ninja 250 supersport build

[simook]

I'm getting back into racing and decided to jump into the Ninja 250 Cup with OMRRA.

This build will be on a budget so I'm only doing what is essential for OMRRA, safety, and base performance.

I feel I can get away with using the stock suspension for the first couple months as I'm 5'9" and only ~150lbs suited. With that said, I do think having the ability too adjust the suspension is crucial so I may try to achieve that sooner rather than later.

So I picked up a 2008 Ninja 250R with a branded title for $1,900. It was branded because somehow had a low speed wreck.

2014 Race Prep:

• Safety wire
• Woodcraft clip-ons
• Woodcraft rear-sets
• Yoshimura full exhaust
• Dynojet
• Race fluids (water wetter, amsoil, fork oil, etc...)
• K&N Airfilter
• EBC Brake pads
• Race Fairings
• Steering Damper
• Snorkel removal
• Radiator fan removal
• Front fork emulators
• Front fork springs
• Rear-shock rebuild???
• Kickstand mount & sensor removal
• Lights & choke controls removal
• Misc. street farkles (e.g. Horn, wire harness mounts, etc...) removal

I think that's the gist of what I'll be working on this winter. Now on to the pics!

10/31/13 Update: I do plan to improve the suspension within reasonable means that meet Omrra regulations.

[simook]

So as you can see, I have a compact space in a parking garage. Not the best conditions for a race bike but its covered and is dry. Thankfully it was only a temporary situation but for the time being it wasn't going to stop me from starting the conversion.

[simook]

Inspecting the carbs before jetting. I was very surprised with how clean they were.







Yay parts!

[JohnnyBravo]

That a good lookin bike! Race it up!! This is def the kind of post I like!!! plenty of racers around to get info from

[simook]

A friend of mine offered to help me out with my racing dreams. He's gifted me a dedicated shop space, bike transportation, and tools. We're in the process of outfitting one of his shop bays to be a dedicated space for racing. (He's also a racer.) We're installing a bike lift, shelves, and work benches. Did I mention he has a paint boot and access to a motorcycle dyno.

But for the moment, I'm storing my bike in an empty corner as we work on outfitting the shop.





Removed the kickstand mount with a sawzall. Still need to clean it up, grind it down, and spray paint.





Ok so I was in a hurry and didn't take any pictures of installing the exhaust, removing the tail section, or cleaning up the fender.





But here's how she stands with the fiberglass fairings. I didn't spend any time on alignment, just wanted to get a gauge on how much work will be needed to align them up. I always have bad luck with fiberglass fairings.


(The building in the background is the paint booth.)

[JohnnyBravo]

No... But that's good ****!!! You color matching or goin mean green??? Y'all lookin for a third?
Lookin good so far, an at least you aren't in a Parkin garage anymore

[simook]

Originally Posted by JohnnyBravo

No... But that's good ****!!! You color matching or goin mean green??? Y'all lookin for a third?
Lookin good so far, an at least you aren't in a Parkin garage anymore

Amen to not being in the garage. Regardless of what I end up doing, I will color match everything to a flat white.

[simook]

Here's a couple clips of it running with the exhaust, jets, stock airfilter, and snorkel removed.

Currently it almost dies when giving it any gas, is slow to respond, and surges. So I'm going to pull the carbs and verify the internals are proper and didn't clog up anywhere.

I also just realized as I was writing this that the gas in the tank is the same gas that the previous owner had put into it and it's almost empty. So hopefully it's just picking up a bunch of crap gas.

The first video has a vacuum leak. I think I plugged the leak in the second.

Link to original page on YouTube.

Link to original page on YouTube.

[Fuzion7]

Watching. I will be doing this when I get back to the states.

[alex.s]

150lbs is too much for stock suspension i think. the suspension mods are more important than the performance mods on the track

[simook]

Originally Posted by alex.s

150lbs is too much for stock suspension i think. the suspension mods are more important than the performance mods on the track

Would you be able to reference any facts that can back up your opinion? I ask out of genuine enthusiasm to learn and am completely open to hearing you out. But I prefer to have factual evidence to base my own opinions off of.

