ET: Engine (Twin) 276 Carb Float Levels

[Cyborg]

You can dress the needles but that raises the float level which is a problem if the needle
has only one groove or hole to attach it to the float. I made new seats to get the needle
back to correct fuel level.

Hopefully I won‘t have to do that. I have a couple more seats, so will pick the best, but will wait until I check for leaks and determine the float level. If the seat is still ok, maybe make a thicker gasket to go between the bowl and float valve assembly?

 

[greg brillus]

those Amal type large floats the top feed ones that use the short alloy needle that sits on top of the brass float........these are very suseptable to bad flooding, as the needle is a very snugg fit in the bore of the float cap. Any tiny particles of grit in the fuel will cause the needle to jam........this flooding is very common with these big floats........seen it many times at the track with fuel running out madly even with the engine running........best to make sure the tank is as clean as you can get it.....On my twin racer I ran a pair of inline filters, the type you can disassemble and clean out.......I never had any flooding issues after that. On my big single racer now, I use large Dellorto SS1 float bowl......these look similar to the type 302 Amal, however they are actually 1 1/2 times as big, have lever type float needle design and flow much more fuel that the Amal........no fuel delivery issues with this set up coupled to the big Keihin smoothbore race carby......

 

[oexing]

Vincent, I think it would be not too easy to get your soft lapping pastes in my country. But diamond for lapping the float needle is not so critical and I´d get 5 micron type as common valve grinding paste is much too primitive to take for the needle job. And with two fingers force there should not be much diamond left after cleaning the carb parts.
Yes, for lapping plain bearing bushes I would not have diamond, rather try a reamer or a bit of abrasive cloth - but that does not happen often.

Vic

 

[Cyborg]

The manufacturer is in California. One of their test kits is a lifetime supply for me…. Lifetime may be short though.. one of these days I’m going to have a stroke trying to open the @#&$%+# tin. The compound gets between the lid and tin which seems to turn it into an immovable object.

Test Kit - Ws2coating

Contains eight 3 oz Tins, 1 each of 40N, 60N, 80N, 100N & 55N, 77N, 111N, 333N

ws2coating.com

 

[Cyborg]

those Amal type large floats the top feed ones that use the short alloy needle that sits on top of the brass float........these are very suseptable to bad flooding, as the needle is a very snugg fit in the bore of the float cap. Any tiny particles of grit in the fuel will cause the needle to jam........this flooding is very common with these big floats........seen it many times at the track with fuel running out madly even with the engine running........best to make sure the tank is as clean as you can get it.....On my twin racer I ran a pair of inline filters, the type you can disassemble and clean out.......I never had any flooding issues after that. On my big single racer now, I use large Dellorto SS1 float bowl......these look similar to the type 302 Amal, however they are actually 1 1/2 times as big, have lever type float needle design and flow much more fuel that the Amal........no fuel delivery issues with this set up coupled to the big Keihin smoothbore race carby......

Do you have any experience running TT’s on gas? My slides are 7’s which is what the list calls for….however the list also says 1700 mainjets, so I’m assuming the #7 slides are also for the alcohol setup. Maybe 6 would be better for pump gas?
The TT’s have 380 mains, which will do for now. I have a feeling I may have asked you this before… long ago?

 

[PhillSpain]

As to brass floats I would not think they could be attacked by ethanol fuel. BUT it seems very old floats made from brass - and other parts in brass - can develop cracks in time, even when sitting on the shelf. That happened with my R 69S Bing carbs a few years ago in short time when at least two floats failed on the road. In the photos when you zoom in you can see cracks, one was soldered for quick temporary repair.
These Bing floats are very thin walled, only 7 grams . Sure, new production Bing brass spares are € 50.- each but you won´t be surprised I went the full Monty and fabricated a pair from Stainless, even lower weight of under 4 grams. Stupid me, I picked sort of springsteel stainless foil, so my deepdraw efforts did not come out as desired and I only used the top and bottom parts and had a middle section from extra sheet finally. So these are most likely the only pair in stainless worldwide in BMWs.
When dealing with ethanol fuel you can have some corrosion from collected water like holed float chamber from water in the bottom - had this some time ago - and I have this 69 S since 1972 and never had that kind of corrosion with olde time gasoline !

