Amal set up

Well, here is the problem:
" After a lot of work to start it it will not idle." It was like it started out flooded, and after a while kicked in. Can you flood a Norton?

Tried dropping the throttle needed setting down one notch (it was on the lowest one), and it made it rev up even more. So, that adjustment worsened the problem. I thought it would reduce fuel but had the opposite affect.

It appears to be just getting to much fuel, as I am sure the throttle cylinders are resting all the way down and cabling doesn't appear to be involved. The throttle cylinders move easily and travel together well through the full range.

The part that surprises me the most is last time I started it it would idle down, not low enough but reasonably low. I've checked over and over for cable binding and throttle cylinders sticking but haven't seen any issues there. I'm wondering could I have a jet clogged? Can it be a float problem?

Hope some one out there has a good idea or two. I bet some old timers are chuckling.

Some more info please... about the bike, recent work, and about you. What do you know about carburetion? Just helps know where and at what level to start. You could have bad needle/seat, float, etc. but first we need a baseline.

Have you visited this place yet? http://www.jba.bc.ca/Bushmans%20Carb%20 ... html#FLOAT

If not, you need to.

Dave
69S

Tell us what else you have done. Like adjusted the throttle stop screws, adjusted the pilot curcuit, sync'ed the carb?
What is your experience with amals? Try to leave us as little as possible to assume.

Are they new, old, have you ever rebuilt them? What carbs, other than Amal, are they. What bike are they on>

You just can't post and say, " hey, my bike won't idle", without some supporting information.

Go to the Amal site and get a tuning guide. Here's a bone. http://www.amalcarb.co.uk/downloads.aspx

Ok, more input, lets see:
Amal 932 twin carbs, 850 Commando with 750 bottum.
My experience with carb rebuilding is good, but not a master mechanic (shade-tree kind of guy).
So far I have just cleaned them and replaced the filters, didn't see a lot of issues in the process, but could have changed the float level I suppose, not sure yet. The bike sat in a barn literally for over ten years (have you seen the pictures yet?), and I had to go through the whole thing, gas tank first, petcocks, and stripped and cleaned the carbs. It was running when it was parked, and I felt pretty good when it fired up after a lot of making sure it had spark (still does) and a new battery and starter condenser. Oil system looks ok and acting normal according to the original owner.

I'm sure the cables are letting the throttle cylinders all the way down, I backed out the Idle adjust speed screw all the way out until they didn't lift or let the cylinders rest on them. The cylinders seem to be resting as far down as they will go, but still the motor is running very fast, (Had to shut down after start up). That's when I adjusted the throttle speed needle down a notch to try and reduce fuel flow and got the opposite affect I expected.

For now I guess I'll pull them out and clean them again, and put the throttle needle back where I started (change one thing at a time and watch the affect).

I did read the article recommended above (recommended by DogT), but I'll go back and do it again, also the tuning guide recommended by pvisseriii. I'm going to try and study the cabling some more too, but they seem ok, no binding, full travel.

I really think this problem will turn out to be simple because it was idling fine last time I started it.

The first time I started it it raced, and I found cables hanging up. Fixed them and all was ok, and she idled fine. Since then I have put a new throttle handle on, and may have messed up the cabling again. I'm just surprised it runs up so fast with the throttle cylinders all the way down.

I'll put more information out as it comes, I can answer specific questions a lot easier.


Thanks for the help guys.

Is it possible you have an air leak? Do you have the rubber hose (balance pipe) connecting the nipples together on the manifolds? When you say you lowered the needle one notch, does that mean you put it from the bottom notch to the middle (raising the clip lowers the needle)? Also, do you have the choke pulled off? On Amals, pulling the choke cable pulls the choke slides up out of the airstream, slackening the cable lowers the slides, richening the mixture. If you have an air leak, needles set rich or float level too high, and the choke on, the engine would run pretty fast.

How did the slides work in the bodies after you cleaned the carbs? if they fit very loose to the point of even rattling around a bit, you won't get the bike to idle down, even with the air screws (the front horizontal ones) screwed all the way in. Too much air will come in around the slides. This is the main reason why the carbs are changed - the slides wear to the point that the engine won't idle down, usually after 10-15K miles.

There are companies that will sleeve or chrome the slides, but new Amals with hardened slides, better floats, removable pilot jets and brass drain screws are available for around $185.

