Author Topic: A CB750 race bike build...  (Read 2590 times)

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Offline Santiago

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A CB750 race bike build...
« on: January 11, 2018, 09:22:04 pm »
Gidday gents, depending on how things go and time permitting, I thought I'd do a post on my attempt at a build, having picked up a still born project and a bunch of parts, and having read every word of H2Erics thread. I normally play around with CB350 twins, so the 750/4 will be a big learning curve, advice from the experts here will be welcome.

Some of the parts I've collected so far....be great if it looked like the other picture though.

It's not meant to be a CB750 Racing Type replica, more of a "homage" to the Daytona racers.

Cheers.
« Last Edit: January 11, 2018, 09:23:43 pm by Santiago »

Offline slikwilli420

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Re: A CB750 race bike build...
« Reply #1 on: January 12, 2018, 04:05:47 am »
I love these builds. Building just for fun or to actually race? Build it right and it could be competitive in the AHRMA formula 750 class.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline FuZZie

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Re: A CB750 race bike build...
« Reply #2 on: January 12, 2018, 04:26:17 am »
A couple of pics of the 350 in his introduction thread.
http://forums.sohc4.net/index.php/topic,170060.0.html

Offline Sam Green Racing

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Re: A CB750 race bike build...
« Reply #3 on: January 12, 2018, 06:49:13 am »
Gidday gents, depending on how things go and time permitting, I thought I'd do a post on my attempt at a build, having picked up a still born project and a bunch of parts, and having read every word of H2Erics thread. I normally play around with CB350 twins, so the 750/4 will be a big learning curve, advice from the experts here will be welcome.

Some of the parts I've collected so far....be great if it looked like the other picture though.

It's not meant to be a CB750 Racing Type replica, more of a "homage" to the Daytona racers.

Cheers.

It looks like you have a good start if the top pic is your project starter pack Santiago, where did you pick it up from ?

I had a mate in NZ that was building one but he's not been on here in many years, he lived in Invercargill.
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Santiago

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Re: A CB750 race bike build...
« Reply #4 on: January 12, 2018, 08:43:58 pm »
I love these builds. Building just for fun or to actually race? Build it right and it could be competitive in the AHRMA formula 750 class.

I'm going to race it, but I run at the back of the pack ;-)

Offline Santiago

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Re: A CB750 race bike build...
« Reply #5 on: January 12, 2018, 09:28:31 pm »
Gidday gents, depending on how things go and time permitting, I thought I'd do a post on my attempt at a build, having picked up a still born project and a bunch of parts, and having read every word of H2Erics thread. I normally play around with CB350 twins, so the 750/4 will be a big learning curve, advice from the experts here will be welcome.

Some of the parts I've collected so far....be great if it looked like the other picture though.

It's not meant to be a CB750 Racing Type replica, more of a "homage" to the Daytona racers.

Cheers.

It looks like you have a good start if the top pic is your project starter pack Santiago, where did you pick it up from ?

I had a mate in NZ that was building one but he's not been on here in many years, he lived in Invercargill.

I did pick up the original project in Invercargill, what is your mates name? I got it from Dave Morris, he'd been collecting parts for a few years, and does glass work, which is where I got my seat, tank and fairing (came with the project, at least the moulds did, I had to make my own parts)

I met another guy from Invercargill, Andy Frazer, who has finished his one, it is fairly awesome IMO. It's actually his Mead Speed tank, and Airtech seat and fairing that Dave used for the moulds. The pic is of Andys bike a few months ago when I saw it.

Offline Sam Green Racing

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Re: A CB750 race bike build...
« Reply #6 on: January 13, 2018, 06:45:42 am »
Santiago, it was Andy.
A lot has gone on with me since I last spoke to Andy, I had a big accident in 2014 and was off line for a while.
Andy had not been on line for a few years when I last checked but doing a quick search in the members list shows him to have changed his user name, perhaps why I have not noticed he was back.
He is now here under the user name 750deepsouth but hasn't checked in since early last year.
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Sam Green Racing

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Re: A CB750 race bike build...
« Reply #7 on: January 13, 2018, 07:13:24 am »
Andy has not posted on the forum since early 2008 but did look in from time to time and then he changed his name.
If you should see him, please give him a telling off from me. hahaha.
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Santiago

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Re: A CB750 race bike build...
« Reply #8 on: January 13, 2018, 04:36:51 pm »
I'm hoping to catch up with him at the Burt Munro Challenge in February. I'll give him a rark up.

