Is the CBR250R Throttle body swap worth it?

[jbsurf]

I`ve searched on here and I have ordered a used CBR250 TB to swap out, from some of the input I`ve read it does/doesnt do much to improve things?  Any fresh info on this? A lot of the threads are pretty old and would love some current feelings on this, thanks... I`ve done all stage 1Mods and this is next if ......  

[Evan D]

I had a lead on the TB (and computer?) and decided it wasn’t. If I do anything else it’ll be one of two things, a better all around dirt bike or swap in a bigger motor or big bore kit.

probably would  yu a better bike... and find a way to make it street legal. Or a DRZ400...

Edited February 5, 2018 by Evan D

[Derbigp80]

It does make a difference but where you will see it is towards the top.  The ECU alone makes almost 1hp and revs quicker. But just like anything, to get the most out of it would be in conjuction with other mods.

[CRFThai]

Better off putting in the CBR300 parts with CBR300 TB imo.

[jbsurf]

10 hours ago, Evan D said:

I had a lead on the TB (and computer?) and decided it wasn’t. If I do anything else it’ll be one of two things, a better all around dirt bike or swap in a bigger motor or big bore kit.

probably would  yu a better bike... and find a way to make it street legal. Or a DRZ400...

I have the ECU, and the bike is pretty snappy, hoping for a little punch then be done,,, I like the performance most of the time, I didnt want a violent bike, been there,,,,  just hate to ride this choked down, so the easy, helpful upgrades have been added, this would be the last, with a larger fuel tank. Its like rejetting the older Carb bikes...  Was hoping its worth it, and I did read , plus Dirbigp80 confirmed the upper end feel, thanks.

And the 300R TB is the same size as the 250R, 38mm

Edited February 6, 2018 by jbsurf

[Derbigp80]

Here is my dyno run when I tested all these theory and showed some real numbers.  Go to Facebook CRF250L group and look in the files section.  It will answer more if you have more question.  Hope that helps

[Evan D]

Without Facebook I can’t tell what each line represents...

[Derbigp80]

—Red is custom slipon with snorkel (stock ECU)

—Orange is without snorkel (stock ECU)

—Green is without snorkel and CBR ECU

—Blue is without snorkel, CBR ECU and custom full system exhaust

—Black is without snorkel, stock ECU and custom full system exhaust.

Hope that helps.

[Evan D]

Thanks, that helps a lot. Interesting then trying to figure out the true difference between the blue and black. 

[Derbigp80]

.66hp more at peak/ 1.45 seconds faster to peak/ air-fuel ratio is not lean but actually on the rich side so don’t even need a fuel controller.

[KLeptoLee]

I got a cbr250r ecu and a 300 bank angle. I may part with. If I don’t sell it till the 325 big Bore Stroker is done I may put it in and see how it does.
Is the rev limiter raised on the cbr ecu ? I forget

[<Ian Nicoll/>]

I've done loads of mods on my bike, 305 Takegawa big bore with sport cams, injection controller, full yoshi system etc...

i got the CBR250R throttle body, fitted it, ran it for a day or 2, felt zero benefit, took it off again & put back the original. 

I had it fitted with original CRF fuel injector, the motor seemed to run rough with zero performance gain. 

[stew79]

looking at the dyno pictures is quite disappointing, i thought modern teck would make things so much better than old fashion carbs. the last time my old 250 was dynoed (about 2003)  it was 27 bhp. i havent got the print out but its on the computer system at BDK race engineering in england. thats on petrol with a 32mm mikuni carb, home made ex pipe, basic porting and refining of jetting, timing etc. it was a road reg play bike with lights and used every day as a run around. tuned to be an all rounder, not just set up for racing at over 7000 rpm.

stew

[Derbigp80]

Stew, what kind of 250 was it?  It all depends on the what kind of bike and what dyno.  Modern technology does not mean better performance but more like more efficient.  There is a reason why these LRP can clock 70-80k miles without a skip.  I know my XR600 and 400 could not make that

[stew79]

just a 78/79 xl engine in a yz bike (with IT swing arm) normal inertia dyno operated by very good engineers. they have an enormous data base of bikes they have tested, and predicted about 20 bhp (as the bike has std piston, crank, valves, rs250 road bike cam,) as for reliability, i owned the bike for nearly 20 years (well the engine, it had been in 2 other frames) not many weak spots. (some more pics on here in honda)