CBR RR throttle bodies

[misterprofessionality]

No point blindly throwing a pile of parts at the bike needlessly.

Until you do the math- the stock tb may be perfectly fine, same goes for the valve sizes, head port flow, etc.

You could easily loose power by making parts too big by loosing velocity, changing pulse resonance, etc.

No way would I ever consider ‘converting’ to another bikes TB. You’ll never get it to work correctly the same as stock.

What I would do- *IF* the tb ever became the bottleneck is start with old hot rod tricks-like permanently securing the butterfly screw threads and then grinding down the screw heads, thin the shafts, possibly remove one side of the shafts.

Heck, if you want to go crazy you can have a machine shop remove the stock plates, bore the housings to a little larger ID, fabricate new larger plates.

That would give you ‘bigger tb’ with no conversion mounting / control hassles.

As already said- there is a lot to do before you get crazy.

Bigger pistons and upping the CR certainly would make power with relatively easy work. Like the cams, you would need to have them custom made.

Would be next on my list if I ever want more after the cams are done. Probably will never do them though as I have never seen an aftermarket piston last like an untouched factory engine- doesn’t matter if on a bike or a car.

Why don’t you start by adding 2-3 teeth to the rear sprocket or dropping the front a tooth?


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just curious a bit....but i'm wondering, why not buy something like a ZRX1200 or the like if you really want a modern inline-4 with that kind of power? is it just about the aesthetics of the CB11?

I own a ZRX1200. Has a full pipe and jet kit. Makes a ton of power compared to the CB.

Yes- I like the CB look and vibe.

If you go on the ZRX forum you will still find guys hot rodding- bigger pistons, bigger carbs, cams, etc.





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I wanna say I do actually totally get it. I'd love to have the knowledge and tools to make my CB have more "go," so I wasn't trying to come off as "go buy a ZRX!" I was genuinely curious what the drive was behind making such an extreme change. Now, the question I'm going to ask is even dumber:

is it cheaper to make a CB11 go as fast as a stock ZRX, or to make a ZRX look like a stock CB11?

Well, it would be impossible to make a ZRX look like a CB, so that's that. The ZRX is still cool looking in it's own sinister way.


A stock ZRX1200 puts down about 115whp.

I don't know how close we will ever come to that unless someone goes completely nuts throwing money and probably long term reliability out the window.

And the ZRX1200 responds VERY nicely to modifications, even on old school carbs. http://www.muzzys.com/ZRX-1200/mods/index.html

Here is the review from the site that made me lust after a ZRX1200 for many many years until I finally bought mine- http://www.motorcycledaily.com/2001/03/2...1zxr1200r/

well, i didn't mean what would it cost to get a ZRX to look *exactly* like a CB. that is, yes, impossible. just as it'd be impossible to get a cb to perform exactly like a zrx. i'm talking about degrees of proximity.

from your response about increasing power, though, it seems quite clear that it would cost a stupid amount of money to get ZRX (or near) power and handling out of a CB, if it's even possible. So, you could conclude that doing a bunch of body work to style a ZRX like a CB is the more efficient route.

ignore me, it's just a dumb thought experiment.