Villiers 13D not starting when warm

[Mike Cambray]

I have a Villiers 13D (122cc) in my 1953 James Cadet. The engine starts first or second kick when cold, and will usually re-start if kicked immediately after stopping. But if left for a couple of minutes will only start with a good long bump start and at times a carb tickle seems to help (even then it can take a couple of goes). No hesitation from the engine once she is back up and running.

I've checked fuel supply and main jet setting.

She has a healthy spark both cold and hot but just in case I've fitted new points, condenser and coil.

I've taken the plug out when hot and no sign of oiling or flooding.

Compression is good.

I run her on 97 octane Esso with four fuel cap measures of Villiers 2 stroke oil. This is the ratio embossed on the fuel cap.

It seems fuel related ? And I am wondering if modern fuel is vapourising in the inlet manifold when hot? I have no clearance to put a spacer in between manifold and barrel (air filter would foul the chain guard) and as the bike has been off the road since the early 1970's (engine rebuilt 30 years/100 miles ago) I have no previous 'was starting OK when hot' to compare.

Anyone have any wisdom to offer?

Many thanks.

[A10 JWO]

Seals come to mind, as soon as they get warm this could happen. I had a Bantam that did exactly the same.

[Mike Cambray]

Thanks. Do you mean the seal between inlet manifold and barrel?

[Rex]

I think he means the engine crankshaft seals, but Bantams and RD's aside, I've never had a two-stroke with worn seals. It's one of those solutions that everyone instantly posts when 2 strokes encounter problems, but since the advent of nitrile/neoprene seals the traditional "it's the seals gone mate" has largely disappeared. Personally, on your bike I'd be looking at fuel line vapour lock as a first step; when you're trying to get it to run when warm slacken off the fuel line union and see if juice pours out. Sometimes the convoluted petrol lines that some install are just crying out for some big old bubbles to form...

[33d6]

You describe the standard problem of failing ignition. You say you have fitted new points, condenser and coil. Unfortunately I think you have missed something on the way.
For example, did you also rebush the points box pivot when you renewed the points? If not you may find the points open erratically and the timing wandering a surprising amount. If you did rebush the points box is it a fraction too tight so the points are sticking slightly.
Were the coil/cheek pieces a firm push fit on to the coil? Sometimes when you clean off the build up of years of crud this joint is too loose to be reliable. Nowadays I always drill and tap each cheek piece for a little grubscrew (3mm, easily available from model shops) so as to ensure as good a contact as the original factory fit.
Those are but two of the points you have to be fussy about. Mere replacement sometimes isn't enough.
Villiers ignition can be really good and reliable but you have to know it's little foibles.
Rex is also right about convoluted fuel lines causing vapour locks but I think that secondary in this case.
Tell us how you get on.

[Mike Cambray]

Thanks for all these tips. I have had the Flywheel remagnetised by the wonderful people at Villiers Services and she now starts first kick from cold without choke, and after my first 5 mile run did the same thing when hot. I think the seals may be suspect so will keep a watching eye on things.

[A10 JWO]

I mentioned seals re my Bantam. This could be reinforced by the history of the Lambretta Engines, nearly every Lambretta for sale has had new seals at some stage. There are heaps of the seals for sale on ebay. Seems to be a two stroke trait.

[Rex]

Well, it's a two-stroke trait that everyone immediately thinks of when the engines won't start, but then when they've gone to the trouble of stripping the engine to replace them they then find that the fault's just the same.
Still, if people like unnecessarily stripping engines, who am I to tell 'em differently?

[murdo]

This is what to look for on leaking two stroke crank seals.

[Rex]

Not really. It's not definite that there'll be signs of obvious leakage. Many show no physical signs at all.

[A10 JWO]

On unit two strokes, if the drive side seal goes it blows an oil spray out of the gearbox breather.

[Rex]

Again, those symptoms aren't universal, and a seal would need to be "gone" to the point of destroyed to non-existence before that would happen, but it would have considered to have failed (and impossible to start) long before that..