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@oxymoron avatar
UTC

Hooked
Joined: UTC
Posts: 103
 
Hooked
@oxymoron avatar
Joined: UTC
Posts: 103
UTC quote
After meticulously cleaning out a very gunked up 4T Bajaj chetak gas tank, I put in a brand new tap. The bike came with a ton of spare parts and the spare tap was still in the plastic.

I screwed the tap in tightly (10mm head = 6mm screw so I didn't want to go nuts), but when I turned the tank on to test it, I get a drip.

The gas line to tap is lower than where the drip is coming from. The tap gasket (tap to tank) seems to be great as well.

It looks to me like it's where the fuel rod meets the tap. There are two surface plate screws - both are very tight/flush.

I haven't taken the tap apart to diagnose, but has anyone run into this issue before or may offer a solution?
Drip vid
Drip vid
@steely_dan avatar
UTC

Member
Lambretta GPs Lambretta S1s, Vespa Gl, Vespa P200, Serveta 150
Joined: UTC
Posts: 43
Location: United States
 
Member
@steely_dan avatar
Lambretta GPs Lambretta S1s, Vespa Gl, Vespa P200, Serveta 150
Joined: UTC
Posts: 43
Location: United States
UTC quote
I used to sell these back in the day. Had a few that would leak from this area. First, I'd slightly tighten the two screws that hold back the tension washer and the fuel cam where the rod attaches. When i say tighten i mean just a little bit. If that does not solve the issue or the rod play becomes too tight, take it apart and check the rubber gasket that resides inside. In my experience these bits of rubber are made of cheese and if they have been sitting in a bag since 2001 it may be toast. You might have luck taking parts from the old tap to make one good tap. Good luck.
@greasy125 avatar
UTC

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 14542
Location: The state of insanity, SoCal
 
Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 14542
Location: The state of insanity, SoCal
UTC quote
I went thru this not too long ago. while I didn't have the drip problem, the tap was all gacked out. I had a spare tank w/ a tap and while the tank was roached the tap was salvageable.

however, the two taps had different internals-- one of the pistons was taller and the rubber was different between them. and here's the kicker: the rubber sealing washer isn't a flat disc with holes punched out! it's a small cylinder with a locating tang and flow holes.

I searched to no avail for a tap, then ordered a bunch of different ones hoping I'd get lucky (I did not) and eventually I wound up combining the two that I had with some bits from a used Honda tap to get a satisfactory result-- although the on-off-reserve function was totally different.

all that is to say: good luck with it man, I know that the fix was a total bastard. a real cork soaker of a job.

if I had to do it again, I'd just weld up the stock holes and install something aftermarket with a external control valve, or a vacuum tap and call it done.
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