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Checking fuel level in triple carbs

Posted: Wed Aug 06, 2025 2:44 pm
by Charlie Morriss
I've come up with a cunning (i.e. cheap - approx 20 quid) method for checking the fuel level in the carbs on my new recently aquired S2A. Is that something of interest to other club members? If so then I could do a write-up, but I don't want be doing a re-invention of the wheel! Thoughts please.

Re: Checking fuel level in triple carbs

Posted: Wed Aug 06, 2025 4:56 pm
by skub
I'm always interested in how other folk do stuff,so fire ahead Charlie.

I do mine the Darth method.

https://www.youtube.com/watch?v=wCBzSN7UIbI

Re: Checking fuel level in triple carbs

Posted: Wed Aug 06, 2025 5:32 pm
by Wolfie
Many people have a different take on Fuel level setting and many have already been mooted on here, but do the write up anyway, new people come along all the time.

Re: Checking fuel level in triple carbs

Posted: Wed Aug 06, 2025 8:08 pm
by Triple Parts
I would be interested to hear what your method is, but this one is cheaper... viewtopic.php?t=18210

Re: Checking fuel level in triple carbs

Posted: Thu Aug 07, 2025 10:53 am
by Pierrot974
Hi.
I have quite the same method Tony :

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Re: Checking fuel level in triple carbs

Posted: Thu Aug 07, 2025 3:30 pm
by Charlie Morriss
ImageYep! So definately me re-inventing the wheel then. See pictures below.

Dish is a 100mm dia 'stonylab crystalising dish' - £12.79 from Amazon.
Fuel tap is a 'fuel tank valve switch' - £4.05 from Amazon.
4 screws are M4 x 35mm ones I already had, but Kawa Triple Parts have 'Rear Light Lens Screws M4x35 (x2) – Later Style' for £1.25 a pair.
The gauge, held into postion by a rubber band, I made up from a piece of gash aluminium - marked with an alignment mark (to bottom edge of carb body) and the 3mm and 5mm fuel level points below it.
The stand was made from 2 bits of wood off-cuts and a gash piece of angle metal - all clamped firmly into my 40+ year old Workmate for stability.
The reservoir bottle is an old Scottoil bottle with it's bottom cut off (Ta Fraser! I've been a fan of his kit since 1988).

As these were S2A carbs I set the float height to 25.5mm (middle of 24.5 - 26.5) - this resulted in a consistant 3mm fuel level (below the bottom edge of the carb body) for all 3 carbs.

Note: I checked the right and centre carbs the day before with no issues, but photo time (on the left carb) next morning brought a couple of hold-ups: the old scottoil bottle's top started splitting (mended with gorilla glue and duct tape) and the cheap tap played up (petrol soaking caused the rubber inside to stick and move with the tap lever part) but fixed with a strip, clean and dry-out.

Image

Re: Checking fuel level in triple carbs

Posted: Thu Aug 07, 2025 8:17 pm
by skub
My set up.
Image
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Re: Checking fuel level in triple carbs

Posted: Fri Aug 08, 2025 9:59 am
by Triple Parts
Damn, I thought you had come up with a cunning new plan :lol:

The aluminium gauge is a good addition though, I'll use that one Thumbs Up

Re: Checking fuel level in triple carbs

Posted: Fri Aug 08, 2025 9:06 pm
by Charlie Morriss
Nice to know I can come up with at least one new wrinkle!

Note that my S2 (VM24) carbs fitted into a 100mm diameter dish - and I would assume S3 (VM26) ones will too.

I'd suspect H1/H2 carbs are too big to do so though. So, for interest, what's their max diagonal measurement - from intake to engine side? Like - what (bgger) size dish would be needed to use for my cunning in-dish method?

Re: Checking fuel level in triple carbs

Posted: Sat Aug 09, 2025 8:17 am
by RacerRB159
Don’t forget that fuel level is measured from the gasket face, not the return lip on the bowl joint Thumbs Up
Rich

Re: Checking fuel level in triple carbs

Posted: Sat Aug 09, 2025 9:54 am
by Pierrot974
Hi.
Are you sure Rich ?

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Re: Checking fuel level in triple carbs

Posted: Sat Aug 09, 2025 9:49 pm
by Charlie Morriss
As Pierrot974 most helpfully suggests: RTFM.

My understanding is that the float height is measured from the gasket face

Re: Checking fuel level in triple carbs

Posted: Sat Aug 23, 2025 9:28 am
by Tilly H2C
I use a spare/old fuel bowl drilled to take a small aquarium 'L' piece and a short piece of clear pipe, the advantage of this way is any needle valve leakage shows up pretty quickly as the fuel volume within the bowl is much smaller than sitting the carb body on top of a glass jar,

I have not tried it the way the picture has been inserted yet, maybe next time :lol:

fuel bowl .jpg

Re: Checking fuel level in triple carbs

Posted: Thu Aug 28, 2025 7:59 pm
by Charlie Morriss
Luxury!! Gis a clue as to how you get a spare fuel bowl!

I always thought they were now in the realm of unobtainium - but i'd be extremely happy to be corrected on that.