Also, I have a pretty good understanding of what suspension mods are available for the 250, so having more facts can help me in choosing the right mods.

Btw, I love your avatar Alex.

[alex.s]

if i remember right stock 250 suspension is sprung for 120lb geared rider. weighing 170 geared, i run 0.85mm/kg springs up front and i still come close to bottoming out on hard braking. if i remember right, stock front spring rate is around 0.6mm/kg. fine for 150lbs on the street. not fine if you plan on putting a lot of force in corners or braking.

[simook]

Originally Posted by alex.s

if i remember right stock 250 suspension is sprung for 120lb geared rider. weighing 170 geared, i run 0.85mm/kg springs up front and i still come close to bottoming out on hard braking. if i remember right, stock front spring rate is around 0.6mm/kg. fine for 150lbs on the street. not fine if you plan on putting a lot of force in corners or braking.

I have looked at springs, and the suspension calculators determined my spring rate is around 0.63mm/kg. But that was with guessing the geared and wet weight.

It's been 3 years since I've been on the track, and with not having a racing license I'll be a novice racer for the first half of the season. My main focus will be to not wreck, but still finish in the allotted times.

So with this context, do you still think upgrading the stock suspension should be a higher priority?

[alex.s]

no harm trying it and seeing how it goes. its pretty easy to tell if you need stiffer suspension.

[simook]

Spent all day Saturday working on these tasks:

• Exhaust header gasket
• K&N Air Filter
• Woodcraft Clip-ons
• Carb tune & sync

After getting new gas into the fuel system, the bike starts right up with choke and once warmed up I reset the idle to ~1400ish. Throttle response was good, and the only con was that it bogs down when quickly chopped (lean?). I have no idea if this is normal, but from my experience it didn't seem normal at all.



At this point I felt adjusting the mixture screws was a bright idea to attempt to fix the problem. This is where things went south. Looking back I should of done the carb sync first with the bike warmed up. But somehow I convinced myself I needed to do this first.

So pulled the carb, adjusted mixture screws 1/4 and reinstalled carb. Repeated this process about 6 times. Nothing was improving and it seemed worse so I set the mixture screws back to what I thought I set originally for the dynojet, L-3 / R-3. Now it would only start with choke and barely wants to run, and will slowly start to die. Giving any gas will kill it. (rich?).

With the bike barely running with the default dynojet setup, I realized I have no baseline reference to work from. Reinstalled the stock needle, jets and set the mixture screws to L-2.5 / R-1.75 (w/ Yoshi full exhaust, K&N air filter, and snorkel removed). Starts with choke, idles rough and again will slowly die. Giving it any gas will kill it. (rich?).

At this point I threw in the towel for the day, but I plan to reinstall the stock exhaust and see if that helps ( Already threw out the stock airfilter and snorkel). If I can get it running right with almost stock parts, I will sync the carbs and also check valve clearance. With those sorted that should give me a better baseline to continue.

I've read everything I can find regarding the 250r carbs, mixture screws, lean/rich, etc... but applying that knowledge takes time and patience, not too mention the right tools.

Any thoughts, tips, or advice would be appreciated.

[Ausoi]

YEAR: 2012
INTAKE MODIFICATIONS: Snorkel removed, Uni Filter Panel Filter
EXHAUST MODIFICATIONS: Yosh Full Exhaust, Kleen Removed
JET KIT OR STOCK: Kit
BRAND OF JET KIT: Dynojet Stage 2
MAIN JET: DJ 98
NEEDLE AND CLIP POSITION: 3 from top, then another placed 1 from top, no washers
Pilot Jet: Keihin 42 ordered separate
MIXTURE SCREW SETTINGS: 1.5
ELEVATION: Sea level

Someone posted this in the Jetting database that we have and I followed it and my bike runs stinking awesome. Most days I don't even need the choke. I also drilled my sliders, no lag what so ever. Not sure if your problem is a jetting issue though.

