More amal problems

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Apr 15, 2004
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I'm in need of advice again. My bike has been getting harder and harder to start over the last few weeks and now it will no longer run at all. Electrics checked out fine and it acts like it's not getting gas. So I took off the carbs yet again.

Both float bowls contained a normal amount of gas (I've gotten very good at removing them without spilling any), the floats are definitely not sticking either open or closed, and there was no dirt inside the carbs.

However it appears the pilot jets are plugged up. I removed the air screws and squirted carb cleaner inside. Nothing appeared to be getting thru the pilot jets but it did squirt out the openings at the mouth of the carb and at the bottom of the venturi. I can shine a flashlight in the air screw hole and see the pilot jet with its tiny orifice but I can't tell if they're really clogged or not. Assuming they are, would that explain my progressively-worse hard starting? And how do I clean them? I've read you can poke a tiny wire thru them from the air screw side but what size wire do I need? I don't think I want to try drilling out the blanking plug on the other side.

The other problem is the slides are sticking in both carbs. That's been getting worse too. This time it's not from dissolved tank resin but appears to be warped bodies. Is their any way to fix that or is it new carb time? I've read that you can fix it by squeezing the carb body just the right amount in a vise. Seems like that would take an expert touch though, which I don't feel I have. It seems like resleeving would clean it up but wouldn't that make the carbs even more prone to warping?

I don't think I want to buy new amals after all the problems I've had with these. I really wanted to keep the bike original but this is getting to be too much. It might be time to get the mikuni and live with the 5000 rpm governor effect. The bike will be slower than my GS550 but at least it will run. I hope.

All suggestions and thoughts welcome!

Debby, discouraged
Well Debby,
You say the electrics checked out fine so..............

Have you tried throwing a bit of petrol/gasoline into the cylinders & then trying to start it firstly ? If you have and it does fire up then proceed to clean, I guess.

A recipe for cleaning the amals, if that is the problem then........

An old scuba divers trick to cleaning regulators etc of corrosion is to use vinegar, as it is acidic. That is also how I clean my amals. Buy a bottle, find an old container and soak em for an hour or two. You could probably use it for stuck fork legs also btw.(another question elsewhere)

Rinse em well after soaking in vinegar.

The text book then recommends air to blow em out.

If the bodies are really warped, it shouldn't stop the bike from running at idle or higher.

Persevere & you will conquer it. Hope this is helpfull to you.
The sound & feel of your Norton snortin will lift you up again :D

Hi Debby,

I got tired of praying to the Amal Gods, wore out the toe on my right boot kneeling in supplication. I replaced my dual Amals with a single Mikuni and have never looked back.

I might have lost a tad on the top end, but haven't really noticed it. Am curious what you mean by "5000 govenor", as Daisy will roar up well past the theoritcal red line easily.

The Mikuni was a bit difficult to get set up. I purchased the book from Victory library and that was a huge help. Once I had the jetting all sorted out I have not had one problem with the carb. I changed over about two years ago.
It certainly sounds as if your carbs are plugged. The suggestion to try squirting gas (or ether starting fluid) in the carb throat to see if it will fire is probably a good one. If it does fire, then you can be sure it's carbs.
Commandos usually don't have the problem with warped bodies because they are bolted to the manifolds with only an o-ring. Triumph and BSA has more of a problem with the phenolic heat spacer between carb and head, as it is easy to overtighten and compress the spacer, which torques the carb flange, which distorts the bore. I have a Triumph mechanic friend who swears by his shade tree method of tapping a proper sized socket down the bore to square it up. I think I would be more inclined to send it to be sleeved.

As I have said on this forum before, I have two Commandos running concentrics and one with dual Mikuni's. I have had one set of Amals with the original slides since 1973. The bike still idles below 800 rpm. They do work. I would give serious consideration to new Amals if you can't or don't wish to clean and sleeve your old set. My experience is Mikuni's are not as trouble free as people would like you to believe.

Ron L
Hi Deb,

You appear to have the perfect mind set for a Mikuni. Sometimes you have to get to the point of total frustration in order to justify a Mikuni. So go out and get one and don't look back.

But just in case there is a quiver of doubt, try sending your carbs to AMR for repair. They bore the body and furnish an oversized chrome plated brass slide. I've had this done to the carbs on my 850 Commando and am 100% satisfied.


Re: Mikuni

DaveC said:
The Mikuni was a bit difficult to get set up. I purchased the book from Victory library and that was a huge help. Once I had the jetting all sorted out I have not had one problem with the carb. I changed over about two years ago.
Dave, after 17 years I made the switch to a 34mm Mikuni this spring and so far I'm very satisified with one exception, fast idle at startup is very lumpy and not very fast. It will keep running but fouls the plugs if I let it go more than a minute or so. External adjustments made no difference so the thought is jetting. Any of this sound familliar?

