Help troubleshooting kickback & stalls after starting (2016)

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This may well have been mentioned, but have you got the slides in the right way round?

cash
 
The slides only go in one way as far as i know. There is a locating tab on the slide which goes into the body and the cable for the choke is facing the rear of the bike from what i remember.
 
I'm pretty sure they can be fitted the wrong way round. I could be wrong, but it wouldn't hurt to check that the cutaways are facing the rear.
 
I'm pretty sure they can be fitted the wrong way round. I could be wrong, but it wouldn't hurt to check that the cutaways are facing the rear.
Maybe your thinking of mikuni carbs and slides,they are handed, unlike amal carb slides that are universal,the mikuni slides are left and right you could transpose those ones
 
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baz,
Yes you are quite correct. It's an age thing I reckon ___ well that's my usual excuse and I can't think of another right now.

Cash
 
It's running and idling good now. Starts easy, first kick. Ignition needed to be advanced a little, and I went through the pilot jet again with carb cleaner. Has a little off-idle stumble when the throttle is opened quickly, and the new plugs are black but I am out of time. Will fix that next weekend. Thanks all.
 
Yes, primarily, and a lot of other little things. Timing was off due to gap on one point set being a little too wide. Also, one of the AAU's spring plate tabs was bent inwards (causing weak springback of AAU).

It actually took full choke to first start up which is really strange in 70 degree weather. Never use choke here before.

Then I could get a timing light on to see it needed advancing, and it wanted the throttle stop screws in a turn or two.
 
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After having the Amals sleeved, new needles, Stay-ups, float needles and proper float level setup, the SS clone needs choke to cold start for the first time in it's life. Must have done something right. Now it's tickle, choke, ignition and one kick.
 
I believe the need for choke only start when engine is cold is a really good thing. It tells you the carb mixture is correct when warm. (Not too rich).
 
Has a little off-idle stumble when the throttle is opened quickly

Well done! way to be persistant!

The stumble you speak of can be the fuel mixture varying as the carb's idle screw settings interact with the needle jet influence as you raise the slides.... I use a subtle method to tune the idle screw setting to cure that stumble. I find that the idle screw has almost a half turn where the bike idles well, but turning the screw has seemingly no effect. I think that's the idle screw's setting showing the range of fuel proportions that it will tolerate at idle speed. (Once you go out of that range the bike will begin to stumble) Within that range of idle screw positions where the bike idles well, there's the narrower range where it will more smoothly transition from "running on the idle circuit only" to running on both the idle circuit AND the early influence of the needle jet/needle.

I get the bike warmed up, then I find the idle screw range where the bike idles without stumbling on both carbs. Then I gently raise and lower the slides to run the engine up to 2000 rpms, while I micro-adjust the idle screw setting on each carb, going back over it numerous times looking for the smoothest transition to 2000 rpms. You'll find that you can smooth out that stumble this way. (It makes pulling away from a traffic light with some impatient car on your ass less of a "pray it doesn't stall" event)

My explanation of this issue and method to fix it is simple. The idle screw setting has a range where the mixture is changing the fuel ratio, but that ratio still works for an engine that is only idling. Once you lift the slides at all, you add the influence of the needle jet, so the fuel mixture ratio is altered by this secondary influence. By micro-adjusting the idle screw as you lift and lower the slide, you are trying to adjust the idle screw influenced fuel ratio to eliminate the momentary stumble as the secondary influence is added.

It took a lot of reading about amal carbs before I realized why the idle screw had a wide range of adjustment where the bike idled well but turning the screw while the bike idled seemed like it did nothing. My theory is that turning the screw slightly is actually changing the fuel ratio as you turn it, but so long as that ratio is in a certain range, the bike will happily idle, if everything else is right. That idle screw influenced ratio becomes more critical when you lift the slides and add the needle jet as a secondary influence to it. If that combined ratio goes outside the workable fuel ratios, you get a stumble upon accelleration.
 
Short update. Bike runs really great. Timing was out on one cylinder but fixed now. Still needs full choke to start when cold. I am determined to run points ignition on certain bikes so it takes a while to remember how to dial them in. Now there is a hard backfire out the left exhaust on the overrun only. I am guessing an air leak, excess fuel or the exhaust valve is too tight. As I want to protect my new mufflers, I hope to find the exact cause very soon!
 
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A "pop,pop,pop" when you release the throttle is often an exhaust manifold leak. At least it was on my bike. When my bike is running well and popping out the exhaust happens when I release the throttle, I know it's time to tighten, or replace, the crush washers in the exhaust port. I'm told that if your pipes don't seal well with a single crush washer you can use 2 of them to get a seal. I've never needed more than a single washer in each port.

If it is an exhaust leak, The common method is to assemble the exhaust, warm the bike up by going for a short ride, then tighten the exhaust port nuts. Usually after 1 or 2 heat cycles followed by a tightening, they seal fine and are set for a long time. (or at least that's my experience)
 
If you have a backfire on the over run it will be a leak on the inlet manifold. Also, when you twist the points cam against the spring it will cock over to one side because the clearance on the AAU is too much. (They were crap when they were new, measure the bore and spindle of your NOS AAU) Either bush the spindle/cam to about 0.003" clearance or fine tune the timing with a strobe. In fact, strobe the timing anyway, without a strobe and a carb balance kit you will always be riding a dog IMHO
 
Timing is strobed. The static timing always ends up too retarded in my experience. Just adequate to start.

Will check around the intake manifold for air leaks.
 
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the intake manifold air leak can cause a cough back through the carb or kickback when you try to kick the bike to start it. the exhaust manifold leak doesn't do that. It only goes Pop,pop,pop when you release the throttle and coast.

Also if you're running points the AAU could be sticking which would also cause popping out the exhaust among other things...
 
According to riders manuals: "Retinax A" grease "for the contact breaker pivot post and cam.....and three drops of engine oil to each lubricating felt...."

(Shell Retinax A is/was a multi-purpose grease)
Pardon the Triumph talk, I have many more Triumph manuals than Norton...

According to some Triumph manuals I've checked they say slightly oil the pivot pins and cam pivot and use Retinax A Grease on the felt only. Most of the workshop manuals say "Prior to replacing the cam unit it is advisable to add a small drop of lubrication oil to the pivot pins only, not the cam pivot." For one, see the 74 T120 Workshop manual on page B24. At any rate, I've never oiled the shaft and have put minimal oil on the pivot pins and felt. I've seen greased cam pivots that wouldn't advance or if they did, wouldn't retard.

Also, if the unit is fully closed with the engine turning slowly and it advances properly, I'm happy. You can slightly bend the tangs to get it to close a little more, but I've seen brand new springs not fully close it - generally resistance from the points does though.
 
Mallory distributor grease works for me better than oil or other greases. Buy it on E Bay. Still have gradual timing retardation over several hundred miles ( 1-2 degrees) due to the nylon "foot" wearing and points closing up. '71 Commando with original points system, I remove and clean/ oil the AAU once a year. Starts very easy, runs smooth.
Doug
 
Silicone grease (often sold as di-electric grease in auto parts stores) is perfect for distributer use. Any of the common brands at the parts store will do a fine job.
 
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