Topic: 750 6 speed transmission?

[azuredesign]

While I'm sure other folks have contemplated this, has anyone successfully done it?

Probably like most folks, I've wanted to add a extra gear on every bike I've owned. With the amount of higher level thinking that occurs on this site, maybe it can happen with this bike.

Thanks and any thoughts appreciated!

[Geeto67]

I don't think it is possible to do it internally but you might be able to do it if you ran a jack shaft setup with two different motor sprocket sizes and a way to change in between them.

[azuredesign]

Thanks, but that's not going to do what I was hoping to do. While I currently don't really understand transmissions, I was hoping since it appears that most m/c transmissions work similarly, that a later model set of gears, drum and forks might be made to fit and work without too much case alteration. I was hoping to improve acceleration without sacrificing the comfortable ~4000 rpm I have at 60 now. I guess I could change gearing to make a larger step between 4th and 5th and leave it as a 5 speed, but I don't think I want to drop revs too much between 4th and 5th. Are the gears and forks in modern 6 speed transmissions less wide than the compenents in our boxes, or is ther just more room in the case for the extra gearing?

[mkramer1121]

Email Terry @ TeamHansenHonda.com  He has worked with Nova in the UK on a 6 speed for the CB450 and can probably help get you started.

[azuredesign]

Thank you! I will write to him.

[azuredesign]

The Team Hansen website is very interesting. Bob Hansen appears to have a long history with the original CR750 project. Thanks for mentioning this, if I get a response, I'll post it.

[mkramer1121]

Terry Naughten is the guy running Team Hansen now with Bob's permission.  He is the one that is behind most of what you see on the website, the 450 dry clutch, etc, so that is who you would be writing to.  I have been to his "shop" (his garage) and it is a sight to see.  He had 3 450 racers there when I went, as well as a number of other items shown ont he website.  He bored my 750 cylinders for the 836 kit for me, and is a great guy to talk shop with.

[Sam Green Racing]

The Team Hansen website is very interesting. Bob Hansen appears to have a long history with the original CR750 project. Thanks for mentioning this, if I get a response, I'll post it.

Hey Ben, how much acceleration do you want, With just a bit of tuning you will end up smoking the rear tyre or pulling dirty great big wheelies Sparty hasn't wound his up hard off the mark yet and is reaching for the sky every time

Regarding Bob Hansen Ben. Bob was instrumental in getting Honda to build the CB750 in the first place but didn't have anything to do with the CR750 until Daytona in 1970.
The first CRs were put together by a friend of mine named Steve Murray at Bill Smith Motors in Chester.
The bike went through some serious testing at Oulton Park in Cheshire, (my local track) in preparation for the Bol d Or 24hr endurance race in 69.
The bikes were to be ridden by factory riders Tommy Robb and Ralph Bryan's. Honda France had other ideas and demanded that the bikes had French riders on them and that's how it panned out with them giving the CR it's first blood.
A similar situation arose when Bob Hansen got Honda to Field a team of four riders for Daytona in 1970.
The riders that Honda wanted were Tommy, Ralph, Bill Smith and Steve the mechanic who was himself a very accomplished rider.
The same thing that happened in France happened in the US. Bob who I think was general manager of Honda US demanded that an American rider rode one of the bikes. Steve stepped down to reserve rider and Dick Mann was given Steve's bike.
The rest is history with Dick taking the CR to it's second major victory.
This is not a story but fact,as I have had the pleasure of knowing, working for and racing with all of the British guys before the CB/CR750 had seen the light of day.

Sam.

[fuzzybutt]

i have a friend with a 12 speed sportster. he has the original 69' ironhead sporty motor and a 3 speed trans from an old ul behind it in the rigid frame. he did it for better drivability with the sidecar.

[mick750F]

The Team Hansen website is very interesting. Bob Hansen appears to have a long history with the original CR750 project. Thanks for mentioning this, if I get a response, I'll post it.

Hey Ben, how much acceleration do you want, With just a bit of tuning you will end up smoking the rear tyre or pulling dirty great big wheelies Sparty hasn't wound his up hard off the mark yet and is reaching for the sky every time

