Topic: cr modification

[eldar]

When these bikes were being raced, I thought there was some kind of CR kit for them. Is this so and what were the mods? I would like to find out and maybe incorporate them on my bike.

[Egil]

Are you looking after the rear disk conversen whits was on the Japan home marked back then fore the 1977-78  K7/8 mods ?
this whit 2 disks brake  one in front and one at rear ?,if you look closly on the rear wheel  you will see the rear disk.
 see link http://world.honda.com/collection-hall/2r/cb750fourk_html

[eldar]

I could not get the page. Site said it was not found. The cr kit was done in the early 70s I think.

[alfabeast]

Honda offered a race kit, it was $10K back in the day which was a lot of money then.

I have an excellent article in a 1984 Classic Bike magazine that explains the mods and talks about the kit and track tests John Longs Honda

[MRieck]

Honda offered a race kit, it was $10K back in the day which was a lot of money then.

I have an excellent article in a 1984 Classic Bike magazine that explains the mods and talks about the kit and track tests John Longs Honda

I'd like to see that article. Funny thing is you can do most of the mods much better than Honda did(cam chain tensionior, rods etc).

[cben750f0]

i have an article from 1969.. on the CR kit that won daytona... am waiting to see if i can post it or not... copy right and all...peace

 begger it, if its wrong then it can be taken down...

[I resized these images; the originals will be added to the website shortly.]

[MRieck]

NICE!!!! Get it on here man....I'll shave the price of that race port job for you  

[the_genrl]

the number 970 is in my mind from somewhere, reguarding the kit.  click around this site:

http://www.worldmotorcycles.com/Pages/kit.html

This is one of my dream machines too 

[Mark M]

M3 racing still make some of the engine parts, meadspeed in the UK can help with bodywork/oil tank and some other stuff.
Lump proof in Aus have a website with a lot of info.
Just do a search, there are quite a few sites dedicated to the CR750, and Dick Mann.

The race kit parts come up on ebay from time to time, but are always highly contested, would you believe $200+ for a Petrol tap?
There is a guy over in France who is confirmed by many to have the orriginal Daytona winning bike from 1970, he makes a lot of pattern parts based on his bike.

finaly, when I can persuade anyone to actually deliver an electronic ignition unit, that works. I will have my version of Dick Manns bike running round the Essex countryside frightening little old ladies.
   

[eldar]

Good article. I would like to do the engine and suspension mods. The cafe look I can do without though. I like to sit up.

[cben750f0]

mate i would just love a cafe that looked like that!!!

[eldar]

Hey everyone has their style! I dont like cafe but I dont like crotch rockets either. I think it is the whole position thing.

[cben750f0]

agreed, i cant do the crouch thing, busted my spine 18months ago... hence why my F1 is in such good condition... No a nice upright ride is good for me....i just think the CR looks unreal...peace

[the_genrl]

that is a neat looking mag cben750f1!  i'd hold on to that one thats for sure. (i bet you already had that in mind)

[cben750f0]

yep in plastic sleave, and plastic hard cover folder... ..got a heap more articles if ppl are interested?

[sander]

Hello everybody,

I'm kinda new to the board, been lurking for a while though ..
I'm in the progress of building a CR750 replica ( got most major parts now), but/and would really appreciate if someone has the images posted here of the magazine (cycle magazine oct 1970 ) in a higher resolution? I already tried to contact him (e-mail/PM) ,but can't seem to get through?!...

All help greatly appreciated! A fellow honda enthousisast.

Sander (from the Netherlands).

[kettlesd]

Holy Jeezus - that is one fine looking motorcycle!

[bill440cars]

        cben & Daniel and anyone I might have missed,

                  Thanks guys for the links to the info about the CR, it was a real blast seeing that stuff. I
         can only imagine what it would be like to see that sucker run, much less ride it.

                                                              Later on, Bill 

[Sam Green Racing]

When these bikes were being raced, I thought there was some kind of CR kit for them. Is this so and what were the mods? I would like to find out and maybe incorporate them on my bike.

Why, have you won a lottery or robbed a bank

Sam.

[sander]

Hi guys,

EDIT: I have gotten through to Ben, he promised to help me soon, he was very busy at the moment, so it took a while to respond.
Or maybe I was being overenthousiastic impatient....

thanks for all the great links, but unfortunately for me I was already aware of those. i have gathered quite a collection of images and data plus movies on the cr750 over the last 3 years, but i've never seen this magazine. Since it's from the era, and pictures from that time are always very low res, I was very lucky to find this post; only too find out that the images are too small once again.

