Wouldn't start when warm

SixtyKnots · Post by **SixtyKnots** » Sun May 01, 2005 9:16 pm

Can anyone offer some advice?

I am the custodian of my late fathers have a 1959 AJS Model 31 DeLuxe. It saw the first outing of the year today. After studiously seeing to all it's vital fluids and making sure that all is in good working order following the winter hibernation I went for a gentle run in the local area. All was well until about 10 minutes in to the run when, on turning around to head home, the engine slowly died on me. It was difficult to tell if it was fuel or ignition, however she would not start for me for at least 30-40 minutes.

This has happed to me once before - last year, but otherwise there has been no bother - she's been very reliable, in good working order - even started after the winter "sleep" on the third kick.

The mag is good - good strength in the spark, no obvious rough running, and pulls well although does take a few kicks to get going when warm - but not like this afternoon!

Has anyone had a similar experience and could offer some explanation?

Many thanks

BobF
Isle of Man

lawrence · Post by **lawrence** » Sun May 01, 2005 11:33 pm

What a lovely memento of your father! The 31 is a lovely bike once set up.
If it is ignition Bob it is most likely going to be a duff capacitor as they can fail when warm but I would initially suspect the fuel supply.

Is the choke opening fully? stick your finger in the carb mouth to check.
Is the fuel cap breather hole clear?
Are all the carb filters clean?
Are all the jets and the float chamber clean,
Auto shops sell a carb/injector cleaner. It is worth spending an hour giving the carb a thorough blow out.

Rich running will cause this problem, this will show up as sooty plugs.
The carb is easy to adjust if you have this problem.
good luck and let us know your progress

Lawrence [}:)]

SixtyKnots · Post by **SixtyKnots** » Mon May 02, 2005 2:21 am

Thanks Lawrence,

The 31 I have was bought by my father new, he kept it in emaculate order, the bike is "conserved" rather than restored. It's a year younger than me!

Choke is opening fully.
Fuel cap breather ok.
There are no carb filters, never has been in my memory.
Carb refurbished last year - once going again she's great.

I'll check the plugs again - but your comment about the condenser is interesting as someone else has commented on this - maybe it's worth a try replacing that first.

I appreciate the advice and will let you know the result. Dad never made it to the TT here in the IoM - he wanted to - so I make a point of taking her out on Mad Sunday ( at a sensible pace!!) - don't want her stopping on me!

Kind regards

BobF
IoM

RogerNorman · Post by **RogerNorman** » Mon May 02, 2005 10:01 pm

[:(] Robert don't wish to be the bearer of bad tidings but if it is the condensor and you have a mag then it will be a full mag rebuild. To be honest its probably worth it anyway. If its on its original windings, chances are that the shellac is starting to deteriorate and this as much as anything is giving the trouble. You haven't said what colour the spark is from the mag - It should be blue but a white spark often suggests the windings are on their way out. Good luck.

Michael · Post by **Michael** » Wed May 04, 2005 2:37 pm

I had a similar problem with a G3LS.

After restoration of the mag the problem was still there.
I solved the problem after realising that the carb is worn out.
So my advice: Check the sparking plug after a few tries of starting.
If it is still dry no fuel will reach the cylinder.
Maybe you are able to borrow a carb for testing ?

Michael

Biscuit · Post by **Biscuit** » Wed May 04, 2005 6:39 pm

I agree with Roger, this has the classic symptoms of condenser failure. I had this problem through the summer of 1999, and carried a thermos of cold water to tip on the magneto to get me through the summer. Some unpleasant souls may suggest you pee on it, this presents two main problems, the corrosve effects of the fluid and if the donor is any where near alive it's too warm!.