I have fitted a new oil seal on the mag pinion housing, taken the mag/dyno off. Cleaned up base and fitted it all together with new shimms allowing a little play in the pinion gear as prescribed.
I have set up as follows:
Piston set at 7/16 before top dead centre with head removed.
Both valves closed with play at followers.
Advance/ retard cable pulled tight. (Cable on right)
Points set at 12thou.
Points just opening at around 11 o'clock. Thin paper can be gently pulled away. Turn on fuel and tickle carb.
Use valve lifter and kick in into life.
After a while it fired up. But it is not running smooth, lots of back firing and then it dies.
Anybody and clues how I can get it to run well. The funny thing is that before I set about changing the leaking oil seal it ran very smoothly and as far as I can see the settings are pretty much as they were then.

email (option): araine11@hotmail.com

Are you sure you have it at 7/16 BTDC and not ATDC? I have seen that! Also I am never usually lucky enough to get it right on the first go. Sometimes up to a dozen goes to get the pinion nut done up so that the points open at exactly the right spot. I always spin the engine round and re check the timing. Ron

email (option): ronpier@talk21.com

I actually took the head off marked 7/16 off a rod and brought the piston to that level. Then I marked the cam gears against the outside case 2 marks one side and 1 the other side then set the points to just open. I then tapped the pinion on with a socket, tightened the nut and rechecked the marks and then checked that the points were opening where they should be.

email (option): araine11@hotmail.com

I'm not doubting your expertise Art. But I have seen guys set there timing who don't seem to know which way the engine rotates. Also you stated that it was running fine before you reset the timing, and the popping and banging seems to indicate a timing issue. Also check that the points block is not loose as that sometimes happens. It could be as simply as a duff plug. Ron

email (option): ronpier@talk21.com

I do have a couple of plugs so will try a different one. But I do know what you are saying. I think the problem we 1st time owners of the M20 have is not having a mentor close by to show us how not to screw things up. I have been around cars and bikes for many years but even though the m20 is seen as something relatively simple it's very easy to get it wrong. We have a big show at Old Buckenham aerodrome in Norfolk next weekend so I will go and see if I can tempt an old-timer to come help a rooinek (rookie). In the meantime any advice is still very important. I am sure I am close to getting it right.

email (option): araine11@hotmail.com

I have the same problem With my M23 i have do it for 40 years by M20 M23 M21 they have all 11 mm btdc 7/16 so strange I put a new rewinded Magdyno on it and i have the same problem so i take the old magdyno and clean it up it have a brite spark and have it have the same problem again i chec the valve setting and the carburator the petrol taps everything. When it starts it go fine but when i move the trotle a bit it gives big bang and fire out the carburator. I will know wat i am doing wrong I am make a mistake But wat am i do wrong Gr. Theo

email (option): oldbikes@kpnmail.nl

I doubt very much that you have a TIMING problem. Static timing setting is not an exact science and small variations should not produce your symtoms. It sounds more like a fuel problem or a weak spark (in that order).

I have installed a carb fuel level sight glass made from plastic tubing which I find useful to ensure that I have fuel and that it is not flooding.

If you remove the plug, you should see a healthy spark when turning the engine by hand via the kickstarter. (Make sure the external plug has a good earth.) If not, check HV pickup and LV earth brush. Also ensure you have about 8M Ohm HV coil resistance.

email (option): pvlietstra@gmail.com

I'm sure the last M20 I worked on ( I may be wrong ) the points opened about the 7 o'clock position, have you got the face cam in the right way round?. Just a thought.

email (option): davmax@ntlworld.com

Dave 10-11 oclock is correct for a tight wire M20 mag.

Ron

email (option): ronpier@talk21.com

It's easy enough to check what timing you have got by turning the engine over by hand on full advance with a ciggy paper in the points and a screwdriver held in the plughole (I know you need 3 arms for this! ). If the points open at 7/16s BTDC then your problem is elseware.

It doesn't work down the plug hole on a SV! But as you say it's easy to check. The problem seems sometimes in the re setting it and getting the pinion nut tight at the right spot. Ron

email (option): ronpier@talk21.com

Yep the M20 has a plugged timing hole also. Just big enough for a drinking straw
Ron

email (option): ronpier@talk21.com

You older guys probably realise by now that getting older really is a pain in the backside so as I am one of you I will get my cushion out, take all your notes plus my manual and start from scratch again. I think it is a case of me not paying attention to the rules. I will report back later.

email (option): araine11@hotmail.com

You older guys probably realise by now that getting older really is a pain in the backside so as I am one of you I will get my cushion out, take all your notes plus my manual and start from scratch again. I think it is a case of me not paying attention to the rules. I will report back later.

email (option): araine11@hotmail.com

You older guys probably realise by now that getting older really is a pain in the backside so as I am one of you I will get my cushion out, take all your notes plus my manual and start from scratch again. I think it is a case of me not paying attention to the rules. I will report back later.

email (option): araine11@hotmail.com

I find repeating yourself is a hazard as well... ...and repeating yourself..that's a hazard as well..Ian

email (option): ian@wright52.plus.com

My excuse, new laptop with some (many) new features. I am not quite sure what any of them are for or what they do!
Ian I am coming down to Dorset on 21st. I think you are down that way. If you have some handlebars I could pop in and get a set Please e-mail me and tell me if that would be OK,

email (option): araine11@hotmail.com