Amal float height.. An example of why it really matters.

Deets55 said:

Here is how I check mine.

Click to expand...

So in this set of pictures, it clearly shows the difference in fuel level between the two carbs, did this cause an impact in performance?
if so, was that the reasoning of the test?

are the drain plug attachments home-made, or the products offered from the posts on page 1?

david7212 said:

Deets55 said:

Here is how I check mine.

Click to expand...

So in this set of pictures, it clearly shows the difference in fuel level between the two carbs, did this cause an impact in performance?
if so, was that the reasoning of the test?

are the drain plug attachments home-made, or the products offered from the posts on page 1?

Click to expand...

That is actually the same carb showing the difference in fuel level when measured in the center of the bowl vs the front of the bowl due to the 10 degree tilt in the carb. I was checking the fuel level because I was getting slightly different color pipes also. When I first checked that carb it was lower than the other so I raised the level by bending the float tang. The level shown is slightly higher than I like it and have since dropped it so there is a 1 mm gap measured at the front of the bowl, same as the other side.

I made the "tool" by drilling and tapping an old plastic bowl drain (1/4 x 28 I think), screwed in an old MIG welder tip (which I drilled out to a larger ID) and attached a piece of fuel line.

Pete

Thanks Pete, I figured out the pics after I saw your pics on another post.

I will likely just order the kit to check the bowls while on the carb, vs fabbing something up.

this has finally made the necessary sense to me so I can diagnose the situation, hopefully a simple fix of either float height, which may or may not require the update floats with the metal tangs.

FWIW,
I also made a device similar to DogT's to see if the stay-up floats react the same as the plastic floats. Happy to say that work the same. When the bowls fill normally the fuel is just slightly above the top of the float on the end opposite the hinge for both materials.

Pete

I got rid of the old plastic floats first thing and bought the new adjustable tang stay-up floats from Amal. I also bought all new parts, and it didn't help much. I had to have the slides sleeved by Lund's. Now it idles perfectly, which it never did before with only 13K miles. I can actually take my hand off the throttle in traffic and not worry about it. The difference between rebuilding with new parts plus sleeving and buying new Premere's is about the same, it's up to you, or go for another type carb which I wasn't willing to do.

EI vs a bad mechanical advance will make a difference too.

If you are using the jet sizes specified by the manufacturer without changing them to get performance the actual fuel level in the bowls is important. I never do that. I always measure the float level with a vernier caliper and set it to the carb manufacturer's spec. Then tune the bike from there by changing jets etc. to get best running. That means the ACTUAL float level measurement is largely irrelevant as long as they are the same in both carbs. The jets specified in any bike's manual are only a starting point - usually too rich - but safe.

DogT said:

David,

You can mount the float bowls alone on a metal plate and watch the float level. Or as you indicated check it with a tube off the drain, if you have one. This is how I did it, but I used alcohol instead of gas.

Click to expand...

on your test set up, where did u find the fuel inlet banjo with that type of nipple? or did u make it?
can i run my factory dual carb fuel line and conduct this test off the bike?
I think i could just elevate the fuel line ends and it would have the same effect as if connected to the tank, no?

Thanks Dog

acotrel said:

If you are using the jet sizes specified by the manufacturer without changing them to get performance the actual fuel level in the bowls is important. I never do that. I always measure the float level with a vernier caliper and set it to the carb manufacturer's spec. Then tune the bike from there by changing jets etc. to get best running. That means the ACTUAL float level measurement is largely irrelevant as long as they are the same in both carbs. The jets specified in any bike's manual are only a starting point - usually too rich - but safe.

Click to expand...

I agree with most of this. We tend to overthink our machines a bit I think. I believe that if the float level is in the ball-park, proper running can be achieved with other easier carb adjustments. I know not too many want to hear this but float level is IMO the first and crudest of carb adjustments. If you are using it for fine tuning mixture, you're just skipping around, out of logical order, and ultimately you'll end up adjusting the carb to the 'whatever' float/fuel level any way. I certainly agree that the most important thing regarding float level is that both carbs be equal and be reasonably high enough. I set mine level with the bowl rim. It tickles nicely and does not weep (too much) at the gasket. My plugs are equally off white with no sign of overheating.

DogT said:

David,

You can mount the float bowls alone on a metal plate and watch the float level. Or as you indicated check it with a tube off the drain, if you have one. This is how I did it, but I used alcohol instead of gas.

Click to expand...

Why did you leave the gaskets on, in case they leaked ? :lol:

Biscuit said:

I know not too many want to hear this but float level is IMO the first and crudest of carb adjustments.

Click to expand...

+1 on that statement in getting the Amals dialed and balanced.
Cheers,
Thomas

The float will find it's own level by putting fuel in the baster at the top, determined by when the needle valve shuts it off and how the float bowl is adjusted. Left the gaskets on to keep the lever bar in place, otherwise it just falls out. I did one at a time. But if you have the drain, it's easier to use that method, same effect. This will also check for needle valve seat leaks which one of mine had.