Just to let you know I had the same issue with the bike dying when too much throttle was applied too quickly, rejetting was HUGE and made me WTF the first time I opened the throttle.

[simook]

Decided to improve my tool collection with a proper carb sync tool. http://www.ebay.com/itm/331036925003...84.m1439.l2649

Has anyone used a afr meter?

[cuong-nutz]

Did you clean out all the tiny orifices in the carbs? Sounds like dirty carbs. The fluid in the bottle method works for me when synching carbs.

Yes to the AFR meter.

[FvnnyL3tt3r1ng]

Sounds like you just need to start the whole tune process over. Sync the carbs, then do the Mains, needle height, idle mix and float height in that order. Syncing the carbs shouldn't take long at all.

Remember a bike running rich will run worse as it warms up and vice versa.

[jkv45]

If it was rich it wouldn't need choke, and would start fine cold without it.

Sounds like you need to go through the carbs again. When you removed the idle speed screws, did a spring, washer, and an o-ring come out with it? If not, the o-rings may be damaged and plugging the passage.

If you didn't before when the carbs were off, remove the idle mixture screws and spray carb cleaner through the opening.

Most likely the pilot jets are at least partially plugged (it's an epidemic...). Pull out the pilots and find a very fine copper wire (or something that will go through the jet without damaging the shape) and spin the jet around it while spraying with carb cleaner, then remove it and spray again. Blowing the jets, and the passages in the carb, with compressed air is also a good idea.

[simook]

Originally Posted by jkv45

When you removed the idle speed screws, did a spring, washer, and an o-ring come out with it? If not, the o-rings may be damaged and plugging the passage.

I don't recall if I removed the idle speed screws. If I didn't, should I leave them alone?

[simook]

Originally Posted by cuong-nutz

Did you clean out all the tiny orifices in the carbs? Sounds like dirty carbs. The fluid in the bottle method works for me when synching carbs.

Yes to the AFR meter.

I'm looking for a decent AFR meter, what did you use?

[cbinker]

I am surprised to see nothing there for suspension, power is useless if you can not get to the ground properly. Personal experience on stock suspension, is at the track it dives, from just easing off the throttle. After switching to a GSXR shock, it created far more stability. I am not sure what the rules are for where you are racing, but stiffer springs and emulators would be the first place to start if I was going racing. Then I would go with rear sets, because ground clearance is a bitch, had a little low-side last summer because i wanted a few MPH around the corner my right peg was consistently hitting.

[Mocha Man]

This thread. I like it.

[jkv45]

Originally Posted by simook

I don't recall if I removed the idle speed screws. If I didn't, should I leave them alone?

With the odd idle problems you are having, I would pull them out and confirm that the o-rings are in the proper position and in good condition before moving on.

Typically 2 1/2 turns out on the stock idle mixture screws gets you in the ballpark. Another way is to adjust for the highest idle speed (when fully hot) and then go just slightly richer (1/8 to 1/4 out). Spray some carb cleaner through the opening when you take them out.

Because you found gunk in the float bowls you can assume there is varnish and deposits in other parts of the carb as well.

[simook]

Thanks everyone. You've reaffirmed that I need to do a carb teardown, inspection, and cleaning.

cbinker suspension is on my todo list, but I don't know if I will be able to do it just yet. Also, before touching the suspension I would like to get it on the track first and get a baseline reference of how the stock is. This gives me time to research and save up the $$$. Most likely I will just swap the suspension at the track after getting feedback from the bike.

I'm also awaiting on a ruling from OMRRA regarding the gsxr rear shock mod, it appears it may be a violation with the rule "Rear shock linkage must remain stock".

[Singh2jz]

Subscribed.

Good luck with the carbs..hopefully it's nothing!

[bitaria]

This is pretty much the build I'm doing. Subscribed!

Haven't pulled carbs yet, they will be done much later in the winter when all the other stuff is sorted out. Current plan is not to use the a jet kit. My understanding is that going .05-1mm up on the needle is all that's needed, other mods make no difference unless airbox is opened up much more than rules allow.

