Asking an old, played question .....

I've seen this question asked 1000 times on line, and the answer is always the same. I have a feeling I may be the only different one ...

So I worked on the '75 MkIII Norton this past winter. Lovely bike, but needed one or two things, like:

1) Heavier, longer shocks so Fay and I won't be scraping hardware so early in the turns.
2) Better, aggressive disk brake pads to improve stopping.
3) Handworking the oil pump and the pump outlet valve to stop wet-sumping without resorting to dodgy check valves or interlocks.
4) Electronic ignition to eliminate an automatic advance mechanism that worked slick when OFF the bike, but very poorly when ON the bike.

All done, so I crank the bike back up. It starts immediately and responds to the throttle, BUT will not run unless on full choke, and when the choke is open, will run only at 2000 RPM and up. Let go the throttle and it dies instantly.

We ALL know the answer to this one as the class raises their hands. The bike sat, the dodgy fuel we use clogged up the pilot jets, and so no idle.

So I got out the handy #78 drill bit mounted in a little red spray nozzle tube. I carefully removed the pilot adjustment screw, and carefully (don't want to scratch or scar anything in that little brass jet) worked it in and out of the jet, making sure it was bottoming at the end of the passage. I didn't feel or see any goop ... and sure enough, when I ran it again, nothing had changed. I held one hand on the throttle to keep it running while I sprayed the carb attachments with WD40, but no change in engine speed to indicate a leak.

So I took the carbs off and took them apart. Clean as a whistle inside, no varnish or goop. Made SURE about the pilot jet passages - the drill goes all the way to the bottom, and a squirt of carb cleaner in either end of the pilot circuit results in a strong round clean spray coming out the other end.

So, before I put the carbs back on, what might I be forgetting? I'm running up to the store in a minute for some fresh no-ethanol gas. I'm going to use new gaskets and sealer on the carb manifold. The floats are new and they're dry inside, and freely moving. The bike ran great last fall in all conditions, so there's nothing changed about the jetting or the float height. I'm going to make sure that the needle slides into the jet when I put the carb tops back on. Both pilot jets were set at 1-1/2 turns out from bottom when it was running good last fall, and that's where I'll start them.

Any Jethro Bodine-level items I might have forgotten?

Lannis

Did you sync the carbs? Also, if you put a new EI your timing could be off. Needle off the clip?

Is there good fuel flow to the float bowl , that is no clogged screens on petcocks or carb bowl inlets?



Glen

Lannis said:

4) Electronic ignition to eliminate an automatic advance mechanism that worked slick when OFF the bike, but very poorly when ON the bike.

All done, so I crank the bike back up. It starts immediately and responds to the throttle, BUT will not run unless on full choke, and when the choke is open, will run only at 2000 RPM and up. Let go the throttle and it dies instantly.

We ALL know the answer to this one as the class raises their hands. The bike sat, the dodgy fuel we use clogged up the pilot jets, and so no idle.


The bike ran great last fall in all conditions, so there's nothing changed about the jetting or the float height. I'm going to make sure that the needle slides into the jet when I put the carb tops back on. Both pilot jets were set at 1-1/2 turns out from bottom when it was running good last fall, and that's where I'll start them.


Lannis

Click to expand...

Hi,
If it ain't broke don't fix it. Just wondering why if the bike was running great in all conditions on points why you felt the need to fit EI, I am having a slightly similar experience after fitting recon pump and I am thinking it is ignition timing that is out a bit going to strobe it and see what occurs. No doubt you have strobed yours. Or is it boil in the bag EI ?

Jg

auldblue said:

Lannis said:

4) Electronic ignition to eliminate an automatic advance mechanism that worked slick when OFF the bike, but very poorly when ON the bike.

......'\

The bike ran great last fall in all conditions, so there's nothing changed about the jetting or the float height.


Lannis

Click to expand...

Hi,
If it ain't broke don't fix it. Just wondering why if the bike was running great in all conditions on points why you felt the need to fit EI, I am having a slightly similar experience after fitting recon pump and I am thinking it is ignition timing that is out a bit going to strobe it and see what occurs. No doubt you have strobed yours. Or is it boil in the bag EI ?

Jg

Click to expand...

A fair question ... the bike ran great EXCEPT it wouldn't return to idle when the throttle was closed. I strobed it and found that the timing was staying advanced even when the bike was trying to idle, and would GRADUALLY return to retarded after a minute or two. I had the auto-advance mechanism in and out several times, it was like new and snapped right back when it was in my hand, but to be honest, I was tired of fooling with it. I have EI on my A65 BSA and I really like the fact that it doesn't start going out of tune the minute the engine turns over, like points with a rubbing block do. Plus you're guaranteed synchronization between cylinders just by the geometry of the trigger plate; NOT by some combination of points plate rotation and points gap setting.

