New Amal Strategy?

I'm enough of a purist that my Mk III must have twin Amals. I purchased new ones and have found suitable #3 chrome slides. when I go to tickel these carbs it seems to take forever to get them to weep. Taking a hard look here is what I found:



You will note that the right hand most drilling has been plugged, this would appear to be the float bowl vent pathway, mirror image for the right hand carb---makes it so that the pilot circuit adjustment is the the outside. I suppose that the float bowl gets enough breathing via the lose tolerances of the tickler and the center vent.

My inclination is to drill out the plug (same for ther right hand carb) and let the float bowl really vent, but I'd really appreciate any thoughts you folks may have about this plugs origin (emmissions???) and the wisdom, or not of removing the plug.

With thanks,

RS

RoadScholar said:

You will note that the right hand most drilling has been plugged, this would appear to be the float bowl vent pathway, mirror image for the right hand carb---makes it so that the pilot circuit adjustment is the the outside. I suppose that the float bowl gets enough breathing via the lose tolerances of the tickler and the center vent.

My inclination is to drill out the plug (same for ther right hand carb) and let the float bowl really vent, but I'd really appreciate any thoughts you folks may have about this plugs origin (emmissions???) and the wisdom, or not of removing the plug.

Click to expand...

Do not drill the plugs out.

As you would disable the fuel side of the carbs' pilot circuits if you did that: http://www.jba.bc.ca/Bushmans%20Carb%20 ... tml#2PILOT

If the carbs are taking more than a few seconds to flood when you tickle them, then there's either a partial blockage in the fuel system, or the float heights could be set too low? http://www.amalcarb.co.uk/TechnicalDetail.aspx?id=13

I see that now, thanks!

The floats measure .080 (+-) down from the forward lip of the bowl, they are both consistent in their "tickeling" behavior. The machine runs beauitfully after just 3 minutes of light load.

I once wondered if the tickeling stem on the newer carbs was a bit shorter than the older style???

Again thanks!

RS

RoadScholar said:

The floats measure .080 (+-) down from the forward lip of the bowl, they are both consistent in their "tickeling" behavior. The machine runs beauitfully after just 3 minutes of light load.

Click to expand...

I suggest you use the new Amal information to set the float heights by checking the float bowl fuel level?

RoadScholar said:

I once wondered if the tickeling stem on the newer carbs was a bit shorter than the older style???

Click to expand...

Yes, the tickler pins may not be pressing the floats down far enough?

This can be adjusted by pulling the tickler pins out of their buttons slightly, so that each tickler has approximately 5/16" range of movement.

RoadScholar said:

The floats measure .080 (+-) down from the forward lip of the bowl, they are both consistent in their "tickeling" behavior.

Click to expand...

L.A.B. said:

I suggest you use the new Amal information to set the float heights by checking the float bowl fuel level?

Click to expand...

My experience of this is, I bought new carbs about 18 months ago and set the floats at 0.080" below, as all the info at the time suggested. I had a similar experience taking a long time tickling, and also difficulty getting good idling. LAB posted a link on the "Anything else ... " board about the Amal float heights. I reset the floats to give a fuel level between 0.17 - 0.24" below the top of the bowl. Tickling is correct now, the idle screw is about 1 turn out vs 1/4 turn previously, and the bike idles well.

It appears that the old info about 0.080" below for the floats is not applicable to newer carbs.

Corona850,
Thanks, your experience mirrors my own, special thanks for the air screw data, one of the reasons I purchased #3 cutaway slides (had #3.5). My air screws were about 1/3 turn out, which seemed way to little. My idle was OK, but took a few minutes to stabilize after a hot start and took a few minutes to stabilize after a cold start.

I went to the Amal site and purchased the Mk1 StayUp Float and Needle Valve Kit and will adjust to the spec LAB pointed to and you stated (thanks to both!!). BTW I was impressed with the prices Amal is charging for all their gear, not bad at all.

When I go out this Spring it will be with the 932s jetted with 220 mains, 106 needle jets with needles set in mid position,# 3 cutaways on chrome slides, floats set at .020 (I assume this is what you meant??), air screw where it works best, all joints sealed and properly torqued breathing through a K&N.

My engine has a calculated 9.8:1 CR with a Web Cams 12a cam, the head has been availed of every service offered by Leo Geoff, he also did the boring/honing of my jugs and supplied the Hepolites. The bottom end was balanced and clearanced by Lindskog, beyond gram/inches. I fully expect this Norton to be on its game this coming season.

