Hi all,

Just wondering if someone would be able to offer some tuning tips for the WM20.

She has a new carb from Amal, fuel pipes all replaced, new HT cable and plug, engine honed and seats done etc, and timing set as per the recommendations. Checked spark from the mag and seems ok.

I've had it running a few times, but can't seem to get it tuned properly to tick-over smoothly.

I've read through the Amal instructions, but because I'm a simpleton I'm still a bit confused about the lever positions for the advance/retard and air - and if these should be in the up or down position etc, and where they should be for starting / hot / cold conditions.

Any tips much appreciated.

Andy

email (option): adh325@hotmail.com

Andy, if your mag cable enters the back of the mag near battery, then tight wire advance. So both levers fully towards you for choke off and full advance for normal running. However you should retard the ignition a bit for best tickover result. Ron

email (option): ronpier@talk21.com

Hi Andy,

The air/Choke shutter should be pulled all the way up,(Tight)
Not blocking the air intake when the engine is running.

You can slack it for starting, but usually there is no need for it,
And giving the tickler a press of about 1 sec would get the engine starting.

If your magneto is of the earlier type, its lever would need to be normally pulled
All the way, under normal driving conditions, for the correct spark advance,
If the ignition was set up correctly.

If the mag is of the "Slack advance" type, then the cable would need to be
Free, all the way in, (Towards mag) to get the correct ignition timing.



Sorry for the duplication Ron,
We typed together...

Noam.

email (option): noam10@gmail.com

Excellent - thanks guys, that's the exact laymans explanation I needed.

So it's much easier to get going now with those settings, and runs much smoother - in terms of fine tuning, I can't seem to get it idling at a nice slow rhythm, I always need to keep the throttle cracked open a bit, but it seems to run too fast. I could obviously adjust the throttle stop - but the idle would still be too fast. Maybe it's just the advance / retard that needs pushing back further - but when I get to what I think is a good idle it just cuts out.

I've seen the videos on YouTube of these machines idling beautifully at a very slow pace, does it take further adjustment of the pilot screw or something to perfect this? Is there a recommended place to start with this screw? Like I said earlier - carb is brand new, so I guess I don't need to factor-in age related wear.

Thanks in advance.

Andy

I always start with the idle screw 1 1/2 turns out. Then it's just a case of screwing it in or out to get the fastest tickover then bring the tickover down with the throttle stop and then go back to the idle screw. All done on about 2/3rds advance at the lever, and best after a short run to get the engine up to normal temp.

The idle settings are all a bit academic once you are riding it though, as by then you are on the slide and main jet.

If you can't get it to tickover with a new carb? It's possibly something else.....

Timing/valves/compression/plug etc. Ron

email (option): ronpier@talk21.com

Ah - my pilot screw was almost all the way out, I'll try adjusting it next time. The fuel I'm using is also ancient, so I'll use fresh next time. Oh, and although I thought all the head bolts were tight, I noticed a bit of vapour coming from the gasket. I nipped up the bolts and seems fine now. Must be the new gasket just bedded in.

Thanks again.

Andy

(Bike pretty much finished by the way, just finishing touches to go, hopefully I've done enough to make sure it survives another 74 years!)

Andy if you have a modern composite head gasket fitted. You might have to tweak the head bolts 5-6 times till they stop moving. There is advice about it on the technical page. Ron

email (option): ronpier@talk21.com

There's an excellent guide to setting the timing correctly, by Ian Wright I think, on the tech side of the forum. Getting this spot on made all the difference to how my bike ran. Just check it 6 monthly now or before a big run and all is good to go.

Stuart

email (option): stu.gibbins@btinternet.com