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Author Topic: cbr f2 motor in a 75 cb  (Read 3437 times)

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b16a

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cbr f2 motor in a 75 cb
« on: February 17, 2010, 10:18:01 PM »
This may be random possibly unheard of and distasteful to some. That being said don't bash me for not being a purist or whatever. I'm just thinking about the possibilities and wondering if anyone has tried this swap? Would it throw the weight off to much and make the bike unbalanced? What problems would i have to look out for in attempting this? The reason I ask, is I want to build something unique and I am building a CB bobber, and recently came across an f2 motor and the idea of it kind of intrigued me. Thank you for all your input and help.
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Offline MJL

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Re: cbr f2 motor in a 75 cb
« Reply #1 on: February 18, 2010, 12:27:24 AM »
The first issue I see is that the newer sport bikes have a different style frame than the CBs, so motor mounting may be a hassle.
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Offline Terry in Australia

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Re: cbr f2 motor in a 75 cb
« Reply #2 on: February 18, 2010, 02:38:54 AM »
Geez mate, have you got a death wish? I can understand folks efforts to improve their CB750's by using later model forks, shocks, wheels and brakes to make 'em handle and stop like a new bike, but sticking a wickedly powerful engine in a bike that didn't handle or stop for sh1t seems to defy common sense? Anyway, not trying to be nasty, just shocked. Have fun and post a pic if you go through with it. Cheers, Terry. ;D
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Offline MasterChief750

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Re: cbr f2 motor in a 75 cb
« Reply #3 on: February 18, 2010, 02:49:45 AM »
things to ponder, motor will need to be centered on the bike. and does the engine come with necessary components like carbs because i think you may want to use the carbs for that bike so you dont run into any issues. also think about how much power the 75 cb frame was designed for and think about how much power the cbr puts out. it wouldnt be impossible but there are some adjustments you would need to make. im assuming the cbr is watercooled as well. it would be sweet if you did it.
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Offline Sam Green Racing

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Re: cbr f2 motor in a 75 cb
« Reply #4 on: February 18, 2010, 06:02:13 AM »
I don't think the 100bhp and 46ft lb of torque would be an isue for the frame but will it fit in.
The CBR has a twin spar frame that the top of the motor and induction system sticks up through, the top frame rails of the CB might be in the way.

Sam. ;)
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Offline dusterdude

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Re: cbr f2 motor in a 75 cb
« Reply #5 on: February 18, 2010, 04:40:42 PM »
i agree with sam,my f3 is basically the same engine and the carbs point up instead of out of the head.you would need a lot room at the top of the frame i just dont think a 750 frame would work without a lot of fabrication,however i do like your idea,it shows moxie.
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Offline Shenanigans

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Re: cbr f2 motor in a 75 cb
« Reply #6 on: February 18, 2010, 05:39:40 PM »
Didn't someone mention a old oil cooled GSXR motor in a CB750 frame? I guess it was in some magazine. Seems like it would be a better candidate.
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Offline Alan F.

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Re: cbr f2 motor in a 75 cb
« Reply #7 on: February 18, 2010, 06:34:35 PM »
I'm sure you could do it if you have the skills, money and persistance.

But....when it's finished will it resemble a CB at all?  It might be easier to find a different big-bore UJM to 'customize' that way.
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b16a

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Re: cbr f2 motor in a 75 cb
« Reply #8 on: February 18, 2010, 07:23:59 PM »
i did not know that the carbs pointed up that would be a big issue. i was thinking of using a cbr1000rr front end, i heard they are fairly easy to retro fit on to the CB necks. this may help with the breaking aspect and and some of the handling, although I'm not really to concerned on the handling since it will be a hardtailed bobber. i would have a shop fabricate the mounts since i found a shop locally that customizes bikes and fabricates and welds all in house. I would also have the shop beef up the frame a little in high stress areas. Now i am really worrying about the clearance of the carbs. still thinking about attempting it because i do believe it will be something unique and different which is overall my goal. And would be fun as well. Any other input would be greatly appreciated.
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Offline MasterChief750

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Re: cbr f2 motor in a 75 cb
« Reply #9 on: February 19, 2010, 01:53:43 PM »
you could design some kind of carb adapter to place the carbs behind the motor, might make a little room
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Offline Retro Rocket

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Re: cbr f2 motor in a 75 cb
« Reply #10 on: February 19, 2010, 03:35:22 PM »
Quote from: Shenanigans on February 18, 2010, 05:39:40 PM
Didn't someone mention a old oil cooled GSXR motor in a CB750 frame? I guess it was in some magazine. Seems like it would be a better candidate.

I have seen pics of an early GSXR engine in a 750 honda frame, i think it was in a UK bike magazine.

Mick
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Offline Shenanigans

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Re: cbr f2 motor in a 75 cb
« Reply #11 on: February 19, 2010, 04:02:54 PM »
Quote from: retro rocket on February 19, 2010, 03:35:22 PM
Quote from: Shenanigans on February 18, 2010, 05:39:40 PM
Didn't someone mention a old oil cooled GSXR motor in a CB750 frame? I guess it was in some magazine. Seems like it would be a better candidate.

I have seen pics of an early GSXR engine in a 750 honda frame, i think it was in a UK bike magazine.

Mick

I cant find any pictures of it on the net'. I would like to see that bike.
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Offline Retro Rocket

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Re: cbr f2 motor in a 75 cb
« Reply #12 on: February 19, 2010, 04:13:49 PM »
Hi mate, i was into the "streetfighter" look a while back and bought a similarly named magazine for a couple of years and i am sure it was in one of them. Problem is while i was in Hospital for a while i got sick of the poor old blokes reading the left over womens magazines that were provided for reading material so i donated hundreds of bike and fishing magazines to them, all the streetfighter mags went with them.....

Mick
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b16a

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Re: cbr f2 motor in a 75 cb
« Reply #13 on: February 21, 2010, 09:12:26 PM »
I decided not to go through with it. If i change my mind i will post up pics of the progress but thanks everyone for all the information and input.
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