Modified NSR250 - Geometry issues: Advice?

[sharp2183]

Hey guys,

I have an NSR 250 that has been slightly changed over the years by previous owners and myself. I need some advice with a set up issue.

Firstly, fitted to the bike are '95 ZXR750 forks/triples, running the standard front wheel. The rear is an SP shock (remote reservoir type) with standard SP spring. I have done no valving/rebuilding work, though that is the plan when money permits

The issue I have is that I believe the front forks as they are sit the front end up too high. When static the bike appears to be balanced front and rear, but when loaded and moving it looks like the rear sits too low/or the front is too tall. What I want to determine is whether it is more likely that I have a spring issue, or are my forks positioned incorrectly from the get go?

Is there some form of basic geometry settings that I can apply to the bike to get a good starting point?

[Crasherfromwayback]

Dude...your NSR weighs what...140kg? A ZXR weighs 215 odd. What are the chances of the forks being suitable for your nsr off the bat?

[Mental Trousers]

Dude...your NSR weighs what...140kg? A ZXR weighs 215 odd. What are the chances of the forks being suitable for your nsr off the bat?

Pretty much


http://www.youtube.com/watch?v=FjGgq1z9zbo

[sharp2183]

Dude...your NSR weighs what...140kg? A ZXR weighs 215 odd. What are the chances of the forks being suitable for your nsr off the bat?

Yeah yeah granted, and they are going in to be modified to suit very shortly. But I didn't put them on, thats why I want to have some understanding of correct fitment (aka positionin in clamps vs the rear).

You make a good and obvious point though, which probably indicates its mix of both. The front feels fantastic though so must have been fairly soft on the zxr..

[Crasherfromwayback]

. The front feels fantastic though so must have been fairly soft on the zxr..

In the ZXR750 chassis...it's one of THE best front ends I've ridden for a street bike.

[sharp2183]

In the ZXR750 chassis...it's one of THE best front ends I've ridden for a street bike.

I guess that's why it got put on the bike. I'll look at setting them up for the lighter bike but I do wonder if they are actually not too far off right as they are? They are no harder than my brothers RS250 forks....

[Crasherfromwayback]

I guess that's why it got put on the bike. I'll look at setting them up for the lighter bike but I do wonder if they are actually not too far off right as they are? They are no harder than my brothers RS250 forks....

Yeah but you don't know what sort of offset they've got or what height they are compared to yours or anything really. You need to find the measurements of the stockers first.

[sharp2183]

Yeah but you don't know what sort of offset they've got or what height they are compared to yours or anything really. You need to find the measurements of the stockers first.

Thanks for the advice. Did some research and measurements and it appears that the fitted forks are 20mm longer than NSR originals.

I'm not skilled in this department, but is the solution to drop the triple clamps down by this amount and then set the sag/preload etc?

I'm also running a 120/70 front as opposed to the 110/70 standard option. I assume I will need to take account of this too?

Any advice appreciated.

[Crasherfromwayback]

Thanks for the advice. Did some research and measurements and it appears that the fitted forks are 20mm longer than NSR originals.

I'm not skilled in this department, but is the solution to drop the triple clamps down by this amount and then set the sag/preload etc?

I'm also running a 120/70 front as opposed to the 110/70 standard option. I assume I will need to take account of this too?

Any advice appreciated.

You may find if your drop the forks that far through the clamps the front tyre will collect the radiator on full compression.

Do you know the std trail measurements etc?

[sharp2183]

You may find if your drop the forks that far through the clamps the front tyre will collect the radiator on full compression.

Do you know the std trail measurements etc?

Not on me but not hard to get I don't think. Use that as the guide you reckon? And you might be right, though I think it will rub off the plug cap (sticks out more than anything else) before it gets to the radiator guard...

Any negatives to dropping them a bit - handling/safety wise?

Cheers

[Crasherfromwayback]

Not on me but not hard to get I don't think. Use that as the guide you reckon? And you might be right, though I think it will rub off the plug cap (sticks out more than anything else) before it gets to the radiator guard...

Any negatives to dropping them a bit - handling/safety wise?

Cheers

Personally mate, I think you'd be far better off trying to find a stock front end!

[sharp2183]

Personally mate, I think you'd be far better off trying to find a stock front end!

Yes that has been said, and I kinda agree. But they are there and dont work badly as they are, so I'm treating it as a learning experience. Thanks for the advice though, I'll follow it all up with a bit of research.

[Crasherfromwayback]

Yes that has been said, and I kinda agree. But they are there and dont work badly as they are, so I'm treating it as a learning experience. Thanks for the advice though, I'll follow it all up with a bit of research.

Yeah get the std rake and trail measurements, and get the ZXR forks to as close to the original specs as you can.

[kiwi cowboy]

Yes that has been said, and I kinda agree. But they are there and dont work badly as they are, so I'm treating it as a learning experience. Thanks for the advice though, I'll follow it all up with a bit of research.

Hey bud you and your brother been out on these smokers latley?.
Unless i miss my guess i met you guys at a cams meet a fair while back {blue gsxr400 u left behind]at a cams meet.