If you can get some dyno time with AFR meter...

[simook]

Thanks for subscribing everyone!

I've been a bookworm lately, currently reading Motorcycle Fuel Systems Techbook and Sportbike Suspension Tuning.

So far both books are great reads and have lots of technical teachings. The biggest realization I've had is with what the Airbox actually does for the intake system. I suggest anyone considering to remove the Airbox to learn about carburetor theory and how the intake system effects it.

On to the pics!
Carb teardown, inspection, and clean (again).





First attempt at carb synch


The carb synch gagues didnt work so well, so I switched it out for my homemade system. Some air was in line from each bottle and it turned out to help with the process.

Link to original page on YouTube.



Time to modify the fairing stay, I plan to reuse it with the race skins. I have thought about building an aluminum stay but for the time being modifying the stock stay will work just fine.


After using the sawzaw.


After cleaning it up (not my best work, was all out of locking sanding disks).


And it turns out I didn't take a picture after spraying it.

Anyways, bike is running like a champ now with the stage 2 dynojet. I need to check the valves this coming weekend and hopefully my woodcraft rear-sets will arrive tomorrow.

[Fuzion7]

Glad to see you got it all figured out.

[bitaria]

If you build a stay I might be interested in one as well. I'm keeping mine street legal-ish so didn't want to cut up the stocker.

[Floki]

What are you going to be doing with the old plastics? My left lower is scratched up and cracked

[simook]

Originally Posted by Floki

What are you going to be doing with the old plastics? My left lower is scratched up and cracked

At the moment they are collecting dust. But I plan to sell them, if your interested shoot me a pm.

Also, can anyone reference what they used to replace the front wheel speed gear? Specifically part #41078 and #601 (http://www.bikebandit.com/houseofmot...8915#sch550349). I've read a couple guys have used spacers, but what kind of spacers?

[bitaria]

Originally Posted by simook

At the moment they are collecting dust. But I plan to
sell them, if your interested shoot me a pm.

Also, can anyone reference what they used to replace the front wheel speed gear? Specifically part #41078 and #601 (http://www.bikebandit.com/houseofmot...8915#sch550349). I've read a couple guys have used spacers, but what kind of spacers?

You can keep it as is, just plug the speedo cable hole. Spacer would have to be custom cut tube with internal diameter matching the axle. It's on my todo list, but not a must have to go racing.

[simook]

Spent this last weekend getting a lot of little things down, but my main goal was to get the bike ridable.





Modified the stock cowling stay to work with the race fairings.
















Installed and adjusted the rear-sets.






Well that's not ideal.


Cleaned up the bike stand mount.




Time for a ride.


These fairings are getting dirty, probably time to start thinking about a paint job.



Also got the bike ready for winter storage, that's a load off the mind. As of now I'm feeling pretty good with where things are at. Still have a lot of work to do but it should be all down hill from here.

[mgentz]

How did your rearsets fit? Many people have posted about issues...

[simook]

They installed perfectly.

I just received my rear-sets from one of the latest batches from Woodcraft, so I'm thinking they may have made some adjustments to the manufacturing process to fix any fitting issues.

[mgentz]

Are they even on both sides?

[jkv45]

Originally Posted by simook

Looking good.

One suggestion - notch or drill plenty of holes around the peg to give them a clean breakaway point in the event of a crash.

The Woodcraft rearsets are strong enough to rip the mounts out of the frame in any type of crash. A lot easier/quicker/cheaper to have an extra peg in the toolbox than having to repair the torn-out mounts.

[bitaria]

Originally Posted by jkv45

Looking good.

One suggestion - notch or drill plenty of holes around the peg to give them a clean breakaway point in the event of a crash.

The Woodcraft rearsets are strong enough to rip the mounts out of the frame in any type of crash. A lot easier/quicker/cheaper to have an extra peg in the toolbox than having to repair the torn-out mounts.

Picture of holes you drilled?
I crashed a set of these on R6 and it rode from 120 to a stop on it and saved the bike. With Ninja frame isn't strong enough to handle that sort of a crash.