Advice on fitting new petrol taps
- Thread starter BlackLightning998
- Start date
Thinking about fuel starvation. I had to get a new 229 float bowl and before I fitted it I decided to measure the 4 holes in the base union.
A 1/4inch bore petrol tap has a opening with an area of 0.049 square inches.The 4 holes in the base union appear to be about 0.078thou diameter which would give an area of 0.0047 x 4 = 0.019 square inches.I expect everyone to double check my maths as I'm not always the greatest.But if I am correct fuel starvation from the taps may not be the problem,the size of the union holes may be..
The holes would need to be opened to 1/8 inch to equal a 1/4 tap.
A 1/4inch bore petrol tap has a opening with an area of 0.049 square inches.The 4 holes in the base union appear to be about 0.078thou diameter which would give an area of 0.0047 x 4 = 0.019 square inches.I expect everyone to double check my maths as I'm not always the greatest.But if I am correct fuel starvation from the taps may not be the problem,the size of the union holes may be..
The holes would need to be opened to 1/8 inch to equal a 1/4 tap.
Yes the holes in the float bowls on the original carbs have holes with a smaller total cross sectional area than the petrol taps, but the carbs are lower than the taps and so have a greater head of fuel above them and so the fuel will flow into the bowls at a faster rate. Any restrictions upline (ie smaller bore fuel taps) will have a big affect on the flow of fuel in the float bowl holes. This is only my limited knowledge of fluid dynamics, maybe somebody who understands it more will comment.
Also if using the gas taps from plumbers, they don't usually come with filters (unlike the originals which had filters protruding into the petrol tank). So either fit filters to the tops of the taps or ensure any filtration downline is good. A friend suffered from this last year in the IOM.
Regards,
Simon.
Also if using the gas taps from plumbers, they don't usually come with filters (unlike the originals which had filters protruding into the petrol tank). So either fit filters to the tops of the taps or ensure any filtration downline is good. A friend suffered from this last year in the IOM.
Regards,
Simon.
Thanks to all - I've decided
Thanks to everyone who replied and contributed. I had a good look at a pair of gas taps and whilst I can see they are superior in construction I did not like the look of them, and could not see an easy way of filtration. One WLS member said he had taken off the filters from an old pair and soldered them onto gas taps before fitting. Anyway, the VOSC replacements appeared to be of better design than the ones I took off (which look very much like the ones my Dad fitted in the 1970's) so I opted to replace with like for like. They look to me like the rotating section is sealed with an O ring. Anyway I am not planning to do huge mileage and don't mind contemplating replacing them every couple of years if that's what happens.
Regards
Stuart
Thanks to everyone who replied and contributed. I had a good look at a pair of gas taps and whilst I can see they are superior in construction I did not like the look of them, and could not see an easy way of filtration. One WLS member said he had taken off the filters from an old pair and soldered them onto gas taps before fitting. Anyway, the VOSC replacements appeared to be of better design than the ones I took off (which look very much like the ones my Dad fitted in the 1970's) so I opted to replace with like for like. They look to me like the rotating section is sealed with an O ring. Anyway I am not planning to do huge mileage and don't mind contemplating replacing them every couple of years if that's what happens.
Regards
Stuart
Fuel flow
Without disputing anything else said, my personal experience has been that I only ever nipped up a motor after a couple of miles cruising at 60 mph. The fuel tap was almost completely blocked. In more normal riding you'll hear it popping on the over-run long before any damage is done. I think the concern about inadequate fuel flow stems from US sprint experience. Since a Vin will do something between 45 and 55 mpg in normal use, the equivalent of 90 to 110 mpg if it were a single, I think the desire for fuel taps like sea-****s is misplaced. Maybe if you spend much of your time thrashing full bore up Shap it's a concern, but not otherwise. My concerns, addressed by using gas taps, was that every other damned tap I used, leaked.
Without disputing anything else said, my personal experience has been that I only ever nipped up a motor after a couple of miles cruising at 60 mph. The fuel tap was almost completely blocked. In more normal riding you'll hear it popping on the over-run long before any damage is done. I think the concern about inadequate fuel flow stems from US sprint experience. Since a Vin will do something between 45 and 55 mpg in normal use, the equivalent of 90 to 110 mpg if it were a single, I think the desire for fuel taps like sea-****s is misplaced. Maybe if you spend much of your time thrashing full bore up Shap it's a concern, but not otherwise. My concerns, addressed by using gas taps, was that every other damned tap I used, leaked.
These gas taps don't have filters which is not a big problem if you are running with modern carbs with integral filters(Monoblocs,Concentrics,ect.) but with 289's &276's watch out if you have had your tank repainted recently. I've had a few cases where overspray inside the tank has been disolved by fuel and you end up with what looks like wet black soot in the system.The answer is to ask your painter to mask off the filler neck or put a big cork in it!
Taps and ****s, and ignorance.
Note to censor: when one turns off the domestic water at the mains, the water board operate a stop****, not a stop****. Taps for fuel are called fuel ****s (on vintage bikes they might be called pet****s). They are not called fuel****s or *******s respectively. Huge bore taps that are used to scuttle ships by admitting sea water into the hull at high volume are called sea****s, not sea****s. "
Anyway, must rush, I'm off to stick some new stamps in my stamp al***. I got them from a dealer in S****horpe.
Note to censor: when one turns off the domestic water at the mains, the water board operate a stop****, not a stop****. Taps for fuel are called fuel ****s (on vintage bikes they might be called pet****s). They are not called fuel****s or *******s respectively. Huge bore taps that are used to scuttle ships by admitting sea water into the hull at high volume are called sea****s, not sea****s. "
Anyway, must rush, I'm off to stick some new stamps in my stamp al***. I got them from a dealer in S****horpe.
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This looks like an interesting game.....
Tom,
full marks, outstanding, great fun - I think I sense a thread that could go on and on and on.
I just wish I could think of a few to add off the top of my head. Mmmm - of to the dictionary for me.
S
Tom,
full marks, outstanding, great fun - I think I sense a thread that could go on and on and on.
I just wish I could think of a few to add off the top of my head. Mmmm - of to the dictionary for me.
S
B&Q gas ****s
Recently fitted a couple of gas ****s to my Rap. A few quid each from B&Q. They are made with 8mm compression fittings, which by good luck and despite metrication are threaded 1/4" BSP. Used a bit of PTFE tape round the tank end. Made up some neat little stainless steel levers to replace the plastic ones. Fitted the filters and "main" weir pipe from my old taps. Easy to operate. No leaks. Good flow. Very pleased.
Recently fitted a couple of gas ****s to my Rap. A few quid each from B&Q. They are made with 8mm compression fittings, which by good luck and despite metrication are threaded 1/4" BSP. Used a bit of PTFE tape round the tank end. Made up some neat little stainless steel levers to replace the plastic ones. Fitted the filters and "main" weir pipe from my old taps. Easy to operate. No leaks. Good flow. Very pleased.