Author Topic: Finally! 6 years on....the 1969 Hishiki Sumiya CR750 (Read 42314 times)

lordmoonpie · « **Reply #100 on:** November 12, 2009, 12:29:27 PM »

Maybe that's an idea Simon - an SOHC4 forum stand....we can get a few folks up for that I'm sure?

turboguzzi · « **Reply #101 on:** November 12, 2009, 12:48:09 PM »

I will state the obvious: you should race it in the next Daytona!

750Caferider · « **Reply #102 on:** November 12, 2009, 06:34:17 PM »

Anders - thanks for your kind words, I guess anythings possible if you throw enough money at it LOL!

Yeah I know, now I regret all those damn bar tabs and money wasted on cigarettes and cigars... Wait a minute I'm starting to sound like some granola munching hippie... Ugh!... Disregard... If I make it over someday I'll PM ya, I'll treat on Man U match!

Cheers,

Anders

kos · « **Reply #103 on:** November 12, 2009, 08:23:21 PM »

You would be very surprised at what we ran on our CR750's. We did have some very special ELF racing fuel with a bit of oxygen in it (not a lot) but 28-30 degrees advance, was the number. Pull of corners like a beast! And would rev out all the way to 11,000 RPM...but we shifted at 9800 RPM,m as all the torque was down there.

Also, always run a stock advancer, as it makes starting soooo easy! Push started all the time, never had much use for rollers. Hell, even Adam, who raced the thing, could push start it by himself...when I failed to turn on the petcock and he ran out of fuel, half way 'round Daytona!

What most people don't know, is that the CB750 head is a very good two valve design and for small displacements of 810cc-750cc's one should be very careful prior to machining out the swirl ridges of the combustion chamber. This head works well and has very fast flame travel, left alone. EG: if you have fast fame travel, you need less advance.

KOS

lordmoonpie · « **Reply #104 on:** November 13, 2009, 01:58:52 AM »

Thanks for the insight Mark - always good to hear a top class race example from you to relate to build issues in normal life, it kind of makes the build and its challenges feel special if that makes sense!

Hmmm, now racing at Daytona is a fantastic goal but I'm a pretty talentless amateur racer so I can't see it being an option for me. Perhaps I need to find sponsorship and a fast young gun rider to have a go, now there's a pipe dream....

Actually I have a related dream in that I want to build my own V-twin and have it raced at Daytona in the Bears class. I'm kind of half serious about making that my next project but given the timescale to do it in, I suspect by the time I finish anything, Daytona will be running the Bears Electric race!!

voxonda · « **Reply #105 on:** November 13, 2009, 02:12:11 AM »

I happen to know a young gun, 52 years of age and only 116 kgs

. you only have to find another 30bhp or so, and firm up the suspension and I......ehhh, sorry he will ride the beast.

Rob

lordmoonpie · « **Reply #106 on:** November 13, 2009, 03:18:00 AM »

Wow Rob, that's not so much of a young gun as an old cannon LOL

You've made my day - I'm 20 kilos lighter than someone on here...

MRieck · « **Reply #107 on:** November 13, 2009, 04:19:11 AM »

Quote from: kos on November 12, 2009, 08:23:21 PM

You would be very surprised at what we ran on our CR750's. We did have some very special ELF racing fuel with a bit of oxygen in it (not a lot) but 28-30 degrees advance, was the number. Pull of corners like a beast! And would rev out all the way to 11,000 RPM...but we shifted at 9800 RPM,m as all the torque was down there.

Also, always run a stock advancer, as it makes starting soooo easy! Push started all the time, never had much use for rollers. Hell, even Adam, who raced the thing, could push start it by himself...when I failed to turn on the petcock and he ran out of fuel, half way 'round Daytona!

What most people don't know, is that the CB750 head is a very good two valve design and for small displacements of 810cc-750cc's one should be very careful prior to machining out the swirl ridges of the combustion chamber. This head works well and has very fast flame travel, left alone. EG: if you have fast fame travel, you need less advance.

