ET: Engine (Twin) Vincent Float Bowl Setting 289's

[CarlHungness]

The first thing to understand is I don't know precisely what I'm doing and trying best I can to learn and effect a cure for starting my twin. As noted earlier there are about 16 pages of suggestions as what to do, and it sure seems as though my problem lies with fuel delivery as I'm now sure as I can be that good spark is being delivered, on time as it should be.
Thus I'm attempting to ascertain float height and from what I've been told, and read I am attempting to do a test, which I did, which wasn't particularly successful, so I'm on bended knee asking for advice.
I have another rear carb banjo in stock, so I removed the banjo that was in place, replaced it with the spare, hooked up a feed line, then another line that I was hoping would show me the level of fuel inserted into the float bowl itself.
I poured fuel into the feed line, and instantaneously the fuel entered the second line! I could see that the entries into the float itself are small holes captured by the top bolt, so I waited, hoping to see fuel enter the float bowl itself. It didn't happen. I didn't seem to be getting any fuel into the float chamber, but the second line was filling. I popped off the feed bolt and can see the point of the needle 'high' on the float bowl and (surmised) that possible some fuel was entering. What to do next? Not a clue. I removed the bowl from the carb and tried to empty it..and it just doesn't seem to have much fuel in it. While it was on the bike I depressed the tickler, and it seemed as though the tickler was touching the float itself. So what's my next step. The needle doesn't have any adjustment, just a single clip holding the float in place. Here's some pics of my set up so seeking suggestions.

 

[timetraveller]

Carl, I am not sure that I understand the photo correctly but are you sure that you are not just measuring the height of the fuel in the tank?

 

[Chris Launders]

That is what it is doing, Carl to measure the fuel level you need a pipe off the carb bottom banjo bolt OR where the cross drilling plug is in the float chamber arm.

 

[fogrider]

As said, you need to measure from the bottom of the bowl.
As a very rough guide, the fuel will be an inch or so down from the top of the bowl, but it's where it is relative to the banjo nut under the main body that counts. On the bottom fed bowl, removing the top will reveal where the fuel is, just visible down the side of the float. Watch it rise ,as , without the top on ,the needle may not totally seat.
I'm not clever with computors, but have been shown how to whatsap. If you PM me, I could draw up the details/dimensions of the float arm adaptor and whatsap it to you. Someone local could make one easy enough. Should be of use long term....Not sure how you do it on here !

 

[CarlHungness]

Carl, I am not sure that I understand the photo correctly but are you sure that you are not just measuring the height of the fuel in the tank?

I was measuring height of the fuel in the float bowl...have discovered my Setting of the ATD was not strong enough as I am positive when I set it the ears were at the top, and went to check it today, and they were at 11 o'clock with my piston stop in and should have been at 12 o'clock. So removed timing chest cover, have re-lapped ATD and will re-set it tomorrow...and maybe that was my problem..the plot started, ran great..then possibly the ATD slipped..it moves A LOT when set properly..maybe 3/16" and I wasn't hitting it hard enough to move it that far..I checked it in a vise, set it and watched how far back the ATD moved on the shaft, and I'm pretty sure I did NOT move it back onto the taper as much as I should have...made this mistake probably 3 times, so a bit embarrassed...and will find out tomorrow. Put the float bowl on with top finger tight, turned on the fuel, took the top off and can see the level is just about the height of the air screw, so don't think that's my problem...I DID cause a problem for lots of members if the ATD setting was duff. If she starts all I can do is apologize and have a sigh of relief. And surmise the B-TH WAS iffy.

 

[Stanley Chappell]

I think we all get problems with the old separate float chambers flooding even with new chambers.i have a Scott flying squirrel and it will not stop flooding it really pisses me off I have tried everything I would like to fit a Viton tip to the float needle as per most modern carbs they don’t
leak any one out there got any information.the carbs I’m talking about is pre mono bloc Amal’s.

 

[Chris Launders]

Make sure there is clearance behind the ATD when you fit it on the bike, I seem to recall hearing of them occasionally fouling the crankcase and not sitting on the taper hard.

 

[Simon Dinsdale]

Make sure there is clearance behind the ATD when you fit it on the bike, I seem to recall hearing of them occasionally fouling the crankcase and not sitting on the taper hard.

The easy and quick way to check this is generally the front face of the ATD gear should align with the front face of the gear that drives it and it can be checked by just remoning the small ATD cover in the timing side. There may be a little misalignment but if the ATD gear is more than 40 thou recessed from its drive gear (breather on a twin) then maybe years of lapping in the tapers over its 70 year history by previous owners has removed too much metal. As Chris says if the back of the ATD bottoms on the crankcase or on the oil seal on the mag shaft then the tapers will not lock properly. Unfortunately the only real solution if this is the case is a replacment ATD.