Wishing you all a Merry Christmas and a Happy New Year, ride safe! The CB500Club team

noisy overrun and quiet(er) overrun

Share
avatar
trevor machine
the 900
the 900

Posts : 1203

noisy overrun and quiet(er) overrun

Post by trevor machine on Thu 25 Feb 2016, 7:08 pm

Hi everyone. Quick question RE my two CB500s - both running unbaffled Fuel exhausts. One bike has a comparatively lively i.e. noisy overrun (e.g. closing the throttle at say 4k in 4th or 3rd results in quite a prolonged salvo of pops etc.), the other hardly any. Both pull through the gears well and in general perform very similarly - the younger bike being predictably a little more crisp and responsive. The latter is the quieter bike.

Am I right in concluding that the bike w/ the loud overrun is running leaner than the quieter one (if so, this strikes me as a bit counter-intuitive because in some ways it seems more common-sensical to think that fuelling which is too rich would result in more unburned mixture making its way to the exhaust and igniting there)? Secondly, is there reason to be concerned with either set-up? E.g. will the leaner fuelled engine wear more quickly? Thirdly, is plug inspection the best way to check exactly how lean / rich either bike is running? I'm assuming that the ideal colouration for the bikes' plugs would be a very light brown shade - and that anything erring towards white would be too lean, and blackened plugs would be indicative of a potentially overly rich mixture? Fourthly, what colour do the plugs tend to be on your bike when you've checked them? Fifthly, how easy is it to alter the fuel mixture?

A lot of ponderables there, fbow. But I'd be grateful for any info. Cheers guys.
avatar
mcalvert39
Silver Bullet
Silver Bullet

Posts : 113
Location : Salford

Re: noisy overrun and quiet(er) overrun

Post by mcalvert39 on Thu 25 Feb 2016, 7:43 pm

Id start with plug condition / gap etc. Also check air filter condition and carb seals.
Apart from that try get an emissions check or even better, get them both on a dyno and you can then see exactly what each one is doing.

    Current date/time is Sun 17 Dec 2017, 12:38 am