Thanks to all,

RS

RS - Do you know if it is possible to purchase just the chromed slides from Amal? My carbs seem to be in good shape (due to low mileage) but I'm thinking that chrome slides might prolong their life.

RoadScholar said:

floats set at .020 (I assume this is what you meant??)

Click to expand...

The current Amal recommendation calls for the float heights to be set to give a fuel level[/u in the float bowl of 0.21" (+ or - .040") below the gasket face of the bowl:


http://www.amalcarb.co.uk/TechnicalDetail.aspx?id=13

"The correct fuel level for all Mark 1 Concentric carburetters is 0.21” plus or minus 0.040” below the top edge of the float bowl. Thus when the needle valve is being held shut by the tangs of the float, the level of the fuel will be between 0.17” to 0.25” (4.33mm to 6.35mm) from the top of the bowl."

sidreilley said:

RS - Do you know if it is possible to purchase just the chromed slides from Amal? My carbs seem to be in good shape (due to low mileage) but I'm thinking that chrome slides might prolong their life.

Click to expand...

I'm not sure if Amal are selling chromed slides at the moment, as I heard they'd had some production problems with them a while ago?

However, Surrey Cycles sell the chromed brass slides. http://www.surreycycles.com/exclusive.htm

But note that not all 'chromed' slides are in fact the superior brass type.

I got my chrome plated brass slides from Commando Specialties in Plymouth, MA

http://www.commandospecialties.com/default.asp

Ask for Duane or Jamie, these parts arn't advertised.

RS

RS, TVMI !

I got the Amal "Stay-up" adjustable floats from Burlen Fuel Systems in England, the two kits cost me $60.06 and took about two weeks to arrive as they were out of stock when they received my order.

I set up my bench so that I had a single nipple fuel feed on a float bowl and that it was gently clamped in my vice and level in two dimensions (X,Y). I first tested the plastic float set up by introducing gasoline, through a hose attached to the float bowl and a funnel. With the plastic float (stock set-up) the fuel came up to .340 from the front edge of the bowl, way off spec! Spec being .21 +- .040, no wonder these carbs were hard to tickel and had air screws out bearly 1/4 turn. And they were new! Another forum member said as much.

I fitted the Stay-up floats and began the testing/bending. To make a long story short: when the new floats are parrallel with the edge of the bowl the fuel level is almost a perfect .21, in one case and well withing spec with the other. I worked both to achieve .21, it doesn't take long.

A note of caution: Please be respectful of using gasoline inside your dwelling. I was in my basement studio and I shut down the furnace while doing this work. When I finished I opened a window and vented for 5 minutes to be safe.

RS

You have not mentioned how you are holding the hinge pin down in the grove as you do this test. Or not in a way that I can visualize. I would think that being out of level (a little) is not that important with the concentric or the mark two design. Why not just eye ball the general mounted position on the bike when doing the setting? To make this post a good reference for others as time goes by why not post some pics and explain your thinking a bit more this is something that is base line for all other settings in the carb and something that many people with problems over look it's worth some effort. thanks for explaining your work thus far glad you took the plunge.

Norbsa,
Good point about the pictures, unfortunately it is too late for that the carbs are fully assembled and on the engine.

As far as dealing with the pivot shaft for the floats I had a small piece of screw stock that I was going to lightly clamp over it, but it turned out that I didn't need it, the pivot shaft stayed at the bottom of the two cuts in the bowl, even when I purposely overfill the float bowl, YMMV--my carbs were new less than 1000 miles ago. Several times during the trial and error setting process I snuck up on it with a micro screw driver to see if it was off the bottom of the cuts and each time it was securely bottomed; I admit to being surprised; however using an old drift pin, piece of wire, piece of screw--with head cut off and lightly clamping with micro vice-grips or "C" clamp will solve that problem if it arises.

I do wonder about the angle. For my float setting endeavor I set the bowl up level using the top edge as reference in two dimensions; on the bike the front edge is about 7-8 mm lower during normal motoring, which should result in less fuel in the bowel, but the .21 +- .040 setting should stay the same. I'd welcome the wisdom of others, but I think I'm right---everthing Amal sent me made no reference to angle, nothing on their website either. I did what I did for the sake of consistency perfering a precision error to a random one.

Overall I have .106 nedle jets, needle in the mid position, 220 mains and #3 cut slide aways, this for a relatively warm 850 with roughy 9.8:1 CR and a Web Cams 12a bump sitck, stock valve sizes and Leo Geoff ported head, all other internals have been clearanced, balanced and magna fluxed where appropriate. I am hoping that everything will come together this riding season.

RS