Just a plug...

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My 72 roadster was not running properly, no carb adjustments/vacuum gauge synchronization seemed to improve things. Ignition timing (Boyer) was good too. The bike would idle fairly OK and run fine from about 1/2 throttle and up. In between it was very rough, jumpy and downright unpleasant to ride.

Tried different plug NGK/Champion types - no improvement. Then I bought some Bosch Super 4 WR 56 plugs (with four electrodes) and it was like I had a new engine installed. Smoother than I ever thought possible - throughout the entire rpm range, idled at 7-800 and dead steady. Carb adjustment response was instant.

Of course this is too good to be true. So - have any of you out there ever tried these plugs, and what are the horror stories ?

Your spark plug story does sound too good to be true. I suspect you have some hidden problem, as your 72 Commando should run perfectly fine with Champion N7Y spark plugs.

I have no experience with the Bosch plug you mentioned; however, as long as the reach and heat range are the same as the Champion, the Bosch plug should be OK to use in your Commando engine.


That's good to know. My bike had a voracious appetite for plugs when I was sorting through all the problems with the amals. Hopefully that's behind me now. Was worried that fouling plugs would continue to be a problem.

I took it out for a ride last night after work. Started first kick, ran great! I hope it stays that way for a while...

Ah jeeze fella's, plugs smugs, I had the very same
esperience, no other brand or sytle of plug would allow
me to run my Combat if it even sat at a traffic light.
My signle carbed Combat became a delight and fast
and sure with the Bosch Plat 4's durring period I
did not know even where the points were located.

On Mid Ohio Trip Wesly's '71 was fouling plugs
horrorablely d/t worn rings with big gap to point
finaly would not run with his weak charging system
and boyer. We switched plugs and got back on
road and to place to sleep in bed instead on hwy.

Sure these plugs don't solve underlying problems but
boy howdy can they make it work darn well until
then. I'm hoping they will work with the supercharger
to fire a dense Hi comrpession mixture with their
buildt in wider than standard hook electrode heat range.
Welcome Hobot, I'd recognize that writing style anywhere!
Plugs are fun I have been playing with mine and have found them to be useful once your close on the carbs. In third gear wind outs trying to get the bike to red line. Bosch Plat. WRP 7 100 mph than Auto lite AP63's 105 mph then AP 64 110 mph at 6500 rpm with my fat 240lb straight up in the wind. Now check to make sure that long runs on the x-way in fourth at 80mph and 4250rpm don't run too hot. They seem fine on my bike. So run as hot as you can sistain on the x-way at consant speed because that helps the most with all the other riding. I tryed the Bosch plat fours they were great down low really smooth but were braking up under high rpm's were life is exciting. norbsa
super 4 plugs

My gut feeling leans towards dynodave`s opinion - it should run OK with the standard plugs. But - the Amals are brand new, as well as the ignition cables and plug caps. I had adjusted the throttles and the idle jet to my best knowledge, really taken care to make the best out of it.

But as I said, once the Super 4`s were in, everything just fell into place, even when the engine was started cold. I can understand that the effect of a hotter plug can be felt in a warm engine, but should it be so evident in a cold engine ?

When I feel brave, I`ll put the NGK`s back on and see if things change again. I`ll let you know..

Thanks for the replies !


Std for the combat engine is NGK BP7ES or Champion N7YC. NGK used to make a BP7EV platinum tip, the President of NGK US gave me a dozen of these in 1983. They work pretty well for low voltage applications.

The mid range uneveness is what I had before replacing the needle jets and jet needles on my combat. If you're Amals are new, make sure you have the right size needle jets (106).
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