KOS

TG is right about not needing a lot of advance and Mark proves it. The only thing I'd mention is the chamber ridges shroud the intake valve when you start getting into larger sizes. I wonder if the Dyna 2000 was allowed in Heavyweight as it has a pretty good retard built into it for starting.

turboguzzi · « **Reply #108 on:** November 15, 2009, 03:34:42 PM »

Quote from: MRieck on November 13, 2009, 04:19:11 AM

Quote from: kos on November 12, 2009, 08:23:21 PM
You would be very surprised at what we ran on our CR750's. We did have some very special ELF racing fuel with a bit of oxygen in it (not a lot) but 28-30 degrees advance, was the number. Pull of corners like a beast! And would rev out all the way to 11,000 RPM...but we shifted at 9800 RPM,m as all the torque was down there.

Also, always run a stock advancer, as it makes starting soooo easy! Push started all the time, never had much use for rollers. Hell, even Adam, who raced the thing, could push start it by himself...when I failed to turn on the petcock and he ran out of fuel, half way 'round Daytona!

What most people don't know, is that the CB750 head is a very good two valve design and for small displacements of 810cc-750cc's one should be very careful prior to machining out the swirl ridges of the combustion chamber. This head works well and has very fast flame travel, left alone. EG: if you have fast fame travel, you need less advance.

KOS
TG is right about not needing a lot of advance and Mark proves it. The only thing I'd mention is the chamber ridges shroud the intake valve when you start getting into larger sizes. I wonder if the Dyna 2000 was allowed in Heavyweight as it has a pretty good retard built into it for starting.

So Mike, what kind of advance do you run in you mills?

Jim F · « **Reply #109 on:** November 16, 2009, 03:49:05 PM »

very nice indeed..............
Where did you get the oil tank from or did you have that made?
If so can or would you share that info
thanks
Jim

lordmoonpie · « **Reply #110 on:** November 17, 2009, 01:27:05 AM »

Jim,

Oil and petrol tank plus sundry other bits came from Asa Moyce in ireland - Bartel Automotove Engineering. Asa was a successful racer from the 60s/70s and runs this engineering business now. He doesn't have a web site but will deal with you over phone and fax which can be found on google by putting in "Bartel Donaghadee"

Jim F · « **Reply #111 on:** November 17, 2009, 05:43:15 AM »

Quote from: lordmoonpie on November 17, 2009, 01:27:05 AM

Jim,

Oil and petrol tank plus sundry other bits came from Asa Moyce in ireland - Bartel Automotove Engineering. Asa was a successful racer from the 60s/70s and runs this engineering business now. He doesn't have a web site but will deal with you over phone and fax which can be found on google by putting in "Bartel Donaghadee"

Thanks so much
Now I need to get over to Bills to help Sam get his bike sorted

JS550 · « **Reply #112 on:** November 17, 2009, 06:16:26 AM »

What size tires are you running on that moonpie? Set up looks great.

lordmoonpie · « **Reply #113 on:** November 17, 2009, 06:29:20 AM »

I'll have to check - the front is a Dunlop KR124, normally used for a rear I believe? It's a WM3 and WM5 rim but will have to check the numbering of the rear tyre....

Don R · « **Reply #114 on:** November 19, 2009, 11:36:04 PM »

Now I know why it looks familiar! In 1970 I had a shirt that color.

zzpete · « **Reply #115 on:** November 20, 2009, 12:54:51 AM »

;)LOVE THAT PAINT

lordmoonpie · « **Reply #116 on:** November 20, 2009, 01:24:13 AM »

Thanks Pete - it's even nicer close up, that black has a tiny hint of 60s metalflake in it just for a bit of glam rock sparkle LOL!

JAG · « **Reply #117 on:** February 26, 2010, 05:25:58 PM »

Quote from: lordmoonpie on June 13, 2009, 05:56:01 AM

Sometimes over this last six years I wondered whether it was worth all the hassle (slotting a DOHC crank into a SOHC motor) and all the money. I could have just had KOS build one for me for the same money, but then I get to stand back and look at this finished bike and think....maybe it was worth every last drop of blood sweat and tears, just maybe.

Now the $64,000 question.....what do you guys think?!

I haven't the words to express how beautiful this bike is..

Standing back and looking at the finished product- something of which YOU created- It's word every penny, as well as those blood sweat and tears.. I just wish I can one day have the knowledge to build something of this magnitude.

