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Honda CB750 DOHC, general and perfomance questions.

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Old 04-30-2008, 03:05 PM   #1
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Default Honda CB750 DOHC, general and perfomance questions.

Im picking up a 1981 Honda CB750 custom. its an ugly bike but i will soon have it transformed into a nice cafe racer.

1: why is the dohc CB750 rarely used over the sohc cb750.
2: can the big bore kits for the sohc work on the dohc? (im gessing no because the dohc probably has 4valves per cylinder.) if not who sells a kit, also looking for cams.
3: Was tyring to source a rayjay turbo kit for the cb750 but only found them for the sohc. why is that. is the dohc that bad that there is limited upgrades for it.
4: fuel injetion. has anyone converted a cb750 to fuel injection. i have a set of cbr900rr throttle bodies, and was considering converting the cb750 to fuel injetion. would use mega squirt or DAT s40 computers. run waste spark igntion, and semi sequential fuel injetion 1/4, 2/3.
5: do the sohc exhausts fit the dohc engine?
6: will the sohc cafe style seats, bars, and tanks fit the dohc frames?

thanks for the help. ill be striping the bike down this weekend and was wanting a heads up on which direction to head before i started.
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Old 04-30-2008, 03:52 PM   #2
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I have heard of some people having problems with the DOHC heads, I think they're considered to be less reliable than the old SOHC. I wouldn't bother with EFI, too much hassle, I'd rather pick up some throttle slide carbs off of some other CB750, or just tune the ones you have.
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Old 04-30-2008, 05:28 PM   #3
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Default Re: (CivicWagonRUS)

the reason for the efi would be to boost the bike later. i know alot more about tuning an efi than a carb. i know the sohc rayjay kits use a 44mm zineth or zenith carb before the turbo. but id rather use efi after the turbo. stock carbs will get rebuilt and ran for now. but im looking into the future.
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Old 11-13-2014, 12:06 PM   #4
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Default Re: Honda CB750 DOHC, general and perfomance questions.

Just stick with the carbs to much hassle switching ot efi and you can tune then almost as good a efi.
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Old 11-13-2014, 07:38 PM   #5
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Default Re: Honda CB750 DOHC, general and perfomance questions.

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Originally Posted by Snail Tuning View Post
Im picking up a 1981 Honda CB750 custom. its an ugly bike but i will soon have it transformed into a nice cafe racer.

1: why is the dohc CB750 rarely used over the sohc cb750.
2: can the big bore kits for the sohc work on the dohc? (im gessing no because the dohc probably has 4valves per cylinder.) if not who sells a kit, also looking for cams.
3: Was tyring to source a rayjay turbo kit for the cb750 but only found them for the sohc. why is that. is the dohc that bad that there is limited upgrades for it.
4: fuel injetion. has anyone converted a cb750 to fuel injection. i have a set of cbr900rr throttle bodies, and was considering converting the cb750 to fuel injetion. would use mega squirt or DAT s40 computers. run waste spark igntion, and semi sequential fuel injetion 1/4, 2/3.
5: do the sohc exhausts fit the dohc engine?
6: will the sohc cafe style seats, bars, and tanks fit the dohc frames?

thanks for the help. ill be striping the bike down this weekend and was wanting a heads up on which direction to head before i started.
1. Reliability and less moving parts is less to break and easier to service/maintain.

2. you are correct i believe, i dont thing you can interchange a lot of parts.

3. honestly, forced induction is going to substantially limit your engine life and i wouldn't advise it. if you want to turbocharge a motorcycyle, just pick a newer fuel injected bike that can easily be tuned to compensate AND that you can easily find parts for.

4. a conversion is honestly not worth the effort and i wouldnt do it unless you just have to have it done. changing to cone filters and a rejet would do just fine.

also, read here
http://forums.sohc4.net/index.php?topic=108113.0

and here,
Does anyone know if this exhaust will fit a SOHC CB750?
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