Topic: Performance engine build, what's required?

[paulages]

i think he was referring to "high performance" when rb said "hi-po," but the cb750A does in fact have a hy-po style cam (and primary?) chain, which is something altogether different.

It's HY-VO chain. The A crank has a hy-vo primary but standard camchain - the DOHC has both in hy-vo format. Check out the thread Ultimate Engine and you can see pics of my DOHC crank conversion to fit in a SOHC motor...

uh yeah... brain fart. been staring at my 718 project too long tonight. i'm lucky- the 550 has hy-vo primary, and my 650 crank uses the hy-vo cam chain as well. they say they're clunky and heavy, but they sure don't seem to make all that noise my 750s make...

[eldar]

I have the perfect solution. Lets all buy up all the 30+ year old parts that are made of old metal that is not as good as metal today is, and build machines specifically to blow up from said old metal!

OR we could use newer stuff that still has years of street use and research in the design and uses better metal.

[City Boy]

Just wondering?All you lads suspicious of old parts;why would you be messing with 30 to 40 year old bikes?

[MRieck]

Just wondering?All you lads suspicious of old parts;why would you be messing with 30 to 40 year old bikes?

I've said that same thing about women.  I've owned my bike 32 years so I'm pretty much stuck with it. I bought an FJ1200 in the late 80's and bought a busa in 2001....it keeps everything in perspective. I've added many modern parts to my CB and I just enjoy working on it. Therapy some would say. It performs well beyond what the original engineers who designed it could have expected which is always nice too.

[eldar]

We like to live dangerously I guess but that does not mean we want to use old junk.
A frame takes much less abuse ON AVERAGE than engine parts do. You can tell when your spokes are going bad cause you can see them. Same with everything else on a bike except the engine. Besides, the bikes were designed for a certain amount of power,and if that power is retained, little will happen.

I guess I trust the info from mike about engines parts more than anyone else other than probably hondaman. They are probably the 2 smartest guys here on these bikes. They have probably done almost everything possible on these bikes OR have seen it done.

As a final note. We ride these bikes cause we like them but to assume they are the best is just stupid, kinda like HD riders thinking hd is the best. Same goes with rc parts. Todays parts are better, there are just fewer around.

It is like saying that a punched out and turboed and whatever cb750 can beat a busa. Maybe if the cb rider is excellent and the busa rider cant find 1st gear.

[rbmgf7]

hy-vo, hi-po...lol. understand what i mean, not what i say 

[paulages]

hy-vo, hi-po...lol. understand what i mean, not what i say 

re-reading my post from last night now that i am awake cracks me up. yesterday was a long one.

[mlinder]

hy-vo, hi-po...lol. understand what i mean, not what i say 

re-reading my post from last night now that i am awake cracks me up. yesterday was a long one.

Yer still dumber than a mud fence, Paul. Don't try to pass it off as 'fatigue'.
By the way, hows YOUR performance engine build coming? Going to start it today?

[paulages]

hy-vo, hi-po...lol. understand what i mean, not what i say 

re-reading my post from last night now that i am awake cracks me up. yesterday was a long one.

Yer still dumber than a mud fence, Paul. Don't try to pass it off as 'fatigue'.
By the way, hows YOUR performance engine build coming? Going to start it today?

i doubt it. lots of wiring to do. by the way, it fell off of the stand last night.  not kidding. no damage, but the center stand slipped out when i was lowering it back onto the front wheel. i saw lots of dollar signs flash before my eyes...

[scondon]

Just wondering?All you lads suspicious of old parts;why would you be messing with 30 to 40 year old bikes?

I've said that same thing about women.  I've owned my bike 32 years so I'm pretty much stuck with it. I bought an FJ1200 in the late 80's and bought a busa in 2001....it keeps everything in perspective. I've added many modern parts to my CB and I just enjoy working on it. Therapy some would say. It performs well beyond what the original engineers who designed it could have expected which is always nice too.

   Yeah, like those three bikes are all you've worked on. Ain't buying it Mike

   Job change and finances means that the next head you send will be my last bike related purchase for a while. This means that the '72 900cc motor is going together "as is" with all the old stuff. I've been trying to get "new stuff" to fail spectacularly and have gone unrewarded in this endeavor. Hope to have better luck with the old stuff. Hope you're not insulted, wish me luck

[rbmgf7]

ok, i'm back where i was before i sold one of my hondamantic cranks. i'll be picking up the engine next week. guy said he had a few more 750 engines lying around if i was interested, lol. everyone needs to move to missouri. we have an abudant supply of CB750's, just no one to claim them, lol  .

school starts in about 3 weeks so looks like i'll be building bikes in my room again, lol. good thing i go to an engineering school and have machine shop access. geez, now if it wasn't for schoolwork getting in the way, i'd be cranking out all kinds of crazy projects.

also saw another 750 today. first time ever since i lived here. it was a 78K. guy was on TDY from leavnworth. was all stock except for a sissy bar.

