McCulloch at Bonneville??

[Jeff Campbell]

I have been trying to dig up some of the history on McCulloch's land speed runs at Bonneville in the early 70's. I have a page from McCulloch published a large fold out poster ad, it was folded to a 8 1/2 x 11 inch size, on one of the panels was mention of several class runs at Bonneville ...



it mentions the MC91B1 setting a World Record of 100.888mph in the APS-A-200 class, and while this ad is written in cryptic ad speak, I think it goes on to say that the MC101A set a World Record of 100.587mph, and ran an unofficial 110.56mph during practice in the A-AG-250 class.

I remember reading this when I was a kid, and at the time was really amazed that a single MC91B1 could go over 100mph, but that was the cryptic ad speak mis-leading me, these records were set running dual engines .... I did a little digging into Bonneville class designations, APS-A-200 is an Altered (stretched) motorcycle with Partial Streamlining not running gasoline with 200cc. In plain speak ... a stretched dual 100cc engine motorcycle with extensive fairings, running open fuel. The A-AG-250 was a stretched dual 125cc engine motorcycle with some fairings, running gasoline.

mcculoch_bonneville_motorcy.jpg

I believe this is the McCulloch Powered A-AG-250 class land speed Bonneville World Record holder (100.587mph on gasoline)?

(102.29 KiB) Downloaded 1205 times

Does anyone know anything more about these McCulloch powered land speed motorcycles? who built them, what were the specs, were the motors modified, did they run pipes, clutch or direct drive, and of course where are they now?

How do these records compare to those of today???

(designations in a nutshell: the first letter A means stretched altered frame, a PS following that means Partial Streamlining, G is for pump gas, F is for open Fuel, BG is with a Blower running gas, BF is with a Blower running open Fuel, the 2 or 4 at the end stands for 2 stroke and 4 stroke engine - note the designations from the early 70's were a little different)

Jeff

[steveohara]

Jeff,

I don't have any info on the Bonneville efforts but I can tell you that my old notes from Ontario Motor Speedway 1979 Nationals for my 125cc Mac entry running a "stock" 101B on alky have the following data...
gear ratio 23/85, top rpm 12,100, rear tire OD standing still 35.25"..... run the calcs and you get 110.06mph
lap time 2min 17 seconds, average speed 84.09mph

for my reed light entry with the stock 91B1 on straight alky the numbers were as follows..
gear ratio 21/85, top rpm 13,000, rear tire OD standing still 34".... works out to 103.4mph
2min 23 seconds, average speed 80.55mph

The numbers you mention in the article seem realistic to me based on the results I had with my Hartman enduro chassis on a long track.
Regards,
Steve O'Hara

[Ron Carbaugh]

Jeff,
You might try asking the people at SCTA (Southern California Timing Association) and see what records they have and a name to go with it? I may be able to help you if you have a builder/owner or rider as I have spent most of my life in the Racing Motorcycle circles. He is their web site.

http://www.scta-bni.org/

[ted johnson]

Hey, Steve! Tire O.D. 35.25 and 34? Man, that's some huge tire ! BTW, Steve, the print for the side mounts worked out great! I clocked the engine up 22-1/2 degrees and designed the plate around the pattern. Thanks again.
I hope all enjoyed the Easter Sunday. TJ

[Tom Luttenbacher]

Ted, I have to beleive Steve is measuring around the tire with a flex tape, as in roll out...could be wrong, but my Harley 19" front wheel has a Dia of 25.5", rollout over or near 3 feet.

Jeff in my 8 years of racing at Bonneville there were never any bikes as pictured with other than manufactured motorcycle engines in use. I beleive that kind of machine was outlawed years ago as I did in the local museum see a bike chassis with a 2 cylinder motorboat engine from many years gone by, or if there wasn't enough entries for a class none would be established, tho if such a vehicle, 2 or 4 wheeled came they would allow, if passing all tech preceedings, a run for "time/speed" only.
Everyone ran production, all years, with various mods as you point out, the exception being when you entered in the plus 2000 cc classes you could freight train 2 engines. Motorcycle classes started at 50cc and went as high as 3000cc. These usually were open or PS framed bikes. TL

[ted johnson]

Hi, Tom. I figured that, just wanted to give Steve a hard time! The dual Mac bike is cool. Bug's dual Mac minibike was cool, also, but I'd rather ride the big bike at that speed! 12" tires don't have much gyro effect! TJ

[Rob Voska]

A few years back Mike Clemens took a enduro frame with 4 Briggs on it. As I remember the story he got like 135 MPH and it just spun the tires because of the wind drag. Don't know if he ever went back.

[steveohara]

Ted,

Did you see what time I made that post?..... it's a wonder that any of it made sense
As Tom surmised... I meant circumference, not O.D.
I can say one thing... I would not want to go that fast on a glorified mini-bike!
Steve

[ted johnson]

Wow, Steve! Don't you sleep? That's about the hour I get up for the office! Mac mount side plates in powdercoat shop. I will pick them up Friday.
I still think 34" tires would fly...The Turbonique axle powered kart from the early sixties actually had mag dragster front wheels and tires all around. I believe it was a first-series Bug Stinger, but I'm not sure...Heck, I'm old. Anyhow, it looked silly, but it was fast on the strip. I'd like to see a picture of that one again! Later, Ted

[Rob Voska]

I remember one of the early kart mags (1960-63?) had a picture on teh cover of a kart at Bonneville on it but don't remember anything about the article.