Complete noob. Need help, please.

Alright, I'm sure this is a retread of past threads but to be honest, I'm not even good at the lingo yet so for my particular issues I'm unsure of what to search for. When I do try I come up with stuff miles over my head. I probably shouldn't even own a Norton with my level of mechanical understanding. But I do. Here goes:

1973 Norton Commando 750. Trouble kickstarting it, trouble keeping it running after started and trouble with engine "hesitating" when accelerating. A further breakdown of the issues: When kickstarting, it tends to cough and sputter and sometimes backfire. I probably get it started 1 out of 40 or so kicks. Once started it may stay running for a few seconds and die or it may decide its ready to go. If I leave it idling it will still tend to sputter a tad and throw a backfire in there for good measure here and there. It has trouble keeping its idle as well and if I don't babysit the throttle for quite a while it decides its nap time again. If I'm lucky enough to get it moving first gear rides fine but second or third seems to have a dead spot where the power drops out even while opening the throttle. Really, I've only made it to third because when the issue occurs there it stalls and dies.

I *think* this means carb issues from some I've read, but to be honest I'm clueless and am like a blind man fumbling around in the dark here. Any help would be immensely appreciated.

I live in Oklahoma City, BTW. If there are any Norton owners around the area that would like to have a lot of beer purchased for them, I could use some guidance in person for sure.

Welcome! It sounds like you have little to no experience tinkering internal combustion engines, yes? There are many basics things to check, like carb cleaning, ignition, etc. Any family member or friend who could work with you? Do you have a set of basic hand tools? Sputtering is good, kinds, it ALMOST wants to run. May be ignition or carburetion. Remove the spark plugs.. what do they look like? black and sooty? clean and almost white? Oily? One step at a time..

Start with the simple things first. Running requires compression, spark at the right moment, and fuel. Assuming compression is good, go with the spark next. Points, EI, what are you using? Fuel new? Then if you have a day, go here, read and weep. http://www.jba.bc.ca/Bushmans%20Carb%20Tuning.html If you have Amal carbs, if not I don't know. Make sure your idle circuit is good. Look at the top of the main AccessNorton page and look in the technical section, I think there are links to manuals there. Read tune up sections. Get lots of beer and invite the local Norton club over, they will help, it sounds like you need some first hand help. Don't keep kicking and starting every 40eth kick, it's not doing the bike any good. I always assume something is wrong if it doesn't hit at least 1st or 2nd kick, plus you'll wear out the pawl or crack the kick start shaft.

Good luck,
Dave
69S

Well, ALL of us were "noobs" at one time ...

I'm sure Norton enthusiasts are in OKC, but without a club it's hard to know who they are. I'll be in OKC for a week in May ... AND I would be glad to help out. (However, you''ll owe me a "pint" from "shawn cummings" Irish pub, which is up near Lake Hefner. If in a big hurry, ya can also give Chris Wedman a call, he and Phil have a combined shop over on NW 10th ... real close to Lake Overholser. Just PM me for more info ... us Norton guys gots to alway help eachother for sure, I'll tell ya what

was it running okay for the previous owner?

Concours:

Little to no experience describes me well. No family or friend with experience worth anything to me. I've had the closest person to that come over and I'm pretty sure he did more harm than good as he tinkered with the 'pilot jet screw' and 'throttle stop screw' which has seemed to worsen the issues. I have no idea where they were to begin with now. I've read that the base position for the pilot jet is 1 1/2 out from base and have done that, but the info for setting the throttle stop is above my pay grade at the moment. I do have a decent set of tools. I actually just went back out earlier and it started 2nd try. Ran well for a bit, enough for me to go around the block, but then stalled again. I'll remove the spark plugs first thing tomorrow after work and check back.

DogT (Dave):

Haha, I'm only catching a bit of what you are saying. Points? EI (I'm guessing Electric Ignition?)? It has brand new fuel. It was actually running last season and I 'winterized' it and just 'de-winterized' it recently, so I've drained all the old oil and fuel and replaced it. I think I have Amal Carbs based on pictures I've seen. I've read enough on these forums to know trying to tune the carbs isn't something I'm super interested in trying right now. My favorite was seeing someone call it a "dark art" at best. I've got both the riders manual and the workshop manual on hand. I definitely need to find some Norton friends...

nortriubuell:

Thanks, I'll PM you in a few.

goo:

as far as I know, it was.

