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Mk V mixture

Started by Catweazle, 07 May 2013 at 18:16

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Evening all.

I've been exploiting the good weather to take the old girl out for rides of increasing length, very encouraging, apart from one bolt disappearing from the rear mudguard (that'll teach me to check round more frequently!), no problems at all.

The performance appears to be improving by leaps and bounds as I put a few miles on, however, this afternoon while riding into quite a strong headwind she seemed to get a little warm, lost power and threatened to nip up, a few minutes cooling and we were away again. 

Would I be correct in considering that modern lead-free fuels run leaner than the stuff that she was designed to run on?

If so, would raising the needles a notch be sufficient to compensate, or would larger main jets be necessary too?


Hi Catweazle,
                   When we had to resort to using the dreaded unleaded, I found my bikes were running very lean at full throttle, so increased the size of the main jets by 10. I also found there was a flat spot just above tickover, so reduced the slide cutaway - this then made the mid range a bit rich so lowered the needles to compensate. Also, beware the super unleaded seems to run even weaker - something to do with increased viscosity!


Thanks Eddie, I suspected as much.

I don't seem to have the flat spot above tickover, but it's early days yet.