Author Topic: The 1970 Daytona CR750s.  (Read 161269 times)

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Offline Honda Just

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Re: The 1970 Daytona CR750s.
« Reply #850 on: November 05, 2014, 01:05:15 am »
CR replica for sale (Australia)

http://www.gumtree.com.au/s-ad/parkerville/motorcycles/honda-cr750-replica/1059086065
Nice replica that, but it worries me to see $30k spent and $20k asking price! What determines the value on these - closeness/accuracy (I mean lets say you had the 4 bolt forks etc), or racing provenance? I must be careful to not over-capitalize, but still see myself going for the magnesium rear hub replica :P 

Offline turboguzzi

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nice story & poster...
« Reply #851 on: November 25, 2014, 02:19:57 pm »
sam, feel free to move to the CR750 megathread.....

http://superbikeplanet.com/2013/Nov/131104cr750.htm

Offline rklystron

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Re: nice story & poster...
« Reply #852 on: November 25, 2014, 02:59:50 pm »
Awesome read. I did not know about the magnesium cases expanding under high temps or the camchain tensioner from the CB450.
Very cool!
1970 CB750 K0 (Bought in 73)
1972 XL250 (Bought new in 72)
1973 ST90 (Free)
1975 XL250 (Free)
1975 Rickman CR750
1982 CBX1000 Pro-link
1975 CB750 DRAG BIKE
1977 Custom Built CB750 Sturgis Bike (GL front end).
1977 CB750 F2 (Big Resto)
1977 CB750A (Auction Buy)
1978 CB750 K8 (My San Francisco ride)
1984 VFR750 (Bought New)

Offline chris

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Re: The 1970 Daytona CR750s.
« Reply #853 on: February 07, 2015, 01:37:44 pm »
It is my bike for sale . What determines the price is what the market may pay but often it's the replacement costs of the parts. Mine has hand made alloy fuel tank,alloy oil tank and exhausts. Look at the cost of replacing those. Also look at the cost of the manufacture of things like the triple clamps etc etc,it goes on and on. If you then look at the cost of the engine ie 836 with all the good and fast bits and carbs etc,it doesn't take long for the cost to add up.
Many people will look at a bike like that and say that they can make one for less. It's not until they get into the project that it's not possible if you want good quality .
I have had some enquiries but no sale yet.I rode it at the Phillip Island Classic a couple of weeks ago and even though I had front end pattering issues which slowed me down a bit I fell I love with the old girl again.its so reliable and SOUNDS AWESOME !!!

By the way did the original CR have a standard frame could anybody tell me ?

Offline H2Eric

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Re: The 1970 Daytona CR750s.
« Reply #854 on: February 16, 2015, 09:34:15 am »

By the way did the original CR have a standard frame could anybody tell me ?


Hi Chris
The answer to your question is no. Do a search on 'A CR750 Build' and go to the top of page 2 where you will see pictures of both the standard frame and the CR frame. The main difference is in the headstock which is 25mm lower in the CR frame. The positioning of the main frame tubes where they meet the headstock is also different. Note also the mountings for the coils. The CR frame originated from Bill Smith Motors in Chester was for sale at the Stafford Bike Show a couple of years ago and went it Italy I believe. I did hear that the gentleman who purchased it was going to have it copied, but whether anything ever came of it I know not. Perchance someone else from the forum may know something.

Cheers
Eric
Honda CR750
Honda CB750K3
Kawasaki 750H2B
Suzuki GS750
Honda CB175

http://forums.sohc4.net/index.php/topic,94588.0.html

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Offline wevans

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Re: The 1970 Daytona CR750s.
« Reply #855 on: April 29, 2015, 03:16:28 pm »
Anybody know of a manufacturer that makes a top clamp similiar to what the cr750 may habe had ? Im currently working on a replica bike and I'm unsure of which clip ons and top clamp to purchase. Any help is appreciated!  Thanks

Offline Carco

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Re: The 1970 Daytona CR750s.
« Reply #856 on: April 30, 2015, 02:38:01 am »

Offline johno

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Re: The 1970 Daytona CR750s.
« Reply #857 on: June 01, 2015, 04:49:25 am »
I have always been curious about the HP numbers quoted for the famous 4 CR 750's   from 89HP to 94 HP I believe, what interests me is what type of dyno they were measured on.

