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Old April 22nd, 2010, 06:28 AM   #1
sktrs_kpr
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Some upgrades to my í90...

Some upgrades to my í90...

I. 08 R6 Shock
II. Ninja 500 springs
III. K&N 0990/rejet
IV. Chain/sprockets
V. Fender chop / LED brake lights
VI. Throttle zip-tie mod/grips

I picked up my í90 ninja 250 in July of last year, and put some 6000 miles on it since then. I got it for only $350 because it had been sitting for almost 10 years in someoneís garage and he hadnít been able to get it running etc. It was dropped by the PO but only had minor cosmetic damage, so I brought it home, put in a set of freshly cleaned carbís and in about 3 hours from when I started working on it was riding it around. At the time I told myself I wouldnít mod it. It was purely to have some fun on, get 60mpg, and learn how to ride... a commuter bike with weekends on the parkway.

But, Iím a tinkerer. One look under my í91 ford festiva and you will see a mazda 323 engine, bigger brakes, coilovers, etc etc... I have found that the festiva and the ninja have many of the same benefits, and after our first 12Ē of snow this winter my tinkering self went to work on the ninja... and here are the results.

I. 08 R6 Shock
I take friends for rides pretty frequently and had bottomed out the stock shock a few times. I read through many threads on doing the 250R shock upgrade, the GSXR shock, fox shocks, etc. and after a lot of picture-shopping on e-bay and various forums I decided that the new R6 shocks looked like they would work better than most of the other shocks people were using, and I saw one on e-bay for about $25 shipped from a bike with only 2k miles on it. Pre 03 (I think?) R6 shocks didnít have a Ďforkí on the bottom, so they wouldnít work. At 295mm long the R6 shock is shorter than the stocker (320mm) and it has a spring rate of 9.8kg/mm, stock is 7.9 kg/mm. The R6 shock has pre-load, compression, and rebound damping adjustments (I read something about low/high speed damping too, but I havenít gotten to fooling around with all that yet).

The main reason I picked that shock is because the external reservoir sits much lower than almost all the others I saw. Since the ones w/ high mounted reservoirs required a lot of modifications to the inner fender, battery mount, etc. I thought this might make keeping the bike side of things in one piece easier. Iím certainly not afraid to mod things, but I wanted this to be reversible in case something didnít work well and I wanted to go back. I messed around with several ideas on how to mount the new shock, and this is what I came up with a design for a bracket to mount the R6 shock a little more than 1Ē lower than the stock shock mounted, so I ended up actually raising the rear of the bike a little (which was fine by me). With this bracket the only modifications on the bike side were a very little bit of trimming to the lower inner fender. No metal or anything was cut on the bike, so swapping the stock shock back in would be super easy.

Old vs New:


The beginnings of the bracket:




welded up:


after a bit of cutting, welding, grinding, drilling, primer and paint (yes, john deer yellow ):


The upper mount for the R6 shock bolts to a bracket... if you want to do this swap make sure the shock your buying comes with the bracket that the top of the shock mounts to.


A few pics installed:








The only other mod required was I had to grind about 1mm off of each side of the lower fork on the shock in order to get it to fit on the ninja uni-track linkage.

Iíve ridden a few hundred miles now and its amazing! I still havenít dialed in the damping adjustments yet. I weigh about 120lbs and have it on the lowest preload setting and its not too rough of a ride at all, but the sag is only about 1/5-1/4 of the total travel... maybe not ideal, but it seems fine to me.

While I was working on the shock I completely disassembled the linkage and replaced all the o-rings and greased everything up real good... there are a million o-rings in there!


II. Ex500 springs

I got some 500 springs from ronayers and swapped those into the front... not too much to that, I didnít even bother taking any pictures. I also filled up with some 15w and set to fork oil height to 180mm, Iím going to play with the fork oil height a bit. I wanted to put in emulators but just couldnít justify the cost.... yet.

The front end feel has improved, and the horrible dive under braking is somewhat better. I marked full travel on the fork tubes and put some zipties on them so I can keep an eye on if I ever bottom them out. If I donít then Iíll prolly pull out a little bit of oil.

III. K&N 0990 and re-jet

I got really sick of how hard it was to pull the carbs. After having to clean them twice I had enough and decided while I had the bike stripped down for the other work Iíd put in a pod filter and re-jet. I ordered DJ 106, 108, 110 mains and got some washers to shim the needles and pulled the idle mixture screw plugs... much cheaper than buying a whole kit (the DJ jets are like $2 each).

