[webnash]

I followed Matt's example and ordered an amal concentric from Hitchcock. Our hosts don't seem to have manifolds for avl's. I love the look of it and once I get it tuned, I believe it will work well. I replaced the stock CV because I had trouble getting it rich enough after changing the exhaust and removing air box. My amal came stock with 106 needle jet, 200 main jet, #3 slide, I believe the needle is #26. I have put in the biggest main jet that came with it - 210, needle is at highest point and needle jet is changed to 107. At the last plug chop: idle is good brown plug, 1/8-1/4 is ever so slightly tan plug, 1/2 thottle is mostly white plug,  full throttle is very white plug. I have new main jets, needle and needle jet on the way. I'm thinking that I'll try a 230 main next and check plug at both 1/2 and full throttle.

I'm wondering why my bike seems to run so lean with carb settings that other avls seem to be spot on with. The manifold seems to fit well and is tight and petcock seems to run a steady supply of fuel. My stock CV carb had to be run with the biggest needle and main jet and the enricher on to get a tan or brown plug. Is there anything about timing or valves that could make a bike run lean? Are these excessively large jets that I'm using or somewhat typical for avls?

One thing that threw me on this amal carb to begin with is that the choke is a spring loaded slide that needs to be pulled "open" with the cable - thus if the cable broke the choke would be stuck closed. Interesting design - goes with driving on the left I suppose. My first hour of attempted tuning was with the choke closed. Also, the booklet that came with it was blurry and the diagrams were unreadable.

Good news is that it looks great and runs and accelerates well - this leaness issue aside. At the moment I'm running it slightly choked to keep it cool until I get the bigger jets and needle....

[t120rbullet]

Check to see if you have some air leaks by spraying some WD-40 around the joints while the engine is running. You'll hear the difference in the sound of the engine if it's sucking something in.

You can warp the mounting flange on an Amal real easy by tightening them down too hard. 

[Adrian]

The other issue with an Amal Mk1 Concentric is that the standard plain zinc alloy slide they used to fit can wear out very quickly. This was sadly due to the British motorcycle industry forcing Amal to keep the price down in the 1960's when the Mk1was designed, and not being prepared to pay for carbs with a nice chrome slide that would last a bit longer.

Hopefully your Amal would have been shipped with a chrome slide, but if not you can track them down fairly easily in these days of a more informed after-market. I can provide you with a link if our hosts don't stock them.

[webnash]

I'll try the wd40 to check for air leaks. The slide is not chrome, how long will this one typically last before I should order the chrome one? What are the tell tale signs that the slide is worn?

[Thumper]

Are you basing the lean condition only on the color of the plug?

More importantly, how is it running?

I wouldn't even check the color of the plug unless there was a performance issue.

There's no reason I can think of that your set-up would run so much leaner than any other.

Don't worry about the slide and sleave wear until you need to.
There are places that rebore the carb (http://www.amr-of-tucson.com/concen~1.htm) and others that will resleeve it (http://www.amalsleeve.com). I've got over 3500 miles on mine so far...

By habit I lower the choke slide to relieve the spring every time I turn the bike off.

Finally, I *did* have to order a new slide with a cutaway that was one-step richer than the one that was provided in the kit; but that was the only mod. It made a big difference in the mixture (evidenced by a consistent drop of 3-5mpg and smoother running at off-idle speeds, and less popping on decel).

Matt

[webnash]

Well, I'm up to 230 main jet now and in general the bikes runs great, starts on first kick or push of button, has good accelleration, lots of power. It pops a little on decelleration. I have absolutely no color on the plugs - bright white insulater and grey metal electrode. I am paranoid about lean running since every manual I look at has a big warning sign about it. I ordered a richer slide (2.5), richer main jets (240 and 250), a 108 needle jet, and a richer needle taper. I guess I'll keep jetting it richer until I get some color or it seems to have less performance. I did seat the float needle jet a bit lower, so that the bowl filled up a bit fuller, which seems to smooth it out and add a bit of power, but still no plug color.

I also confirmed good fuel flow from petcock and no leaking around manifold.

Matt, do you know what size needle jet and main jet that you are running?

[Thumper]

Matt, do you know what size needle jet and main jet that you are running?

No idea. Whatever Hitchcock's provided in the kit as it was designed for the AVL in conjunction with a freer flowing header and exhaust.

Matt

[webnash]

While I'm waiting for my richer parts, I've got a strip of duct tape over the filter to try and keep the mixture a bit cooler.

[Thumper]

One thing to consider is that the AVL is designed to run lean. It would be difficult to make it run any leaner than it does in stock form. One way to get an estimate is to compare your before and after (conversion) gas mileage numbers.

When you say you're bike is running great then that would preclude a lean running condition. I always check spark plugs last because if there are not performance indicators then there's no reason to check them.

Matt