Evan in production bikes there has always been discrepency between advertised HP and actual HP

Over the many years  I have often heard the factory measure on a crankshaft direct drive dyno, not evan off the sprocket.  Does anyone know how the factory measures , especially in the 70's ,   maybe Honda man can shed some light on the old Honda system. ::)

I am curious as my goal is to match the CR 750 works bike performance, just not sure what their real HP is ?
cheers johno
GRASSHOPPER SOHC HONDAS ARE THE MEANING OF LIFE.

Offline johno

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Re: The 1970 Daytona CR750s.
« Reply #858 on: June 06, 2015, 04:53:30 pm »

Re the dyno subject I an had email from Hondaman in responce to me asking if he new anything about the R&D  CR 750 bikes and how they measured the HP., thanks Marko ;D   I have put it here to share hope you dont mind.

"The only picture I ever saw of the Yosh dyno setup had an adjustable frame to fit the engines, with a short chain that went to an axle-like shaft that was likely the dyno input shaft (the dyno was out of the picture toward the right).  A short chain between the engine sprocket and a same-size sprocket on the axle shaft was what I saw: it struck me at the time because I wondered how fast that chain must wear on those little sprockets?

Yosh worked on all the Japanese bikes in those days, on contract from the Big Four in Japan. They made racing parts for Honda, Kawi, Suzy, Y'hammer and Hodaka that I have seen. Yamaha stubbornly claimed they did their own R&D, but their racing parts, when ordered, came in Yosh plastic bags(!).

Did you know that at one time you could get a Yosh kit for the step-thru C70? :) "

GRASSHOPPER SOHC HONDAS ARE THE MEANING OF LIFE.

Offline Tintop

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Re: The 1970 Daytona CR750s.
« Reply #859 on: June 06, 2015, 07:10:12 pm »

Did you know that at one time you could get a Yosh kit for the step-thru C70? :) "


 8) that would be a great little pit bike ;D ;D ;D ;D
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
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Offline H2Eric

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Re: The 1970 Daytona CR750s.
« Reply #860 on: June 14, 2015, 03:28:20 am »
Has anyone fitted the Airtech cooling ducts to their bike? If so how was it done? Some pictures of the inside of the fairing with the ducts fitted would be much appreciated.
Thanks
Eric
Honda CR750
Honda CB750K3
Kawasaki 750H2B
Suzuki GS750
Honda CB175

http://forums.sohc4.net/index.php/topic,94588.0.html

Growing old is mandatory, growing up is optional.
Honda CB350F being restored
Yamaha R1

Offline gschuld

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Re: The 1970 Daytona CR750s.
« Reply #861 on: October 07, 2015, 06:18:51 am »
I recently managed to locate a 1970 October Cycle Magazine.  So for those of you who have not seen the article, I'll upload it here.

George

Offline gschuld

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Re: The 1970 Daytona CR750s.
« Reply #862 on: October 07, 2015, 06:20:40 am »
Enjoy:
« Last Edit: October 07, 2015, 06:24:30 am by gschuld »

Offline gschuld

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Re: The 1970 Daytona CR750s.
« Reply #863 on: October 07, 2015, 06:44:36 am »
Individual photos in the article, in order.
« Last Edit: October 07, 2015, 06:49:59 am by gschuld »

Offline gschuld

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Re: The 1970 Daytona CR750s.
« Reply #864 on: October 07, 2015, 06:53:54 am »
Front cover:

George

Offline gschuld

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Re: The 1970 Daytona CR750s.
« Reply #865 on: October 07, 2015, 11:37:15 am »
Has anyone fitted the Airtech cooling ducts to their bike? If so how was it done? Some pictures of the inside of the fairing with the ducts fitted would be much appreciated.
Thanks
Eric