Otherwise she runs like a top when warm and pulls from 2000 revs to redline with ease, probably not quite as quickly as with twin carbs but very smoothly and evenly. Throttle pull is now one or two finger easy.

Is the book you mention the Mikuni tuning guide?

George K.
This issue of carburetion stirs more controversy than probably anything else. The biggest problem with the Amals is they are probably 30 years old. If the bike had original Mikuni's on it, there would also be issues.
The pilot jet is no doubt plugged. Source a piece of 12 ga. stranded copper wire, about 12 cents a foot at the hardware store, peel a single strand and have a go. If it won't clear, it may be needed to be soaked in 'Parts Dip', methylene chloride.
The carb bores may be OK. A good soaking or new slides may solve the issue. Remember to install the carb top before tightening the manifold carbs nuts to keep the bore from deforming.
AMR does a nice job, however you do lose the choke.
Changing to a Mikuni does not solve all the issues, just changes them. If the bike sits for long periods or runs unfiltered nasty fuel, it will need attention also.
My experience with an 850 in changing to a Mikuni is took some off the top and some snap off the bottom. This is further backed up by the Victory tuning manuel. I quote, "isolated runner intake systems allow finer tuning than plenum (common manifold) systems. They have (generally) much better idle, low speed torque & response than plenum-type manifolds, as the vacuum pulse is not weakened by exhaust gas returning from the other cylinder's overlap..."
I am currently going thru a 71 Roadster that some one had given up on the Amals and installed a Mikuni. Upon depotting the Amals, doing a thorough soaking and cleaning I have cleared one sticking slide, cleared one partially and one fully blocked air jet, cleaned the needle seats, replaced the float needles, corrected one badly adjusted float. No wonder someone gave up these.
A single Mikuni will correct your problem specifically because it will be new. It will give you nice servicable ride, but to extract the best performance from it will require more work and jetting than everyone is letting on.
I prefer the dual carbs as it leaves the 'Snort' in the Norton.
The choice is yours. Decisions, decisions.
Well, maybe I'll give these carbs a good soaking and poking before I give up on them. The vinegar soak is an interesting idea. That's what I use to clean the scaling out of my humidifier in the winter. I have a can of carb cleaner too. Maybe I should try both!

I don't know about the sticking slides though. I didn't know about tightening the flange nuts with the carb tops in place the first time I took them apart so I did it the wrong way. Is it possible that ruined the carb bodies? I could try new slides but I hate to spend more money on these things at this point. And new amals seem to be running about $200 USD each so I don't know about that either.

My previous experience with Mikunis was on my old 850 and didn't go so well. When its amals wore out my brother convinced me to try dual mikunis. He had some spare carbs for his Kawasaki H2 so we put those on. Of course the jetting was completely wrong and we had no idea how they should be jetted. So we gave up on that and I put a single 34mm on it. Perhaps it had setup issues also - I couldn't get the bike to idle below 1500 rpm and it was really dead on the top end. The motor just hit a brick wall at about 5000 rpm. I ended up selling the bike not long after that, never did get it running right. So maybe there's no easy solution. Of course now there's a lot more information available about tuning the Mikunis. But I'd like to spend my weekends riding the bike not taking the freaking carbs apart over and over and over...

Another option is new Amals. I've installed new carbs on three bikes this past year, all with good results (1 650 Triumph and 2 850 Nortons). They all came pre-jetted for the application and, with a little adjustment and sychronizing, worked great right out of the box. I believe the cost for the pair was about $300 US. I realize that they will probably need sleeving some day, but at least they will get you back on the road!!


It is possible you have distorted the carb bodies. I know this from first hand experience. I distorted a very good bored carb body with a stainless slide on my Mark III. Totally p#$&^d me off. That's when I took the Mikuni off the 71, rejetted it and put it on the 850.
I would probably strip the carbs, take them to a local Brit bike shop and see if new slides would even work. If not, I would determine if the carbs were worthy for a rebore. If so, I would ship them somewhere for a rebore and new slides. Mine worked flawless till it sat for two years, clogged an air jet and then I screwed one up on reassembly.
Properly done, the rebuilt Amals will be better than new, far less costly and probably less than a Mikuni set up.

P.S. I would have the extended ticklers installed.
Yes, I have experience with him - I had him resurface and drill my rotor. Easy to work with and he did a nice job. I thought I'd send him the carbs if I decide to go that route.


Small world, Bruce is good friend of mine, lives about 20 miles from me.
Which drilling pattern did you go with?

Bruce drilled my rotor and sleeved my carbs. Good guy and stands behind his work.


Hi Derek,

I had mine drilled just like the photo on his web site - large holes in the center section and the smaller holes in the braking area. It looks really nice. Now I need to find a good plater in this area since the nissin caliper won't span the entire braking area. Don't want a permanent rust band on my rotor!

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