If the carbs were working in the past, they will work in the future, believe me they're not magic. Must set floats correctly, read JBA site a must read until you understand. Idle pilot at 1 1/2 turns out, minor adjustments after that. The other screw just sets the idle and moves the slide up and down for idle rpm, everything else is mechanically set, but the idle circuit must be clean or it will not work, at least not right. Carbs is the first place you need to go, right behind knowing you have good spark. If it's running as much as you say, you have spark. Timing is the other thing, you must know what you are doing there or you'll break your ankle or one of the piston heads. Yes EI is electronic. You need to know what's going on there too or if you have the points and condensers and how it works. Otherwise you need to pay someone or buy lots of beer for free? advice. You need to start moving in single steps instead of shooting in the dark. It ran fine once and it will again, you just need to believe that and figure out how. BTW, the carbs may say Amal right on the side.

Dave
69S

The throttle stop screws you adjust, with experience, so that it idles nicely and evenly on both cylinders. With the engine warm. ( doing it with a cold engine is a waste of time, it will rev when it warms up.)

Does this bike have a choke lever ?
A newish (good) engine often needs either choke, or a lot of tickling and throttle blipping to keep it running until it warms up. You do know about tickling the carbs ?

If the engine, or carbs, are old and really worn, it can take a lot of everything to make it run properly - or even at all. Folks even went and bought a new bike to get away from this sort of problems....

Asa said:

It was actually running last season and I 'winterized' it and just 'de-winterized' it recently, so I've drained all the old oil and fuel and replaced it.

Click to expand...

It ran OK before you put it up for the winter? What did 'winterizing' entail? Sta-Bil and a battery tender? It sounds a lot like crud in the pilot jets.

If was running decent prior to storage, sure feels like my mower does with either water or zine oxide sediment or both to clear, again. Solvents no help, must physically clear. Pilot air screw 1.5 turn out for best idle is gained by adjusting float level richer or leaner. If more turn out needed then raise float some, If less turns lean fuel feed by lowing float level via a nail tapped on the valve seat, usually cold but can put in hot water first if too timid yet to knock a nail into a cold Amal body. Standard practice to run a wire or #78 drill or torch wire into pilot hole. Some even end up drilling em out for a new insert.

Back fires could imply timing too advanced.

Can only rarely go wrong putting in new plugs, but me and others had bad ones right out the box to fool us real good for a time. Never throw anything away till you know for sure replacement ain't even worse.

Check brake fluid every gas stop till you know for sure a new leak ain't blowing away till brake is gone completely in an instant.

If you are into old Nortons, then by defualt you are in for a wide scope of mortocycle lesions and tools and study and ugh, hand holding like I had and still need time/time even after 12 yrs and about 5 rebuilds.

We've the only family that cares about your Commando turmoils.

Dont let the purists put you off.... Get hold of a single mikuni, get it running sweet. Enjoy riding this season, then after you have fallen in love with your ride, spend next winter sorting out all the problems with the original items. You won't regret it....

I don't think you need a single Mikuni as you sound like you would equally struggle with fitting/setting that up ( no offence). As others have said we all started somewhere. Things like carbs are very simple yet despite that confuse all of us at times. Take up the kind offers for help on here but the biggest thing is accept now that you have to learn or you would be better selling the bike. I'm on my second commando (nearly 30 yrs since first) and you have to commit to fixing them and enjoying fixing them or they will really pee you off. ATB

We've all been there before, if you're not familiar with these old tarts it can be an almost vertical learning curve!

As others have already mentioned, the carb idle circuit could be the source of your problems and is a good place to start. Just remove the mixture adjustment screws (thats the ones that sit horizontal in the carb, the angled ones are there to adjust the idle speed) and poke a bit of wire in there, reset the screws to 1 1/2 turns out.
You need to figure out what type if ignition system you have, EI needs more battery power than points. Either way double check your battery and make sure it's fully charged.
It could be several other things, but as the bikes been sitting these would be the most common problems.

Let us know how you get on.

All the best

Webby

Asa said:

Concours:

Little to no experience describes me well. No family or friend with experience worth anything to me. I've had the closest person to that come over and I'm pretty sure he did more harm than good as he tinkered with the 'pilot jet screw' and 'throttle stop screw' which has seemed to worsen the issues. I have no idea where they were to begin with now. I've read that the base position for the pilot jet is 1 1/2 out from base and have done that, but the info for setting the throttle stop is above my pay grade at the moment. I do have a decent set of tools. I actually just went back out earlier and it started 2nd try. Ran well for a bit, enough for me to go around the block, but then stalled again. I'll remove the spark plugs first thing tomorrow after work and check back.