Vic
View attachment 59710

As to brass floats I would not think they could be attacked by ethanol fuel. BUT it seems very old floats made from brass - and other parts in brass - can develop cracks in time, even when sitting on the shelf. That happened with my R 69S Bing carbs a few years ago in short time when at least two floats failed on the road. In the photos when you zoom in you can see cracks, one was soldered for quick temporary repair.
These Bing floats are very thin walled, only 7 grams . Sure, new production Bing brass spares are € 50.- each but you won´t be surprised I went the full Monty and fabricated a pair from Stainless, even lower weight of under 4 grams. Stupid me, I picked sort of springsteel stainless foil, so my deepdraw efforts did not come out as desired and I only used the top and bottom parts and had a middle section from extra sheet finally. So these are most likely the only pair in stainless worldwide in BMWs.
When dealing with ethanol fuel you can have some corrosion from collected water like holed float chamber from water in the bottom - had this some time ago - and I have this 69 S since 1972 and never had that kind of corrosion with olde time gasoline !

Vic
View attachment 59710

View attachment 59711

Ethanol attacks fiberglass tanks but doesn’t attack metal, it absorbs moisture from the atmosphere. While the bike is being used no problem, when laid up for some time the water drops out to the bottom of the tank and float bowl. This is the reason for corrosion.

 

[greg brillus]

Sorry not ran these carbs on petrol fuels.......however the factory spec for methanol at 1700 main jet is crazy.......they only said that because the jet size is the largest you can buy from Amal........My twin racer was a reasonable spec engine using 12.5:1 pistons, larger inlet valves with bigger inlet ports, and 2 of Terry Prince Mk 5 cams and radius followers......several other mods but not anything really special....... I ran with 820 mains and the engine still ran on the rich side, not lean at all. So with a ratio of 2.5:1 meth verses petrol your mains should be around 330 to 360 max........My guess is the engine put out around 70 to 75 HP at the rear wheel at best.

 

[vibrac]

I picked up on time saver paste from this forum a year or so ago easy to find in uk
I used it on the big bronze bush at the front of a Douglas 90+ crankshaft its impossible to get it perfect before fitting and then it contracts slightly
Bananaman machined it to within a thou or so and I lapped it in with the paste

 

[oexing]

Just looked up time saver in our Ebay, only to get in UK. But I hate importing goods from UK or USA, can be very frustrating. But dead easy having orders sent from China via Aliexpress. Ebay still seems to be very unqualified to include the IOSS customs/VAT system in their electronic sales system. So I am in danger of dealing with customs plus Ebay to get back VAT and sometimes customs charges - well, actually DHL customs section - once I see that VAT was charged twice on imports. Story on request . . . .
Back to time saver, basically I´d hate to have an extra lapping operation on plain bearings but will keep that in mind . . .
Vic

 

[Cyborg]

When using Timesaver, keep in mind it’s a little different. Use a lap that is harder than whatever you are lapping.
As for the time saving part…..

“The decision of which lapping compound to use is determined by the base material to be lapped. Timesaver works opposite of most lapping compounds. Lapping compounds containing aluminum oxide, silicon carbide and similar charging abrasives use a lap that is softer than the pieces requiring lapping. With Timesaver, the softer of the two mating pieces will see most of the lapping/cutting action. However, Timesaver Lapping Compounds will not charge into the metal, reducing or eliminating the need to disassemble the work pieces, eliminating the need to clean the parts prior to changing grit size, and reducing the time required to remove the lapping compound once the procedure is complete. Simply flush out the lapping compound with solvent or clean oil.