petrol tank - front mount dimensions

[PeterW]

Hi

Could someone kindly let me know the distance between the petrol tank front mounting holes?

I'm rebuilding a bike that has had the mounting chopped off, bodged back on then chopped off again. I want to fabricate a new mount now while sorting the frame out but don't have a tank to check it against.

Thanks
Peter

ps. if anyoe knows of a tank for a 53ish rigid single please let me know - not worried about condition.

[john.nash]

What kind of model ? ...
I have a 51/52 twin plunger partially built and can measure that if needed

[PeterW]

sorry - 1953 rigid NH, though I suspect they're standard.

[brenton.roy]

Hi Peter, an earlier (panel tank) NH is 15.5cm
Brenton

[john.nash]

51/52 twin plunger .. 15.5cm between hole centres...

[pete.collings]

Be aware that as well as the distance between mounting holes, you need to get the height of the mount correct. If the rear mount is still present, this can be the reference (level between mounts), otherwise get the correct mount height.
On a friend's swingarm frame where the front mount had been cut off, the new mount was welded a bit too high, and the handlebar clamp nuts dug into the top of the tank on full lock. The mount had to be removed and remounted lower down. If there is only a slight difference, the steering lock can be reduced by building up the stops on the frame. I have used a bent bit of alloy strip secured by the steering damper plate bolt.
A mod to consider (I have done this with a swingarm tank, but it should be possible with rigid/plunger models) is to use car rubber exhaust mounts (I think I used MG ones as being the shortest I could find), which can be attached to the tank (possibly turn down the nuts to slip into the tank mount recesses), and just bolt the tank in place. It would help location of the tank if the bottom nuts are turned down partially to the diameter of the frame mount holes. You then have a completely rubber mounted tank, if it moves about too much, wrap some old tyre inner tube around the frame centre spine to limit the movement. You will need to check the steering lock for handlebar clamp nuts touching the tank, depending on the degree of contact this may be solved by the use of half or reduced hex nuts .

[PeterW]

Thanks for the help, so about 6 1/8 inches in old money.
Good point about the height.
I was planning to do the mount pretty much as standard - ie big rubber grommet thicker on top but the exhaust type mount sounds worth investigating.

[nevhunter]

If you are going to look for a steel tank The W/NG ones are pretty right. Small without panel. Think they are used on the VCH too. Nev

[simon.holyfield]

I sketched the tank mount up for someone recently. PM me if you want the sketch?