Anti Bias Spacer (gasket)

[Terryb]

Ok guy's.  Thanks for all your input.

Now I'm not using a mag with points, I have the Thorspark electronic trigger unit fitted, so I can't see there being any difference to the L/R timing which would be caused by any mechanical wear & tear. I've owned my Shooter for 6 years and the mag was converted to electronic just under 5 years ago. I've always experienced an imbalance of fuel mixture,  which I've never resolved. It's only now after my winter refurb that I'm experiencing difficulties. The only change I've made to my set-up is the needle position in the carb. Before I had the carb set-up for a lean mixture, by lowering the needle. At the moment it's in the mid position, so I may try going back to that.

On yesterday's road test it ran ok at low speeds, but when you opened her up, that's when it started to misbehaved.

[KeithJ]

Interesting topic.

Rebuilt my Rocket with 8:1 pistons and a Mikuni carb.  Needed a bias spacer to get the plugs reading the same.  Checked all this by using a lambda sensor fitted in to some bungs welded in to the exhaust pipes.   Checked the air fuel ratio with a voltmeter.  Also had the temperature checked at the top of the exhaust pipes which showed they were equal.

Since then, I have used two mags, one manual and the other auto advance, and just fitted a Thorspark.  After the initial set up using a bias space, it made no difference to the look of the plugs whatever spark means I have used.

My suspicion is the head castings for each inlet tract are not the same.  The heads were probably cast and fettled by hand with the machining for the valves and carb.  So I think the bias may just accommodate the variability of manufacturer. 

Just my thoughts.

[Tomo]

Bias gasket. What a load of twaddle thought I........
Got one....perfect! No sense!
The wonderful world of British bikes...is this why we love em?