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Dominator 99 problems update

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Re: Dominator 99 problems update

Posted by peter_oconnell at June 06. 2011

Sorry about starting a new thread but when I tried to update the previous one I keep getting error messages for some reason. I have discovered that the problem seems to be electrical and it is getting worse. The left cylinder starts to miss after even a short run where before it took about 10 miles before it started to die. I got an old set of leads and used a plastic tube with a gap so that I could see what was happening and found that the spark in the left lead starts to miss then dies completely. To date I have changed the plugs, caps, leads, coil, points, cap, condenser, and rotor arm all to no avail. The only thing left is the distributor itself but I cannot understand why only one cylinder would be affected. There is a little side to side movement in the shaft and about 1/4 upward movement. Is it still possible to get replacement bushes and seals for the 18D2?.

 

Peter

Re: Dominator 99 problems update

Posted by robert_dixon at June 08. 2011

I had a similar problem and done what you have done. The last thing to do was the bush in the distributor, I had very little play but made a new bush and that cleared the problem. Just check the plug caps as I got a faulty one. Hope this helps.

Re: Dominator 99 problems update

Posted by Barry Carson at June 08. 2011

Previously wrote:

Sorry about starting a new thread but when I tried to update the previous one I keep getting error messages for some reason. I have discovered that the problem seems to be electrical and it is getting worse. The left cylinder starts to miss after even a short run where before it took about 10 miles before it started to die. I got an old set of leads and used a plastic tube with a gap so that I could see what was happening and found that the spark in the left lead starts to miss then dies completely. To date I have changed the plugs, caps, leads, coil, points, cap, condenser, and rotor arm all to no avail. The only thing left is the distributor itself but I cannot understand why only one cylinder would be affected. There is a little side to side movement in the shaft and about 1/4 upward movement. Is it still possible to get replacement bushes and seals for the 18D2?.

 

Peter

 

Hi. 

       are the coil and condenser 12 volt. make sure no dents in the coil it may short internaly ..

        are the plugs and plug caps normal ones and not for electronic ignition

       

        Baz

 

Re: Dominator 99 problems update

Posted by Gordon Johnston at June 10. 2011

Previously wrote:

I had a similar problem and done what you have done. The last thing to do was the bush in the distributor, I had very little play but made a new bush and that cleared the problem. Just check the plug caps as I got a faulty one. Hope this helps.

Re: Dominator 99 problems update

Posted by peter_oconnell at June 10. 2011

 

Thanks for the suggestions guys but I am still stumped with this one. The left cylinder gives the odd miss while ideling but continues to run. After a short uun the left cylinder looses its spark and will not run below about 1500 - 2000 RPM. I have tried three coils three sets of leads, two sets of plug caps, three distributor caps. numerous plugs, two rotor arms and have also replaced the low tension lead. A friend suggested that the distributor cam might be changing the points gap when warm so I tried increasing and reducing the gap with no luck.

I have tried NGK B5ES and B7ES as the recommended B6ES is not available locally. I have run the bike with B7ES for a number of years without difficulty. I thought that it would be easy to find the reason that a spark stops as the only things affected should be the plugs, plug caps, leads, rotor arm and distributor cap but the problem persists.  

 

Peter

Re: Dominator 99 problems update

Posted by Barry Carson at June 11. 2011

Hi .   the only other thing i can come up with is the lobe on the distributor corresponding to cylinder thats missfireing could be worn causing smaller gap in the points

         with a lesser spark to that cylinder then plug fowls up

        then when you rev it up the bike starts to charge more perhaps supplying that little extra voltage at the coil to clear the plug.

         hope this helps .

      

 

Baz

Re: Dominator 99 problems update

Posted by dominic_gomes at June 13. 2011

Hi Peter

 

Have you had a good look at your wiring loom as it seems that you may have an intermittent break either in the loom or the connections (read dry joint). I would put an electronic  timing light on the faulty cylinder while it is misbehaving to find out what is happening to the spark. If it is indeed intermittent you will see the light flashes being intermittent. You will need to try to recreate the fault. Iwould manipulate the loom to try to find a possible break or dry joint.

