the rear coming soon. i plan to put on my diablo 70 front tire on soon and would like to do this mod. thanks. also can raising the rear be done to an 02 (blue) with the stock suspension. thanks again, sorry about my ignorance.



did anyone with the diablos have to modify the front fender to make the tire avoid melting the fender......... (on an 02 again if possible)



THANKS
 
#20 ·
good info all around, as for raising the rear on the 02... technically NO, actually yes (assuming all stock components). Set your sag (see other "how too's") When you adjust preload, if it was set too soft you will notice that you do ride a bit higher, it is simply the spring compressing to much under your arse. More preload = tighter spring= higher ride height. but to technically adjust that you need aftermarket.

As for the front...keep in mind that a 70 series tire (also pending brand and model number) will carry a different profile completely and cause a difference at turn in. I wouldnt necessarily adjust the forks right off the bat. If you like it one way or another...thats whats best for you. I know that the 2 guys I race with are freakin fast and these adjustments are what they use. I thought my suspension was set up pretty well until I started getting fast on the track. I was WAY off. Stick with what you like, as always just spreadin my knowledge.

tim
 
#21 ·
i raised the forks on my '02 8mm's and WOW did it ever make a difference!!
i was running stock settings with a 70 profile tire. Went to track with that setting and every turn i was running wide as shit. Now with the forks lowered, it holds its line soooooooo damn well. I'm very impressed.... feels so stable.
 
#23 ·
good write-up, but are all those steps really necessary?

I've adjusted the fork height for a 70 series front on my sv with it sitting on the side stand, no jack. I just loosened one fork from the triples, raised it up, and tightened it back down. Then did the same to the other fork.

Is there any reason this wouldn't work on the r6?
 
#24 ·
Metcalfe said:
good write-up, but are all those steps really necessary?

I've adjusted the fork height for a 70 series front on my sv with it sitting on the side stand, no jack. I just loosened one fork from the triples, raised it up, and tightened it back down. Then did the same to the other fork.

Is there any reason this wouldn't work on the r6?
Technically, that's not ideal. If you have weight on the front end, that means that one side may be partically compressed. In theory, it should be fine, as your are just hooking up the top tubes, and they should be equal distance on either side, but I'm not sure that I'd want to do it that way.
 
#25 ·
This was a great write up! I just did this to my '04 earlier today. Granted it took a little longer than expected, I think it was because I kept checking my measurements all the time.
 
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