KTM no spark at plug

[duggie]

My son has got a ktm500 1981, l'm trying to help him get it running but there seems to be no spark at the spark plug, tried different plug still no spark, any advice from you fellows would be welcomed.
                                             Regards.
                                                    Duggie

[G Ellis]

I would try your coil ground first. Coil has to have a good ground. If you still have no spark, I would try a new coil first.Did it just quit sparking all at once? Hope this will help. Had the same trouble with my 77 GS 175 it was the coil.

[farmer58za]

Hi Duggie
Is the ignition a Motoplat? If so it's important that the coil is well earthed to the frame. Similarly, the stator plate must be in good earth contact with the motor and the motor with the frame. Have you had the frame powdercoated or sprayed recently?
regards
David in S.A.

[duggie]

Hi David, the bike is fitted with the motoplat system.
   My son brought the bike a few weeks ago without seeing the bike run (first mistake)l'm now involved helping him (second mistake) all l've done so far is to remove flywheel and give the obvious contacts a clean. If this motoplat is defective what options do we have?. My next job is to clean all the contacts on the coil and l guess to remove the stator plate and make sure that has a good conection with the engine. If you have any more advice please feel free to educate me!
   Duggie

[farmer58za]

Hi Duggie
The Motoplat coil has a large and a small terminal. The blue wire from the stator goes on the large terminal. This blue wire splits at the terminal and goes to the kill switch which, when pressed, shorts the blue wire to earth and stops the motor. It follows that the blue wire must not be earthing anywhere. If the bike has a kill switch, disconnect it before testing for spark. The black wire goes on the small terminal. Other wires coming out of the stator will be from lighting coils.
 
Your Motoplat system should be a later model and the coil should have a red HT lead. The earlier model coil has a black HT lead and I believe that these may not work with the later model stator. It's possible that the previous owner may have put in an incorrect coil.

If that is ok and still no spark, borrow another coil and try that to eliminate the coil as tthe source of the fault. These systems were used on many European brands so a similar item from another make of bike should work.

I've got some Motoplat testing data which I can Email to you or put on the board. Some of this data I got from Mark Annan, who is also a member here. You will need a (preferrably analog type) Multimeter to test the system.

Regards
David

[farmer58za]

Duggie
go to http://groups.yahoo.com/group/vinduro In the "files" section is posted the article by Mark Annan on the testing of Motoplats
Cheers
David

[ksithumper]

Duggie, try Steve on 01736 754522 - he's the Motoplat Master! (//www.uk-motoplat.com)

[firstturn]

Besure to isolate the kill switch first as David has stated.  It and a improper ground as previouly described are thtwo things that I mostly see wrong with motoplat systems.


Ron Carbaugh

[TGTech]

Duggie,

   All of the advice I've read here is spot on, and the only thing that I can add regarding the grounding, is that in cases of an engine that has been together for a long time and exposed to the elements, the ground path between the stator and the spark plug can be lost through the cases, cylinder studs, cylinder, head studs, and the cylinder head.

   You don't say which model of Motoplat you have, but if it is a 9600176-1 or 9600198-1 (I think; I'll have to check tomorrow), we still have NOS stators on our shelves and of course, the PVL 105 465 coil wil replace the single spark plug wire coil. If you have the twin plug coil, we also have some NOS Motoplat coils of that style here as well. If your magneto is the 9600162-1 or the 0616026 unit, I'm afraid that we no longer have any of these parts, and you will have to rely on one of the repair experts for help. These numbers, by the way, can be found on the outside circumference of the flywheel.

   We can be reached by e-mail at [email protected].

   One other note about the red wire/black wire coil thing. You may have one of the late model black wire coils on your machine. These were made in the early '80's when Motoplat reversed the polarity of the systems. They are electronically interchangeable with the red wire coils, but still have a black spark plug wire.

   To identify the compatible coils, here's what you need to know: if the coil has the large terminal between the small terminal and the spark plug wire, then it must have a red wire. If the small terminal is between the large terminal and the spark plug wire, then coil can have either a red or black spark plug wire.  

   I hope I have helped a little. If you need more help, please let me know and I'll see if I can offer up any further assistance.

Dane Leimbach
Penton Imports Co., Inc.