Atlas timing/gearchange pawl

Previously malcolm_parker wrote:

Has anyone an experiencedview of the best timing settings to use for Pazon Surefire on an Atlas please?

The original (magneto) setting, as I understand it, was 32 degrees BTDC fully advanced. My Pazon instructons say to use 31 degrees. (Oddly though, they also quote the original setting as 28 degrees?)

The installation set up for Pazon is to align the rotor and the trigger plate within the magneto replacement unit, with the motor set at full advance, then start up and adjust accurately through strobe timing.

It isn't practical to strobe at full advance without risking the bike leaping into next door's garden, so my question is what the timing setting should be at say 2,000 RPM. It looks from my Pazon notes that it should be 24 degrees BTDC at 2000 RPM?

My questions therefore are 1. What is the full advance setting best for a standard set up Atlas on Pazon Surefire and 2. What setting should the timing be strobedto at 2,000 RPM?

My other need for advice is as follows.

I have rebuilt my gearbox and it works perfectly well. It engages all the gears, and doesn't jump out of gear.

I've had an intermittent/occasional problem though with sticking in gear (usually first), and losing any functionality in the gear change mechanism. The gear change pedal springs back, both up and down, but clearly isn't engaging inside the box. Eventually, it returns to normal, and I can change gear once again.

It seems as though the pawl and ratchet plate are the likely cause? I replaced all the springs in the box but notthese two parts.

Before I take anything apart, has anyone any thoughts please?

Thank you,

Malcolm Parker.

Hello Malcome try 29 degress at 2,000 rpm and see what thats like , do not forget your now running on (E5) ethrnol content and try out Bosch W7DTC , with sinlge caburettor or Twin carburettor W8DTC hope this may help

yours anna J

The Pazon set-up is aimed at the Commando engine using 8.9 to 1 pistons and 28* of mechanical advance. The Atlas should have lower compression pistons at around 7.6 to 1. You may have Commando pistons in your engine in which case you will need to retard your ignition a bit from 32* to 28* BTC.

I found the Pazon difficult to time with a strobe because, whether Atlas or Commando, the engine is bouncing about at low to medium revs. What looked like 31* using the strobe at 4000 translated into the engine kicking back when starting, poor idling, lumpy over-running plus bad pinking when accelerating. In the end I settled for listening for pinking when pulling hard at low revs and then knocking the timing back 2* each time until this had gone.

I would suggest that your gear selection problems are due to the 2 springs operated by the gear lever. They both sit above each other and must be the correct shape....not cracked or distorted andin the right position. See attachments..............

I suspect that the reason Pazon (and prevously Boyer) specify timing settings at such high rpm and don't quote progressive advance is that the curves are not always identical. It only takes a brief burst to 5000 rpm. I'd suggest putting it on a carpet and asking for assistance.

Your gearbox problem really sounds like pawl spring. Is it the right way round ? Is the gap each side of the pawl absolutely identical ? If so, it may be worth trying another spring. The AMC box is oddly critical on this. Once it's set up OK, it will go on for years, but a small bias on assembly can cause a consitent malfunction. For the sake of a couple of quid, I'd certainly try substitution.

Thank you for these responses.

My bike has flat top Commando pistons, and a Commando camshaft (breathing modified), so I have completely missed the point you make, that the standard full advance setting should arguably be 28 degrees BTDC.

It appears that strobe timing on Pazon is not favoured anyway, from your responses. (I suppose that I could actually put white marks at full advance and at an assumed 2,000 RPM setting to try?) I will try the carpet and help as well.

I'm now at the fine tuning stage and have my twin concentrics ticking over quite well, and in balance on the Carbtune. I had so many air leaks both sides of the throttle, it only became clear late on that the pilot passages were blocked. Once they were sonic cleaned I started to make progress on the idling.

I previously had good help on here about plug fouling and have realised that my RH plug oils quickly if I run stationary to scavenge a wet sump, and the LH side is sooty because I still haven't quite corrected all the richening adjustments I did to cure the weakness caused by air leaks. I've established that the needle is in the right groove and not dislodged; the main jet isn't loose, the float isn't sticking and even that I don't have a weak spark on one side, so it's on with the tuning.

Where I'm coming to is that one reason for asking about the timing setting is to check that I haven't over retarded it to contribute to the sooty plug. Thefact that, as you point out,I have used the more advanced Heavy Twin setting says in itself that there is no issue with this. Apologies for being so long-winded.

The spring reply is also much appreciated. It sounds as though I'm not barking up the wrong tree. I will replace it and look again at the pawl and ratchet condition.

Thanks again. It says something about the fraternity of this club that I can put a query online at 9.30 Saturday night and have three replies before bedtime.

Malcolm Parker.

Hello Malcolm yes I know what your saying about the timing , But were all now running on (E5) fuel and most of this is made out of suger cane, its a petrol subistute with addatives your old type spark plug have a hard time trying to fire it, that why I changed my spark plugs to the Three point Plugs they do the job better than the old N5s did, My Norton has some wet sumping But it dose Not bother me or the Bike just start has normal , a bit of white smoke , and rev or two its then gone, the plug burn any oil of has there self cleaning that why my bike runs nice, so I must be doing something right somewere , and I think you do not need to retard the timing too far back 30degress to 29degress should about right , you can go to far in retarding the timing so do bear this in mind, and when fitting you gear ratchet do try and fit it in second gear has stated in the manuel, yours Anna J