Author Topic: A CB750 race bike build...  (Read 11831 times)

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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)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
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2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.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 and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

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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
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - 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

Offline Santiago

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Re: A CB750 race bike build...
« Reply #38 on: June 29, 2021, 02:27:44 am »
Well, work, Covid and other bikes has meant this build stalled for a while. A CB450 needed finishing, but have now done things like making wheel spacers and getting the alignment right, and setting up the foot peg hangers, getting them welded and the exhausts as well. I do small welding jobs but farmed out the exhausts to a pro, they are very thin and my bird#$%* splatter tig welding skills would have blown holes in them 🤣. These are dummy cases just for aligning the wheel sprockets, but my race motor is complete and ready to lift in once the rolling chassis is finished. But I'm away again for work so it will be another 6 months off the bike.....
« Last Edit: June 29, 2021, 02:37:42 am by Santiago »

Offline johno

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Re: A CB750 race bike build...
« Reply #39 on: June 29, 2021, 03:54:29 am »
Hi Santiago,
Your making good progress, for a first time 750 build your doing well. It will start to come together quickly after all the #$%*ty little jobs are done like spacers etc. What are you planning for the ignition ?
You must be the only bloke in the world travelling to lots of countries with all this Covid crap going on. Stay safe.
cheers Johno
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Offline Santiago

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Re: A CB750 race bike build...
« Reply #40 on: June 29, 2021, 04:07:01 am »
I've got a crank mounted magneto by Electrex world and I made a semi original style cover out of a DOHC cover cut and welded, circled in this photo. All the holes line up except 1, but I'll get around that by counterboring the electrex world mounting plate, installing a reduced head fastener in the counterbored hole, and using a short bolt threaded into a heli coil in the cover.

I do aircraft lease returns for a job, so need to travel, and covid be damned. But had no work for 7 months in 2020 (I rebuilt a NS250R and did most of the work on the CB450 race bike in that period), then had 6 months in Jakarta, just had 3 months off and now heading up to the UAE for a few months work.
« Last Edit: June 29, 2021, 02:06:28 pm by Santiago »

Offline Sam Green Racing

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Re: A CB750 race bike build...
« Reply #41 on: June 29, 2021, 01:58:55 pm »
Santiago, jetting about all over the world, it's a wonder you got half of what you did get done, keep up the good work, It'll be worth it in the end.

Sam.
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 #42 on: July 01, 2021, 03:35:12 pm »
Managed to score this off the local auction site, I thought it was a LH hanger and was buying it as a spare, but it's actually a RH hanger, so the hanger for my RH caliper that I'd made from a LH one using spacers etc is now back on the shelf.

Offline johno

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Re: A CB750 race bike build...
« Reply #43 on: July 01, 2021, 04:34:40 pm »
Nice pick up, You know the ol saying, Arse beats class.  ;D
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Offline Santiago

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Re: A CB750 race bike build...
« Reply #44 on: July 01, 2021, 05:19:03 pm »
It was certainly very arsey.🤣

Offline scottly

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Re: A CB750 race bike build...
« Reply #45 on: July 01, 2021, 07:29:46 pm »
The right side CFC bracket I had did not have the lugs for mounting the fender brace, as it was meant to be used with the stock fender??
Don't fix it if it ain't broke!
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Offline Santiago

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Re: A CB750 race bike build...
« Reply #46 on: July 01, 2021, 07:44:48 pm »
yeah, this one is  symmetrical to the LH side, and appears to be perfect for the race type fender bracket (that I am now making, what a PITA😖)

Offline scottly

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Re: A CB750 race bike build...
« Reply #47 on: July 01, 2021, 07:59:09 pm »
That bracket is a unicorn!! :o Even the CR "kit" was missing the fender lugs..
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline Santiago

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Re: A CB750 race bike build...
« Reply #48 on: July 01, 2021, 08:09:59 pm »
It’s definitely a Honda part, didn’t come in a bag with a PN but it’s clearly a factory part and not a home made casting. The cognoscenti on this forum will know why it exists I’m sure.

Offline Santiago

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Re: A CB750 race bike build...
« Reply #49 on: July 02, 2021, 01:47:27 am »
I'm trying to do small jobs before I have to go back to work, I drilled out the cemtre of the rear axle, took about 3 hours of very slow machining all the while panicing about not clearing the swarf fast enough, loading up the drill, and seizing it and snapping it off. Saved about 160 grams 🤣. I mounted the unicorn RH hangar (all the bolts are temporary) to mess around with the front mudguard, now I have to turn the cardboard template into a metal one. 😖