Author Topic: seeking 1970s pro stock bike regs (Read 7101 times)

Greg H · « **on:** September 16, 2012, 01:19:41 PM »

Hi Guys .I need some help off some of you guys who were racing back in the 70s cos I've been going stare crazy on the old lap top today $:-\$ , and I seem to have hit a brick wall in my quest to find some construction regulations for 1970s pro stock bikes .I did used to have the ACU handbooks, which were the British equivalent of the rules from that period, but they went in the trash many moons ago .So if anyone has a rule book for sale from that period, or would be willing to provide me with some information regarding stuff like, what was the maximum allowed wheelbase/minimum ground clearance etc, you know anything like that , I would be very grateful . Cheers Greg "H".

Sam Green Racing · « **Reply #1 on:** September 17, 2012, 06:15:20 AM »

http://www.dragbike.com/forum/showthread.php?63284-construction-rules&p=638459#post638459

There's chance of a result here Greg.

Sam.

Greg H · « **Reply #2 on:** September 17, 2012, 12:08:46 PM »

Thanks for that Sam . I've registered on there , so we'll see what happens .

jweeks · « **Reply #3 on:** September 17, 2012, 08:09:24 PM »

The oldest NHRA rule book that I've got is 1987. There are no Pro Stock Bike rules at all in that book. Same for 1988. In 1989 the NHRA rule book showed the Pro Stock Bike class. 2-valve motors up to 86 cid ran at 6.48 lbs./cubic inch. Over 86 cid, ran at 6.42 lbs/cubic inch. 530 lb minimum. Front suspension OEM fork tubes minimum of 35mm; aftermarket allowed down to 32mm dia. 1.5" minumum fork travel. 2" minimum ground clearance with rider sitting on bike with 6 psi in rear tire. Stock shape factory windscreens allowed. No aftermarket ones allowed. Windscreens may be trimmed. No external scoops or air intake hoses allowed. Use of existing air intakes on fairings permitted. Front portion of gas tank shell may be cut for air intake opening. No belt drive magnetos. Gas only

1988 International Drag Bike Association rule book. 68" maximum wheelbase. 2" minimum fork travel. Magnetos allowed. Gas or alcohol allowed for fuel. 2valve motors 6.47 lbs. per cubic inch, 1500cc maximum. Wheelie bars maximum 60" from rear axle center to wheelie bar wheel center.

It may be from a too late era, but it's a start.

Jon Weeks

Sam Green Racing · « **Reply #4 on:** September 18, 2012, 07:58:49 AM »

I wondered if pictures might help and typed Honda Pro Stock drag bike 1975 into Google images, look who turned up.

http://www.google.co.uk/search?hl=en&q=Honda%20Pro%20Stock%20drag%20bike%201975.&gbv=2&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi

Sam.

Greg H · « **Reply #5 on:** September 18, 2012, 10:20:53 AM »

Thats great info Jim (Jon)

. Like you say a little late , but it's a start . I've managed to find a 84 NHRA book on fleabay , the seller states that there is some bike class content in it . I guess I'll just have to keep on digging

Sam , I really enjoyed the pics particularly the old Harley pro stocker , right up my street . I just love that bare look of the early bikes .Talking of nostalgia, I've got three meetings lined up for the end of this season , two are going to be up at York Raceway , I just love the old Pennine Dragstrip , proper "old school" but it has to be said a bit hairy up the top end on the Busa

Sam Green Racing · « **Reply #6 on:** September 18, 2012, 03:47:52 PM »

Will you be at York this Sunday? I'll be racing my secret weapon, can't give out any info or it wouldn't be a secret.

Sam.

754 · « **Reply #7 on:** September 19, 2012, 08:32:47 AM »

What are you planning to do with the bike.. mostly drag racing ? or ?