So I went ahead while I was doing the oil system and installed a Pazon. I haven't had a chance to strobe it yet; on the other hand, on the 3 other Pazon and Boyer ignitions I've installed over the years, I've never changed the timing from the static setting based on a strobe test. The white dot in the middle of the circle is always bang on ....

Check for and fix blocked pilot jet.

Gotcha , so after the EI fit it still won't tick over, after cleaning jets etc. Looks like you'll be doing a Julie Andrews, " start at the very beginning " . I have no doubt you'll get it fixed to your own satisfaction. It could be a dodgy EI , Best of good luck.
Jg

Intake manifold rossover hose disconnected.

Save yourself some grief. Ditch the Anals and fit a single Mikuni. Trouble free and economical.

Sounds like it might be the classic low voltage to the ei problem. Above 2000 rpm the alternator is putting out enough volts that the ei functions. Below that it starts to malfunction. First verify battery is good. Load test or since you have several bikes substitute a known good one. Then run a jumper from battery negative (assuming still positive ground) to Pazon box input wire. I have one made up with a nifty switch and fuse for just such occasions. Beats trying to pull the wire off to stop the bike. If that improves the situation, check the ignition and kill switch. Both have tendency to quit for no reason, often intermittently. I've fixed more carb problems by working on the ignition than working on the carbs.
With the points you would have never noticed the low voltage problem.

I agree with Fullauto...if the amals have been around for awhile, kick them to the curb.
The electrical idea is good too. start there and make sure all the connections are tight and clean

When it won't rev above 2000 rpm does it seem like it is rich or running out of fuel ? Or neither ? What do the plugs look like when it dies ? Does closing the choke make any difference ? Do the coils have a good ground ? Did mouse build a nest in your air filter...

Greg

concours said:

Intake manifold crossover hose disconnected.

Click to expand...

If the bike will only run at full choke and over 2000 rpm, sounds like a vacuum leak.

I once started my bike and it backfired. Started right up next kick, but ran like crap - needed throttle and full choke to run.

50 miles from home and just a small screwdriver in my pocket. Checked the plug wires, played with the idle and throttle screws - everything seemed fine.
Noticed after 20 minutes of looking that the balance tube was not connected to one of the manifolds.

Found that - apparently - the backfire popped the crossover hose off one of the nipples.

Re-connected it and the bike ran right again

That was about 20,000 miles ago - still the same carbs

Any update?

With the risk of stating the obvious a trap for people new to amals is to tbink the choke works as on other carbs. It doesn't. The choke cable needs to be tensioned for the choke to be off and the cable slack for it to be on. Tbe reverse od other carbs.

concours said:

Any update?

Click to expand...

Guys -

Thanks for the answers and help on this to date. Let me let you know where I am on it. As usual when working on old bikes, working on one thing leads to another thing, and so on and so on and scooby dooby dooby like the old song says ….

1. Carbs are mechanically synched, slides moving at the same time.
2. I was careful to assure that the needles are on the clips when I reassembled the tops to the carbs.
3. Flow to the float bowl is good, splashes out like a good ‘un when the bowl drain is off.
4. Carbs were taken apart, pilot circuit is clean all the way through, the progressive holes squirt little fountains cleanly.
5. Intake crossover hose was connected, has been reconnected including oil separator hose.
6. Not packing it in and going to a Mikuni yet! Still have Amals on everything (8 total) and I haven’t given up on them so far!
7. Choke cable is operating as designed, “pull” (tight wire) to open choke, “let fall” to close it.
8. Plugs were clean and tan, but cleaned them up again and reinstalled.
9. Drained out all the old gas, refill with non-ethanol 91 octane.

So, when I was draining the old gas, I realized that one petcock was a “non-reserve” petcock with a standpipe, even though the tank has “saddles” and no crossover between them. That means that about a quart and a half of fuel is always unaccessible. So I turned the tank over to pour out the last quart, and out came sheets of old tank sealer and rust flakes. There are filters in the petcocks, filters in the line, and filters in the banjos, so none of this stuff had gotten to the carbs, and fuel was still flowing well, but I’ve got to get this sorted out before I run the bike any more ….

So the Moto Guzzi will have the duty of riding me to the Euro-Bike Day in Raleigh, NC tomorrow, and I will start soaking the inside of the Norton tank with rust remover …..

And THEN, when I have a clean tank, I will have a voltmeter hooked up to monitor the battery voltage to the EI, and a timing light hooked up to the plug, to immediately check the EI timing and see what’s what.

