MK5 FLOAT CHAMBERS

[digcot65]

I`ve been replacing parts on the Amal 274 carbs, just when I thought  I`d finished, I refitted the carbs and the LH one floods fromthe  vent hole at the top.I contacted Surrey Cycles to order a float and needle also the top female nut the needle goes into.They have just phoned me back, to say they do not have any, and they advised me to contact the technical chap in the club, and ask if the Douglas club has managed to sort anything out, it is the 4A body.Mine has the copper float and the needle is soldered in it. Len

[eddie]

The float needle should be retained by a spring clip - if it has been soldered in, make sure it is at the correct height, and that the float doesn't contact the tickler button before the needle seals against it's seat.
Another problem that is not always obvious is that sediment can build up in the bottom guide for the needle, causing the float action to become sluggish.

  Eddie.

[digcot65]

Thanks, the float does clear the tickler before it should be sealing.I tried Surrey Cycles for another float, but they no longer stock them.They can offer a chamber body of a different model, but you are looking at approx.£250. I would imagine there are other MK5 owners who have met a similar problem,  without having to buy new chamber bodies. Len

[eddie]

Len,
       The problem doesn't lie in the float chamber body, so buying a new one wont cure the flooding problem. If one carb is OK, take that float out and compare it with the one with the needle soldered in. If there is a difference i.e. the soldered in needle is lower than the clipped in needle - that is the problem you have to overcome by unsoldering the needle and resetting it to the correct height.

  Eddie.

[digcot65]

Thanks again ,the float isn`t hindered by the"tickle" button it as though the needle isnt sealing the input flow.Also since I took the carb apart,what are the basic settings for the throttle screw and the mixture screw Len

[eddie]

As a starting point, set the throttle stop screw so that it lifts the slide by 1/32". Wind the air screw in until you feel it contact it's seat, then unscrew it 1¾ turns.

  Eddie.

[digcot65]

Thanks Eddie, I will remove the other chamber and measure the needle heights. As I said the float when at it`s highest point, isn`t fouled by the "tickler"button When I contacted Surrey Cycles they suggested as a last resort,to use the float chmber off another Amal carb.it is a larger diameter but should not be a problem.The trouble is you are starting to get away from the originality of the bike.How much that matters is one the members can answer.Len

[digcot65]

Hello, I have just measured the height of the neede,l from the top of the float to the point and they are exactly the same on both.The point of the needle and the recess it fits into on the top of the float chamber must not be a perfect seal.Len

[Rex]

Not unusual with the 274/5/6 external float chamber carbs. Thankfully any seepage stops (unless there's a real problem) with the engine running.

[eddie]

OK, while you have the float out, hold the float assembly by the ends of the needle, between finger and thumb. Spin the float assembly to check whether the needle is straight. If it is straight, turn your attention to the bottom of the float chamber - there is a blind hole that the needle sits in - use a 2.5mm drill to clean out any debris from the hole - the needle should be a slack fit in the hole (to allow the top of the needle to self align with it's seat). The only other likely cause for the flooding is physical damage to the actual seat.

  Eddie.

[digcot65]

Hello again, there does appear to be a slight bend in the needle,I will check this tomorrow.The flooding was when I tickled the float,I haven`t yet started the bike as there was no spark and the carbs were quite dirty.Cross fingers I will try tomorrow.I bought the bike for something to do, as my classic car is sitting under wraps waiting for the better weather.I`m not taking it out if there is any dust in the air!!!! Len