Converting CBR engine, 150 ==> 250?

[papa al]

Someone told me bolting a CBR 250 top end to a 150 bottom is do-able.

Anyone have an opinion on the feasibility?

[ll2]

there were bore up kits available for cbr150 to make ti upto 200 cc as above that is creating problems.

there are others mods like a sporty camshaft, carb change, air filter and pipe etc.

[papa al]

there were bore up kits available for cbr150 to make ti upto 200 cc as above that is creating problems.

there are others mods like a sporty camshaft, carb change, air filter and pipe etc.

Not sure I understand your post due to run on sentence, spelling, syntax, lack of capitalization & punctuation.

I believe my question was not about camshafts, carbs, filters nor pipes.

Thanks anyway LL.

Edited November 5, 2014 by papa al

[ll2]

there were bore up kits available for cbr150 to make ti upto 200 cc as above that is creating problems.

there are others mods like a sporty camshaft, carb change, air filter and pipe etc.

Not sure I understand your post due to run on sentence, spelling, syntax, lack of capitalization & punctuation.

I believe my question was not about camshafts, carbs, filters nor pipes.

Thanks anyway LL.

well man, we are not doing an English test here and i believe it is clear.

there were bore up kits available before but not sure if they are still around.

trying to recommend other solutions as never heard of what you are mentioning.

and i feel like i am doing a mistake by answering your posts.

Edited November 5, 2014 by ll2

[ttakata]

I think it would be cheaper and less trouble to just sell the old and buy a 250 since the 250s are cheap used.

The bigger head probably needs a bigger carb, intake, exhaust, and maybe ECU.

Edited November 6, 2014 by ttakata

[papa al]

LL: Undoubtedly clear to you as the writer; less clear to me as mentioned above, but you won't recognize this of course.

Not sure, but I have the impression you once had a 150, and modified it, ultimately resulting in engine failure...

...not my goal;

& "never heard of what you are mentioning"...exactly why I will not take offense if you refrain from replying to the post.

TT: Good points, but I already have a CBR250.

I prefer the smaller, much lighter, and ~90% as fast (140 vs.154kph) early model 150s.

Eccentric I guess.

But if I could find a very cheap wrecked 250 with intact FI, exhaust, control module, etc. ... .

Edited November 6, 2014 by papa al

[ll2]

LL: Undoubtedly clear to you as the writer; less clear to me as mentioned above, but you won't recognize this of course.

Not sure, but I have the impression you once had a 150, and modified it, ultimately resulting in engine failure...

...not my goal;

& "never heard of what you are mentioning"...exactly why I will not take offense if you refrain from replying to the post.

TT: Good points, but I already have a CBR250.

I prefer the smaller, much lighter, and ~90% as fast (140 vs.154kph) early model 150s.

Eccentric I guess.

But if I could find a very cheap wrecked 250 with intact FI, exhaust, control module, etc. ... .

So this post of your had a great grammar? Hard to understand what you are saying:)

I am a working guy not an aged retiree like you. Sometime i need to post something fast and a touch screen keyboard does not help.

And look buddy, you are opening a thread for what?

Just to hear exact answers?

And others giving advices or recommendations cannot post? If that is the case, a forum is not for you papa al. You can check manuals and can see if cbr250 head fits cbr150! manuals gives you exact answers so why post in a forum?

Ttaka also recommends something else so he also did wrong on answering your topic?

Anyway man good luck for you. From now on as a long time carbed cbr150 owner, i will refrain myself and will not pass any of my experiences and knowledge.

You just wait exact answer here if you can find any:)

[seedy]

I would imagine that the 250 has a larger bore ?

If so, and even is a 250 head will bolt on, the combustion chamber will be oversize to the cylinder. This will destroy any squish area, resulting in poor fuel mixture turbulence and hence a poor combustion event,

But for us fiddlers - if it fits and you would like to try, keep us posted.

Good luck with the experiment if you so choose.

[papa al]

Seedy:

To clarify, I was hoping 250 cylinder & head (+ piston, fi & exhaust) onto 150 bottom (crank & tranny) if it would fit.

LL:

Of course you are free to post whatever off-topic gibberish/rant you choose.

Edited November 7, 2014 by papa al

[Don Mega]

http://www.thaivisa.com/forum/topic/166096-250-top-end-on-a-cbr-150/

[Overandout]

I've always understood that anything over 176cc was practically impossible for the CBR. And the linked thread above seems to confirm.

In fact I have lately been looking closely at all single cylinder Honda 250 LC engined bikes that I walk past, just to eye up how easy an engine swap would be..... A CRF 250 engine in an old CBR would be kind of fun....

[papa al]

Post #2 suggests that 200cc is available.

CFR250 is air cooled, right?; not for me.

I doubt the motor mounting points would match.

Fitting a CBR250 mill in whole, vs. just a top end graft could appeal to me.

I once saw advertised a Wave125 bored & stroked to 250.

"Not for the faint hearted" the seller advised.

[mitsubishi]

The only people I've heard that come close to this are those that bore out their engines to just under 200cc.

A 250cc project sounds like fun though. I would make sure the thai mechanics are up to the task on doing it.

Or are you going to spanner it in yourself?

Edited November 9, 2014 by mitsubishi

[papa al]

Reviewing some old TV thread from 2008, I see that the cost of the 200cc rebore kit alone was ~39,000baht.

Carb &c not included.

More than the price of the bike, so not worth it IMO.

That is why I was hoping to eventually find a wreck, maybe for <10K.

I'm patient.

I have a cracker jack Thai mechanic in mind who would do the wrenching.

I think he would jump at the chance to do something more challenging than day-in, day-out flat repairs & oil changes on taxi mocys.

He has always been impressed me with the quality & efficiency he has shown on smaller projects.

My German buddy, a lifelong enthusiast and 17-year Thailand expat introduced me to him.

Edited November 10, 2014 by papa al