[754]

To answer the original quesation..
 If you can get  rings and gaskets, and pistons are not badly worn, you can probably reuse what you have..

 Check the parts carefully, , some bits like springs should be replaced.

 Not everyone need the lastest, lightest , most modern parts..

 Think about what you are using it for..

 Some of us got 25 years or more out of a big-bore CB750, and take them on road trips.

 Build what suits your needs..

 They are vintage bikes, and are usually worth more with period correct parts, nothing wrong with a accurate example of a 70,s bike..

[sohc4]

wow, i think i just started something...lol 

well, to redeem myself, i think i may have scored another hondamatic crank about an hour away from me. this time i'll hold onto it for when i come around to building this hi-po engine.

if you buy a bunch of small stuff through yamiya, their primary chains are cheaper than anywhere here in america. it's the shipping that kills me. they have the best deal on DID rims but it was an extra $160 in shippping.

M3 used those A cranks. The tensioner is the interesting part.

In 10 words or less, what's the benefit of the "A" crank? News to me but I certainly don't know everything. Quite a bit less. TIA

A better primary drive, a hi-vo chain instead of the two simplex chains.  Oops, that was more than 10 already 

While I'm over the limit anyway, here you go: You will of course need a matching primary sprocket on the clutch drive. The early (GL 1000) Gold Wing will work as a donor, their sprocket can be riveted on the 750 cush drive.

As MRieck said, the funny part is the tensioner. Some people just run without one, some use sliders off a Gold Wing, some (as M3) use the hydraulic tensioner and sliders from a 750/900 DOHC model. Needs an oil feed to pressurise the tensioner, easiest off the oil gallery.

Primary chains from a 750/900/1100 DOHC or Gold Wing are all too short, you will need two of them to make one. For those interested, Egli-Racing in Germany has new primary chains with exact length.

Cheers,
Axl

[MCRider]

wow, i think i just started something...lol 

well, to redeem myself, i think i may have scored another hondamatic crank about an hour away from me. this time i'll hold onto it for when i come around to building this hi-po engine.

if you buy a bunch of small stuff through yamiya, their primary chains are cheaper than anywhere here in america. it's the shipping that kills me. they have the best deal on DID rims but it was an extra $160 in shippping.

M3 used those A cranks. The tensioner is the interesting part.

In 10 words or less, what's the benefit of the "A" crank? News to me but I certainly don't know everything. Quite a bit less. TIA

A better primary drive, a hi-vo chain instead of the two simplex chains.  Oops, that was more than 10 already 

While I'm over the limit anyway, here you go: You will of course need a matching primary sprocket on the clutch drive. The early (GL 1000) Gold Wing will work as a donor, their sprocket can be riveted on the 750 cush drive.

As MRieck said, the funny part is the tensioner. Some people just run without one, some use sliders off a Gold Wing, some (as M3) use the hydraulic tensioner and sliders from a 750/900 DOHC model. Needs an oil feed to pressurise the tensioner, easiest off the oil gallery.

Primary chains from a 750/900/1100 DOHC or Gold Wing are all too short, you will need two of them to make one. For those interested, Egli-Racing in Germany has new primary chains with exact length.

Cheers,
Axl

Thank you Axl:
I had put that together from reading some other posts and threads, but your answer spells it out succinctly in nearly 10 words or less.     After jogging my memory, I remember reading references to this modification on your SatanicMechanic.com site as well.

Don't think i'll be attempting that mod, but it is amazing what people are doing to these bikes.

[rbmgf7]

got me the hondamatic engine today. boy do i feel guilty tearing apart a complete (and said to be running) engine just for one part. the guy also had the aluminum wheels but sold them before i could get to them. cool guy. had two '42 indians. one was running and he was restoring the other. also had some real old volvo (guessing 60's) and a late 50's chevy pickup.

ok, i'm now hunting for the primary off the gl1000 mainshaft on ebay and a DOHC tensioner. it just boils down to the chain.

i wrote M3 a week ago with no reply on a source for the chain. moonpie, how much did the chain end up costing you? DOHC primary chains run $200 alone and i know it takes riveting two together to make it work. thanks

[rbmgf7]

sweet, just got some 33mm keihin CR's to go along with this 915cc engine. it's getting closer...