This is my bike, already listed in Pictures as R90/6 Project
I have owned it since 1993 and have been constantly messing with it whilst riding it too. After an accident in 2006 it was taken off the road to sort out some problems and then it got sidelined due to the usual reasons - new baby, renovating a old apartment, lack of time and money. I have been working on it since this spring and hope to have it on the road for the beginning of next year.
It has the usual engine modifications as listed below, plus a system which I have been working on to deal with the oil thrown out of the breather at high rpms (8200+). this system is based on Udo Gietl's solution for this and on information from the eurospares forum. This would not have been necessary if I had listened to Jim Cray, the engine tuner that re-built my engine. He said that there would be problems with crankcase pressure with an early R90/6 crankcase and that we should use a post '81 crankcase. I didn't listen, as I like the earlier timing cover, hence have had problems with oil coming out of the breather and leaking base gaskets.
Crankcase breather tank. This involves removing the reed valve from the engine block and plumbing a large bore hose to an extra "tank" with two chambers, it is 75% complete:
Chamber 1 which is at a low vacuum (crankcase pressure) to increase crankcase volume. Chamber 1 will have in it a sort of labyrinth, foam or mesh to catch the oil thrown out of the breather, this can then return to the sump via a drain line. Chamber 1 vents into chamber 2 via a 2 stroke reed valve block (six reeds: Roughly six times the area of the standard reed mounted on the engine block).
Chamber 2 is at atmospheric pressure, also has a return line to the sump (which enters below the oil level) and will have a flat panel filter in the lid.
A separate line will run from chamber 1 to the exhaust header to create an exhaust sucker. This will have a regulating/off valve and an inline reed valve to ensure one way flow.
Specifications
Chassis
R65 swing arm and subframe
/7 seat shortened to fit /7 police tank and R65 subframe.
K100RS 1992 forks, adjusted pre-load and oil weight
R1100s floating discs and calipers: under tank master cylinder.
(Jon Lars asked me for information on this front end for his GS cafe racer)
Koni dial a ride rear shocks
Clip on handlebars
Engine and drive
Engine blueprinted and balanced
post '81 crank,clutch and gearbox
336 cam
40mm dellorto phm's
Heads ported and flowed
Waisted (stellite?) valves from CC products 44mm intake, 40mm exhaust.
R90s pistons, valve pockets relieved, twin plug heads skimmed for 10.2:1 compression
Dyna coils, boyer ignition
40mm exhaust ports
SS Exhaust headers 40mm OD to 42mm OD
SS Silencers based on Jim Cray's design for Keihan (need to be glass packed and assembled)
Battery mounted under gearbox.( I am on the third attempt of the battery box, space is tight)
Here is an earlier incarnation of this bike when I was more into the cafe racer look. The seat was ratchet strapped on and had a plywood base with 1/2" foam cushioning.
