I've been doing a lot talking lately...........now its time to start the show. Many of you know that I have been competing at the BUB Speed Trials at the Bonneville Salt Flats in recent years. I have invested a lot of time and a small fortune (for me
into a TRIUMPH T20 Tiger Cub. I have a good friend, Dave Murre, to help me
;)as in I do most of the research and pay the bills, Dave builds the chassis and the motor, as well as most of the tuning and other mechanical chores at the salt-flats. We travel together in my van with an old Wells Cargo enclosed trailer to hold the bike and tools.
We have been very fortunate to have passed through tech on both of our trips and achieved a class record as well. No blown motors or any other carnage........just TIME-SLIPS and good memories of hanging out in the impound area to get the motor certified for the record. In 2013 fellow members Grasscutter (Zak from Omaha) and Rxman (Jerry from CO) joined us as part of the pit-crew.
Our top speed on the Tiger Cub has been 89 mph in the push-rod 250cc class. We are making a few changes to the bike for 2014 and hope to get into the mid-90s.
Now begins the SOHC/4 saga...............I've been riding a CB750 since August of 1969. My avatar is my K3 that I have had since new in May of 1973. I've played with a few others but never did anything to a motor other than change head-gaskets and seals. I went to my first swap-meet in 1999 and bought a very sorrowful excuse of a 1970 K0 thinking I could make some money...........and I surely did. I have made over $3000 selling parts from that bike....and I still have the very clean motor. Over the past 15 years I have gathered about a dozen motors and chassis and now plan to build a bike to compete in the new CLASSIC category of 1956 - 1980 bikes sanctioned for records by the AMA.
The basic frame is from a CB750A because I hope to be able to remove the head with the motor in the frame. If I get a record, the rule is that the motor has to be measured to verify the stated motor size. In this class a .050" over-bore is allowed. My motor will be 761cc but legal for the 750 size category. I will build the chassis to comply with the MODIFIED rules which basically means the seat-height must be above a horizontal line at the top of the rear wheel, and the overall wheelbase can be no more than 10% over stock. There is a host of other rules of course, but the motor and the frame around it must be recognizable as the stated make and model on the entry forms.
We have cut the top-rail from the rear of the frame and made a new 'hoop' to be mounted a little lower and somewhat narrower were it re-attaches to the frame. This will get my butt a lot lower with a flat seat and no foam, as well as allow my knees to be a few inches narrower so they catch less air. We have selected an early Kawasaki alloy swingarm that needed very little modification, and moved the oil-tank mounts inward to avoid my right leg.
The front end is converted to a GL1000 set of forks for strength and axle stability. We have several wheel choices but will likely be an 18" rear and a 19" front with 110/90 and 100/90 speed-rated tires to exceed 150 mph. The motor started as a K4 that was very clean and shows no wear on the internal parts. For this build Dave and I agree that stock rods should work but they will be shot-peened and polished. The J&E 12.5:1 pistons were secured from Bill Benton ($2 Bill). Boring will be done by MELLENNIUM TECHNOLOGIES.........I get a deal and carry their decals...........The head is from an F2 motor and will be ported and polished by Dave Murre. We know that will cause a loss in compression.........but with a little shaving, decking, skimming, thinner head-gasket and such, we hope to be at 13 to 1.
We are sourcing parts from CYCLE-X, A.P.E. and DYNOMAN. A few others will likely be needed........and all advice is welcome. I am leaning toward using the Megacycle 125-30 cam but have not ordered until we get the valves installed and measure clearances with the F2 cam.
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Dave modded the dyno cover............we kept the starter clutch and gear to use the electric start powered from a remote battery.