DogT (Dave):

Haha, I'm only catching a bit of what you are saying. Points? EI (I'm guessing Electric Ignition?)? It has brand new fuel. It was actually running last season and I 'winterized' it and just 'de-winterized' it recently, so I've drained all the old oil and fuel and replaced it. I think I have Amal Carbs based on pictures I've seen. I've read enough on these forums to know trying to tune the carbs isn't something I'm super interested in trying right now. My favorite was seeing someone call it a "dark art" at best. I've got both the riders manual and the workshop manual on hand. I definitely need to find some Norton friends...

nortriubuell:

Thanks, I'll PM you in a few.

goo:

as far as I know, it was.

Click to expand...

Ok, an often overlooked question when this comes up.. do you WANT to learn a bit about mechanics? Serious Q, many find it so overwhelming it's pain, suffering and frustration every time. If that's the case, owning a vintage anything will be a lesson in frustration and a retro styled modern bike would be a better choice. If you DO want to learn this stuff, find it interesting and satisfying to solve some of the problems and be confident in your ability to not be stranded, then we can all help you learn. "SUCK, SQUEEZE, BANG, BLOW." Memorize that. Repeat that. Read, understand and get comfortable with that. EVERY engine we know uses it. Back when these bikes were built, everyone who operated them, and other vehicles as well HAD to have at least SOME basic knowledge to get by day to day. Things have changed into today's put gas in it and ignore it until the Check Engine Light comes on.

Look here: (let's start with the FOUR stroke engine, part way down the page, nice illustration) http://en.wikipedia.org/wiki/Internal_combustion_engine

So it ws the sleek, sexy lines and curves that sucked you into this Norton?

I purchased my first English bike (a BSA 500 twin) and two weeks later I became a mechanic; that was many years ago; my introduction to motorcycle mechanics would have come sooner had I not gone on a two week holiday the day after draging this mechanical monster home. Even then, however, I was known as the go-to guy if your Briggs and Straton powered lawn mower was ailing.

This Norton you own can easily ruin your summer; given your addmitted lack of experience, tools and knoweldge of the nomenclature I see one frustrating moment after the next as you endeavor to get this piece of mechanical mayhem around the block. A Norton, you see, is an un-necessarily complicated mechanical system whose parts fight eachother for promenance in failure, active entropy, you might say. If you are young enough and rich enough you can get around many of the Norton's short-comings by simply increasing the various tution payments and your knowledge of the known specialists. If you choose to stick it out start with a work shop in anger management...

I hope that you will stick with it, but now is the time to decide if you have a viable asset (for sale) or a rolling piece of motorcycle history that will strain your personal relationships and drain your bank account; it will also make your spirit soar with every completed mile and every nod sent your way from people that get-it.

Good luck!

RS

I didn't even know where the points were on my first Cdo in '99. Rode it for for 6 mo's but had so many oil leaks and smoking decided how hard to just re=new the rings and seals and have the head gone through. Found bent crankshaft and cracked cases, twisted shafts, rusted wheel bearing and a whole bunch of other stuff over my head. I bought a modern SV650 for the interim - that lasted 5 yrs of learning curve that was more like series of vertical steps to smack into and more special tools. Ruin a summer, hehe, last one with a rod bolt failure took me 9 mo's of almost daily fiddling, knowing what I was doing and where to find parts and even a seasoned helper. When ya see someone on Brit Iron, especially a Cdo, then you know they are rather rich with a store bought wonder or poor boy that earned his ride the hard way. Take the thing apart and send the complex stuff off to a shop, then put back as able over the long haul. Oh yes, you can screw up real easy and blow it up real soon too.

If it hasn't been recommended by now it should have been: Get a workshop manual and learn something about the different systems the make up the bike. There is a digital copy in the tech section or I have on in PDF on my desktop that I can send via email.

I must admit I did not read the entirety of the early posts so this may duplicate.

The original electrical connectors are junk and need to be replaced. The kill switch needs to be clean and offering good voltage to the ignition. The carbs need to be clean and properly adjusted and the points need to be properly adjusted and hopefully the mehanical auto-advance is not worn out and is working correctly. These are all within the realm of basic maintenance.

When I bought my first Norton I was young and into testing myself to prove my manhood. So I messed with the points until I got it down and could adjust them properly in the dark by the light of a match on the side of the road in downpouring rain. Now I have a Tri Spark!

Russ