This is the batt box after cutting off the filter box:


New main jet:


Oh yea, tons of room now!!


Blue breather installed on crankcase vent:


I still need to work on the tuning... the 106s are deff a little too lean Iím pretty sure, but I havenít had a chance to swap them out yet. Also I think Iím going to need another washer or two (I have 3 in there now). I also want to sync the carbs etc... soon. But for now, its running pretty good, but I can tell its not as best as it could be!!

IV. Chain/sprockets

Since this is a commuter ride with heavy riding on the weekends I wanted to bring the highway revs down... with the MT75 rear tire I was turning like 10k on the highway... way too much. I needed a new chain anyway, so I sprung for JT 15t front 41t rear and a RK XSO chain. Also picked up a motionPro chain tool for installing the new chain... worked like a charm!

Putting new sprockets/chain on is pretty straight forward... no need for pics really. Iím very happy with the results. I think if I were running a larger (130/90 or something) tire I wouldnít want to have the 41t rear, maybe a 43 would be better. But with the 120/80 the revs are much better and the takeoffs arenít too bad at all. Of course if youíre a fattie then you might need a little more low end Ďoomphí, but at 120lbs I wasnít too worried about that

V. Fender chop / LED brake lights

Since I got the bike I wanted to put extra lights in the side pods in the back. For Christmas my dad bought me some LED 1157s for the side pod and a rotating/flashing LED to put in the center. I took some old 1157 sockets from old car lights I had laying around and put them in the outside pods, wired it in to the stock wiring and I think its great Ė much more visible, and if a light goes out its not your only one.

I also chopped the fender... I know I have pics of this around somewhere but I canít find them right now, Iíll have to edit them in later. But it looks pretty much just like everyone elseís fender chop, lol.

VI. Throttle ziptie mod/grips

I also did the throttle ziptie mod... I like it! WOT can now be reached w/o re-gripping etc. Once again no pics necessary... pretty straightforward and it has been beat to death.

I also put on some pro-grip grips... I take long-ish (3-4 hour +) rides frequently, and the stock grips just werenít real comfy... I LOVE these things!! Make long rides much nicer and they look good too (I got the blue/black to match the bike).


Over all after doing these few little mods the bike is awesome. I canít wait to get a new front tire so that hopefully I can get rid of the front-end shimmy at hard lean angles. Iíve still got a few other things to do to to wrap it all up, like tune the suspension as best I can (any good tips for messing with the R6 shock?) and get the carbs adjusted just right, but over all its like a completely different bike... I love it!!

Till next time folks, nate out.
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Old April 22nd, 2010, 07:18 AM   #2
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Very nice shock mod. I like the custom fabrication.
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Old April 22nd, 2010, 07:22 AM   #3
sktrs_kpr
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umm... I had a retard moment and posted this in the wrong section, can someone move it over to pre-gen tech? Thanks!


And thanks for the compliments Rick, I think it turned out pretty nice!
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Old April 22nd, 2010, 11:07 PM   #4
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/moved to pregen tech
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Old April 23rd, 2010, 03:32 AM   #5
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tinkerer???
your garage looks a lot like a machine shop to me
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Old November 8th, 2010, 08:31 PM   #6
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Hey if you don't mind could you post pic of how the bike sits or measure the rear end height of you bike. im considering the r6 mod but im afraid its going to raise the rear end too much
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Old November 9th, 2010, 06:10 AM   #7
sktrs_kpr
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Well this is the best shot I have for now; it raises the rear of the bike about an inch or so. Another member on here is working on the same mod and it seems to have raised his a bit more, I'm waiting to see if perhaps he can just adjust the pre-load to lower it a bit. My pre-load is at the lowest setting.

I know someone else near me who rides a stock 250, I'll have to try to get a picture of the two of them next to each other sometime.

As you can see when its on the side-stand it leans over a bit more, I'm still considering putting some kind of a pad on the bottom of the side stand to help it sit a little more upright. But I've been using it like this for like, 8 months? So it works OK even w/ the side stand at its stock length. The center stand no longer raises the rear tire off the ground, but it is able to hold the bike up. I just put a piece of 1/2" or 1" board under the center stand when I need to work on the rear wheel.
Attached Images
File Type: jpg NinjaSideShot.jpg (263.1 KB, 24 views)
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Old November 10th, 2010, 12:15 AM   #8
Tony B
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Nice contrast, Ninjette and a B25 ............

