Blowing bulbs

RichardJ

RichardJ

Full member
Location
London England
I got my bike in August and due to weather and other distractions I haven't been able to ride it as much as I would like. However,  the bike has just blown it's third headlamp bulb !  Is it just cheap bulbs or is there something more serious going on ?  These are H4 halogen bulbs, and I know that you are not supposed to touch the glass so I always hold them by the metal parts.

Any ideas ?
 
Does it have the standard headlamp brackets in place, along with the large rubber blocks to insulate the headlamp from excessive vibrations?
 
May indicate a charging system fault, stick a meter on the battery with the engine running and measure the voltage when giving it a rev, should be no more than 14.7v


  Keith.
 
In view of your avatar, I presume it's a Laverda we're talking about, a 500?
Do like Keith says and make sure that your headlight is as isolated from vibration as possible.

Paul
 
I replaced the H4 bulb in my 1974 3c in 2006...original was still working fine..did it as after over 30 years, it was time. Still had some wound safety wire on the holding bulb clip from the factory..I don't think Laverdas are hard on headlamp bulbs.

Has to be vibration or over-voltage.
 
Thanks for all the replies.
Yes it is a 500, and no it doesn't have any rubber blocks between the headlamp brackets and the headlamp itself.  I don't know if this is standard as my bike has been modified.
I guess the first thing I can do is put some rubber between the brackets and the lamp.  Checking for over charging could be interesting given the decibel levels of the bike, but perhaps I can do that at my local airfield. They shouldn't be too bothered about noise.

I would expect to see over 13 volts going back into the battery, but what would you say is too high ?
 
If it is vibration you could try sticking alloy wheel balance weights to the inside of the headlight bowl.
It worked for me but that was on a 350cc twostroke
 
Or... Try and find heavy duty bulbs. There is an extra support-leg up near the filament.

Honda dealers used to do them, also Halfords in the UK.

HTH, Paul H
 
My old jota used to eat bulbs as if it would starve to death without a regular supply of the fuckers. Took a while to sort it out. Dodgy recterfier.


      FFF
 
Thanks again guys for the extra posts.  I have new bulbs and rubber to insulate the headlamp from vibration. The bike doesn't feel vibey, even at high revs. I guess this is a feature of the 180 degree twin. Plus the addition of the balance shaft of course.
So, it may be the regulator/rectifier, but that appears to be a new item.  Should find out over the weekend.
 
Hi Grant,
I just used some rubber tap washers from my local hardware shop. Inserted these between the headlamp shell and the brackets. Also on the outside of the brackets but with the original steel washers under the bolt head too ( hope that makes sense ). 
I just took the bike out fo a 30 mile ride, giving it plenty of revs whenever possible and the filament has survived.
If I get a chance tomorrow, I will try to get a meter on it to check what voltage is coming out of the regulator.
 
A few years back I experienced the same problem and this was with the headlight mounted with the Tommaselli mounts,lots of rubber there. It took me quite a while and many blown H4's before I figures out the problem. The headlight assembly (glass,chrome rim,reflector)was an easy push fit into the headlight shell and that there was the problem the easy push. There was just a tiny bit of movement between the light assembly and the shell but enough that when the bike was running the 180 vibes would shake the shit out of the assembly (obviously not visible to the eye). The problem was resolved by applying a little more tension to the flat spring thingy on the bottom of the headlight assembly to ensure a firm fit. For good measure I also drilled a small hole thru the chrome headlight rim into the shell and used a small screw to keep it all tight. No more blown bulbs
                                          HTH, Cheers Dave.
 
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