If you notice how the zinc alloy looks in this photo you can see it's bone dry after being cleaned:
I had salvaged an extended tickler from another old carburetter.
The next thing I checked was the float bowl. These can be damaged if they're overtightened (something that happens easily when replacing the standard screws with allen bolts) so you need to put it on a flat surface and check if they're out of shape. In this case there was a little bit of distortion so I fixed it: to get a good idea of how the float bowl refresh/overhaul is done, I strongly recommend this two-part video: [http://www.youtube.com/watch?v=XIYgj5m9RW0 and http://www.youtube.com/watch?v=JHYnSua8ZZ0] and while you're at it, check out all his other Triumph videos too, he's great and a lot of that stuff applies to British bikes in general. Another thing I used to rebuild the whole carburetter is this kit:
Nipped up with my trusty 1/4" Withworth spanner.
The float is of the new type with metal tabs, great for adjusting the level - something you just can't do (at least not easily: I have seen people bend the tabs using a lighter, etc.) with the standard nylon type.Now, the new type of material (with metal tabs) was supposedly developed for use in Army Land Rovers as they needed to be as strong and reliable as possible, and is finally available for our beloved classics.
You can see the surface of the float bowl is all shiny after I sanded it. I checked again and it is properly flat now. The thickness of the gasket will take care of any unevenness on the carburetter body side, not that there is any, mind you.
Here's a new gasket and two brand new float bowl screws with split washers.
There, starting to look like a carburetter...
I managed to retain an original air filter backplate, which has a bit more character than a brand new one.
Other specs (these may change after I test the bike and see how the whole carburetter is working):
- Needle jet - 106
- Main jet - 220
- Needle position - middle groove
The carb will ideally be mounted on an extended manifold, mainly because I really like the look of these. That depends on whether or not there will be enough room within the frame's main loop.
Most of you know what I'm talking about, you try a bike that just doesn't do what it's supposed to and sometimes all it takes is a good clean and an overhaul kit and it's like you got a different engine. Think how small the jets are. Think how "flimsy" the whole float/needle assembly is, perennially balanced (until it punctures) and letting in just the right amount of fuel. It's all very small, precision stuff, yet those tiny jets are responsible for breathing life into the engine. Raucous, snarling, 'sploding life. In most cases these carburetters can last a long time if cared for properly. Don't believe the fearmongers who tell you that they will warp and melt and emit toxic radiation. Most problems found with Amals are down to careless owners who overtighten them, leave them full of gunk for a year, never change the gaskets and just don't know how to tune them. Ok, metal does wear, and in very extreme cases you can have slides that rattle a bit or stick in the fully open position (what a fun way to go though, hey?).
Amal have recently introduced a new hard anodised forged alloy slide that's supposed to be stronger and more resistant to wear.
I got one to try it and see what they're like, also because it could be a great major upgrade for others in my Club. Just looking at this I can tell you it is a great piece of machining, it looks absolutely flawless and if it works as well as it looks, we're in for a treat:
They also offer what they call the "premier" version of the Mk1, basically incorporating the StayUp float, the hard anodised slide and introducing an official version of a modification many people have been doing for a long time now, by drilling opposite the air mixture screw, in order to access the idle circuit. This makes it much easier to clean (and much more effective).
There's one more advantage here: the idle bush that was used on mark-ones until now has been replaced by an external jet that screws in opposite the air mixture screw. Anyway, you can read about it for yourselves here: http://www.amalcarb.co.uk/News.aspx?id=54
It was like an Amal-themed Christmas morning at the garage!
There's something about this photo that makes me think of a rifle:
New needle and clip:
I decided to go with a couple of Allen bolts for the top cap. Bizarrely, they have a 4mm socket. You have to be careful with these because since they can be tightened so much more than the original screws, it is all to easy to warp the zinc-alloy. I re-used a couple of split washers from two old screws that had badly damaged Phillips heads.
Doesn't it look like a model spacecraft like this? The HMS Concentric...
After I was done with the carburetter, I went through my stock of Amal spares - I really have a lot now - and picked a few essential things that I'll keep with the BSA. There is a spare float, springs, float bowl screws, an air mixture screw, spare jets, a fuel filter and a new set of gaskets: bring it on, road-side repair! It all packs neatly into a small hard plastic case that I think I'll keep in the toolbox I recently got.
Your new carb will last for a very long time and give you countless miles of dependable service. I would strongly recommend against replacing Amal for another make - any make - as they are the unsurpassable best for British bikes (and others, even Ducati at one point).
Long live the Amal.