@everyone:
I have specific interest in the 5 pages posted by cben750f1  ( Cycle Magazine, oct. 1970 )
The resolution is too small to make out good details/and read it properly. He was referring to putting them online somewhere, but I have not been able to locate them ( in the gallery for instance)...

@Samcr750: since you have been making a nice cr750 replica ( do you maybe have the pages I am referring to? )

Anyway, all help greatly appreciated, and I can/will ofcourse send some of my pics/data in return.
I got images and movies shot a spa franchorchamps last three years, some article in Bikers Classic on the m3.
Many from the web,  a lot through contact with other enthousiasts etc etc.

For example

errr. How to post a pic on this board?!

Ps. I am the owner of a:

CB750 K7 (to become CR750)
Cb750 F1
CB750 F2

[Geeto67]

the actual 970 CR engine mods were never intended for a street engine and I think replicating them on a street bike is a recipe for disaster. Chances are you'll have to run race fuel because of the high compression, and god forbid you get stuck in traffic. I think you can probably get the same hp out of a big bore kit, proper cam, and carbs, and still be streetable. 90rwhp is a lot for any bike, espically a SOHC so it is better to build the engine with streetability in mind.

The reason there are so few 970 kits around is that honda bought back or recalled almost all of the kits after 1970 and (supposedly) destroyed them. Some stuff never made it back and foud its way into other forms of racing. For instance one of the drag front ends I have has CR750 brakes and wheel but on stock forks. The original hub has been relaced with an akront front wheel instead of the DIDs the kits came with. I was offered the CR tach too but I passed on it because I felt the seller wanted too much for something that was non functioning. It might show up on ebay soon.

AS for suspension mods, finding an original set of 970 forks is going to be expensive. I'd like to think that the new stuff that is out there now for our bikes is better than this 70's stuff ever was.

[isred]

Just wondering if any other company's may have made a twin leading rear bake plate for the 750? maybe for chopper applications or such. Just bought something off ebay and it hasnot arrived yet to see if it fits, but it was cheep so if it does not fit no big deal.It was pretty cheap , so I took a chance.. when it arrives I will post some pics. thanks brent

[736cc]

M3 carries the rear magnesium brake hub replica; $3500+ and spokes not included.
970 is the middle 3 digit part number code for CR750 parts (CB750 K0-K1 is 300 code, CB750 K2-K6 is 341 code)

[GroovieGhoulie]

Ben, it's weird that you mention a CR cafe.  The 750 Cafe I have planned is going to basically be a naked CR750.  Can't stand fairings, so I'm keeping it uncovered.

It's gonna be streetable, but barely, and will incorporate the latest suspension and engine tricks, which I'm sure are better than 30+ years ago.

What makes me cry is the price of that M3 rear brake.  I WANT one so bad, but am not sure if I can justify the price.

[Sam Green Racing]

Hi Groovie, nice to hear from you again, are you back home yet ?

I really do agree with you, the CR does look good naked.

On our CR, we run the stock hub with a custom made vented twin leading shoe mechanisum.

The shoes and leaverage system are from a CB160 front brake.

Sam.

[Ricky_Racer]

For what's it's worth - which is a lot more than I can afford - the magnesium CR rear hub replica is also available for 2050- Eur ($2,650) through http://www.motocicliveloci.it/inglese/catalogue/frenitamburo_uk.htm, or through Disco Volante in the UK at http://www.discovolantemoto.co.uk/showpage.do?page=Brakes for L1260 ($2,500). Of course, with currency fluctuations these prices could be as much as 20% off. RR

[GroovieGhoulie]

Hi Groovie, nice to hear from you again, are you back home yet ?

I really do agree with you, the CR does look good naked.

On our CR, we run the stock hub with a custom made vented twin leading shoe mechanisum.

The shoes and leaverage system are from a CB160 front brake.

Sam.

Not home yet.  Still enjoying the beautiful Afghan mountains.  Just planning my cafe projects for when I get home gives my mind something to focus on that is not trying to kill me.

Now how much better is the TLS rear set-up compared to the SLS stock item?  I recall from period tests that they said the rear brake was very powerful, but hard to modulate, making it easy to lock.  Is the TLS brake more"powerful" or easier to modulate?  Does it fade less than the stock item?