Eric,

While I haven't mounted a set of these cooling ducts personally, the October 1970 photos that I recently posted shows that there were 3 removable fasteners around the duct exit area.  There is a generous flange molded into the fairing mating surface of exit duct end.  These were perhaps the only direct hard fasteners involved along with perhaps some modest positioning at the oil cooler itself.  The idea was, of course, to draw oil cooler exhaust air from behind the oil cooler and pull it out the duct.  This, in theory at least, both allows the oil cooler to work more efficiently and takes some of the heat the oil cooler is putting off and getting it away from the engine allowing the top end to be cooled easier(rather than having preheated air from the cooler blowing directly on the upper end of the engine).

To be honest, I haven't seen a set mounted to a bike in person.  The early style CR750 fairing racers that I have seen skipped the oil cooler ducting.  It would very likely add a bit of complication when taking the fairing on an off as the fairing is designed to pull off forward and the ducts are meant to fit in behind the oil cooler.  So I would think that this would require having to detach the oil cooler ducts every time the fairing is removed.  Not fun I suspect. 

No doubt they had some functional merit, but perhaps the inconvenience involved overcame the potential benefits for most.

George
« Last Edit: October 07, 2015, 11:41:14 am by gschuld »

Offline teebee67

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Re: The 1970 Daytona CR750s.
« Reply #866 on: October 07, 2015, 11:52:22 am »
I have the ducts fitted on mine and, with a little fiddling and twisting I can remove and replace the fairing without removing the ducts.
I'm only old on the outside.

Offline gschuld

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Re: The 1970 Daytona CR750s.
« Reply #867 on: October 07, 2015, 02:20:43 pm »
Good to know, thanks.

George

Offline oldskullero

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Re: The 1970 Daytona CR750s.
« Reply #868 on: July 10, 2016, 09:44:01 pm »
The link goes to 404 Error not found. Is there anybody who has a pdf copy of this magazine?

Also, here is the October 1970 Cycle magazine article on a Dick Mann Daytona racer replica - its pretty tech involved. Most of you probably already have this info, I would imagine? - but its a kewl read.

(the perks of selling automotive/motorcycle/construction literature for a living - ALL the reading material you can imagine!. . . lol.)

Honda CB750-90HP Kit - Cycle - OCT 1970.pdf




Offline gschuld

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Re: The 1970 Daytona CR750s.
« Reply #869 on: July 11, 2016, 07:27:11 am »
Try post 862 a few posts up. This is the article you are looking for.  Post 863 has close up photos.

I put these up since that link died a while back.  I have that magazine on hand.

George

Offline JacobMm

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Re: The 1970 Daytona CR750s.
« Reply #870 on: December 20, 2016, 02:38:01 pm »
AMA roadracing was a backwater for much of the 1960s, a two-wheeled fiefdom dominated by America’s only remaining motorcycle manufacturer, Harley-Davidson. With success more or less guaranteed by archaic Class C rules that gave The Motor Company’s antiquated, side-valve KR750 motor a 50 percent displacement advantage over more modern engines from European manufacturers, racing in America was essentially an all-Harley affair. It wasn’t until the late-’60s, when the British brands began spending serious money in an effort to increase their U.S. sales, that the racing results began to change.

Offline jruff5585

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Re: The 1970 Daytona CR750s.
« Reply #871 on: July 12, 2017, 04:19:53 pm »
Hi I'm looking for some information on a set of forks that came from Bob Hanson's estate, they are an early set of CB750 forks with Marzocchi trees with needle bearings. Written on the stem Marzocci ex Stewart it is also written on one of the tubes. This set of forks has the bike sit 2" lower. I believe I have read the the neck on a CR750 was moved back and lower. I know these are not the 4 stud CR forks but I'm wondering if any might know why ex stewart is written on the forks and why did Bob save them all those years. Maybe it's something maybe it's not. Any help is appreciated.
« Last Edit: July 13, 2017, 07:09:31 am by jruff5585 »

 

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