Still won't run...

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I need to win the lottery and retire from my job to keep working on my Norton!!!

The plastic tube to check the float level sounds like a really good idea. Unfortunately my float bowls don't have drain plugs. So I took one bowl off, hooked up the fuel line and watched it fill up while I held it in my hand. Couldn't run the engine like that but I think that's a more accurate measurement of the float level than dry measurements. The top of the float was a little below the top of the bowl. I didn't measure it but it looked in the ballpark as they say. I've previously measured them both dry (lot of conflicting info about that!) and they're both the same.

The other thing about this problem is it had a sudden onset. It did not develop gradually. The last time the bike ran normally was the 4th of July weekend. All was well then. The bike then sat for two weeks before I had time to ride it again. That's when this problem presented. Something happened during that two week period that broke the bike. But what could it be??? I don't think the floats suddenly changed their position, nor do I think the float bowl gaskets suddenly moved over and grabbed the float. So I'm skeptical about float settings being the cause, even though the symptoms otherwise seem to indicate it. Besides, if the float level is too rich how would that make the bike starve for fuel? Although I'm not sure it really *is* starving for fuel because when I pull the float bowls they're full of fuel not empty.

So it remains the unsolvable problem....

71 750 Roadster parts bike
Winning the lottery sounds like a good thing !! If you do fly me over for a visit & to fix your Norton maybe.

Ok then, if it isn't fuel... have u checked any spade connections u may have on your coils. These can be contacting for a while & then not contacting when the bike is running/vibrating if they slip off.
You get what I mean........this may be happening somewhere along the electrical side.

No matter how simple this problem ends up being, pls let us know what the problem was when u find it.
Well guess what - I got it running!!! I can't really say what the problem was. A combination of things I guess. Those carbs were in pretty sad shape when I got the bike. It originally had the nylon float needles, the floats were gummed up with gasket sealer, the slides were sticking, the needle jets were worn out, the jetting was wrong for this altitude, and the pilot jets were clogged. There wasn't much of anything *right* about them.

I worked through most of those issues over the last four months but the pilots were always a problem and trying to compensate with the airscrews just did not work. I fouled out at least a dozen plugs. So I finally cleaned the pilot circuits but as you know it still wasn't running.

Today I noticed it seemed too rich below 2000 rpm. Sort of felt like it was loading up right before stalling out. So leaned out the air screws some more. They're at two turns out now which is probably about right for this altitude. It was still stalling out though, so on a whim I installed another set of new plugs. That got it running! I did some test rides around the block and he was running well! That's the first time since July 3. The old plugs didn't look fouled, just black and sooty but they sure didn't work.

Now I should probably take the time to get the float height exactly right. I think they're a bit too high (rich) right now. And I'll have to spend some more time adjusting the idle. And I think whenever I ride the bike I'll be carrying a new set of plugs and a plug wrench! It will take me a while to get my confidence back with the bike. But this is very encouraging.

Lesson learned? I guess I'd say everything has to be set up just right. You have to be fanatical about the details. Anyway, wish me luck. Hopefully it will be ok for a while now. May still need new carbies before long though...

71 750 Roadster, running! :D
end of the rainbow

Sure Reg, if I win the jackpot the airline ticket will be on it's way! Or maybe I'll come down. I've never been down there, would like to visit someday.

Electrical connections were part of the problem. The spade lugs on the ignition switch had pretty bad corrosion and the junction blocks under the tank were actually broken. The wires were just sitting in there loose, including the wires from the kill button. The bike had been poorly maintained for years and now it has to be made right. That's proving to be a much bigger job than I anticipated but I am making progress.


ps - front brake still doesn't work. maybe a careful adjustment of the linkage would help...
Debby, Always good to tune a running bike instead of reviiving a dead one. Try some Auto Lite AP64's plugs that's what I run in both my Nortons they don't gas foul. Just went through my front drum brake and got some learning taken care of. First there are a lot of parts to this job that need a helper so charm some one soon. My brake worked well but the old shoes would glaze over causing fade right after hard use. So time for fresh Ferodo shoes. These need to be turned but no need for a lathe or hundeds of dollars. This is what I did it works well. Clean the drum with sand paper on the inside with 60 grit this knocks down the glaze and prepares the surface for rubber cement. Cut some strips of 60 grit the width of the drum, you will need three paint up the back of the strips with rubber cement as well as the inside of the drum. The paper needs two coats, let it dry and line the inside of the drum no gaps with 60 grit. now assemble your new shoes on the backing plate just like you were going to run it this way. You will need to back off all your adjusters but go ahead and hook up the cable. Ok now for the helper bikes on the center stand and the stands on a piece of 2x wood helper is on the bike keeping the bike on the rear wheel and gently applying the front brake you are on your side on the ground turning the front tire buy hand when your helper tells you the handle has touched the handle bar it's time to pull it apart for a check. When you get 90% touching your done with the sanding. You now need to sand a half inch of taper on the leading side of each shoe don't skip this step or it won't quit stopping. Now after you have got this done and every thing is clean and relubed don't forget to put a little grease on the shoes were they contact the cams, It's time to adjust the two shoes. Again you need a helper to get this right. The first shoe is the one that the cable pulls directly on and the second shoe is the one that is pulled on by the adjustible rod. You need to start by backing off the second shoe so there is no contact when the brake is on. Now hold the brake on with your hand and have your helper slowly adjust the second shoe till you feel the lever move just a little in your hand. This is critical and may take a few trys to get right. Each time having your helper back off the adjuster just a little while you take rests from holding the brake on by hand. Make sure that it's as close as you can get it re adjust and tighten everything, time for a brake in also critical. This is first gear work take the bike up to shift point and use the brake easy at first than harder and harder each time till your skidding to a stop. You are heating the brake up to very hot on this first run. Now let it cool down all the way and re adjust everything. I took mine apart at this stage just to clean out the dust and recheck the lube and such. With all the cleaning and fussing plan on four hours work and an hour of cool off time than another hour of cleaning and readjustment. The only time this system shows it's weekness is when your riding with bikes that have two front disk brakes and they are using them hard in their riding style. My brake will lock the front wheel at anything shy of 65 MPH if I really grab a handfull. I have left out some details on grease types and tighting sequinces to keep this shorter but you get the idea. If you need more info PM me.norbsa

I have been watching this thread with interest. My 850 has been idle for about 6 weeks (travel & family commitments) and has proven difficult to get started. Everytime I try I end up with wet plugs and a sweat.

