Here's bringing some motocross history back to the surface with a visit to Bob Hannah's 1986 Unadilla USGP winning, Boyesen link equipped RM 250 and we couldn't help but highlight this bike as we felt there couldn't be a better rider's bike in the history books to highlight than one of Hurricane Hannah's old USGP winning steeds.
Before getting into too much about "Hurricane" Hannah's 86 Unadilla USGP race winning bike, we thought we'd better let you in on some background about the Boyesen Link setup on this bike.
Beginning in about 1981, Boyesen Engineering began developing prototype linkage systems for motocross bikes with the idea of eliminating "Chain Torque" and during the subsequent years, there was an enormous amount of testing and fabrication which was performed on each of the major manufacturers dirt bikes.
After the bulk of this testing concluded with the major brands which included Honda, Yamaha, Kawasaki, Suzuki and KTM, Bob Hannah climbed aboard and rode a production based model Suzuki RM 250 equipped with the "Boyesen Link" designed to eliminate chain torque to a victorious win at the USGP held at Unadilla Motorsports in 1986.
Incredibly enough, we were able to spot Hurricane Hannah's former link bike as these bikes were also referred to as, which was on display at a Florida Vintage Motocross (FLVMX) race which we were attending, as it was brought out by one of the founders of the "Legends and Heroes of Motocross" tour which is traveling the country and happened to be at Lake City Motocross (LCMX) in Lake City Florida while we were attending, at which time we were able to take some pictures of this, and that combined with the excellent assistance we received from Dag Boyesen of Boyesen Engineering, we are able to present Bob Hannah's former race winning link bike to you with some details that you should find interesting.
Now in addition to the points outlined above, you'll likely also notice what you should recognize as the Boyesen "RAD Valve" but what was most interesting about this particular unit was that in 1986 the "RAD Valve" had not yet been placed into production, and this unit was a hand made piece built specifically for Bob Hannah's RM 250 which he piloted to victory at the 1986 USGP at Unadilla ahead of Johnny O' Mara after what has been rumored of Bob Hannah pushing the O' Show so hard that the "Hurricane" caused O' Mara to run out of gas on the last lap handing the win to Bob Hannah aboard this RM 250.
Now considering all the modifications to this bike you may be left wondering how this bike could be referred to as a "Production Bike" and we wondered the same thing, so we asked Dag Boyesen at Boyesen Engineering and after posing the question of: We've heard talk about Bob Hannah winning on this bike and that he was the only one to win a USGP on a "Production" bike, but is that accurate? Is a bike considered "Production" with an exotic rear suspension such as that? At which Dag Boyesen commented: "I would say that it was a production based bike. Started as a stock RM250, bought from a dealership and modified."
Then we just wanted to find out directly from the people who designed this setup what the true benefits of using this setup were, so again, we went back to Dag Boyesen and asked him: Could you tell us the benefit(s) of this setup? We heard it was something to do with constant chain tension but are not certain on that. At which Dag Boyesen Replied: " The system eliminated chain torque. The chain could be set with tension because the distance between the countershaft and rear axle never changed. In stock form the shock dampening had to be firm enough to offset the chain torque. The Boyesen Link eliminates the "squatting" from the chain torque and allows for much improved traction and feel over acceleration bumps."
And finally... We wondered why this was discontinued: So, Again we asked Dag Boyesen; Why was it abandoned? At Which Dag Boyesen replied: " All major manufacturers tested the system and saw and acknowledged the benefits. The cost to retool and manufacture this is what was always the negative from the decision makers."
And with that the rest is history but you may enjoy some of these pictures of Bob Hannah's former Unadilla USGP winning bike ...
Wondering If We Cover More of Your Dirt Bike Interests?
Find Out Right Now.