Regarding Bob Hansen Ben. Bob was instrumental in getting Honda to build the CB750 in the first place but didn't have anything to do with the CR750 until Daytona in 1970.
The first CRs were put together by a friend of mine named Steve Murray at Bill Smith Motors in Chester.
The bike went through some serious testing at Oulton Park in Cheshire, (my local track) in preparation for the Bol d Or 24hr endurance race in 69.
The bikes were to be ridden by factory riders Tommy Robb and Ralph Bryan's. Honda France had other ideas and demanded that the bikes had French riders on them and that's how it panned out with them giving the CR it's first blood.
A similar situation arose when Bob Hansen got Honda to Field a team of four riders for Daytona in 1970.
The riders that Honda wanted were Tommy, Ralph, Bill Smith and Steve the mechanic who was himself a very accomplished rider.
The same thing that happened in France happened in the US. Bob who I think was general manager of Honda US demanded that an American rider rode one of the bikes. Steve stepped down to reserve rider and Dick Mann was given Steve's bike.
The rest is history with Dick taking the CR to it's second major victory.
This is not a story but fact,as I have had the pleasure of knowing, working for and racing with all of the British guys before the CB/CR750 had seen the light of day.

Sam.

   Thanks for the history lesson Sam. With one post you've increased my knowledge of Honda racing history by about 100%.

Mike

[Sam Green Racing]

Hi Mick, I have a black and white photograph at home of the guy that designed the CB750 motor.
I can't remember his name off hand but it is written on the back of the photo, it also says he was not responsible for designing the gearbox.
It was taken at Oulton Park in 69 when they were testing the Bol D Or wining bike.
It shows him getting his hands dirty doing something with a back wheel, dressed in his best suit and tie.

Sam.

[azuredesign]

Thanks Sam for the info on Bob Hansen. There's a pretty comprehensive Hanson history on teamhansenhonda.com

I just want to see if it's feasible to add the gear and what's involved. I've heard back from Terry Naughtin, but nothing to report just yet, and will keep you posted.

Best,
Ben

[bryanj]

Nothing really to do with it but i remember a 5 speed quaife box for a 4 speed Triumph or Norton used to cost £1,000 ($2,500).
I used to collect New Hondas from Bill Smith in chester years back, nice guy and very Honest/trusting

[andy750]

Sam I think you should post that photo! It sounds like something we should all see 

Great history lesson as well! Just goes to show you old guys know a thing or two after all 

cheers
Andy

[754]

Yeah i was thinking about what it would cost.. IF you could find a drop-in... my guess woulda been 3K...

 You can mess with your motor enough that you will not worry about 6 gears for that money... JMO..

[MRieck]

Sam I think you should post that photo! It sounds like something we should all see 

Great history lesson as well! Just goes to show you old guys know a thing or two after all 

cheers
Andy

Key word...."old"

[Sam Green Racing]

Your hotel bill is going up by the minute

Sam.

[Sam Green Racing]

Sam I think you should post that photo! It sounds like something we should all see 

Great history lesson as well! Just goes to show you old guys know a thing or two after all 

cheers
Andy

I frequent another forum, Dragbike.com. In it is a thread for pics of bikes and riders from the past.
It has been going for a long time and some of the top riders from the past started posting on the thread.
Instead of my history lessons, wouldn't it be good if we could get all the works riders and mechanics from Daytona 1970 and start the mother of all CR750 threads. We could ask Glenn if it could be made into a sticky at the top of one of the pages.
What do you guys think ? Does anyone Stateside know how we can find Dick Mann and Bob Hansen etc ?
I can do my bit over here and contact the 3 British riders and their mechanic, how about it guys ?

Sam.

[andy750]

Now thats a GREAT idea Sam! Clearly you have a wealth of knowledge to share and you have a captive audience! Im in!

cheers
Andy

[HondaMan]

While I'm sure other folks have contemplated this, has anyone successfully done it?

Probably like most folks, I've wanted to add a extra gear on every bike I've owned. With the amount of higher level thinking that occurs on this site, maybe it can happen with this bike.

Thanks and any thoughts appreciated!

Yoshimura made them, circa 1970-1976, for this CB750K. They cost over $500 in 1970 dollars, but most of the faster roadracers I rode with had them. Several claimed that bolting in the narrower gears took their top speeds from the stockish 130 MPH to 140+: they certainly kicked my butt on the tracks with longer straights. (I had 5 speeds, because I usually ran in stocker class, not often in open class, mine typically topped out at 132 MPH.)

That kit dropped in, bearings and all. It consisted of a shift drum, different shifter mechanism (beefier, mostly), thinner gears, dimpled bronze "super Oilite" bushings in the gears. The shafts looked polished, too. Knowing Yosh in those days, they were likely hand-finished kits, and worked as smooth as a baby's bottom! I would think that either some of those bikes, their engines, or the parts GOTTA still be around. In middle Illinois-Missouri-Iowa where I raced, there were at least 6-7 riders who had them...