Old bikes, eh?

Lannis

Pick up a can of acetone by the painting supplies in any autoparts store. It will remove any remaining tank sealer. Be careful not to get it on the outside of the tank. I'd drain it out through the bottom by removing the petcocks. Might not be too good on the petcock seals anyway, replace them with some 3/8ths bolts. The stuff evaporates super fast so don't worry about leaving a little bit in the tank. Just let it air out good.

htown16 said:

Pick up a can of acetone by the painting supplies in any autoparts store. It will remove any remaining tank sealer. Be careful not to get it on the outside of the tank. I'd drain it out through the bottom by removing the petcocks. Might not be too good on the petcock seals anyway, replace them with some 3/8ths bolts. The stuff evaporates super fast so don't worry about leaving a little bit in the tank. Just let it air out good.

Click to expand...

Thanks, I'll try that. I keep a quart of acetone around anyway because I use it to mix with ATF to make my own "Break Free" or "Liquid Wrench".

I'll carefully plug the petcock holes, seal up the cap, and shake some acetone around in there to get the old sealer. It's some sort of very thin stuff, not a thick layer like Caswell or Kreem, so it ought to dissolve and come out easy.

Then the dog chain and WD40 to get the rust out.

I have my own plan to prevent future rust, which works for me and my rides. I've had Kreem and Caswell fail on me so many times, both my own and others installations, that I'm never going there again ....

Lannis

Lanis is new to Commandos, not to Amals.

concours said:

Any update?

Click to expand...

I do have an update; the bike is kicking my ass.

To recap -

'75 Norton was running pretty well last year, but the AAU wouldn't pull the weights back and the bike wouldn't return to idle like it should, but otherwise ran and idled perfectly.

So, after fighting the AAU for a while, I bought a Pazon digital ignition and installed it.

Fired the bike back up and it started immediately, and runs and idles (roughly, but it doesn't cut off) with the chokes closed. But warm it up, and try to open the chokes, and it will NOT run below 2000 RPM, just pops and dies.

Has to be the pilot jets, right? even though I drained the carbs before starting work last fall. So I took the carbs apart - they were clean as a whistle inside. Put the #78 drill through the pilot jets, there's nothing there, the drill bit is clean. Cleaned the passages from the "progressive" jet holes, nothing there, and carb cleaner shot through the jet comes out in two fountains from the progressive holes in proportion to their size.

Floats are dry inside, everything OK there. Reassembled the carbs, synced them, put the jet needles back at 1-1/2 turns out from seated, where they ran well last year.

Started it back up, no change, neither side will run with the chokes open (tight wire open choke, I checked to make sure I knew open and closed). If something magic happened, it happened to both carbs at the same time. And since I didn't change anything about the carbs, now I'm looking at ignition, at the thing I DID change, and the only thing that affects both sides if somethings wrong.

Pazon ignition, using the same 12V coils as ran last year, and which the Pazon instructions say to use. Bike fires up instantly and runs and responds OK to the throttle with the chokes closed, running like a normal bike would run with the chokes closed. Wired-in voltmeter shows 12.6 volts at idle, 13.0 at 2500, 13.8 at 3000 RPM.

Static timed Pazon, red dot right in the middle of the "anti-clockwise" Norton hole at 30 degree mark on the rotor. Strobe light hooked up to plug. Fired up bike, ignition is advancing and retarding smoothly, like an electronic ignition should. Showed 32 degrees advanced at 4000 RPM, a little more than the 30 spec, so moved the trigger plate to compensate, and it hits exactly the 30 degree mark. Retarded it a couple degrees so it hit 28, and no change, bike still won't idle at all, just dies when you let it get below about 1800 - 2000 RPM. Voltage never gets below 12.6 when it's running.

So ... suggestion has been made that perhaps the trigger rotor on the Pazon might be sitting too deep on the taper, and is too far away from the trigger plate, and will trigger when the magnet is sweeping fast but not when it's running slow? I'm going to check the spacing tomorrow. Still can't figure out why it would idle with the choke on, but perhaps bad trigger spacing is causing a weak spark that will fire an over-rich mixture but not a proper lean one? Or is the Pazon an "all or nothing" trigger, and won't do just a weak spark?

I'm running out of ideas here. It sounds like it HAS TO BE a carb problem, but I didn't change the carbs, then I cleaned the carbs in case they changed themselves with fuel varnish, and both of them are doing the same thing. Under the principal of "What Did You Change?", then the problem HAS TO BE the ignition, but absent just installing another EI, I'm not sure how to proceed ....

Any good suggestions?

Lannis