Ninja 300 engine into a Pre-gen 250

[DirtyD]

Great riding, great video. That Moto3 bike is not slow.

 

[tora-taro]

Hi, I'm gonna do same thing like you did.
I have running ninja 300 engine and seized ninja 250r engine.

If you had used ninja 250r engine bracket, you don't need to cut the engine 10mm, I think.

What ic igniter are you using??
Pre 2007 and after 2007 model are different..

I'm living in San Jose and I would like to check out your bike if you have time.
Thanks

 

[Grease_Monkey]

Go ahead and PM me.

I used the pre gen Flywheel, and stator cover (removed the stator for racing). It has only 2 pick magnetic pickups to go with the pre gen igniter.
Im sure the 07 flywheel and stator cover which has multiple pick ups will also work so you can use all 250r stuff already on the bike. But I believe the 250r and 300 share the same pieces in that aspect so you might not have to change anything

The 250r has 28mm throttle bodies, and the 300 has 32mm throttle bodies.
Since I ran Carbs I was able to use 86-87 ninja 250 carbs which are 32mm. (88-07 are 30mm). So, you might benefit from running the 300 throttle bodies, but I have not messed around with it yet so I cannot say for sure it will work, but it should, with ECU tuning.

 

[tora-taro]

Hi Thank you for the nice information

I also have two CVK32 carb from 87's bike.
I saw your video and the bike running with pot filter. the sounds are amazing.

What combination of Jets currently are you using??

Pilot jet # Main Jet #?
also are you using metal vacuum piston comes with CVK32 or plastic one from CVK30?

I think the setting the Carb will the most hardest part on 300 engine...

 

[Grease_Monkey]

I got it pretty close. I am using the plastic slides, as I only found the bodies with out any guts. I believe I am on the 4th clip from the top and running 116 main jet. I left the pilot alone, as Im above 9,000 all the time and just tweaked the mixture screw to get it close. I am not 100% sure about the main jet as I used my jet drill kit in a time crunch.

I tried to do my best on the street, but a dyno it where it is at. I was able to get a session in, but couldn't do any tuning on the machine. Basically had to take the info they game me and use my best educated guess. I was 12.0 to 1 on the dyno, so I leaned it out to where I suspect I'd be around 13.0 to 1 But Ill have to do another session to see how much I actually changed it.

I am also playing with the idea of getting the offset woodruff key and see if I can squeeze a few more ponies by advancing or retarding the timing, but that is just more Dyno time. If I can only find some one that would allow me a day on their's, I can get all my data and dial it all in perfect.

I do a lot of dynoing of cars at my shop, street cars, vintage race cars, forced induction modern cars, etc. So I have the skills to pay the bills, just learning to apply them to bikes.

 

[tora-taro]

Oh Ok, so just use body and inside parts are from newer model.

I need to carefully choose parts which use, because it is really hard to get perfect setting!
I will try 110~120 main jet, and 38 or 42 for pilot jet depends on air filter.
But l guess with stock pilot jet it may harder to get start at low rpm...


will you try just change CDI?

08~
10° BTDC @1 300 r/min (rpm)
35° BTDC @4 000 r/min (rpm)

I have 08 CDI and if you like to try it I can give it to you.

 

[Grease_Monkey]

The timing, though quite critical, seems to be all over the map in terms of years They state the timing at 4,000 rpm-ish. It doesn't confirm or deny what the is the timing is above 8,000. And I know that when i comes to emissions, WOT is not a parameter that is taken into consideration. So it could be a different timing setting between 4k and 8k rpm. The fact that the 86-87 is different, that might be an idea to try before tearing down the side cover to swap a woodruff key. I believe the 08 is controlled by the computer, no?

On the topic of pilot jet, there seams to be enough adjustment to get a proper idle mixture for easy cold starts, and hot idling. Though again, I have my idle set to 2500, so not to accidentally stall on the starting grid.

 

[tora-taro]

300 engine are
10° BTDC at 1 300 r/min (rpm)
31° BTDC at 7 000 r/min

So if you are using 87-07 CDI it may too early?
I guess 08 250r CDI is close to 300 timing.

if the bike is carb model, 08 CDI is same system, just need to change wire socket and fit to 87-07model.

 

[Grease_Monkey]

The problem is it, its not comparing apples to apples. The timing spec is 31 @7,000 on the 300. and 42 @ 4500 on the 250. Who is to say that the 250 isn't 31 @7,000. or the 300 at 42 @ 4500. What I need is an advance curve graph showing timing at all RPM levels for a true direct comparison.

 

[tora-taro]

I think between idling and 4Krpm its 10 degrees and, 35 degree throughout the rest of the band.
It is not changing after 4Krpm 08' ninja 250r CDI.

The graph is not for ninja 250, but it should be like this.

 

[Grease_Monkey]

That is what I would be looking for applied to a 250. I thought about making a plug with a clear sight in it, using a timing light and just get the information myself. But again, a dyno would make that task much easier.

 

[tora-taro]

Sounds like really fun. I need to know some good dyno work place.
Just let me know if you need 08' CDI. I have some extra and give you.

I will also make connector and make it just plug in to 90' model

My number is 415-24o-3561
Thanks!

 

[Grease_Monkey]

If have to change my flywheel and cover over back to the 300. I'll do what I can and if I hit a brick wall, then I might entertain your setup.

 

[tora-taro]

You don't need to change anything.
Just take off existing CDI and replace it.
BTW, this is what CDI looks like.

it's 30sec job.

 

[owen.hamilton]

I set both engines to DTC on the Flywheel pulled both off and found the woodruff key to be in the exact same spot. After bolting the pre-gen on the the 300 engine, I took the pre-gen cover and success!!! The cover fits!!!!!! stay tuned!!

DTC? did you mean top dead centre and make a typo?

Some fantastic info in here! I'm considering doing the same. It's looking to be a cheaper horsepower upgrade than selling my (pretty rough looking) track 250 and buying a ninja 300, then setting up for track. Even factoring in buying a track prepped ninja 300, this still seems cheaper.

If I can get up to 35-38hp, with an exhaust I'll be thrilled!

 

[owen.hamilton]

Will any 32mm carbs work? I can't find the 86 Ninja 250 ones but seem to be able to find other kawasaki Kehini carbs that are 32mm.