[Sam Green Racing]

Andy,I can speak to Tommy Robb and the mechanic Steve Murray tomorrow, Steve will have Billy Smiths number but I'm not sure about Ralph Bryans. I haven't seen him for six years and he had moved to Scotland, can't think why anyone would want to move up there Maybe one of the others will know of his whereabouts.
Saying all that, there's no saying that they would be intrested. I know two of them are on the net but have they got the time.
Some really big names are on the dragbike forum and they have been badgering RC to come on but he's having none of it.
Does anyone know if Dick Mann is still about ?

Sam.

[MRieck]

While I'm sure other folks have contemplated this, has anyone successfully done it?

Probably like most folks, I've wanted to add a extra gear on every bike I've owned. With the amount of higher level thinking that occurs on this site, maybe it can happen with this bike.

Thanks and any thoughts appreciated!

Yoshimura made them, circa 1970-1976, for this CB750K. They cost over $500 in 1970 dollars, but most of the faster roadracers I rode with had them. Several claimed that bolting in the narrower gears took their top speeds from the stockish 130 MPH to 140+: they certainly kicked my butt on the tracks with longer straights. (I had 5 speeds, because I usually ran in stocker class, not often in open class, mine typically topped out at 132 MPH.)

That kit dropped in, bearings and all. It consisted of a shift drum, different shifter mechanism (beefier, mostly), thinner gears, dimpled bronze "super Oilite" bushings in the gears. The shafts looked polished, too. Knowing Yosh in those days, they were likely hand-finished kits, and worked as smooth as a baby's bottom! I would think that either some of those bikes, their engines, or the parts GOTTA still be around. In middle Illinois-Missouri-Iowa where I raced, there were at least 6-7 riders who had them...

As a side note, a good 6 speed shifts better as it requires less travel to engage the gears. It is a "tighter" transmission.

[azuredesign]

Thanks Hondaman for the info concerning the Yoshi gears. I would be interested if someone had a set for sale, but in my dreams I was hoping that there was some later year Honda 6 speed set that would drop in.

Well, here's the response that I received from Terry Naughton. I was initially put off by what I perceived as a condescending tone, but he interpreted what I was looking for correctly, and his answer is thoughtful. When I asked my definitive resource for all things mechanical, Mike Rieck, his immediate response to my question concerning more speed quicker, was bigger displacement. I'm going for that next time, but Mike built me a stock displacement motor that's strong and just about as satisfying as I need as is. I'd love to add a tooth or two to the back sprocket, while keeping 15mph/1000rpm in top gear. I don't mind if the ratio between 5th and 6th is a bit wider, but don't want to drop revs between 4th and 5th.

Smaller displacement bikes, like the Yama RD350 and the Suzuki GT380 used to use a 6 speed in the 70's, I figured this application could be similar, but Terry doen't seem to think my idea has much merit:

well, what have we hear...a guy who wants power at the top end and doesn't want to lose any at the bottom,  ( not with carbs ), try a blower or turbo !
and that 6 th gear is not going to make any difference where your looking for it.
you chanced the balance of the motor, it wants to run at higher RPM now because of the cam timing.the only way to get better bottom end NOW !...is with more rear end gearing, which will limit your max top end a close ratio gearbox will keep your rpm from dropping in between shifts, while  accelerating.

adding another gear doesn't keep the ratio close its the ratio between the gears that are in the motor.
( you could have a wide ratio 6-speed ) or  a ( close ratio 5-speed )

a close ratio 5 speed box for your motor is a drop in replacement you turn the motor over, remove the bottom case and replace the parts

Terry Naughtin....THH

 -------------- Original message ----------------------
From: "Ben Atkins DMD" <benatkinsdmd@comcast.net>
> Hello Terry,

[HondaMan]

The 5-speed close-ratio kits are probably available on eBay still: I saw one last Fall and it sparked memories of my roadracing desires of old. Even that one was expensive back in the day. You had to be real good at the race start with them, or risk losing the clutch on a real hard start, because 1st became pretty tall: I remember guys saying they were doing 70+ MPH at redline in 1st with them (redline was a little over 10k, most times).

[azuredesign]

The 5-speed close-ratio kits are probably available on eBay still: I saw one last Fall and it sparked memories of my roadracing desires of old. Even that one was expensive back in the day. You had to be real good at the race start with them, or risk losing the clutch on a real hard start, because 1st became pretty tall: I remember guys saying they were doing 70+ MPH at redline in 1st with them (redline was a little over 10k, most times).

That's interesting, as first gear with those sets must have had been similar in size to a stock second gear. In my naive mind that seems like a 6 speed set without first gear. I find it embarrassing to try and get away from a light in second gear now, imagine what it must have felt like at Daytona with tons of people watching!