Aprilia plug connectors.

[Raahauge]

Leaking Aprilia plug connectors.
Some notes.
Using dye penetrant crack detection only one out of my stock of eight connectors seemed to be completely free of cracks and one other had only limited very small cracks. The rest were to varying degrees extensively cracked.
I have modified the worst unit by drilling out the middle of the main stem to 14mm and the shorter outlet leg to 9mm so that an ordinary piece of wire cored HT lead could be threaded down and connected to the spring that loads the disc onto the top of the plug. (This lead is then connecter directly to the distributor cap)
The four units fitted to the engine are now the “modified”, the “uncracked”, the “slightly cracked” and the least worst of the rest.
A resistance test on each unit in the above order when cold gave values of 100 megohm, 7 megohm,10 megohm and 8 megohm.
The test when repeated on a hot engine gave in the same order 100 megohm, 0.5 megohm, 1.25 megohm and 0.5 megohm.
The results did not change if there was no plug.
A 500v Megger was used.
As a very rough rule of thumb in industrial applications it is desirable to have 1 megohm of resistance for every 1000v of pressure.
By that standard a resistance of 10 megohm would be desirable although from experience 5 would probably be reliable.
With this setup I now don’t have any misfiring under load but I detect that the engine is not as smooth when up to temperature and the induction noise is slightly different.
Even though the modified unit has had very limited testing I am now modifying three more units.
Any comments or other contributions most welcome.

[Martin9]

My word Mike, that is a neat piece of work. I can't see any downside to your 'modified' solution except that you have to detach the leads from the top of the distributor, which is a pretty minor inconvenience. And it is low cost, certainly compared with the alternative of manufacturing copies of the originals. Martin

[peterblenk]

Or, new ones are available from Cavalitto and perhaps other suppliers, but at a price. Probably a good investment for trouble-free running. Peter