Now that I am on the road, thanks Henk for that carb body, I am finding a few other things to look at...starting when warm and gear selection.

I guess that the warm starting, or pack of, is most likely to be a weak magneto and so I should be thinking about a rewind or replacement. I see in anger post http://bt-h.biz/mag-dyno.htm Has anyone tried one of these and if so how did they get on? That said this looks like a lot of money...but I don't know how much a rewind will cost! I'm based in Singapore, so either I look for a local engineering specialist who will take on the work or wait till I make a trip to the UK. Can anyone recommend a good place for rewind? Is there a good specification to use if I went the route of a local specialist?

Now for the gearbox. Slow and steady was what I expected for. The gear change, and that is mostly how it is. But I get most selections of first from standstill jumping back to neutral, which I only notice when I try to pull away. My first step should be to adjust the gear change, but do I have to remove e whole gearbox for that or can I do this with the box in the bike?

Thanks

Richard

email (option): Dickie.bobbie@hotmail.co.uk

G'day Richard,
I think hot starting problems are condenser issues, put condenser in the search box and read what comes up.
As for the jumping out of first this could be a few things.
Control rod mal-adjusted, incorrect end floats on the lay and selector shafts,
worn selector dog, worn selector fork, worn ratchet and pawl mechanisim or a combination of these.
Start with the easy one first, the control rod, this can be done with the box still in the frame. Lengthening(I think)the rod 1/2 or one turn should make first gear engage better but it might at the same time upset the engagement of 2nd, 3rd, and 4th, It can be a matter of trial and error.
Apart from checking the ratchet and pawl for excessive wear the gearbox will need to be removed for further inspection.
Let us know how you get on.

email (option): spacemonkeym@gmail.com

Hi Folks
I had a problem with stating when warm several years ago and 1000 miles after a magneto reconditioning. Naturally I took it back to the engineer thinking the condenser had failed. He said, No, and that it was due to a substandard materials fault with the new slip ring he had fitted. He said this problem had first come to his attention with the failure of two magnetos in a Tiger Moth aircraft in Australia, luckily with no deaths. He replaced it with a better one free of charge although he said this episode had cost his business £10,000.
Regards

Hi Matt

Thanks, I did think capacitor aka condenser as the other option. Getting a replacement for that is easier, more down to me to work out a suitable alternative from modern options that will fit. Certainly a simpler place to start. Will take a look at the service sheets for magneto so I can visualize before taking anything apart :-)

I'll update when I've had a twiddle with the gearbox. Maybe I will be lucky...upward changes feel different and tend to be ok so suggests the mechanism is biased a little one way. Only time will tell!

Thanks :-)

email (option): dickie.bobbie@hotmail.co.uk

Hi Keith

Thanks... I don't know when my magneto was last worked on. Suspect upwards of fifteen years. I can always try localized hair dryer tests if I feel keen :-)

Are you guys in Aus?

Richard

email (option): dickie.bobbie@hotmail.co.uk

Richard
Check out item 261194199303 on ebay. I have no expeirence of this product but if it works it looks like a cheaper alternative to an armature rewind and condenser replacement. Anyone on this forum used this product ??
Im in England by the way, Richard

Could the warm starting problem just be due to vapourising fuel in the carb due to heat transfer from the cylinder? Might be worth fitting a heat insulator or tufnol block if your carb is bolted on direct.

Regards,
Bernie

email (option): bernie.a.jones@gmail.com

Hi keith

I have this external condenser arrangement on my m20, runs sweet as a nut

Starting from cold, warm or even after weeks of inactivity is vastly improved

Best regards

Job

email (option): Jonnyob1@googlemail.com

Hi,

This capacitor should be good.
I have corresponded with the developer allot at the past.
It sounded like he really did a serious research and testing job on it.

Please note that in order to fit it, you would need to get the original one out.
Starting problems when hot can also be an air lock, as mentioned here,
and sometimes even just wrong spark plug type,
or faulty one, even if new.

For me it was the idle fuel passage clogged in the carb.
I cleaned it with a thin wire- and the bike came alive
at first kick every time again.

I personally would start with plug, HT wire and plug cup (with no resistor) first.

Noam.

email (option): noam10@gmail.com

Thanks for all the input. I'm keeping it under observation. Seems to have settled into liking the Bosch plug, but isn't an easy warm start, but next time she refuses to start warm I'll see if I'm getting a spark between the lead and fengine, instead of just looking at the plug - to see how much is down to partially fouled plug. Also going to look for a fancy iridium plug just to see.

Gear change will be next job, but I'm getting much better after my first 100miles mostly in traffic (not much else on the little island of Singapore)

Richard

email (option): Dickie.bobbie@hotmail.co.uk

Hi Richard,

Almost every one you’d ask will recommend another plug maker.
I do not know why it feels so to me, but with the Busch the bikes feels “heavy” to me,

I used in all my bike over the past 25 years “Champion” spark plugs, and also using it for the M20.
The correct model is ”L86C”, if I remember correctly.
(The original Champion for the M20 was the discontinued “L10”)
** IRON HEAD **

Not sure if there is an iridium equivalent to it, as the “L” stands for lead core, but maybe there is..

