sudden failure

[Barry]

NGKBP7ES are ideal plugs, probably the best.

I don't subscribe to the theory of plugs causing a coil to overheat and fail. The only thing I can think of that would cause a coil to get hotter than normal would be closed up points resulting in longer dwell. Even then I doubt it would be an issue with 6 Volt coils.

As far as I know the only impact a plug could have on the coil is the HT voltage needed to jump the plug gap so a grossly excessive plug gap might stress the coil a little but that's about it.

[Bob_Roller]

The plugs you have are the correct ones .

[montmil]

Bill, Those NGKs live happily in both my R65s with no problemo.

[Tony Smith]

Also just finished hours of cleaning connections etc. It started up and I put the tank on and it won't start now..

I'm sure I suggested this before, sorry if I did not. The three prime suspects are (in order of likelihood) 1/ Kill Switch, 2/ Ignition switch and 3/. Main power wiring to Ignition switch.
 
I think you have eliminated the kill switch - suggest strongly that next time you have no spark that you wriggle the ignition switch. By the way, it would take you about 2 minutes to make up a jumper lead to permanently supply power to the coils which would eliminate some really strange fault with the coils or wiring to the points. Probably a good idea to make the jumper lead up so that you can get home if it plays up again.

BUT, do check the ignition switch as that what was proved to faulty on my wife's R65 which nearly drove me mad trying to find and eliminate an intermittent loss of sparks.

[Bill Conquest]

Thanks everyone ..will check the ignition switch if it dies again but I did try jiggling the wires into the switch & it didn't affect anything..but still is suspect. The idea of the jumper wire sounds good..where do I put it?
Thanks, Bill

[Tony Smith]

The idea of the jumper wire sounds good..where do I put it?
Thanks, Bill

 
Bill, its been a while and I am at work and cannot check. But, your coils (I think you have a twin coil model) will have a terminal that receives +ve 12 volts via the ignition and kill switch. Identify which wire it is and disconnect it, then make up a lead direct from +ve battery terminal (with an inline 10amp fuze if you desire) and connect it directly to the +ve coil terminal - your coils are now "hot" and if you turn the engine over - it should start. Go for a ride sufficient to cause the sudden failures you have been experiencing - if it doesn't fail you have positively excluded the coils and wiring between coil and points/ breaker. If it does fail, then your problem is confined to the coils and contact breaker - next step would be to make another jumper direct to the breaker and see if you still have sudden stops - if you do, replace the breakers, if it still stops, replace the coils (but I very much doubt it will be the coils of breakers - the reason I propose going the way of jumpering out chunks of the bike's wiring harness is to "move the fault" as my old apprentice master used to say. Once you stop an intermittent fault from happening, you can positively eliminate everything still connected at the time the fault stops manifesting and can then work from a known base.


DON"T FORGET TO DISCONNECT THE JUMPER TO THE COILS or you will have a flat battery, cooked coils, or both  

[Barry]

Bill

Make up a short lead from the +ve battery terminal to terminal 15 on the rear coil. You should find there is a spare spade on the coil to connect to.  Don't leave the jumper on for more than a couple of minutes without the engine running. An in line fuse in the jumper cable would be an added safety feature in case of a short circuit.

[georgesgiralt]

You should have a free spade on the harness to plug the optional voltmeter. This makes a good candidate for connecting the ignition directly bypassing the kill switch. This wire is shut off by the main key switch (so if it is the culprit, it won't show...).
If your harness is original, the female spade will be stored in the area of the speedo and tacho wiring.

[Bill Conquest]

Thanks so much you guys for the explanation & diagram.. will check after work this week - end and now understand ....
Thanks, Bill

[raypond]

I have to tip my hat to our new member Dugald, who lives in what has got to be one of the most interesting-named towns we have represented in our international community!

I'm sorry I can't help much with the bike problem (my money's on the ignition switch) but, yes, here in the north east of Victoria we do have some interesting place names. Not far from Yackandandah is Tangambalanga which is just down the road from Tallangatta. In the other direction is Mudgeegonga. For speed tests the roads around Tarrawingee and Carraragarmungee are flat, straight and empty. But my favourite is Colac Colac which, for no apparent reason, is pronounced Clack Clack. I'm easily amused.