Carburettor resleeving

[david.anderson]

Brenton
I have no experience with Teflon coatings. With regard to the venturi divider again no experience but I have my doubts. Particularly with the divider going over the spray tube and extending to the rear of the carb. I would think that it would prevent proper atomisation of the fuel above the divider concentrating the fuel to the lower part of the port.

The only carburettor add on bit that I am aware of that genuinely works is the UFO bit for Mikuni round slide carbs ( http://thunderproducts.com/u_f_o.htm ) It is generally considered that round slide mikunis are based on an amal, but are better made from suitable metal and do not distort. They do not however give the same performance as the same size amal. When the UFO is fitted to a mikuni they may then out perform an amal concentric.

John
I do not see how you thought you were denigrating my work. I certainly did not take it that way. I am happy to consider different opinions take criticism or advice. After all that is how we learn, and I've still got a lot to learn. Yes I agree that the chrome plated brass or anodised slides are a far superior option with a new carb. Two rubbing surfaces should never be the same material. There should always be a hard and a soft metal which greatly reduces the wear on both parts. My concern is the amal slides of a few years ago that were chromed mazac (zinc pot metal). A friend had the chrome peel and end up in his bore. It got trapped alongside the piston and stopped the rings from sealing, which resulted in no compression. Fortunately he removed the head to find the problem before any real damage was done. A light hone was all that was needed. But many others were not so lucky when the chrome peeled from their zinc pot metal slides.
There are firms that specialise in carb resleeving. It is a cheaper option than a new carb and will last a lot longer than the original did. I have worn out a few amals over the years and have sworn that I will never buy another amal, but have relented each time as it does not seem right to fit a mikuni or keihin to a British bike. The repair that I have just done was an alternative to a new carb, will last a lot longer than the original and I hope also to have cured the flange distortion problem.
Another fix for a worn amal is to fit a mikuni slide. They are slightly bigger so it is just a matter of boring the body to suit. They are chromed brass. The only disadvantage with this fix is that you can no longer fit a choke to your amal.

Danny
The carb will never get hot enough for the different expansion rates to cause a problem. There are numerous firms that resleeve with steel, brass or stainless and I have never heard of a problem. Also I would think that the slide would have a higher expansion than the steel sleeve. As Adrie mentioned a couple of drops of Loctite bearing lock under the sleeve will prevent any movement between the two. Alternately super glue works well.
David

[brenton.roy]

Thanks David. The UFO looks to be aiming for the same sort of thing as the divider, to reduce turbulence. You may well be right. My total experience with it is via viewing the web page..
I would have thought that at low throttle openings, the slide would already be doing a good job of stuffing up fuel atomising in the upper areas?
The one that makes the most visual sense to me is where it is divided into thirds (like jetting). The bit I think just might work is the improvement in velocity at low to medium throttle openings. This may well be compensated by friction / turbulence problems at full throttle.
I guess you'd have to actually try it to see.
Brenton

[daithomas]

I have done this repair quite a number of times, I used brass for the sleeve and making them an easy sliding fit on the the turned down slide and fitted using Locktite bearing seal. They have stood the test of time doing thousands of miles with no problems.
The brass slides are harder than the original ones and a dissimular metal to the body and I belive beter than the original ones.