update on elegibility for thunderbike

The bike I'm building is 21 years old and sometime hopeful of entering it into thunderbike championship like my other blog cbr640. The 1990 vfr750 is currently not legible but soon may be as the rules for thunderbike have kind of stayed static on 4 cyclinder water cooled up til 1990 since 2006. Heres what they said to me recently

Hi Bill

I can only comment on 2011 at the moment and yes as it stands your bike is ineligible.
How ever the rules for 2012 will be issued later this year and you should reasonably expect there to be some major updates as this will be the 2 year upgrade cycle time we normally have. I will not be drawn into a discussion now, but your bike and others like it are being considered for inclusion. Keep watching and building.

Best regards

My bike should be ready by then!

Managed to get the pesky exhaust off, one nut was so rusted it sheared , the lower came off with a lot of brute force and the final grawnched nut I had to resort to the angle grinder, blow torch and chisel, which luckily split in two. Then it was easy getting all the suspension off. The log came in handy as a stand, very useful as it was just the right size.

took this while walking the dog, bsa bantam standing up in the bog. been there for years!

dismantling

carbs off, exhaust has beaten me today, typical rusted rounded nut, ones already sheared on the back end, the link between the header and down pipe. looks like i will have to remove all the back suspension so i can get at it.

Next!

Strip the bike down completely!......enough making and fitting...time to take things apart....then I can go back to tidying up the bits I ve made.

step one start removing fairings, sub frames, clutch/front drive sprocket cover, ignition coils. Then Spray copious amounts of Plus Gas lubricant,leave over night............tomorrow exhaust and carbs.

bottom fairing

Bottom fairing cut across and shunted forward picture on the right. Looked at it again thought it could go further forward. So Now the picture on the left has it in its final position a good 10 inches from its original position. Put three flat allen bolts to secure it. Next step will be to out some kind of flat rubber seal where the rear part slides over. For racing it has to seal to capture oil. The rules says it needs a 25mm sealable hole/drain plug for if it rains during racing. I wonder if my removable lip can qualify as a sort of drain because it can be unbolted as it does have a 50mm lip required by the rules. Just to finish off i made a aluminum bracket to suport the fairing side. Now the whole fairing is basically complete.
While I was at work I had some spare time so made a new housing for the temp gauge and found a spare lug to fit it. using Corel draw and a laser cutter I cut out a new surround for the temp gauge..picture later....now its time for the next step.

Oil cooler Air vent

As the old beast is 21 years old! The late 80's and early 90's honda used a small oil radiator for cooling. Later designs got rid of the annoying pipe work and instead used a cooling device around the oil filter......like a water jacket. It saved on pipe work, I guess it made the oil pump more efficient, less umph to push it through the Metre or so pipe work. I guess thats engineering progress but I'm stuck with it, it works so Ive soldiered on and created my air vent duct from a ford air intake(previous post), fixed it into position with an aluminum bracket. The tricky bit to do was to measure and cut the front hole. It had to be slightly smaller than the plastic vent so not to look untidy................................ Job done!

Tachometer mounting

Took the clock completely out of its housing exposing the inner part holding the circuit and electromagnetic dial gauge. Thought if I could thin it down as much as possible then it could fit in the centre area. I used the old clock mount and cut the original 3 point fixings off and filed, sanded bare, then welded into position. The mounts were welded on in a L shape onto the front perimter frame...where the frame dips in a curve( see other picture back last post). Looks quite neat.......remember I'm trying not to spend much money at the moment so I'm looking at re-using as much as possible from the vfr......might as well as its not going back to being a road bike..I guess I can do the same to the temp gauge...wont need the fuel gauge.
Incidently If i could get my hands on a vfr750f-h wiring diagram it would be interesting to see how the older bike wired its Tachometer. The usual 3 wire tachos have the +,- and pulse from one coil. One coil sparks usually 1,4, and 2,3 needing only 2 coils as there is a dead spark when one piston is BDC. BUT here the vfr's unique firing order needs 4 separate coils so how did the old vfr's tacho work? May be it was the same as this one, 2 wires from the cdi box. Time to buy a haynes manual...funny while I write this I can here an owl in the distance...must be late.

windscreen/oil cooler

Windscreen is now fixed at 3 points, went to a scrap yard to look for air ducts/pipes. cars usually have lots of odd flat plastic ducting that funnel air into the air filter. Found a selection, most useful was a mid range ford late 90's, got a few the same shape from different models. keep them just in case I have to make another fairing. Ive cut it down. All I need it for is to direct air from the front nose cone( hole yet to be drilled..not looking forward to that bit) onto the oil cooler. Made a small aluminum angled bracket to hold the air duct in place. Good fix, I may not even need to attach the end of the duct to the nose cone. Not done much else today as the wife wanted to go the pub...couldnt refuse that!

front perimeter frame finished!

front nose cone is now secure. Used parts of the old sub frame, reversed some brackets and it all seemed to go quite smoothly. The oil cooler will sit inside the nose cone but i will create some air ducts to force fresh air around it...........I think, oil cooler pipes were swopped sides because it had to sit upside down because it would reach my fixing point and the pipes would have fouled the fat forks. Thinking about which clocks I will use. The original vfr one has 2 connections, one goes direct to the cdi box the other to earth, works by the cdi box sending a voltage, the greater the voltage the more revs. I was hoping to use my old cbr600 fh clocks as theyre already cut down to bare bones and quite small. even has the temp gauge next to it but the problem is that it has 3 connections, earth, coil pulse and cdi box so works on the pulses from the coil. So 1990 on new model honda's tend to have the 2 connections.
Fairing lower is still a worry that its too low.Not sure how to get round this because of the race regulations insist on a lower fairing to contain oil. Most bikes of this age had the fairings as a 2 part because the exhaust were directly under the sump.
perhaps i could try and put a small belly pan.....or try and cut the lower tlr fairgn down a bit because its quite long and tends to dip at the back end.
Had some thoughts on various ideas too, could i make a manual exhaust valve flap so i can vary the back pressure at different revs, try and give it mor etorque low down by restricting the flow then opening full above 8000. Also could I create a variable airbox. Got me thinking now for the future. At the mo though I have to deal with the mundane issues like making sure all fairing brackets, steering obstructions, clock mounts, radiator, coolant tank....list goes on....then its finally stripping it all down, engine tweaking, suspension twiddling then finding ive run out of money to test it!