Offline kmb69

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Re: A CB750 race bike build...
« Reply #9 on: January 13, 2018, 07:42:23 pm »
Curious where you found that rear wheel?

Offline Santiago

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Re: A CB750 race bike build...
« Reply #10 on: January 13, 2018, 08:09:42 pm »
Curious where you found that rear wheel?

I picked it up in Japan.

Offline Sam Green Racing

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Re: A CB750 race bike build...
« Reply #11 on: January 14, 2018, 04:23:18 am »
There was a company making them Keith, in Italy I think but production may have stopped now.
They were very expensive.
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Sam Green Racing

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Re: A CB750 race bike build...
« Reply #12 on: January 14, 2018, 04:32:21 am »
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Santiago

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Re: A CB750 race bike build...
« Reply #13 on: January 14, 2018, 04:50:41 am »
I believe the batch of replica brakes were made by Menani in Italy, who I understand bought the MV foundry. They do not have any left and probably won't make any more unless enough orders are placed to make it viable.

I tried Mark McGrew for the rear brake, he didn't have any left. I also tried Daniel Mercier (MotoJLMReplica) but he didn't have any either. I did buy his oil tank though, it's a thing of beauty, top quality.

I was told there may be an original one for sale in England, by Lord Moonpie (I bought his exhaust, also great quality) but it was pricey.

The one I ended up getting in Japan came with the front as well, laced up to Borrani rims (probably the new ones made in China, but they look OK), stainless butted spokes, new Dunlop TT900GP rubber, a sprocket and a cable. For about the same price as the genuine hub that may be in the UK. More than I originally wanted because I already had rims and rubber at home, but I really wanted the brake. Also I was on a project in Bangkok at the time, so it was relatively simple to fly up to Japan and pick it up and take it home as checked baggage.

I sold a few bikes and other parts to fund this build, I've almost got all I need and hope to start assembly in the next month or so.

It's easier to say it than do it I know, but will give it a crack...

Offline Santiago

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Re: A CB750 race bike build...
« Reply #14 on: January 14, 2018, 05:18:12 pm »
I love these builds. Building just for fun or to actually race? Build it right and it could be competitive in the AHRMA formula 750 class.

Here's the plan for the engine (I have most of the parts I need).

Head: CB750F3 head with Kibblewhite 5mm valve spring kit, guides etc. Modified with cam tower hold down bolts.
Barrel and pistons: CB750K0 "sand cast" with sleeves removed, bored to suit Dynoman Performance CB750F2 70mm piston kit (incl sleeves)
Cases: Unknown year (numbers ground off) but crankcase mouths bored to suit new sleeves. Heavy duty studs and nuts from APE.
Crank: Lightened crank with Carrillo rods (from DP).
Gearbox: Nova Racing CR box
Clutch: basket disassembled and cush rubbers replaced, kevlar clutch plates (need to get some of these).
Primary drive: heavy duty chains (not bought these yet, been reading the forum and still trying to decide: thinking Cycle X and their teflon tensioner - anyone got an idea on this?)
Cam: Webcam 363c, hardened rockers, adjustable sprocket
Cam chain: Camellia chain, tensioner to be decided (I have 2 types of wheels, the steel ones and some made of a nylon type material that I bought for my CB350 and haven't used), or I may try to source a KA Performance slipper (I have one of these in the CB350, and no issues so far).
Carbs: I got a set of VM29 smoothbores with the project, so will probably use these rather than buy Keihin CR's. Thats a 29mm carb on (roughly) 242cc cylinder, I was using a 30mm Amal on my Ducati 250 racer and that went well, so I will try it.
Ignition: I decided on an Elextrex world crank mounted magneto, which is basically PVL components. I use a PVL on the CB350, and its faultless.
Exhaust: a 4-4 system from Lordmoonpie.
Oil cooler: VF700R modified to resemble the original oil cooler

It should go ok, hopefully not go "boom"

« Last Edit: January 14, 2018, 05:25:26 pm by Santiago »

Offline 754

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Re: A CB750 race bike build...
« Reply #15 on: January 14, 2018, 05:26:09 pm »
Hey you are from the Island and you have a ducati 250..racer so maybe.
 I sold a 250 Mach1 project to fellow over there, was in beer or brewery distributing I think, does it ring any bells ?
Great project you got there..
« Last Edit: January 14, 2018, 05:28:31 pm by 754 »
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Santiago

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Re: A CB750 race bike build...
« Reply #16 on: January 14, 2018, 05:33:48 pm »
Hey you are from the Island and you have a ducati 250..racer maybe.
 I sold a 250 Mach1 project to fellow over there, was in beers or brewery distributing I think, does it bring bells ?
Great project you got there..