I'm watching an R6 shock on ebay, but it doesn't have the top bracket. I guess I could fabricate a longer link than the one you did, and put a spacer between the sides, possibly welded too.
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Old November 10th, 2010, 01:31 AM   #9
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The guy that owns the BSA is the guy I bought the ninja from, actually! I bought it from him more than a year prior to that picture. He and I switched up for a little while that day, riding that thing was just a bit different than the ninja The whole shifting with your right foot took some getting used to
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Old November 10th, 2010, 02:58 AM   #10
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Hope you didn't rev it to 14,000 .........
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Old November 10th, 2010, 09:31 AM   #11
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Thanks so much for the reply. this thread is very informative. I think Im going to try and fabricate a new top bracket (even though the one i bought came with one). after measuring, it looks like i might be able make the shock length 325mm so with the suspension geometry it would only raise the rear 10mm or 1cm (hopefully).
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Old November 10th, 2010, 09:37 AM   #12
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Quote:
Originally Posted by sudapuff View Post
Thanks so much for the reply. this thread is very informative. I think Im going to try and fabricate a new top bracket (even though the one i bought came with one). after measuring, it looks like i might be able make the shock length 325mm so with the suspension geometry it would only raise the rear 10mm or 1cm (hopefully).
I'd be interested in seeing pics of that
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Old November 10th, 2010, 10:36 AM   #13
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Here is what i was thinking

(the dimensions are not to scale, its only a rough drawling)
I may have to shave the bottom of the top of the old shock or might not use it so i can have make the bracket shorter
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Old November 10th, 2010, 11:46 AM   #14
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SO i took off the side faring of the bike and realized this wont work due to the fact that at the mounting point on the bike the bolt is a little recesses/tabs stick out on the side.... I'm going to try and think of another solution with out having to mod the bike (just mod the shock/bracket) hopefully i can think of something without raising the rear end too much
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Old November 25th, 2010, 09:30 AM   #15
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Quote:
Originally Posted by sudapuff View Post
SO i took off the side faring of the bike and realized this wont work due to the fact that at the mounting point on the bike the bolt is a little recesses/tabs stick out on the side.... I'm going to try and think of another solution with out having to mod the bike (just mod the shock/bracket) hopefully i can think of something without raising the rear end too much
Good luck, (I've temporarily stopped worrying about changing the rear shock at the moment, more pressing problems with the bike )
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Old March 2nd, 2011, 05:40 PM   #16
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I'm looking into rejetting sometime this season, but I'm having trouble finding a breather for the crankcase. Where'd you find that online/what part is it?
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Old March 4th, 2011, 04:32 AM   #17
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Hey Chris - i got that breather at autozone. Its just a generic breather they had sitting on the shelf. You have to "loosen" it up a bit, I used a razor knife and a file.
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Old March 25th, 2011, 09:26 AM   #18
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you really show me what a techno tard i am, but i think you'd be happier if you split the difference on the rear sprocket at 42. yes i've ridden 41's and every last rider ended up with a 42 down the road. Great bike, unbelievable workmanship, happy trails. so f'in impressed.
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Old March 25th, 2011, 11:07 AM   #19
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Another question for you Nate, how did you get your battery box attached once you took off the airbox? Just use the two holes already in the bottom and bolt it to what? Any problems with the battery bouncing out while riding since you can't use the strap anymore?
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Old March 25th, 2011, 03:54 PM   #20
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Actually I'm glad I went with the 41... I'm still turning 9-10k rpm on the highway (75-80), so I don't want it geared up any more for sure! First gear is a little taller than I would like, but I'm not drag racing the thing And when just my scrawny self is on there it still takes off OK, and once it starts to get up in the revs it accelerates nicely

About the battery, it bolts to a piece of the frame underneath, so you just bolt it down the same way as before you cut the airbox off of it with the two bolts underneath. they are more than enough to keep the battery in place. Mine never had a strap running over top of the battery, it was just "free" inside the box... I thought thats the way it was from the factory? Anyway, if the box is bolted down there is no way the batt can jump out because there is only an inch or so between the top if it and the bottom of the seat.

I have recently put a much larger battery in... so i had to make a box for that, but it was more work than it was worth IMO. If you can stick with a stock sized battery you'll be much better off!
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