All the advise you have been getting has given me a few pointers.

It seems that my Champion N7YC plugs are lasting less than 200miles..I changed to NKG B7ES and if Ican get Iridiums I'll give them a go.

It started after about 5 kicks...

Carbys next.
Congratulations on getting it running.

Now you need to make it a reliable runner.

Your quote earlier
Electrical connections were part of the problem. The spade lugs on the ignition switch had pretty bad corrosion and the junction blocks under the tank were actually broken. The wires were just sitting in there loose, including the wires from the kill button.
This looks like more of a problem than measuring float levels for your road bike, how far out do they have to be to stop it running ???

All this talk about putting single mikunis on & stuff is simply not required.

One bloke I ride with (a harley mechanic), but loves nortons, uses a single amal carby & he is quickest off the mark. His bike idles & is reliable.

A rewire or new harness & connectors might be a good step in the right direction.

I am sure you are enjoying the next riding chapter in the nortons life.

Has the norton got a reprieve ? Are you keeping it for now ? :D
The reason I put this quote in
One bloke I ride with (a harley mechanic), but loves nortons, uses a single amal carby & he is quickest off the mark. His bike idles & is reliable.
Well I thought you may find it easier to "tune" your norton.
Dual/2 carbys need to be pretty well synchronised.........
Frankly they can be a pain in the proverbial.
But a single amal keeps the "norton aunthenticity" & is simple to set/tune.

When one wears out swap em over, the only difference will be the tickler.

Any one with a norton will testify to the maintenance required to keep them in "top tune" & a single amal will only cost you a manifold.
For now the electrics are ok. I "reassigned" some good terminal blocks from the turn signals and switch cluster. At the moment I don't have power to the high beam flasher or the turn signals but that's ok. The bike doesn't have turn sigs fitted and I can live without the beam flasher. I bought some new terminal blocks from Old Britts but they don't seem to fit. So I need to figure out what's up with that...

The bike does have a newer wiring harness and the ignition switch appears ok. And, as Jason likes to hear, it has a nice fat blue spark. So that's good!
I rode it Monday after work and it started *first kick* and ran great :D

You know, regarding carbys there's been a whole bunch of glowing testimonials on the INOA list recently about single Mikunis. They make a compelling case. Maybe I should consider that when these amals are finally shot. Some of the benefits:

carb body doesn't warp
slides don't wear out
needle jets don't wear out (until you have really high miles)
float bowl gasket doesn't foul the float.
adjusting the float level is a simple matter of bending a metal tab
pilot jet easily removed for cleaning or replacement
pilot jets available in various sizes
jetting increments are finer, making it easier to get the right jetting (on the amals I've noticed all available settings seem too rich or too lean)
don't have to deal with the miserable stock airbox - what a pain!

Maybe I could spend more time riding and less time messing with the carbs! All those bennies and the only cost is a slight loss on the top end. And I'm told I shouldn't rev it up to redline anyway or the engine might blow (not sure if that's really true but don't wanna find out!) Hmm...

Sounds like you have it sorted for now then...........

If I can make one more comment about amals.

A lot of people pull the "choke" slides out as they don't use it.

Some of us believe that leaving it in will stop the slides wearing out as quickly. The reason being it stops the slides rattling around as much.

I ain't no engineer, so what does anyone else think of this conclusion ?
In my mind, the greatest carburetor slide/body wear occurs when the throttle slide is moving against high manifold vacum. This condition sucks and scrapes the slide hard against the body, which literally tears away the surface of the metal. Evidence of this phenomenon can be seen as vertical score marks on the manifold side of any used AMAL carburetor slide.

Now, there is additional wear owing strictly to vibration. However, I feel that this wear is not nearly as severe as the wear incurred when the throttle slide is operated up and down. Installing choke slides may help slightly to resist slide movement from vibration, but I feel the benefits would be miniscule.
Amal wear

Hi Jason,

I've run sleeved original 932 concentrics for over 6 years and am not getting much of that wear at the front of the slides. I'm not convinced that vibration doesn't cause considerable wear. The vacuum doesn't affect the jet needles and I will assume vibration wears these out in about 10,000 miles. There were some rubber mount kits in the early 80s to slow down the wear on Amals. The problem with these is it sets the carbs so far rearward you can't use the air filter.


The Amals can be made to work very well, but I believe they will wear quicker than a rubber mounted carb such as Mikuni or Amal Mk2. It really comes down to how you want to use your Commando. I ride less than 3,000 miles per year and when I do ride, I want all the original "snort" a combat can give.
Hi there illf8ed,

I too run a sleeved AMAL of sorts; it's actually a chrome plated brass slide but similar in concept to the sleeve arrangement. Sleeved or chrome plated brass slides do last longer than the stock pot-metal slides.

And yes, vibration has more of an effect on jet and jet needle wear than slide wear.


Did you know that AMR place went out of business? (they're the place that bores out the bodies and fits the mikuni-style slides) According to their website they've closed their retail location and plan to reopen as an internet-only operation in a few months. Don't know what their future plans will be regarding the amal repairs...

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