Forum

[Jamesy]

Has anyone used Gunson colourtune on their Royal Enfield Carb bike.Just wondering if it's a worth while purchase.

[Leon Novello]

Be wary, I have heard that they don`t work well with unleaded petrol, of course this information might be wrong.

[Rattlebattle]

It’s more likely that it won’t work properly with petrol with ethanol in it. Petrol and ethanol have different stoichmetric ratios such that 10% ethanol in petrol is equivalent to a 7% leaner mixture. Whilst EFI engines adjust for this, with a carb it is unwise to use fuels with differing percentages of ethanol because a carb cannot compensate. Where this leaves a colourtune I don’t know but the old plug colours in workshop manuals etc no longer describe accurately what is the state of the fuelling.

[Jamesy]

Interesting comment rattlebattle about spark plug colours.My b350 is running as sweet as a nut and kicks first or second time.I am concerned about the whitish spark plug colour which if I am correct used to indicate a lean fuel/mixture.I am thinking of adjusting the mixture or should I just leave it?.