Greg H · « **Reply #8 on:** September 19, 2012, 09:43:06 PM »

Yes Sam , this coming Sunday . It's the same day as the wifes birthday ( or should I say my main sponsor

) so I've had to be on my best behaviour this week . It's our first meeting of the year so we'll treat it as a test an tune day , and I'm sure for at least the first eighth I'll be taking it easy

754 , There seems to be a growing interest over here in old Drag/Sprint bikes . People are dusting down some famous old bikes that havn't seen the light of day for years and running them at classic race meetings . Even though the bike that I'm building won't have a racing pedigree, I just thought it would be cool to build a bike that will be different from all of the modern stuff , and who knows I may even take it to a few shows , but yes I will be racing it . I guess it's just a nostalgia thing , I just fancy going back to my roots racing something interesting, simple and low tech and just having a good day out

johno · « **Reply #9 on:** September 21, 2012, 05:55:18 AM »

Yeh baby do it.

RP · « **Reply #10 on:** November 03, 2012, 08:19:57 AM »

I still have most of the AMDRA, IDBA, and NHRA rulebooks from the 70's. Pick a year you are building a replica of and I will give you the info I have. 73 was probably the first year for the class and the rules changed a bit by 79. Seems like all the competitive Hondas were gone by 75 or 76, RC Eng switched to Kawasakis and that was the end of the SOHC . Byron built a 1100F that set the record first time out and was done after that.

Greg H · « **Reply #11 on:** November 03, 2012, 03:01:01 PM »

From what I've read the AMDRA held the very first pro stock bike races in 73. However , I'm aware that as the class grew , other organisations had their own sets of different construction regulations for pro stock bike .Therefore as what I'm building could be described as a replica of a generic early 70s Honda sohc pro stocker , it makes sense to me to build it to the early/mid seventies AMDRA rule book .
Any info you can provide will be greatly appreciated . Cheers

Greg "H".

RP · « **Reply #12 on:** November 06, 2012, 03:54:16 AM »

I have the 1972, 75 & 76 AMDRA rule books. From the 75 rulebook: Min disc brake size is 7 inch dia x 1/8 inch. Handle bars must be mounted in stock location, no part of grip may be below bottom edge of top fork crown. Must use stock frame, only mods are removal of unused mounting tabs ad removal of outer top tubes on Honda for easy engine access. I was suprised that raking was not allowed yet. Aftermartet forks allowed, 34mm min tube dia, and within 2 inches of stock length. Stock type head light and mounts must be retained. Aftermarket Swing arm allowed, max is 28 inches from center of counter shaft sprocket to center of rear axle. They gave the 2 strokes 30 inches. Struts and wheelie bars permitted. Looks like Bruso won the 74 PRO championship without wheelie bars. 2 inch min seat padding. No ground clearance rules or wheelie bar length in PS or general rules.

Greg H · « **Reply #13 on:** November 06, 2012, 01:59:09 PM »

Nice one mate . That info is really helpfull . I fancy fitting a set of cerianis up front ,if I can find a good set for the right money. Wheelie bar wise, I'll just have to do them so they look right for the era . The only problem I've come up against so far is finding a suitable rear tyre . Ive got a new 18/7 Mickey Thompson which is way wider than was available back in the day . I've found a suitable 19 ins race front , but so far I havn't managed to find an 18ins road race rear slick of the correct width .

jweeks · « **Reply #14 on:** November 06, 2012, 03:55:10 PM »

Greg,
How's this?
http://www.mandhtires.com/M-H-Racemaster-Motorcycle-Drag-Slicks/4.0-26.6-18-Vintage-Motorcycle-Slick#.UJmi22dQSek

4" wide surface, fits 3.5" wide 18" rims. Should go into the 10's easily.

Jon Weeks

Sam Green Racing · « **Reply #15 on:** November 06, 2012, 04:20:59 PM »

Jon, we were using those back in the 60s, I think they were a bit wider come the 70s.

Greg, contact my mate Tony Salt, he is the UK distributor for Avon and Micky Thompson drag slicks.

http://www.tst-tyres.co.uk/

Sam.

Retro Rocket · « **Reply #16 on:** November 06, 2012, 07:26:05 PM »

Quote

Jon, we were using those back in the 60s, I think they were a bit wider come the 70s.

