Topic: Salt Racer CB 750 OZ style

[sohc boy]

 Johno ....wouldnt worry bout those water buckets, BOB  who set  the record in MG/750 ,want be going back with that bike , he's doing nostalgia racing , i heard the other water bottle (Brett Destoop )) came off at 240 mph ,

[bear]

Johno ....wouldnt worry bout those water buckets, BOB  who set  the record in MG/750 ,want be going back with that bike , he's doing nostalgia racing , i heard the other water bottle (Brett Destoop )) came off at 240 mph ,

OUCH!!!!
Hope the man's OK

[Sam Green Racing]

Did you find out what speed that 175 reached ?

Sam.

Hi Sam, I was looking at your mates Tiny thread and the results for your 175 class were 95mph on the Monday which was #$%*e day 45 degrees and 10 to 15mph head wind    and the wind changed on Tuesday and he ran 97 mph.       So Sam the man your 116mph is still out there for all to catch

I looked but couldn't find them but I'll take your word for it, not to shabby for road bikes.
My 118.30mph was not a record, only a PB achieved into a 15mph head wind in testing prior to an attempt on the outright 175 British Land Speed record of 118.51mph (we don't have sub classes like the rest of the world). The bike should have been good enough for around 135mph but at the time, I didn't realize I had a weak ignition system, I thought it was my weight that was knocking down the top end speed.
After two failed attempts due to melting a piston and a complete ignition failure, I had to shelve the project as I had committed to racing the Samauto drag bike with Billy Benton in the States.
I still have the bike (now sitting in my living room ) but I'm not sure if my health will permit me to ride it again.

Sam.

[scottly]

Scottly,
just for a laugh I run the reduced stroke 750 specced engine, high comp, 125/75 cam, 33.5mm valves, webbers, etc          so  displacement is 500cc at 62mm bore and 42mm stroke.   the software wasnt happy and showed a massive dip in hp and tq from 3 to 5 grand, wasnt happy with a few other things either but hey,  what Scottly wants,  Scottly gets

Crank horsepower Result.......79HP   @ 9,250 RPM
                                            45ft/lb @ 9,250 RPM

                                            85HP   @ 10,000 RPM
                                            44ft/lb @ 10,000 RPM   

Motor is heavier though than the sohc honda 500 engine,  wonder what horsepower the 500cc boys on the forum get ?

CHEERS JOHNO

Just for grins, what was the stock stoke output for the same combo? Hey, simulations are a lot quicker, and cheaper, than the real world.
What was the output of the 500cc combo at 11k?

[scottly]

   Scottly  kombi run a best of  14.1 (1/4 mle )......not sure about down salt think 120mph ..motor is based on 2.0 kombi . 2.7 Ltr SCAT heads

Are you running a late front ball-joint beam? If so, how was it lowered so far without losing caster? I know at one time there were drop spindles available, but even with them, to get that low would reduce the caster. Not good at 120 MPH!

[sohc boy]

Scottly ,yea is running ball joint front end , not real sure if got lowered spindles or changed mounting posi for front end ,( tilted ),they have changed suspension few times ......yea i had few fast lowered beetles in the old days , bit twitchy at speed allright,

[johno]

I still have the bike (now sitting in my living room ) but I'm not sure if my health will permit me to ride it again.

Sam.

Sam that wouldnt be financial health your talking 


Re the 750 modified gas and fuel record and the suzy waterbottle, I managed to get a phone number from his web site and I rang him tonight for a chat.    He had 1 run and the motor blew up at the 3 mile mark, he did set the 750 MF record though at 149.9 mph    .............. so thats the number to beat baby.

Felt a bit sorry for him as its the second time same cylinder with piston having a giant meltdown and dissappearing down the exhaust leaving the conrod to chainsaw through the crankcase, total destruction.

The custom made barrels were trashed and he will have to make another set.  The guy was friendly on the phone and happy to swap info .   he discussed his dyno shop and discussed his fuel ratios and hp numbers , running slightly rich at 12.5 to 1 at 118hp at rear wheel.

Well .....118hp at rear wheel kind of leaves me cold,  I,m fantasizing about 100hp at the crank,   but I'm thinking the Honda wont be so busy from the front with no radiators or complex two stroke chambers hanging on etc and I think at 150mph the frontal area may be more critical than HP, so stand the old girl up high to let the air have four ways around instead of low and 3 ways too go around , less rolling resistance from very narrow 21 inch wheels as opposed to his low wide tyres, do away with 5th gear and just have a new gear cut for 4th at 1:1
A highly respected skinny ares jockey on the seat .............. what else can I do ? 

[Old Scrambler]

I like your 21-inch thinking..............but I am not aware of tires for 150+ mph.  I also agree that allowing more air to go below the lump should reduce lift at speed and will allow any streamlining to be full dimension.  To me, some of the current PS bodies look like the frontal area will cause a lot of lift. Based on my reading, once the air is broken by the leading "bowling ball" shape, the ideal angle is about 10% to 15% to get to the widest area at 30% of the overall length.......then the shape to decline by no less then 10% to have the best laminar-flow rate. This should apply on a 360-degree basis in the ideal world.