Basically, what would I gain by going to a TLS rear set-up, either the CR-style, or a homebuild like yours?

[TomC]

Hi GroovieGhoulie
     I assume that you will be running a sticky front tire and very good front disk brakes. All most all the weight of the bike will be on the front tire in a hard stop. If you do a brakey(sp?) then all of your weight is on the front tire. The goal for the rear brake should be to make the most of what little traction is there. A twin leading shoe brake is going to be toucher that single leading shoe.
     If I were doing this I would try to find twin leading shoe brake that I could install as a twin trailing shoe brake. If my visualisation is correct swapping sides will do this. A trailing shoe wants to not lock up. A trailing shoe produces a smaller increase in braking force for a given increase in force on the brake pedal. If you do this the rear brake will be very hard when used for a slow stop on the street. But will work great when rolling backwards.
          TomC

[736cc]

Hey samcr750, a pic of that CB160/CB750 hybrid rear brake set-up would help figure this out; you use a CB750 hub w/ a CB160 brake panel, shoes and levers??? They're same diameter and line up? What do you use for the brake cable, or do you use a stock CB750 brake rod?

[Sam Green Racing]

Hi Groovie, nice to hear from you again, are you back home yet ?

I really do agree with you, the CR does look good naked.

On our CR, we run the stock hub with a custom made vented twin leading shoe mechanisum.

The shoes and leaverage system are from a CB160 front brake.

Sam.

Not home yet.  Still enjoying the beautiful Afghan mountains.  Just planning my cafe projects for when I get home gives my mind something to focus on that is not trying to kill me.

Now how much better is the TLS rear set-up compared to the SLS stock item?  I recall from period tests that they said the rear brake was very powerful, but hard to modulate, making it easy to lock.  Is the TLS brake more"powerful" or easier to modulate?  Does it fade less than the stock item?

Basically, what would I gain by going to a TLS rear set-up, either the CR-style, or a homebuild like yours?

Hi Groovie, I'm not sure how much better the twin leader is as I have only been on a stocker once and that was way back in the early 70s, I got the chance to blast one down a drag strip with all the time in the world to stop.

Much the same with Chrises bike, I have only ridden it a few times down a strip.

I would think it would be better otherwise why would manufacturers fit them to the front ends of sports bikes as they did in the day.

Keep yer head down Groovie.

Sam.

[Sam Green Racing]

Hi GroovieGhoulie
     I assume that you will be running a sticky front tire and very good front disk brakes. All most all the weight of the bike will be on the front tire in a hard stop. If you do a brakey(sp?) then all of your weight is on the front tire. The goal for the rear brake should be to make the most of what little traction is there. A twin leading shoe brake is going to be toucher that single leading shoe.
     If I were doing this I would try to find twin leading shoe brake that I could install as a twin trailing shoe brake. If my visualisation is correct swapping sides will do this. A trailing shoe wants to not lock up. A trailing shoe produces a smaller increase in braking force for a given increase in force on the brake pedal. If you do this the rear brake will be very hard when used for a slow stop on the street. But will work great when rolling backwards.
          TomC

Hi Tom, you're spot on with you're analysis but, a twin trailer would not be as efective as a single leader.

On the CR, we swapped the pivot points for the cam points to covert it back to leading link.

Sam.

[Sam Green Racing]

Hey samcr750, a pic of that CB160/CB750 hybrid rear brake set-up would help figure this out; you use a CB750 hub w/ a CB160 brake panel, shoes and levers??? They're same diameter and line up? What do you use for the brake cable, or do you use a stock CB750 brake rod?

Hi 736, The brake plate we used was a custom made one in the style of the factory front  brakes on the 125 and 250 machines.

The CB160 shoes, leavers and pivot and cam gear are used but the cable was custom made.

I don't yet have any pics yet but will post them when I get them.

If you go  back a few post to Ricky Racers post, click onto the discovolante site then scroll down untill you come to a RC163 replica front brake.
This looks the same but back to front.

Sam.

[TomC]

Hi samcr750
     "Hi Tom, you're spot on with you're analysis but, a twin trailer would not be as efective as a single leader."
     Why do you care about the effectiveness of the rear brake? In a hard stop you should be able to lock the rear tire with out much effort with a very ineffective rear brake.
          TomC

[Sam Green Racing]

Tom, have you ever tried to stop one of these things from 150mph, you would strugle to lock any wheel at that speed.

Sam.