Topic: A CB750 race bike build...

[Santiago]

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.

[slikwilli420]

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.

[FuZZie]

A couple of pics of the 350 in his introduction thread.
http://forums.sohc4.net/index.php/topic,170060.0.html

[Sam Green Racing]

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.

[Santiago]

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 ;-)

[Santiago]

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.

[Sam Green Racing]

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.

[Sam Green Racing]

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.

[Santiago]

I'm hoping to catch up with him at the Burt Munro Challenge in February. I'll give him a rark up.

[kmb69]

Curious where you found that rear wheel?

[Santiago]

Curious where you found that rear wheel?

I picked it up in Japan.

[Sam Green Racing]

There was a company making them Keith, in Italy I think but production may have stopped now.
They were very expensive.

[Sam Green Racing]

Here you go Keith.

http://www.motojlmreplica.com/English/sales.html

[Santiago]

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...

[Santiago]

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"

[754]

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..

[Santiago]

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.

[Jerry Rxman Griffin aka MuthaF'er]

What are you doing to mate that F3 head to the early jugs as far as the unmatched oil returns go?

[Santiago]

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.

[754]

 I think Dennis did it on the BonnevilleRacer thread.

[Santiago]

I think Dennis did it on the BonnevilleRacer thread.

Thanks, I'll search it out.

[754]

Check the top , part of it is bottom of page 16 , he is running F250 head on K cylinder.

[Santiago]

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.

[750deepsouth]

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.

[750deepsouth]

I'm hoping to catch up with him at the Burt Munro Challenge in February. I'll give him a rark up.

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!