UKDRN

Do you own or know the whereabouts of a piece of UK Drag Racing History or just want info on a particular machine.

Moderators: timetravel, ukdrn

 #39895  by shasta
 
The original bike first appeared with Amal carbs and as the bike was improved it finally ran with Hilbourn fuel injection running on Nitro. Experience and finances meant I would be using carburettors running on petrol ,but using Kawasaki carbs were out of the question due to their cost; anything related to Z1s or Z1000s commands high prices these days.
The obvious choice were the carbs fitted to the Suzuki GSF1200 Bandit model as these have been around for years so there is a good supply of them on the market. Having obtained two sets and offering them up to the Kawasaki cylinder head showed up a potential problem. The air inlet spacing of the Bandit cylinder head is different to that of the Kawasaki Z900 head and the Suzuki rubber inlet stubs have a different bolt spacing so can't be used either. Trying to fit the Suzuki carbs to the Kawasaki inlet rubbers didn't work either as the diameter of the Suzuki carbs is too big to fit.
The difference in spacing is about 5 mm and by luck it was found that the inlet rubbers used on the Kawasaki GPz600R have an offset of 5mm and are the same size as the Suzuki rubbers although are a push-on design and not bolted on, so all that was needed were some inlet stubs and I'd be in business.
The photos below show the stages in the production of the stubs ending with the carbs fitting the Kawasaki engines perfectly.
Attachments
Difference in carburettor spacing
Difference in carburettor spacing
Picture1.jpg (121.99 KiB) Viewed 8167 times
Inlet stub material
Inlet stub material
Picture2.jpg (62.14 KiB) Viewed 8167 times
Tube turned to accept inlet rubbers
Tube turned to accept inlet rubbers
Picture3.jpg (81.79 KiB) Viewed 8167 times
Stubs progressing
Stubs progressing
Picture4.jpg (116.88 KiB) Viewed 8167 times
Completed stubs after cutting and filing
Completed stubs after cutting and filing
Picture5.jpg (128.64 KiB) Viewed 8167 times
Finished inlet stubs
Finished inlet stubs
Picture6.jpg (166.32 KiB) Viewed 8167 times
Carburettors fitted to engines
Carburettors fitted to engines
Picture7.jpg (197.43 KiB) Viewed 8167 times
 #39910  by shasta
 
The rear brake fitted to the bike was originally a cast iron dished car item which was really heavy, and used a Kawasaki rear twin piston opposed type caliper from a 1970s motorcycle. Due to the design of the car wheel used, a dished disc had to be used to avoid hitting the rim and if this was to be replaced by a modern flat, two piece floating type disc from a modern bike then it would have to be spaced out from the hub.
A disc from a Kawasaki ZR 1200 was chosen and a spacer made to move the disc out enough to provide clearance for a Honda VFR750 four opposed piston caliper to be used. The spacer was lightened and a new mounting bracket and lighter brake torque arm were also made, the total weight saving over all the old components was over 10 lbs!
There was no sign on the frame as to how the rear brake was operated, no mounting points or pivots, so a thumb operated lever has been fitted to the left-hand side of the handlebars using a BMW rear master cylinder.
The photos show 1.Finished brake assembly, 2. The old brake arrangement, 3. Aluminium bar before machining, 4. Finished spacer, 5. New disc fitted, mounting bracket for caliper under construction
Attachments
Finished rear brake
Finished rear brake
IMG_4390.JPG (2.38 MiB) Viewed 7909 times
Original brake set-up
Original brake set-up
Picture2.jpg (137.14 KiB) Viewed 7916 times
Aluminium billet for spacer
Aluminium billet for spacer
Picture1.jpg (155.57 KiB) Viewed 7916 times
Finished hub spacer
Finished hub spacer
Picture3.jpg (140.1 KiB) Viewed 7916 times
Caliper bracket being made
Caliper bracket being made
Picture4.jpg (146.18 KiB) Viewed 7916 times
 #39912  by shasta
 
