hello,
I am new to the forum.
I am inadvertently thrown into the CBR community. I bought what i thought was going to be a yzf r6 engine for a swap into my 1981 xj650 (trusting my coworker knew what he was talking about). after my coworker delivered the engine (in a wooden enclosed box), and i paid for it i opened it. something didnt look right. it said Honda on the side. turns out its a CBR engine.
so not sure what year. i am thinking it is a 91 cause it says MV9 on the head.
luckily the measurements all fit so it will probably still work for my swap idea. came with 2 sets of wheels and tires and just about everything else to finish the swap. only thing i need is a swingarm.

anyways, i figured i better get on here since i'm sure ill have question along the way to my crazy project. like:

1) how can i tell what year the engine is. i dont see any numbers stamped on it.

2) has anyone modified the angle of the carbs. cause i may have to. maybe a different set of carbs.

3) has anyone modified the angle of the exhaust pipes. how badly does it effect the power output.

i have an idea of the answers to these questions. but, actual data is always better than theory.

anyone know of any sites that are more conducive to my level of modification?

 

Welcome to CBRF! It would help if you'd throw up some pictures of your project.


1) If you posted a picture of it, I'm sure other people or I could at the minimum tell you what "generation" of engine it is. Is there a reason you need to know the exact year? Or is it only important what model it came from?

2) As far as carbs - a little bit of a change is okay, but you need to make sure that it's not going to affect the floats and needle valve, otherwise you could be constantly pouring fuel all over the place, or constantly starving for fuel. It also depends on how the intake track is, which is dependent on orientation of the motor and the way it was designed. It's not as important as it is with injectors, but it's still an issue. Using a different set is okay, but make sure that it also comes from a motor that has a similar charge velocity, RPM range, bore/stroke, etc. to the motor you're going to be using.

3)Exhaust - there's no real change as long as it's not drastic. A 90 degree bend is like adding 10 ft. of pipe. So, try to keep the big bends to a minimum. But, it's okay to have some bends. It's all about back pressure. So if you have a wider diameter of exhaust, a 90 degree bend doesn't create as much back pressure on an engine as the same bend would on a smaller diameter pipe all things being equal. There are a lot of factors... I've seen guys wrap a pipe around a motor and run with no baffle so they could have all of the noise that a straight pipe puts on, but still gain the back pressure needed for performance. I could give you a better answer if you told me exactly what your plans are.

SF section here, or try customfighters.com

 

Welcome to the CBR Forum,

Good advice above!


Enjoy your time on the forum.

Cheers, SB

 

thanks for the advice.
intake: i was thinking about making a plenum or adapter. or just some bent aluminum tubing with 2 sets of rubbers (one on each side of the aluminum pipes).
or getting a set of carbs that are meant to be sitting level, or maybe even trying a different set of float bowls. (i have yet to bust the carbs open)

exhaust: i am thinknig about either bending some tubing, adjusting the frame, or mounting the engine back far enough that the pipes will not have to go outside the frame.

i will get pics up soon.

 

havent been able to get back into my photobucket after years of inactivity.
in the meantime:
does anyone know the dimensions of the F2 swingarms.
most importantly the pivot point.

 

Yeah, if the orientation of the motor is changing and the carbs would be a very different angle, I would be careful about using carbs where the bowls will be a different angle other than level.

I look forward to seeing pictures. But as of now - I'd go to the F2 section and ask for some dimensions. Not everyone who has that info looks in the new member area.

Also think about posting your own thread. I don't know which forum would be appropriate beyond the fighter one. Again, if you know which CBR motor you're using, post a thread in that sub-section.

Or frame - if it's a CBR.

There's a TON of info on this forum about the F2 F3 - I'm sure someone will have the dimensions for you.

 

hi and welcome