Vibration or voltage....

[robint]

I know its a V twin but which V is causing my headlamp to blow after about 3-4 hours riding - its the standard Sport shell and light unit. Tried assorted bulbs - halogen 35W lasted least, 40/45W Bosch probably just the longest but not much in it really. Battery is fairly new (18 months) and holds charge fine, sitting at 12.3V at rest (and after 4 months non-use) whilst when running goes up to about 14.7V, though as the rev counter is just an indicator that the engine is running I don't know at what revs! Certainly didn't want to rev much more as noise was high and bike was vibrating its way down the garage on its centre stand.........

The vibration is very noticeable - engine bolts are tight and carbs in balance (it idles at 1750rpm and revs to 8500 plus in 4th and 5th) but fingers tingle and odd bolts loosen and a couple of indicator stems have snapped ( in 2k miles) so something isn't quite right. Doesn't use any oil, no leaks and usually starts first (good) kick - though not at the Hartside Cafe on Tuesday for some reason. Rode 350 miles on Tuesday without a problem (apart from the obligatory bulb blowing) longest trip for a while in a day.

So question is - which do I deal with vibes or volts (or a bit of both) and any solutions to the blowing headlamp bulb other than change the shell etc to fit H4 bulbs.

[tonup69]

I don't think it should vibrate much, but I am familiar with bulbs (tail light to be specific) being quite subject to vibe problems on my Triumphs. That being said, even those don't burn out more than once every six months. I think you have a voltage regulation problem. BTW, my Morini does not vibrate much at all, but I am comparing that to my Brit bikes, so maybe I just can't tell!

LTR

[EVguru]

The voltage is a bit high, 14v would be about right. Check the connection of the brown wire to the regulator. It may not be the cause of the bulbs blowing, but it will make them more vunerable.

Has the engine always vibrated and at what revs is the vibration worst?

I have an engine that is very good at causing engine bolts to slacken off and in fact wore out the frame it cam in. The engine has evidence of having been apart in the past and in fact had fibre gaskets on one cylinder and aluminimum on the other. It may have a set of mismatched internals, or might just have been built on a Friday afternoon after too much Lambrusco at lunch. The engine pulls pretty well and is used as a spare or loaner unit.

If you have badly matched ignition timing you can get vibration. That could be down to the pickup, or the transducers. The flywheel only has a timing mark for one cylinder. To make one for the other cylinder, wrap a bit of paper round the flywheel and mark TDC and timing for the one cylinder then move the TDC mark to TDC for the other cylinder.