A Couple of 650SS Questions

Hi John,

I have a Dommie  racer just finished but not yet used. Same sort of set up,no issues with fitting the mag. Might move to Boyer....

No issues fitting a Boyer mag replacement. 

Thanks to Robert T advising not to overfill G/ box and engine oil. Now first kick starter.

My 88 Dommie Racer.

I was thinking mag in case of an EMP   I'll see how the mag goes. 16H ready to ride......

PS: Oil is from chain Lube (Belt primary........)

curved will change the cam timing, so unlikely to be suitable for cam designed for flat, which is what I assume an X1 is ? Someone like David Newman Cams can advise on whether there is enough meat to have them reground flat.

Curiously, and according to Tuning for Speed, changing from curved to flat does not alter cam timing.  This is because opening starts and finishes with the back circle of the cam in the centre of the follower.  Flat followers increase valve opening acceleration just after the start of opening, and deceleration before the end.  So the valve stays more nearly open for a little bit longer.

That must mean that flat followers increase cam loading from inertia forces from valve gear mass very slightly.  So, conversely, curved followers will reduce cam inertia force slightly.  So you might lose a tiny bit of theoretical horse power if you keep them curved.

Just a guess, but I suspect flat ones were introduced because they were cheaper to make, and gave a small power increase at reduced cost.

The Norton Twin engine Flat followers arrived with the Nomad engines around 1958. They were of course, cheaper to make but also opened the inlet valves slightly earlier and closed the exhaust valvesslightly later. This along with the Q.R. camshaft and Higher Compression pistons gave the 500 & 600 engines much better breathing and increased the power available across the rev range. The 600cc Nomad motor offering 40+ BHP.

The SS camshaft in the later 650 and 750 engines along with the SS cylinder head enabled tuned engines (such as Dunstalls) to push out nearly 60BHP. 

It has been found that adding flat foot followers to most standard pre-1958 Dominator engines can give a 10% boost in oomph while not shredding the fuel consumption figure.

The interesting fact being that most of the 'go-faster' special camshafts, available to 'wanna-be' track lads, work best with the round foot followers. Do not ask me why!!!

was the subject of an interesting article by Vic Willoughby in the early post WW2 years.  His Velo suffered from valve float.  He altered the radius of the cam follower in his KTT to a much larger radius.  It gave more rapid initial valve lift, and closure.  It gave him a useful power boost and surprised the factory with its speed.  The factory recommended that customers do the same.

Mind you, I can't help thinking that a Dominator would benefit more from a much lighter cam follower.  The standard ones are absurdly heavy.

Hi folks , have just made the mistake of using , Ford Silver Fox from a spray can on my 650ss tank . There are what appear to be groups of random metal particles in the paint even though I kept shaking the can vigorously throughout the operation . The overall appearance keeps changing with the light . I am now rubbing the tank down and looking for a flat silver grey that will do a better job minus the sparklies . I will let you know what I choose .

I thought I would post this as a warning to anyone else doing the same procedure .

Regards Bob Cooper

Back in the sixties I painted a friends tank. After the primer three layers of blue. Then a clear coat with silver metallic particles mix. Then 2 layers of clear coat. Much silver on top of tank, gradually less downwards. When riding beside him, street lights made the line between silver and blue go up and down. So your appearance change might be due to different thickness of paint.

Thanks Mikael for the input . I think you may well have a good point as some areas seem to be almost particle free . The tank that I have sprayed also had these features in the paint before I rubbed it down . I think this might be a difficult paint to use from a can as you vary the angle of attack with the nozzle . Regards Bob

Hi Robert,

please start a new thread with a new subject heading rather than following on from another thread.

thanks

 Tony