When you say the slides are all the way down, have you visually verified this by looking into the intake end of the carbs (with the carbs installed on the bike) and observing that the slide is all the way down/feeling that it is there with your index finger? You may have warped carb bodies that are keeping the slides from bottoming. If you twist the throttle fully open and release it, there should be a pronounced "snap" as the slides bottom. Of course, as noted, incorrectly adjusted/corroded cables can also hang up the slides.

If you're uncertain about the float level, it will make a big difference if they're incorrect. It can mean the difference between starting and not, and also running right. You can check the float bowls off the bike on a flat plate and a feed line to the banjo. It may not hurt. Use alcohol or spirits if you don't want to mess with gas.



Dave
69S

Thanks for the helpful suggestions! I have more info to input:
I like the float level tester, think I will make one similar just because it would also check the float needle is seating well also.

It turns out the original owner did remove the choke cable, and the spring that holds down the slide isn't there. Should I remove the slide too? The hole above it is blocked,and I don't think it's leaking there.

The cylinders do seem to drop and bottom out with the throttle all the way down, and are resting on something. I can jiggle them slightly with my finger to lift them. Only .01.-.015" probably. They also appear to be traveling "in sync" full range.

The air tube in between the two carbs is in place and appears ok, where else can I look for air leaks?

Mileage on these carbs is around 20,000mles, so they are old!

I'm going to clean them again, and check everything out very close. Then I'll have more info to post.

I"ll put the throttle needle back on the bottom notch where it ran slower, that should raise them up about a millimeter, and should allow more air flow right?

I understand the Bushmans's Carb Tunning article pretty well, and I think I did everything right. Still I'll concentrate even more next time and report results. When I first got the bike one of the air mixture needle valves was missing and I have replaced both of them new, and they are set at 1 1/2 turns for now.

I really don't like how the cables feel, so I think I'm going to build some new ones just to be sure. The first time it started it revved way up and I shut it down. Found the cylinders hanging up on one side, then adjusted the cables, and it idled after that. Sounded good, so I stopped and went to work rebuilding the brakes which came out fine. Right now I don't see any evidence of the cylinders hanging up, but I'm still suspicious of the cables.

I'll take some pictures to help out, some one may see something that I don't. I'll try to show each step as I go.
I have a short video of it Idling on my phone, I'll try to see if I can get a link posted. Will it work on "Photobucket"?

Did you clean the idle circuit? It's done with a .017" drill bit (or a guitar string, or, or, or...) in a home made holder in through the hole the idle mixture screw goes.

Yes, the float bowl test is good to see if the needle is leaking too. One of mine was, and if you have that problem, we can go there. I had to resurface one of my needle seats. You may want to check the petcocks while you're about it. Since I had a leaky needle float, I drained a whole tank of avgas overnight because the petcocks were leaking. Luckily the avgas evaporates so fast, it evaporated out of the float bowls, not into the crank. We don't need any fires here.

20K miles is a lot for the original carbs. Mine were worn out after 14K. I got the Amal hard anodized slides, and they made a big difference, but I think for the long run I should have done a complete rebore and sleeving. Not that much more, plus it's winter now too.

You can check for air leaks by shooting ether around the carbs while running, but I really don't like that idea. I think a good inspection will do, looking for cracked or deficient parts. Make sure all the mating surfaces are flat. Other thing is, as you notice in the JBA site, there are 3 ports that are associated with the idle circuit. If you shoot carb cleaner in one port it should come out all the others. Do all three, it should be obvious.

I haven't heard you talk about raising the slides and seeing that both slides disappear above the top edge at the same time. That should be done, and easy to feel, it doesn't matter so much on the bottom, you want them synced at the top. The bottom will take care of itself with the idle screw.

Venhill cables are to die for. But I'm still using my originals and they're working fine if a bit ragged at the ends. Take some cable ties to the frame below the seat and make the cables go into the carbs straighter too.

Dave
69S

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|quote=
It turns out the original owner did remove the choke cable, and the spring that holds down the slide isn't there. Should I remove the slide too? The hole above it is blocked,and I don't think it's leaking there.

If you are speaking of the little choke slides that ride in the throttle slides (what you are calling cylinders) then with or without that tight little spring to hold them down or the cables they will end up down at the bottom of their travel and the choke will be always "on". They need either to be connected up so they work with the lever or taken out.
.