That is the same size wheel tire combo that was on my 750 drag bike Sam, fitted easily , no offset sprockets either....

Sam Green Racing · « **Reply #17 on:** November 07, 2012, 02:02:46 AM »

Yes but did it give enough grip Mick and which compound was it ?

Sam waits patiently for answer

Retro Rocket · « **Reply #18 on:** November 07, 2012, 02:04:10 AM »

Quote from: Sam Green Racing on November 07, 2012, 02:02:46 AM

Yes but did it give enough grip Mick and which compound was it ?

Sam waits patiently for answer

It was a methanol 10 second bike Sam, and i still have the tire, where do i find info on compound on the tire mate...?

RP · « **Reply #19 on:** November 07, 2012, 02:55:56 AM »

Most of the PS bikes in 1974 used an 18 inch front rim with a Goodyear road race slick a little larger size than the ones used on current pro stock bikes. I'll try to post photos from old magazines.

Sam Green Racing · « **Reply #20 on:** November 07, 2012, 03:09:20 AM »

Quote from: Retro Rocket on November 07, 2012, 02:04:10 AM

Quote from: Sam Green Racing on November 07, 2012, 02:02:46 AM
Yes but did it give enough grip Mick and which compound was it ?

Sam waits patiently for answer

It was a methanol 10 second bike Sam, and i still have the tire, where do i find info on compound on the tire mate...?

It looks like they (M&H) only do the one compound now Mick, HB-11.
I'll have a look see if I can find the old data from yesteryear.

Sam.

http://www.mandhtires.com/M-H-Racemaster-Motorcycle-Drag-Slicks/4.0-26.6-18-Vintage-Motorcycle-Slick

Sam Green Racing · « **Reply #21 on:** November 07, 2012, 05:58:07 AM »

I just found this on Joes HD forum from earlier this year but it only mentions the HB-11.
In my post I quoted the other compounds that were available in the day.

http://www.phpbbplanet.com/granddaddyjoesm/viewtopic.php?t=293&mforum=granddaddyjoesm

Sam.

Greg H · « **Reply #22 on:** November 07, 2012, 01:16:57 PM »

At first I was all set to use the 7ins M/T with a wide rim from Hagons laced up to a K7 rear hub, but after thinking about it I figured that yes I would have had good grip but it just wasn't authentic 70s .

Jon , I've looked at those slicks , were those type of tyre used on P/S bikes back in the day ?. I thought that people were using road race rear slicks .

RP , I've got an RC catalogue which shows their first P/S Honda sporting a 19ins front wheel , which is why I'm considering it . Although my bike isn't meant to be a carbon copy of the RC bike I reckon that it will end up looking something like it .

Sam , I'll contact Tony Salt . Now that I've decided on the mods that I intend doing to the frame. I really need to sort out wheels/tyres as soon as possible .

jweeks · « **Reply #23 on:** November 07, 2012, 01:54:47 PM »

Was that size tire available back then? Yes, it was. Was it used for Pro Stock Bikes. I don't think so. How accurate a recreation are you trying to make? If you're planning to put into the motor what we've discussed, please get a current
"7 inch" slick. You do realize that those slicks actually measure 5.5" wide? That 4" wide slick will run 10's just fine. You can build a motor that will go low 9's easily with a slider or lockup clutch. That's a little beyond a 4" tire. Most road racing slicks were a little too hard for drag racing. The industry rapidly evolved for drag racing needs. M&H tires were there in the early days. A modern "7 inch" slick on a 5" wide rim laced to a stock hub would be close enough to look something like the early days, but be a lot safer for quicker than then runs. Just my opinion...

Jon Weeks

RP · « **Reply #24 on:** November 08, 2012, 02:27:59 AM »

The first RC pro stock I saw was probably 1974 and they already went to a 15 inch diameter car tire at that point, with an 18 inch front....that bike is on the back of the 76 AMDRA rule book. Someboby should remember what tire was used in 1973.

News:

Author Topic: seeking 1970s pro stock bike regs (Read 7101 times)