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This is a fix that someone did for the front forks. I haven't done this yet but it sounds interesting.


Quote/ CBR 250 Cheap and easy front fork mod that works
I love my CBR but the suspension is a bit lame, the rear was easy to sort out with a new shock but that only amplified how bad the forks were, preloading the standard springs helped, then i discovered that the fork springs from the Ninja 250 are the same length and diameter but have a stronger spring rate. Kawasaki Chiangmai had to order them up from Bangkok but they are only 135 Baht each.
What to do:
Loosen off the fork caps while they are still in the bike.
Remove the forks from the bike and take the stock springs out.
Dump the oil and replace it with a good quality 10 weight fork oil (I used Belray)
The standard amount of oil is 331ml but increase that to 350ml.
Put the new springs in and put it all back together.
End result:
A really nice plush front end that doesnt bounce up and down through the dips and can take harder hits when the road gets a little rough.
The standard spacers seemed to work fine and see no need to preload them.
Set your rear shock to match the amount of sag your forks have and you should have your CBR handling real good. \Quote
Here's the link CBR 250 Cheap and easy front fork mod that works
 

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In the States, Race Tech has done R&D on a member's bike.
I believe they now have cartridge emulators as well as springs for the 250R.

The emulators make a night & day difference in old school damping rod forks.
They make the forks work much like a modern cartridge fork.
 

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This is the major limitiation to the cbr performance, and my only complaint with the bike. The dampening is not too confidence inspiring when pushed hard.
 

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The suspension needs a little more than just stiffer springs, Like adjustable high and low speed compression and rebound. They need adjustabality but like stated above RT does a good job with pretty must all bike suspension. I deal with them alot when it comes to re valving MX bikes.
 

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Stiffer springs would only make it worse.
 

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Stiffer springs would only make it worse.
I guess if you a heavier rider, have stiffer springs would lessen the mushy feel of the forks. It would give you better feel. but if you are a lighter rider, yes, stiffer springs will actually make it worse for you.


Metalstorm said:
In the States, Race Tech has done R&D on a member's bike.
I believe they now have cartridge emulators as well as springs for the 250R.

The emulators make a night & day difference in old school damping rod forks.
They make the forks work much like a modern cartridge fork.
+1. considering how basic the forks are, the easier way is to get springs with the right rate for your weight. get heavier oil. The next step would be to get the cartridge emulators. Otherwise, find forks from sportier bikes that fit and swap them.

Cheers,
 

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Stiffer springs will only make the rebound faster and worse.. regardless of rider weight.
 

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If you want to prevent dive on braking and increase the rebound damping...raise the viscosity of the fork oil by by about 2.5wt over stock. Then raise the fork oil level about 1/4" over stock. This should improve things without any negative side effects.
Sometimes you can end up with negative pressure in the forks due to air getting past the seals on the compression stroke. Simply removing the fork caps and re-installing them, while the fork is fully extended, can make a noticeable difference. It will increase the "air spring" in the fork. Same as raising the oil level does.
 

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^I will be trying that. thanks.

it only needs that lil bit more dampening.
 

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If you want to prevent dive on braking and increase the rebound damping...raise the viscosity of the fork oil by by about 2.5wt over stock. Then raise the fork oil level about 1/4" over stock. This should improve things without any negative side effects.
Sometimes you can end up with negative pressure in the forks due to air getting past the seals on the compression stroke. Simply removing the fork caps and re-installing them, while the fork is fully extended, can make a noticeable difference. It will increase the "air spring" in the fork. Same as raising the oil level does.
What is the stock fork oil weight? Any chance of getting inside the rear shock to reduce the fast compression for less chop over expansion joints on the highway?
 

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If you want to prevent dive on braking and increase the rebound damping...raise the viscosity of the fork oil by by about 2.5wt over stock. Then raise the fork oil level about 1/4" over stock. This should improve things without any negative side effects.
Good point.
Heavier fork oil will slow the fork reaction thus increasing rebound damping. And you are correct to suggest testing by one weight at a time (+2.5).
Fork oil level is indeed important.
As the fork compresses, the air at the top (which is actually a rising rate spring) is compressed, but it is not linear it is exponential. A small change has a large effect and changing it 1/4" at a time is the way to go.
 

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The rear shock does have a lack of high speed compression damping. I think it is aggravated by a rather firm seat. I put a piece of gel on my seat that is about 1/2" thick when I am sitting on it. That little bit of cush makes a huge difference on sharp edged bumps. It also raises me enough that the wind off the fairing does not hit the lower edge of my helmet now. Things are much quieter.
You may want to check the sag on the rear shock spring. Aim for 25% of the total travel. If the shock sags too much, your linkage may be sitting in the stiffer part of it's travel. The linkage is progressive and gets stiffer, the farther it is compressed. Stiffening the rear spring to get the sag right, can often help in another way.....it slows the suspension down and does not allow the shock to get into the high speed damping circuit as often. A bit fiddly, but you only do it once.
 

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You may want to check the sag on the rear shock spring.
My rear sag is 1.5 inches with myself and 40 pounds of luggage which is the most I would ever carry. Set on the lightest setting. The rear spring is a compromise in order to carry a passenger so is bit too hard for light solo riders. But not really that bad on slow speed dips. But the other thing that could be better is the high speed compression as these cheap rear shocks have no type of rudimentary blow off of any sort. The slow speed handling of the rear is balanced pretty well but sharp edged bumps could be better. My front sag is 2.1 inches as I am forward on the bike when tucked. I could use some more pre load to regain some travel. The plush front end is more comfortable for touring than the Ninja though. Street racers need new front springs to reduce the dive and preserve cornering clearance.
 

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1.5" is probably as good as you will get with those stepped preload adjusters. I am 170lbs and ride with mine on the stock setting....I think position 2. I tried position 3 and it was too stiff for my tastes, and it also screwed up the steering and made the bike fall into turns (oversteer). I would like a better shock but just can't get my head around the price.
 

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Changing the fork wt and height will help some, But like I said before the only real way to get the forks to their full potential are imulators, springs and modified dampening rod. Once I get my bike back from Fuem Moto usa for R&D I will be doing my forks along with a real rear shock. I'll take pics too.
 

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Changing the fork wt and height will help some, But like I said before the only real way to get the forks to their full potential are imulators, springs and modified dampening rod. Once I get my bike back from Fuem Moto usa for R&D I will be doing my forks along with a real rear shock. I'll take pics too.
Exactly, no way around it.

I've built hunnerts of 'em. :) We were also the 1st 250 to win the CMRA Mini Endurance w/ an 02 EX250. These forks are almost exactly like the EX forks.
 
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