[sohc boy]

interesting bout that waterbottle Johno, dont know what it is ,but BOB had same problem , seizing one cyl , same one 3 times ,(left) tried lots things try an stop it , not good feeling at 150 mph...

[johno]

Hi Dennis ,
good info, I,ll starting working on my food diet and gym to get the right body shape 

Re the correct speed rating for the 21 inch tyres they are legal for two reasons,
1.  the tyre rating allowed is based on current record so 149.9 mph the available 21 inch Avons are allowed  up to 150
2. secondly to be legal the Avon tyre has to be tread buffed back to 3mm only tread thickness to reduce the heat generated by thick rubber , heat destroys the tread in chunks and it is then fine to 150 plus with buffed tread.

Or so the scrutineer said Dennis.   

  My issue is how will they cope with a front tyre on the rear ? will they spot it , will it be safe ,  I m hoping it will be OK with slow accelleration, light traction etc the main force being G force rather than any directional force,     might be a decision for the jocky    I thinking run it and have a look after a conservative GPS run , then jocky make the call.

[johno]

Peter ,   re suzy problem..    Bring ding ding ding bang !

[Old Scrambler]

Johno...........I run a front on my rear..........no tech problem.  I have considered buffing (shaving) my front Speedmaster tread on the front.  Your on the edge at 150mph.............Maybe considered smaller wheels into the chassis design...........Yes, the tire tread may come apart in chunks........but I would also be concerned with having constant bead contact..........maybe a little more air-pressure.  At high speed the balance of the tire is more critical.........countering any tire-lump by weighting the rim will not prevent the lump from trying to escape from the perfect-circle rim.........Can you balance a tire without the rim?

My personal "shape" is more pear than meteor...........so I'll be doing a few sweating routines just to shed a few pounds to fit in my borrowed leathers

[johno]

Dennis .... more tyre pressure ? what do you run Den....  I,m planning to run about 50psi..... nitrogen   

[Old Scrambler]

I was at 50psi but re-measured on the 2nd day and both were at 45.............every time we checked. We got 11 runs in on 4-days. I'm not very concerned at my low speed

I am thinking of building something for next year that may exceed 150 mph...........so I am trying to get the chassis plan together. I think I have a good idea of what the motor will be.......sohc/4 of course

I tend to note the motor carnage in this sport usually comes from faulty fuel supplies or weak electrical systems that show the ugly side of things a little after the 1st timing tower but usually well before the 2nd tower. That mile in between really sorts the serious builders from the go-fast wan-a-be's

My slogan is GOING FAST......SLOWLY

[cbornotcb]

 Johno, thanks for posting the Gairdner pics mate, have ya heard the November/December meet rumour ?
This is me and mine



Tiny

[Sam Green Racing]

You look nice and relaxed Bob.

Sam.

[cbornotcb]

Not as relaxed as I felt 10 minutes after, it was beer o'clock, and the hole diagnosis was confirmed.
Tiny

You look nice and relaxed Bob.

Sam.

[Sam Green Racing]

Did the beer numb the pain. 

[cbornotcb]

Did the beer numb the pain. 

There was no pain,,I was expecting worse, like a ventilated crankcase, the blurry pic shows worse, luckily, the "spare" engine  donated this trophy



Tiny

[johno]

Hi Tiny,
Thanks for the update !

I was keen to offer some enlighting solution to your lean out problem but after reading your explanation I thought, hmmm    that will be a good one for you to sort out

Have you had any luck trouble shooting ?

Cheers johno

[johno]

.jpg[/IMG]

I went around my mates place to see if his K2 engine will fit in the Yamaha 1996 YZF 1,000 frame.

Wow it looks good, that is a great frame , it swallows the 750 engine, those two big frame rails leave lots of room for carbs etc.

[johno]

IMG]http://i1079.photobucket.com/albums/w511/mjohno3/DSCF1347_zpsb575e053.jpg[/IMG]

Try again with the pic, hell I'm having some trouble with photo bucket , dont know whats going on yet !

[johno]

Sorry about link only its the best I can do for now!   bit frustrating I'll google 
This pic shows the frame rails and how wide they are.   With the big back wheel and tyre the engine needs to be 20mm offset to use the existing chain set up, so we will use a F2 output shaft and an cycle x offset sprocket and that way the engine will only have to be offset 5mm, should be fine.

[Retro Rocket]

Johno, when the link posts with [IMG] at either end, just delete the [IMG] at both ends and the link will work...

[johno]

IMG]http://i1079.photobucket.com/albums/w511/mjohno3/DSCF1345_zps32f5a78d.jpg[/IMG]

This pic shows the room, enough for the webbers.  The engine has to be raised at the front 75mm so the carb angle will be fine.
chers Johno