Took the WM20 out for a spin today, lovely out there it was too, Sun up in the sky and it wasn't too cold. BUT, around 7 miles into me trip to the pub, the engine stopped..? SO, I thought it was petrol, or the lack of, and tickled the Carb, didn't get anything so went on reserve, and away we went...

On the return trip, and about 7 miles into the ride, once AGAIN the engine cut out..? Did the same, only this time turned off the reserve, and put on the other tap, fired up no worries and off I went again..?

So my question to the panel is, do you think the bike needs one of them Tuffnol spacers between the Carb & Engine, cos there's not one there at the moment. Oh..! And by the way, the tank was half full, so it wasn't running out of petrol anyway...

This is most strange, cos it did a 100 mile ride t'other week with no trouble..?

It could be a blocked vent in the filler cap, or it could just be that your taps are getting blocked.

email (option): davmax@ntlworld.com

check for lumps of dissolving petseal, happened to me.

Have you got filters above your taps to prevent paint or rust or tank liner blocking the tap.Also some new taps have heavy grease in them which can move and block the tap. In Australia you need the Tuffnol heat spacer to prevent the petrol from getting a vapor lock on a hot day but then we get much hotter temps. Agree could be the fine hole in the petrol cap causing a vacuum if blocked. Certainly sounds fuel related unless you have a crook condenser in the maggy?

Yes, sounds like fuel.

It can be also a filter, if you have one on the way from the tap to carb.
I use a filter on there, cause I currently do not have a tap filter.

When using a "Paper filter" it is better to use a big-fat one, as the slim ones "choke" quickly,
As paper filters designed to work with a fuel pump, and having problem
Maintaining a good flow on "Gravity" fuel systems, mostly when not allot of fuel in the tank,
which is just the opposite for a vacuum problem-
In this case, the more fuel you have, the less air is in the tank,
And the critical stage of fuel stopping to flow comes sooner..

You can test to see if it is the tank cap very easily-
Just lock it "Half way" gently, to be sure that there will be no vacuum,
And go for a test ride..

Noam.

email (option): noam10@gmail.com

Thanks lads, panic over sound the All Clear...

Got home today and straight out into the fettling shed, now you know them little buggers that infest your fettling shed, and move ya fettling irons so you can't find anything..? Well, I think they've been making Tea with dodgy tea bags in me carb..! It was full of what looked like tea bag dust, so a quick clean up and we're good to go. I'll leave the road test till the VMCC New Years day ride, cos that's the kind of guy I am. But I feel sure that was the trouble, seems this bike wants LOTS of riding, that'll clear out all the tea bag dust, good job I've got a ton of riding to do in 2014 then..

I've been getting the same stuff in my tank and carb Shaun, I've had to drain the tank twice now. It looks like silt from a pond. I'm hoping it will eventually clean out and stop. I don't really want to put an in-line filter on it.

email (option): horror@blueyonder.co.uk

Shaun lad, that there WM20 was jealous after you spent 80 quid on that eyetye machine, next time at Kempton buy it something!
P.S that red dust is rust caused by ethanol which is water based, the water lays at the bottom of the tank with the rust particles, stick an eggcupfull of oil in the tank every time you fill up,this helps a bit. You know I put "R" in my tank and mine is ok, smells nice too! or use esso super unleaded no ethanol yet!

No, the cause isn't just the presence of Ethanol...

Ordinary fuel has (and always has had) a degree of water contamination which will sit at the bottom of the tank and cause it to rust...There were rusty tanks BEFORE the introduction of Ethanol..

Ethanol itself is hydroscopic..ie it attracts water vapour from the atmosphere. So, it can cause a problem if you leave the bike standing for lengthy periods...If a bike is used regularly it won't be an issue as the fuel is replenished over a short time frame...

This M20 has done very few miles after a rebuild so it is a racing certainty the rust was already present in the tank before the rebuild was even started.(or before anyone had heard about Ethanol)..Ian

Redex is the answer

The pilot jet and airways would probably benefit from a clean out as well

Take your tank of get sum pea gravel and give it a good shaking or fasten to something and give it a good spin round .Then wash the lot out with diesel When you refill with petrol put a small amount of 2 stroke oil with it.