Noam.

email (option): Noam10@gmail.com

I've always used Champion plugs (for 40 years) and have had one plug failure in that time..a just fitted new one, so a production fault....
I wouldn't bother with Iridium plugs, it's really not necessary....Just make sure the mag, lead, plug cap etc. is in good order and put a Champion plug on the end of it. Also check the carb settings etc. etc. Starting problems are rarely down to the plug in my experience, there is usually a fault elsewhere.....Ian

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

what are these spark plug things and where do they go never had any trouble with mine NGKs

email (option): roger.beck@node6.com

Those iridium plugs have an inbuilt resister dont they? Surly that cant be a good thing to use with a magneto?

email (option): Gasboy@btinternet.com

Hello Peter,

There are iridium sparkplugs with or with no resistor.

Here is a quote from a sparkplug forum:



http://www.nology.com/silverquest.html#Q18


--------------------------------------------------------------------------------
Question: So non-resistor spark plugs are better for performance?

Answer: Yes. If you are looking for performance you want to use non-resistor spark plugs. A resistor is exactly what the word implies. When the spark crosses the point of resistance some of the spark energy is lost. A resistor is like an electronic obstacle and could be the cause for a weak spark. Non-resistor spark plugs deliver a more powerful spark.

Noam

email (option): noam10@gmail.com

Ha!

Well I knew that mention of spark plugs would "spark" some debate.....groan....

The Bosch was not my choice, it was just what I could get. It is working ok though. Staring cold (keep in mind ambient is circa 30C) is normally first or second kick. Warm is now almost the same, four at most. I think part of the trouble is just me! I have to learn to get the kick right. This is the first bike I've had that used and needed at exhaust valve lifter, and that is what has taken me a little time to learn I think :-/

I want to try the fancy iridium, with no resistor, but it looks like it will be a Denso. Never had one of those before. My preference would be an NGK, they always seem to have done well for me in the past. Personally I have always had trouble with Champion plugs, but clearly some folks love them. I should be able to get NGK in the right spec, so may opt for that.

Athens Bosch is what s specified for air cooled VW flat four engines. Not that this is relevant, just found it interesting.

I've got some carb work to complete, new washers arrived so I can fit those in place of the almost non-existent bottom nut washer currently fitted, so I can check for any blockages when I do that. Mind as it is behaving really I should leave that, be brave and deal with the gear change and clutch.... I can't let the crunching carryon any longer!

Thanks folks :-)

Richard

email (option): Dickie.bobbie@hotmail.co.uk

Hi Richard..Spark plug problems are not generally an issue with the M20. Starting isn't problematical either unless the mag is weak, other settings are incorrect or the carb is worn etc...in other words the usual things...
I really wouldn't bother with Iridium plugs...(I fitted them to my Harley Sportster and found it ran much better on the original plug type, which I reverted back to)
If you're not keen on Champions and prefer NGK, a B6HS is the right one for the M20...gap to .018" before fitting....Ian

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

Hi,
I also switched the s.plug to iridium on my SYM Joyride 200,
hoping to gain some more power, but felt some drop in performance right away,
especially when accelerating. not 50%, but 5-8, I would guess.

The problem is that in order to get to the plug again, I need to dig in, opening few screws, and remove some plastic hood/bonnet, and I do not have the patience,
so it is still there, for more than a year..

Noam.

email (option): Noam10@gmail.com

Hi Folks
I use Denso iridium plugs in my BMW and find it starts with much less of a kick compared with ordinary plugs - the magneto is more than 50 years old. The Denso centre electrode is 0.4 mm diameter compared with NGK which is 0.6 mm and the thin electrode should spark at a lower voltage than an ordinary plug. In the BM motor one plug seems to wear differently to the other and I suspect it is because one spark is positive and the other negative - the mag coil feeds each end to a plug and each plug sparks on the exhaust stroke as well as power stroke. I fitted them when my hips started to clap out and I couldnt kick as well (stupid sideways kick starter!!) and they certainly fire with very low kick over. They dont make any difference to ordinary running. Doug W

email (option): watsond@xnet.co.nz

Iv not had any spark plug problems with my WM20 yet, but several times I have parked my Commando which has been running perfectly, then next morning it will only run on one cylinder. And its always Bosch or Champion plugs that are the problem. So its NGK for me now every time.
That has been my experience, but I do find it hard to believe that companys like Bosch and Champion make inferior unreliable plugs

email (option): Gasboy@btinternet.com

Iv not had any spark plug problems with my WM20 yet, but several times I have parked my Commando which has been running perfectly, then next morning it will only run on one cylinder. And its always Bosch or Champion plugs that are the problem. So its NGK for me now every time.
That has been my experience, but I do find it hard to believe that companys like Bosch and Champion make inferior unreliable products.

email (option): Gasboy@btinternet.com

Yes,

I also use Chanpion and my WM20 runs on one cylinder..

email (option): Noam10@gmail.com