Hitchcocks Forum

I HAVE A BULLET 500 WITH A MIKCARB FITTED AND RECENTLY HAS STARTED PINKING WHEN UNDER LOAD OR GOING UPHILL IT HAS A SHORT SILENCER AND WHEN I STRIPPED THE CARB THE CLIP ON THE NEEDLE WAS IN THE BOTTOM GROOVE WHICH IS RITCHEST SETTING I FITTED ORIGINAL SILENCER ON IS IS STILL THE SAME AND ON REMOVING PLUG FOUND IT WAS NEARLY WHITE INDICATING WEAK MIXTURE ANY IDEAS PLEASE

!st problem, pinking under load is almost certainly a timing issue. Check the points, if worn and pitted, the gap has closed. Fit new points and set gap carefully. If pinking continues, then check timing by TDC method or slacken off the plate and rotate to retard the ignition, but very small movement only. White plug may be due to air leak in the connection between the carb and cylinder head or if the PAV was removed, perhaps the blanking screw has fallen out of the inlet flange.. Perhaps the mixture was always weak and instead of fitting a larger main jet the needle was raised, but this only helps mid range operation. cheers TrevorCH

I had this problem once, the timing was correct; the dealer found that the rubber hose between the carburettor and cylinder head had a split in
it causing air to be sucked in.

Any ideas? you ask...As trev said check the points for wear and check timing. A split inlet manifold is possible but would present poor starting and tickover. spit back through carb? i would check the inlet hose between the filter housing and the dummy filter box, back under the seat. these can perish and fall to bits bypassing the filter.Very lean. If alls well and theres good compression, then buy a gallon of high octane from Shell or BP and try that. Mine will pink like hell on cheap supermarket stuff. Oh well time to off to work. regards gwilly.

Fit new 125 main jet. Return clip on needle to middle position. This will get the mixture very nearly correct (further small amounts tweaking might be necessary) Reset points gap accurately and if it still pinks, retard ignition untill it mostly stops under normal riding conditions...you could also try higher octane fuel but this is pricey.

I'm reading between the lines here and trying to guess. If you put the original silencer back on to try, does that mean it came with the bike as a spare? Or did you fit the shorty yourself. if the latter did you increase the jet size to suit? could still be 110 jet installed. as per LesH fit 125 as start...... You dont say what plug type you have. If an iridium plug you will find they are not good for plug chops. They remain rather pale until way to rich.Fit a new NGK B8ES for testing purposes only, then change back to iridium.... (other opinions may vary)..... Now back to this pinking. Whilst in there checking the points, check the advance/retard unit for free operation and a snappy return. if the've never been changed then invest a few pence in a new pair of springs. MR H has some stronger ones which will help to stop full advance at low rpm. again opinions vary. I found one strong and one standard about right. enough to be going on with. stay in touch. gwilly.

thankyou GWILLY when i bought the bike 2 years ago the short silencer was already fitted and since i have done 11000 kms with no problems it had a 120 main jet in it and i have now fitted a 125 jet and retarded the ignition and fitted new points and condencer only because i already had them also i drained fuel tank and refilled with high octane petrol i will be taking it for a road test tomorrow and if it is cured i wont know wich item it was onlyby process of elimination THANKS AGAIN;;

As per your first couple of responses.
the bike was OK until just recently, this points very definitely to something chaning, i.e. the points gap / timing / advance springs, check and set all of those and the only other thing that could have changed is a split in the intake manifold rubbers between carb and engine and carb and airbox, (assuming standard airbox)?
If the points are pitted quite noticeably change the condenser when you change the points too.