 

 

regards

 

 

Dominic

Re: Dominator 99 problems update

Posted by john_whiting at June 13. 2011

Peter, I suggested that you check for wear in the dist shaft, but it got mixed up with all the other posts.I have been a mechanic for nearly fifty years and I can assure you that all sorts of strange problems disappear on fitting a new distributor. Wear occurs not only in the shaft bearings but also in the auto advance mechanism.Lucas designed this distributor to fit vertically, and provided lubrication of the advance by an oiled felt pad that fitted in the end of the cam. Every oil change, you put a few drops of oil on the felt,and lubricated the shaft inside the cam, and the advance weights.You may find that wear inside the cam is worse in the advanced position, accounting for whats happening. In any case the only thing to do is to dismantle the entire distributor, advance and all, and refurbish the lot.This may mean that parts that are worn must be hardchromed and reground, if no new spares are available. Bushes must be of the sintered type or rapid wear will result, and soaked in oil before fitting.There used to be lots of con artists in the dist repair business doing bodges that lasted about a month,so be careful. Regards .

Re: Dominator 99 problems update

Posted by peter_oconnell at June 15. 2011

I really thought that I finally had the problem sorted.  Originally the miss came in after a 15 mile run but developed to the point that it started after a few minutes running so I decided to redo everything. I replaced the points with an old set ( the two sets I had tried had come from the same eBay seller and I suspected a faulty batch ) and disconnected the condensor and installed a replacement outside the distributer. The bike ran as it had before the problems started until I took it for a longer run and sure enough the problem returned after 15 to 20 miles as bad as ever with an intermittant spark to the left cylinder.

I did as Domnic suggested and checked every connection I could find to no avail. John's theory that the distributor itself may well be the problem may indeed be correct but I cannot find a replacement anywhere here to test it out.

Re: Dominator 99 problems update

Posted by lionel_yexley at June 16. 2011

Make sure you only use new, copper-cored HT leads with unsupressed caps as it sounds as though it's a heat-related HT leakage problem.  Plastic and PVC insulation breaks down at HT voltage levels as it gets older and hotter.  Even though you have replaced the leads once - do it again just in case!  Who know what quality the distributor caps are or whether they are made of the right material to insulate against HT leaks?  Start it and run it in a very dark place and look carefully for violet HT leakage - or worse, arcing  from somewhere along the HT path.  Run your fingers over the leads - keep away from the ends though!  If the HT is leaking you'll see faint violet sparks, a bit like a plasma globe.  It shouldn't hurt - honest!

Good luck, Lionel

Re: Dominator 99 problems update

Posted by Barry Carson at June 16. 2011

Hi Peter.

the focus seems to be all points and leads ect what about the ignition timming this could be way out. if bob weight are sticking in the distributor it may stick full advanced and only be able to spark on the one cylinder until you adjust the points again resetting it all . i think the gentleman that says recondition your distributor is correct, it may have a bent shaft or anything this would shurely cure all.

 

Baz

Re: Dominator 99 problems update

Posted by anna jeannette Dixon at June 16. 2011

Previously wrote:

 

Thanks for the suggestions guys but I am still stumped with this one. The left cylinder gives the odd miss while ideling but continues to run. After a short uun the left cylinder looses its spark and will not run below about 1500 - 2000 RPM. I have tried three coils three sets of leads, two sets of plug caps, three distributor caps. numerous plugs, two rotor arms and have also replaced the low tension lead. A friend suggested that the distributor cam might be changing the points gap when warm so I tried increasing and reducing the gap with no luck.

I have tried NGK B5ES and B7ES as the recommended B6ES is not available locally. I have run the bike with B7ES for a number of years without difficulty. I thought that it would be easy to find the reason that a spark stops as the only things affected should be the plugs, plug caps, leads, rotor arm and distributor cap but the problem persists.  

 

Peter     hello why not try Bosch W7DTC  from the Green Spark plug Co .just go too www.greensparkplug.co.uk

 

Re: Dominator 99 problems update

Posted by Gordon Johnston at June 17. 2011

Previously wrote:

 

 

I had many distributor problems in the first 2 years of owning my 99 (1969-1971). I eventually gave up and replaced it with a magneto. I have never regretted to change, even 40 years later. I have had occasions when I have had electrical failures but still the engine keeps running. Wonderful. The rectifier failing half way between Anglesey and Norwich being a case in point. 100 miles on pilot light only in the dark may not have been sensible but at least I got there...

 

 

Re: Dominator 99 problems update

Posted by Gordon Johnston at June 18. 2011

One last thing, I have never got on with Champion spark plugs. NGK B7ES or BP7ES seem to suit Nortons and last for years and years and years. I have had N4s fail after 20 miles.

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