Dommi 99 cutting out

Previously wrote:

Hi,

I recently bought a 1961 slimline cafe racer with Amal concentrictwin carbsand I have just had a couple of trial runs on it. On the firstrun I discovered I hadvery badly blocked carb filters which were cleaned and refitted. I also checked the fuelflow from the tank too and itis clear.

On my second run I took the bike out and it seemed to be running well, taking it up to 80 mph. Ithen took it on to some slower roads and then into town. Again everything seemed ok but it suddenlyjust cut out at a junction for no apparent reason. It just would not start up again. I checked the petrol was there by using the ticklers and there was plenty. After around 20 minutes or so and 50 odd kicks the bike started again althoughI had to keep it revving. When I got home some 10 minutes later there was no problem at all and the bike ticked over quite happily. I haven't had the chance to do anything else as yet but has anyone else experienced this? Any help appreciated.

Cheers,

Bryan

Hi Bryan This is an ignition problem as I have just experienced the samefault but on a Matchless. So start by checking the points (set gap and clean)and start with the cheep bit, if it runs on a coil change the capacitor in the distributor, take a spare plug with you when you go out and check for a spark if it stops (you may see a small spark like a bit of cotton this is no good you need a spark like a bit of rope)if changing the cap makes no difference then it must be the coil. If it runs on a magneto this will be a littel more expensive as it will be the rotor breaking down when it gets hot, as it did on the Matchless,the fact that it will start again when it cools points to one of the above problems.

I hope this is of help

Ian

Change the copper-cored plug leads too (if fitted). When they get old/overheated they fail and leak HT everywhere before they reach the plugs!

Cheers, Lionel

Previously wrote:

Hi,

I recently bought a 1961 slimline cafe racer with Amal concentrictwin carbsand I have just had a couple of trial runs on it. On the firstrun I discovered I hadvery badly blocked carb filters which were cleaned and refitted. I also checked the fuelflow from the tank too and itis clear.

On my second run I took the bike out and it seemed to be running well, taking it up to 80 mph. Ithen took it on to some slower roads and then into town. Again everything seemed ok but it suddenlyjust cut out at a junction for no apparent reason. It just would not start up again. I checked the petrol was there by using the ticklers and there was plenty. After around 20 minutes or so and 50 odd kicks the bike started again althoughI had to keep it revving. When I got home some 10 minutes later there was no problem at all and the bike ticked over quite happily. I haven't had the chance to do anything else as yet but has anyone else experienced this? Any help appreciated.

Cheers,

Bryan

Bonjour Bryan,

I can confirm most of what has been said above : I had exactly the same sort of problems on my 99 / 6v Lucas 18D2 distributor : stalling at very low rev and when hot. Re-starting after a fewminutes and many kicks!

Nothing looking suspect on the fuel - carb front.

I've just installed a new 0,22 micro farad capacitor (close to the distributor but not in place of the previous one which is -still- inside because not at the correct size) and so far, it's OK : far easier to start when cold and no more stallings when hot!

Lesson learnt : look first at ignition and low-cost components = capacitor, plug leads, coil which may be reactive to Hot or Cold

Hope it helps!

Bon week-end

Previously wrote:

Bonjour Bryan,

I can confirm most of what has been said above : I had exactly the same sort of problems on my 99 / 6v Lucas 18D2 distributor : stalling at very low rev and when hot. Re-starting after a fewminutes and many kicks!

Nothing looking suspect on the fuel - carb front.

I've just installed a new 0,22 micro farad capacitor (close to the distributor but not in place of the previous one which is -still- inside because not at the correct size) and so far, it's OK : far easier to start when cold and no more stallings when hot!

Lesson learnt : look first at ignition and low-cost components = capacitor, plug leads, coil which may be reactive to Hot or Cold

Hope it helps!

Bon week-end

you dont have to keep the condenser in with the points if you cannot find one small enough to fit , it will work exactly the same if positioned at the coil and its wire connected to the low tension terminal ( points wire) always remember the case of the condenser must be earthed to make the circuit ( I note you say your originalis still inside the dizzy, be careful it does not earth out the new condenser,the old, faulty oneshould now be totallyinsulated from the ignition circuit )

Previously wrote:

Hi,

I recently bought a 1961 slimline cafe racer with Amal concentrictwin carbsand I have just had a couple of trial runs on it. On the firstrun I discovered I hadvery badly blocked carb filters which were cleaned and refitted. I also checked the fuelflow from the tank too and itis clear.

On my second run I took the bike out and it seemed to be running well, taking it up to 80 mph. Ithen took it on to some slower roads and then into town. Again everything seemed ok but it suddenlyjust cut out at a junction for no apparent reason. It just would not start up again. I checked the petrol was there by using the ticklers and there was plenty. After around 20 minutes or so and 50 odd kicks the bike started again althoughI had to keep it revving. When I got home some 10 minutes later there was no problem at all and the bike ticked over quite happily. I haven't had the chance to do anything else as yet but has anyone else experienced this? Any help appreciated.

Cheers,

Bryan

Dear Brian,

Posted exactly this response earlier toanother member who had the same problem:-

It is the windings on your magneto that are faulty. Years ago they were insulated with "Shellac" but over time and heat this breaks down resulting in the engine being easy to start whencold because the insulation is better and more difficult when hot because you have a partial breakdown of that insulation.

Best solution is to have the mag rotor rewound by a specialist and it will give you yet another 25 years trouble-free service (and mags loook better too!).

You can pussy foot around forever changing small components here and there but in the end it comes down to getting a re-wind. As our machines get older it is essentially an inevitability that a mag re-wind becomes necessary and the problem will occur with increasing frequency as machines approach their 50 year old birthdays!

Regards,

Peter Bolton