Cbr 250 Engine Into Old Cbr 150- Possible?

[shroomer]

I have the old style CBR 150 and love it, small, light, neutral handling. I got a loan of a friends CBR 250 for a few days and

while it is a great bike, it is a lot heavier than the 150, not as nimble, but has a great engine.

I reckon the 250 engine fitted into the 150 would make for a real fun bike, the best of both. I am wondering how difficult it would be to do. There is probably not enough clearance in the frame due to the 250 being a taller engine, and engine mounts would no doubt need modifying. I am not even sure if it would be possible to buy a new 250 motor from honda.

Thoughts?

[ESB7]

Is it the larger 250cc engine that makes it heavier than the 150CC.is the 150 framework really that much lighter???

[Semper]

Mission impossible. Just buy the cbr 250 or a Nsr 150.

[mrclough]

If you look at the paper thin fairings on the 250 then the thicker (heavier) fairings on your bike you may want to consider that it may be, as mentioned, the engine that the weight comes from. The exhaust probably adds quite a bit to it as well though to be fair.

[jackjones]

What about just tuning your 150? There are lots of mods available such as exhausts, bigger bore kits, bigger carbs, cams, freelow air filters, offset cranks, racing CDI's etc Probably easier and cheaper than trying to source a 250 engine and then trying to shoe horn it in to fit, not to mention possible problems with the green book. There are a lot of posts on this forum under CBR150 in the bike section. You could get a bit of information there incase you do decide to go down the tuning road.

[funcat]

What about just tuning your 150? There are lots of mods available such as exhausts, bigger bore kits, bigger carbs, cams, freelow air filters, offset cranks, racing CDI's etc Probably easier and cheaper than trying to source a 250 engine and then trying to shoe horn it in to fit, not to mention possible problems with the green book. There are a lot of posts on this forum under CBR150 in the bike section. You could get a bit of information there incase you do decide to go down the tuning road.

...totally agree...I've played with my CBR 150 before,changed the exhaust and other things,it was mostly for fun ...than I've sold it to some guy...but he came back and wanted me to change it back to the original...different strokes ,for different folks...if you want,I still have those parts for sale,good all 1/2' stainless etc...and if you will find out how much cost the 250 engine,let me know...

[hehehoho]

Are you planning to change the suspension, brakes and tyres too?

Or just mod it so the engine is almost double the cc, but little things like the suspension and brakes are only designed to deal it as little 150?

[Rooo]

Better info on bike forum.

[submaniac]

You would probably have a better shot if you took the 250cc engine out of one of Honda's dirtbikes. I think that the 150cc engine of the cbr150 (old style) is basically from one of Honda's 150cc dirtbikes that the sell in the rest of the world. I would think that the 250 of something like a xr250 (there is an xr 125, which I think is the same engine base as the cbr150) or may fit, but I haven't really looked into it that much because I do not have a CBR. At the very least used 250cc dirt bike motors are available second hand.

Edited June 4, 2011 by submaniac

[furyrider]

I agree with Jackjones and funcat. There is a lot that can be done with that engine. You have to realize that stock the manufacture has to choke the intake and exhaust and squeeze the fuel back to meat emissions. By simply changing the air cleaner to get more air and exhaust you have just improved it some. But now you have leaned the fuel by add more air. That engine was delivered from Honda with the least amount of fuel they could get by with to pass emissions. If it is carbed change the jets or if injected add an FI or a fuel controller and bingo more fuel.

Buy doing just those 3 little mods you have not broke the piggy bank and all can be done in an afternoon well maybe a full day with beer breaks.

[KRS1]

PE 28 carb, stage 1 cam, 3mm longer stroke, bore .100 over, cdi

hard part is finding someone that knows how to set the shim values.

and you'll be toe to toe with the 250 up to around 130kph.

keep the original exhaust

[MaiChai]

Yup, seems an expensive mod to buy a 250 to make an old 150 go faster

You can easily buy one of those race air cleaners for about 70 baht. I believe all the Honda small bikes have the same size inlet on the carb (NSR150/CBR150/Sonic). Thus try and buy a Sonic race air cleaner. Thats what I did for my NSR. Then you need to choose a straight or angled one (angled is less likely to get soaked in water in Thailands frequently occurring floods/heavy downpours). Keep the old air cleaner box so you can put it back if you want to go back to stock or sell the bike. If I remember rightly it was 38mm; get a caliper and double check.

Other thing is you can buy an NSR copy carb for about 600 baht which will again increase the fuel delivery. This is the normal trick the Thais use to supe up their small bikes (I have seen KSRs with NSR carbs on them; in fact I have seen a KSR with a CBR150 engine shoe horned in with an NSR carb).

Edited June 6, 2011 by MaiChai

[visions]

I went through the cost estimates of increased performance on my CBR150. In the end I realised that I would be spending a hellava lot of money for the performance gain.

But the bike would in fact more than likely have a decrease in value.

Plus I would have the loss of Honda's famous ultra reliability, something which was important to me.

I realiased I could buy a CBR250RR for a similar amount of outlay, (thats the old model not the current one) so in fact have 2 bikes, instead of only one. ( that had probably decreased in value.)

The CBR250RR has the 4cyl 45hp engine with brakes, suspension and tyres to suit. It is arguably the most potent 250 road bike ever sold. Sounds fantastic, and goes like the clappers, revs to 18000rpm

If u are looking for a very significant performance gain.......that is the way to go

Not too many available in thailand but they are there. When i was looking I found 3 all in reasonably good condition.

[JonnyCod]

The CBR250RR has the 4cyl 45hp engine with brakes, suspension and tyres to suit. It is arguably the most potent 250 road bike ever sold. Sounds fantastic, and goes like the clappers, revs to 18000rpm

Doesn't even come close to the Aprilia RS250.

[visions]

The CBR250RR has the 4cyl 45hp engine with brakes, suspension and tyres to suit. It is arguably the most potent 250 road bike ever sold. Sounds fantastic, and goes like the clappers, revs to 18000rpm

Doesn't even come close to the Aprilia RS250.

I cant argue with that of course.......but how many are available to buy in Thailand? I did add the word arguably the most potent...but should have added."in Thailand", or.....maybe I should have said most popular

I know when I totaled what I would be spending to upgrade my 150 it came to what one would expect to pay for the Honda 250RR and the 150 wouldnt come close to the performance of the CBR250RR, even with all that work and cost. However my circumstances changed and I never did buy the 250.

As long as we are all riding what fits in with our needs, suitability, finances, and style, at the time, is what matters. And I dont mean what we "dream" of riding hehe.

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