Words don't express, but I'll I can say is great job buddy!

lordmoonpie · « **Reply #118 on:** February 27, 2010, 02:44:21 AM »

Thanks JAG - I guess a big part of the 6 year build was learning stuff. Sometimes you just have to dive in and face whatever hits you along the way in order to get that knowledge. Go for it I say ...

Having said all that - I've still got to fire her up and get some video down for you guys just so you can hear the noise. As soon as I'm fit enough it's right at the top of my agenda.

CBJoe · « **Reply #119 on:** September 20, 2011, 08:35:01 PM »

This goes way back...but I'd love to know what ever happened with this.
The sheer awesomeness that went into this engine was very inspiring!

So update... preasssseeee

Cheers, Joe

CBJoe · « **Reply #120 on:** September 20, 2011, 08:40:59 PM »

I remember that the main post build issue was with the carbs and ignition, but I can't remember what happened after that.....

late night trollin' on old posts if you cant tell

lordmoonpie · « **Reply #121 on:** September 20, 2011, 11:41:02 PM »

Haha! Thanks Joe, well things have moved on a little bit! The screen has been cut down a bit so it doesn't look so huge, exhaust has been "adjusted" with a Barnsley screwdriver - a hammer to you, to make it clear the chain a bit more on the over-run and then the old ignition has been junked in favour of a more adjustable Dyna 2000 and that's all installed and static timed. That's as far as I've got now though mainly due to house alterations. However, I have made other progress as a result of a chance meeting with a Ferret!

While workingon finishing the restoraton of my XV750 Yamaha, I got into bother with the wiring thanks to a PO butchering the loom. I'm not the world's best electrician so I got a guy in who travels the length of the UK sorting out motorcycle wiring - Ferret's Custom Elecktrickery!!

Ferret sorted the XV and then we got onto the CR750 and the K4 alternator in the 750 stator setup I have. He thinks I'll be losing electrical power with this setup even wih the Dyna, so he's coming back in the new year to rewire the whole bike. The benefit of this is he'll use a set of wires coloured exactly how Honda would colour them and all new old style block and bullet connectors, not the hardware shop versions I have used. His electrical knowledge across all makes and models was just stunning. My XV750 now charges with 14.5 volts at the battery with full beam on and ran first prod of the starter having been in rebuild for 3 years.

So development goes on and I have a purpose at last now. I'm negotiating to try and get a place on the closed roads parade lap in the Manx Grand Prix next year - a lap of the TT course as a racer would see it on the CR750 would be a dream come true for me so gotta get this thing reliable.

CBJoe · « **Reply #122 on:** September 25, 2011, 07:22:50 AM »

Very cool... thanks for the update.

regards, Joe

SoyBoySigh · « **Reply #123 on:** May 31, 2016, 11:14:47 PM »

BUMP!

This bike is AWESOME. Gotta wonder how much "pull" they had with the old man, being allowed to run their own colours up the proverbial Honda Flag-Pole! They were development riders, yeah? So are they the guys we see in all of those photos of the prototype & pre-production CB750K0 Sand-Cast bikes being run around Suzuka etc, with the Black Bomber "toaster" style gas-tank on it & all that? Would be a heck of a thing, to be the first person in the world to have ridden the CB750 - why aren't THEY better known here in the West?

We all need to forget about the Dick Man paint jobs, build more replicas like this!

So was this the only odd-ball colour scheme in early CR750 racing? I know there were some different colours out there by the time of the DOHC racers the RCB & RS1000, CB1100R etc - I'd sure like to hear more about odd-ball bikes like this one.

And what a gorgeous job building it, hey? WOW. I had a few pics of this bike for years now, downloaded from the daily-bike blog sites etc. But I had no idea it was from here on the SOHC Four-um. Definitely downloading all of these new pics!

If you're responsible for any dead pic-links in this thread, could you please fix 'em? Gotta wonder how this thread wound up on the back-burner. Should be a "STICKY" for bikes of this quality!

-Sigh.

SoyBoySigh · « **Reply #124 on:** June 01, 2016, 12:24:33 AM »

Oooh I love those TIRES!!!

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Author Topic: Finally! 6 years on....the 1969 Hishiki Sumiya CR750 (Read 42314 times)