One of the last tasks has been to work out how to start the bike! Using rollers turned out to be a non-starter as the gearbox has a one-way sprag clutch fitted so it does not allow the rear wheel to drive the engines. The obvious choice was to make a plug-in starter to pick-up on one of the engine drive pulleys. However there was always the thought that if the engines started, then the starter drive may become jammed into the pulley preventing the operator to pull it free. The design has made the drive 'fingers' to be angled on the reverse side, so that when (if!!) the engines start then the pulley will drive the starter fingers and force them out of the pulley. It should be tried out in the coming week or so once the few remaining tasks have been completed, including making up a battery carrier and wiring it in, it should be start time. I hope to video that moment, so that could be the next post.
The photos show the stages of making the drive to engage with the pulley.
Attachments
Plate for drive device
Plate for drive device
IMG_4238.JPG (1.68 MiB) Viewed 7819 times
Plate ready for cutting
Plate ready for cutting
IMG_4243.JPG (1.15 MiB) Viewed 7819 times
Drive fingers showing angled rear faces
Drive fingers showing angled rear faces
IMG_4382 (2).JPG (1.7 MiB) Viewed 7819 times
Completed starter motor
Completed starter motor
IMG_4383 (2).JPG (2.43 MiB) Viewed 7819 times
Close up of starter motor
Close up of starter motor
IMG_4384 (2).JPG (1.94 MiB) Viewed 7819 times
Rear pulley for starter drive
Rear pulley for starter drive
IMG_4389.JPG (1.43 MiB) Viewed 7819 times
 #39913  by shasta
 
After putting oil in the engines, plugs out, ignition off, it was time to spin the motors over to circulate the oil. All connected, push the starter button ....and the starter barely moved the engines. Doh! The scene in Jaws came to mind when Sgt. Brodie says 'We're going to need a bigger boat'. Off to the breakers to see what the largest 12 volt starter motor is available...
 #39914  by NitroWars
 
Some nice engineering going on there, good luck with the starter motor
 #39931  by shasta
 
This motorcycle will be on display at Santa Pod Dragstalgia meeting on the Saturday and Sunday along with former Competition Bike BC245 which held the ACU No.2 plate in 1990 and 1992, they will be in the Historic vehicle marquee. Do come along and say Hi, hope the weather holds out.
Attachments
BC245 now back in street legal trim
BC245 now back in street legal trim
Capture 2.PNG (805.44 KiB) Viewed 6903 times
BC245 at Avon Raceway
BC245 at Avon Raceway
Capture.PNG (75.45 KiB) Viewed 6903 times
 #40131  by shasta
 
Just completed modifications to the handlebar layout and controls. New starter motor obtained so will again go for an engine start in the next few weeks. Photo found on the net taken at the Pod during the Dragstalgia meet..a fine looking motorcycle, even if I built it myself!!
Attachments
santa pod 3.jpg
santa pod 3.jpg (325.12 KiB) Viewed 4827 times
 #40132  by shasta
 
When at the Pod back in July, we took the chance to see if the monkey bike was capable of towing the double any distance. It did, but whilst in the riding position it became apparent that there was a slight design fault..namely my thumb couldn't reach the shift buttons or rear brake thumb lever..Doh!!!
Whilst thinking through how this could be overcome, there were several areas where weight could be saved and improvements made. The original fork yokes and steering stem were replaced by an aluminium pair from a Honda CBR400 with much thinner stem, taper roller head bearings fitted, the handlebars were moved back 2 inches and down by an inch, new bracket moved the shift buttons under the bars, a smaller brake reservoir was fitted, smaller rev counter bracket made, towing hitch fitted, titanium fork clamp bolts used and new light-weight handle bar clamps used.
Photos show before and after layouts with the first two showing the state of the bike 9 years ago before a start was made!!
Attachments
Old yokes 9 years ago
Old yokes 9 years ago
old layout.jpg (1.24 MiB) Viewed 4761 times
Front end before rebuild
Front end before rebuild
old bars.jpg (1.24 MiB) Viewed 4761 times
Old layout with shift buttons on top of bars
Old layout with shift buttons on top of bars
IMG_4052.JPG (2.15 MiB) Viewed 4761 times
Old control layout
Old control layout
old layout shift buttons.jpg (1.71 MiB) Viewed 4761 times
New yokes and towing hitch
New yokes and towing hitch
IMG_0015 (2).JPG (1.39 MiB) Viewed 4761 times
Shift buttons and brake lever under the bars
Shift buttons and brake lever under the bars
IMG_0013.JPG (2.05 MiB) Viewed 4761 times
New control layout
New control layout
IMG_0016 (2).JPG (1.3 MiB) Viewed 4761 times