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cbr300r ECU

7K views 10 replies 7 participants last post by  mwlehman 
#1 ·
ok, so I bought another 2012 cbr250r in key west..couldn`t turn it down, $1600 for a 2012 red/silver w/14k miles...needed a little cleaning but looks nice now...anyway me being cheap and looking for way to improve performance I bought a used 300r ecu to slap on..did not get ecu yet but it was $46 shipped from ebay..I will post whether it works out of not.

any thoughts ?
 

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#2 ·
Im no mechanic but I don't think this is a good idea. Yes the 300 (actually 286) is similar but its engine map will not run well on the 250. It will run rich if it works at all. The cams could also have different degrees, probably not, and the timings would be off. That could lead to engine failure/ damage from knock or burning the valves. The main connectors could also be slightly different and not plug in at all. If you really want more performance for cheap you might be able to find a place that can reflash the ecu with a new map but I don't know of any that do it for our babyblade. Again I really suggest just getting a piggyback ecu like a PCV or juicebox. Goodluck!
 
#3 ·
Thanks for reply, I gave those things some consideration but from what I read they only increased the bore...but you know how that is..lol...

I am going to give it some more thought, but knowing me I will just plug the thing in and go, if it screws things up it will be a good excuse to build another motor
 
#4 ·
....
I am going to give it some more thought, but knowing me I will just plug the thing in and go, if it screws things up it will be a good excuse to build another motor
Is it only me, or do it look a bit like, you are hoping for a "srcew up"?
And the 300 ECU is only the first thing, you want from the 300 series?
:wink2:
 
#10 ·
Probably trying to figure out why it won't run right. :p

Seriously though, why? There was a 250r-300r engine conversion thread somewhere (don't think it was on this forum), and it was found the stroke was different (different piston and crank), the cams were slightly different, obviously the timing was a little different (more time required for longer stroke), the engine case halves were a little different, balance shaft, etc. It's not a one and done swap. Honda knew what they were doing when they designed both of these bikes.

Want a 300r conversion? Great, you have one piece of the big puzzle. Want to throw the 300r ECU on the 250? No reason, and I guarantee you it most certainly won't help anything. One way to blow up a perfectly good engine.
 
#11 ·
it started and ran, but did not seem much different than stock...so I stuck stock ecu back on and bought 2 DynoJet Power Commanders for my wife and my bikes, some guy was blowing them out for $90 shipped on ebay, new in box

that made a much bigger improvement, wife even said she noticed a difference
 
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