Not me. I built mine from a 1962 4 speed Monza, to comply with pre 63 rules here: age being dictated by the major components. I had a 1965 Mk3 5 speed that they made me run in pre 72, so I bought a genuine pre 63 Ducati and sold the Mk3, only to see it raced by the new owner as a 1962 Monza in pre 63 class!

I tried to replicate the Cycle World article from 1965 with the mods that Gordon Jennings did, eg coil spring conversion, inlet port re-angled, Carrillo rod etc. It went well, until it didn't. Sold now.

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: A CB750 race bike build...
« Reply #17 on: January 14, 2018, 08:59:07 pm »
What are you doing to mate that F3 head to the early jugs as far as the unmatched oil returns go?
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline Santiago

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Re: A CB750 race bike build...
« Reply #18 on: January 15, 2018, 04:41:20 pm »
What are you doing to mate that F3 head to the early jugs as far as the unmatched oil returns go?

No idea! You have any advice? Got told it was possible, but haven't got to that stage yet.

Offline 754

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Re: A CB750 race bike build...
« Reply #19 on: January 15, 2018, 04:43:47 pm »
 I think Dennis did it on the BonnevilleRacer thread.
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Santiago

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Re: A CB750 race bike build...
« Reply #20 on: January 15, 2018, 04:46:10 pm »
I think Dennis did it on the BonnevilleRacer thread.

Thanks, I'll search it out.

Offline 754

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Re: A CB750 race bike build...
« Reply #21 on: January 15, 2018, 05:30:45 pm »
Check the top , part of it is bottom of page 16 , he is running F250 head on K cylinder.
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Santiago

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Re: A CB750 race bike build...
« Reply #22 on: January 15, 2018, 06:35:27 pm »
Check the top , part of it is bottom of page 16 , he is running F250 head on K cylinder.

Found the info, seems do-able, when I get to that stage I'll post it up. Thanks for the heads up.

Offline 750deepsouth

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Re: A CB750 race bike build...
« Reply #23 on: February 09, 2018, 02:48:57 pm »
Hi Sam,
Just saw this, pm'ed you
Cheers, Andy



I had a mate in NZ that was building one but he's not been on here in many years, he lived in Invercargill.

Offline 750deepsouth

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Re: A CB750 race bike build...
« Reply #24 on: February 09, 2018, 03:11:16 pm »
I'm hoping to catch up with him at the Burt Munro Challenge in February. I'll give him a rark up.
:D
Hi there!! rark up required ... lol ... thats a great picture at the top of the thread, you are going to make a great job of your bike I'm sure. I was unable to attend the BMC this weekend but Jeremy Holmes may have my bike there and he hopes to do a few demo laps.
I had my bike on the dyno a couple of weeks back, I meant to put the clip on youtube but here it is on dropbox https://www.dropbox.com/s/ac9ltgx61cjdkr2/Dyno.mp4?dl=0
Here are both my bikes on display in a local bike shop - the other one being the K2 Honda 750 naturally!

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: A CB750 race bike build...
« Reply #25 on: February 09, 2018, 08:39:57 pm »
What are you doing to mate that F3 head to the early jugs as far as the unmatched oil returns go?

No idea! You have any advice? Got told it was possible, but haven't got to that stage yet.

Plug the extra holes.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline Santiago

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Re: A CB750 race bike build...
« Reply #26 on: February 12, 2018, 12:47:07 am »
What are you doing to mate that F3 head to the early jugs as far as the unmatched oil returns go?

No idea! You have any advice? Got told it was possible, but haven't got to that stage yet.

Plug the extra holes.

Thought about it this weekend (was at the Burt Munro Challenge (https://www.facebook.com/BurtMunroChallenge) and discussed it with a mate who races a CB750 and owns about 20 more: what about a Dowty washer under the head nut on the 4 studs that are open to the air?

