Yes, very much so....Here we are Ken, hope it is of interest.
Mick originally used Metalastic rubber bushes for engine mounting, but he wasn't happy with them, and modified the mounting points to eliminate them. If I recall correctly, the change was just to add large washers to the bushing tubes. I'll try to get some pictures of the mounting areas. I've forgotten the reason he gave for not liking the bushes.I am interested in the following statement from the article:
....The isolastic mountings were dispensed with, only a damping rubber was retained for the cylinder head steady......
Any idea what was used? Where are the pictures referenced?
I used a single rose joint and tube (quite large for the application). The forward end of the rose joint on a 11mm alloy plate on the cylinder head attached with allen bolts as original steel set up but longer (retained and reused in the revised set up. The rear end was the same material alloy plate, bolted to the two original Rickman frame tabs used in their head steady design. It was the tabs on the frame than broke, presumeably from vibration and for/aft pulsing! But remember these tabs were over 40 years old and the frame has carried different motors over the years from 750 to 1007!On my Seeley 850, the head steady is two short tubes with rose joints at each end. The ends at the rocker-box are held by shoulder bolts, which are in shear. The only way the top of motor can move when it vibrates is sideways. When that motor pulses, everything goes down the chain and drives the bike. With a 72% balance factor, the motor is dead smooth at 7000 RPM, and acceptably smooth anything above 4000 RPM. When the motor idles, the whole bike rocks backwards and forwards. If your motor can move backwards and forwards, you will crack the frame. The impact when it stops causes metal fatigue.
A higher balance factor increases horizontal vibes and reduces vertical vibes. A lower balance factor does the opposite. Balance factors in the low 60s (wet) give about the same amount of vertical as well as horizontal vibes. This has been measured. Higher balance factors may seem smooth because the riders gravity is downward on the seat and pegs but this could be BS. Stress on the bike is lowest with balance factors in the low 60s with vertical & horizontal vibes balanced - reciprocating weight being the overwhelming cause of stress. My personal preference is a balance factor between 65 and 68% (wet).... for/aft pulsing...I have JSM extra long short stroke rods and pistons, balanced at high 70s rather than low 70s it is smooth throughout the rev range! Vibration is certainly not enough of an issue at the bars or through your feet too even think about changing the balance factor, unlike other rigid mounted Nortons I have ridden!
There isn’t a 961 in the world with “90 BHP on tap” Al...Stuart Garner sold the intellectual property rights of the Norton 961 engine to Zongshen in China, just before his company went into administration.. I wonder what the motors will cost individually ? With 90 BHP on tap, a Seeley or Rob North would be a real whiz.
Even 80 BHP would be good, and if it is 70 as standard., the rest might not be difficult. At least we would be playing with a new motor. If I lived in the UK, I would be looking for makers of after-market frames. Even an early Commando would probably accommodate that motor.There isn’t a 961 in the world with “90 BHP on tap” Al...
Al, there is already rules like that for some classes, pushrod motors and two Vv's per cylinder!