I'm going to clean them again, and check everything out very close. Then I'll have more info to post.

I"ll put the throttle needle back on the bottom notch where it ran slower, that should raise them up about a millimeter, and should allow more air flow right?

I understand the Bushmans's Carb Tunning article pretty well, and I think I did everything right. Still I'll concentrate even more next time and report results. When I first got the bike one of the air mixture needle valves was missing and I have replaced both of them new, and they are set at 1 1/2 turns for now.

I really don't like how the cables feel, so I think I'm going to build some new ones just to be sure. The first time it started it revved way up and I shut it down. Found the cylinders hanging up on one side, then adjusted the cables, and it idled after that. Sounded good, so I stopped and went to work rebuilding the brakes which came out fine. Right now I don't see any evidence of the cylinders hanging up, but I'm still suspicious of the cables.

I'll take some pictures to help out, some one may see something that I don't. I'll try to show each step as I go.
I have a short video of it Idling on my phone, I'll try to see if I can get a link posted. Will it work on "Photobucket"?[/quote]

If those are still the old floats you should probably get the new stay up ones. If They're. Not bad now then the new gas will eat at them, until they are. Just my 2cents.

DogT said:

Not that much more, plus it's winter now too.
Dave
69S

Click to expand...

Just getting into decent riding season here - high of 81F today. We need another cold front to come through - only got down to 74 last night 8)

There's nothing left to "set up". At 20,000 they are toast ,the slides and bores are finished. The next stage will be slide fracture going into the engine and if lucky out and into muffler. Sorry to tell you the truth but it's credit card time.

Progress! I found a slide sticking. Doesn't do it every time, and is definitely cable related. I found it while going through re-cleaning all the cables . While I was testing the movement of the slide pushing it up with my finger and watching the cable when it hung. So I'm part way there. New cables coming, and will price new slides too. Choke slides are not installed, no leaks at the choke cable entrance, can't blow air through it.
I feel better and humbled, but you learn more from mistakes some times. Now it makes sense. The cylinders were coming all the way down just not every time. Old parts can be frustrating some times. I will take pics when re-assembled with new cables.

Thanks for the help.

Great! Before you install anything...with the carbs installed on the bike and NO cables installed, lift the slides with your finger to their highest position and then slowly let them back down with your finger. No matter how slowly you let them down they should not hang anywhere. If they do that ok, then do the same lifting but release them completely from the full open position. Again, they should fall with definite thump as the hit bottom. If they cannot pass this test they need to be removed and "adjusted" so they will. "Adjusted" may mean using a vice to squeeze the carb body back to a round shape. You just have to keep at it until the slides will drop smoothly in the bore regardless of how slowly they are allowed to move. Overtightening virtually any screws can distort the bore, even those that you wouldn't think have anything to do with that. It's critical that all mating surfaces be true as well as no overtightened screws. If that is done and a complete rebuild kit installed, Amals can be adjusted to idle smoothly at 500 rpm as well as cleanly accelerate to WOT. Obviously, as has been noted, if the slides/bores are worn out, nothing short of sleeving or new carbs is going to fix that.

Thanks for checking back in, closing the loop. :mrgreen: Reminds me of climbing Mt. Washington Auto Road, http://mtwashingtonautoroad.com/drive-yourself/ on a borrowed '69 BSA Lightning, riding two up, NO rear brake, (the brake pedal pivot bolt had ejected 50 miles prior) and ONE carb would stick open when I used any where NEAR full throttle... :lol:

Well, I have to say I didn't think about warped carb bodies, and am surprised they can be that sensitive to it, so It will be interesting to check that out. I'll get some photo's of the throttle slides too for you to see. Then I can get some input regarding how bad they are.

I found another good resource for detailed information, lots of details about different Amal carbs:

http://www.amalcarb.co.uk/TechnicalDetail.aspx?id=11

I found it when looking for a source for new throttle slides and floats.
Stay tuned for future input!
Dale

Progress!!! Learned a lot. It's fun bringing them back to life. First new rule of restoration shall be; "replace all cables" including all throttle, clutch, tach , and brake lines.
Testing to see if I can post video, be kind, it's not done

http://s1282.beta.photobucket.com/user/ ... 2.mp4.html