Offline Santiago

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Re: A CB750 race bike build...
« Reply #27 on: July 25, 2018, 01:39:01 am »
If anyone's still reading my post....been a while since I could get into the shed, I had a job in Europe from March -  June, while I was there I managed to get to France to see Daniel Mercier who has the Daytona bike, which wasn't there when I visited (it's in a Museum) but 2 superb replicas in the making were in his workshop. I bought some parts from him including the oil tank, excellent quality and all parts readily available, now that Asa Moyce is retired Daniel seems to be the only one making replica alloy fuel and oil tanks. If you are in France he's worth a visit, he's a great guy and the wine is recommended.

Anyway, I've started on the engine, fitted the Carrillo rods with new bearings to the lightened crank from Cycle X and heavy duty studs to the cases, put 1 piston on a rod and fitted the head (with valves installed but only 1 cam tower and 1 set set of rockers) and barrel with no gaskets, plasticine on the top of the piston, and turned the cam over with a spanner on the thrust end bolt so that I could measure the squish and valve clearance and work out base and head gasket thickness. Got a .005" copper base gasket and .027" copper head gasket ordered from Dynoman, once they arrive assembly can be done.

Offline blacksmith1

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Re: A CB750 race bike build...
« Reply #28 on: July 26, 2018, 02:39:43 am »
go for it mate,love the cr

Offline SOHC4 Cafe Racer Fan

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Re: A CB750 race bike build...
« Reply #29 on: August 07, 2018, 04:54:13 pm »
There was a company making them Keith, in Italy I think but production may have stopped now.
They were very expensive.

M3 Racing used to sell them, too.  Very pricey hub!
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2014 MV Agusta Brutale Dragster 800
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html)

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1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold

Offline Santiago

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Re: A CB750 race bike build...
« Reply #30 on: August 07, 2018, 06:41:07 pm »
Yes, I emailed Mark and asked him if he still had any, but he had none available. I think they can still be arranged through Daniel Mercier, motojlmreplica.com. This one was bought from Disco Volante in the UK many years ago by the gentleman from Japan that I managed to buy it off. It was expensive and needed a trip to Japan to pick it up, luckily I was already there for work, so it came back as luggage.

Offline Santiago

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Re: A CB750 race bike build...
« Reply #31 on: February 22, 2019, 12:41:14 am »
Managed to find a bit of time to get back into the build, so I took the angle grinder to the frame.....

Offline napoleonb

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Re: A CB750 race bike build...
« Reply #32 on: February 22, 2019, 09:44:19 am »
Looking good!

Offline Santiago

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Re: A CB750 race bike build...
« Reply #33 on: February 24, 2019, 12:38:51 am »
I have to paint my bodywork next weekend (only chance to use a spray booth I have access to), so I have to tack the fairing brackets etc to drill everything off. It's all a bit rushed but that's how it goes. I dummy fit the rear wheel, forks, front wheel so that I could get it sitting on the ground and gauge where the fairing bracket needs to be welded on. Fitting the wheels brought home how much work there is to do...lots of little jobs like making spacers for the wheel, to do that I need to fit dummy engine cases with the output shaft and a sprocket on so that I can line the front and rear sprockets up. The fairing in the pic is just sitting propped up by a pair of pliers on the front wheel and the straps holding the bike on the stand....its not the final position, I was just playing around. So don't panic that it is not in the right position ;) Now I'm getting into the project I'm discovering that the 'project' I inherited (frame, forks etc) was a piece of #$%*, things like the correct engine mount bolts are missing, the swing arm bolt and collars / bushes are junk, the bolts that were attaching the twin discs to the hub were galvanised bolts commonly used for industry and weren't even metric! Better to have started with a complete bike I think....it's going to take a while.

Offline Santiago

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Re: A CB750 race bike build...
« Reply #34 on: February 26, 2019, 12:11:24 pm »
Just getting things into position for now. Not easy fitting the fairing.....

Offline bwaller

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Re: A CB750 race bike build...
« Reply #35 on: February 26, 2019, 02:13:15 pm »
You might want to wait to play with the fairing until the engine and the pipes are installed. Undoubtedly there will be adjustments afterward!

Offline Santiago

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Re: A CB750 race bike build...
« Reply #36 on: February 26, 2019, 02:15:07 pm »
Yep, engines in, got to fit the pipes tonight, nothing's welded on yet, note the speed tape holding the fairing in position at the back.

Offline Sam Green Racing

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Re: A CB750 race bike build...
« Reply #37 on: February 27, 2019, 08:43:31 am »
Coming on well Santiago, I saw your post on FB.
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

 

;
Honda