Fuel tap thread question: PD06 Transalp/ RD04 Africa Twin

[chris]

Hi guys
Hope someone can help. Without going into the whole story, I’m looking to replace my 1987 Pd06 Transalp fuel tap from the oem one with the stupid (IMHO) vacuum hose attachment (that magically turns the fuel off when it wants to… not when I want to, and hence my bike stops when I don’t want it to…) to one that has no vacuum feed from the cylinder head, just gravity.

FWIW, I believe the RD04 Africa Twin fuel tap has the same thread, although it only has on/off, but no reserve.

I have a Transalp oem fuel tap in front of me. My veneer caliper tells me the thread is 12mm. Great, I think to myself… But after a very brief search on Google, it appears there are 1mm, 1.25mm and 1.5mm (and possibly more) pitch 12mm threads on after market fuel taps. My veneer caliper doesn’t fit in the “nut” hole of the fuel tap to measure the pitch.

However I don’t have the bike handy. (It’s in Estonia (I’m in England) and I’m flying there in 7 days to do a trip to North Cape in Norway). So I can’t measure the pitch of the thread on the tank that the tap screws onto.

Can anyone help with the thread size/pitch I need to buy?

I really appreciate a quick reply. Many thanks in advance.

Cheers
Chris

[AIRWOLF]

Chris,
can't you just remove the vacuum diafram from the standard tap ?, it just moves a little plunger (the bit that get's stuck occasionally), or take the plunger off it ?.
I have a spare in the shed somewhere, i'll have a look tomorrow.
If you need the thread pitch just measure the threads on the tap.

edit,
just realised its a female conector on the tap, I'll investigate tomorrow.

[chris]

Hi Airwolf
Many thanks for your quick reply. If you're able to check in your shed that'd be great. I can't get my veneer calipers inside the nut on the tap at the correct angle to measure the pitch of the thread. It's too big for the small hole. At a slight angle it's measuring 0.9mm, so I'm guessing the pitch is 1mm. Can anyone confirm this?
cheers
Chris

[AIRWOLF]

Right, got the tap here.

You sure yours is 12mm ?

The fixing 'nut' measures 24mm across flats, inside measures 17mm across the threads, best pitch measurement i can get is 1mm.

The 'nut' is the same size on my RD04 and thread pitch 'looks' the same.

On the tap i have here I reckon you can bypass the vacuum control by drilling a hole through the chambers.. Can't remove diaframs as the also act as seals.

Typing takes me too long , so i'll call you to explain.

Len.

[chris]

Hi Len
Many thanks for your replies here and talking me through it on the phone. As we discussed on the phone I've swapped the spring to the other side of the diaphram and everything seems to work as hoped (as per my reply on the advrider thread: Show us your TransAlp modifications! - Page 792 - ADVrider post 11874)

I recon it'll work when I fit it to the bike in Tallinn.
cheers
Chris
PS. Through this dialogue I've also learnt to use my veneer caliper properly

[chris]

I recon it'll work when I fit it to the bike in Tallinn.

It does...

Chris