GT 750 Plug gap ?

[T350guy]

I noticed Suzuki says to gap NGK to 28-32 and ND 24-28..why the difference ?..The NGK gap seems large to me for a Points ignition system . 24-28 seems more reasonable.

[H2RICK]

Hmmmm.....that's strange but true. Thanks for pointing that out.
Evidently the factory had a lot more faith in the ignition system's ability to fire a wider gap on the NGK's compared to the ND's. It may have something to do with a slight variance in heat range between the two makes of plugs.....but that's just a guess.

Any other facts/opinions/guesses out there ??

[Craig380]

The gap difference could also be related to the width of the centre electrode. In theory, a thinner central electrode should mean the gap can be a little wider, as the spark will jump more readily from a more pointed electrode. Maybe the NGKs have a slightly narrower electrode, or a pointed earth strap ...

For what it's worth, I gap the EIX Iridiums in my 380 at 24 thousandths, to help the ignition system as much as possible. Runs great and the gaps don't change from one year to the next ...

[Suzsmokeyallan]

My experience with ND plugs for over the last 30 plus years is that they simply dont last and fail without warning when they do.
I've always had excellent results with NGK and use the stock gap they recommend without any issues.

[T350guy]

Thanks for the reply guys.
I remember many years ago there was an article about changing the GT 750 coils to higher output ones as the stock coils were so so.
I guess many coils were so so of the day even the Yamaha RD 350 , the hot set up then was to use Mercury coils.
Ahhh the good ol days.

[jabcb]

Back in the 70s, I used Kmart car coils after one of the bike magazines had an article about them. If my memory is correct, they worked quite well but were hard on the points.

Today, the easiest upgrade is NGK fine-wire plugs. I use the non-resistor NGK B8EGV.

Rex Caunt sells coils that are an improvement over stock & fit the stock coil brackets.
Don't know of any modern aftermarket high-performance coils that fit the stock coil brackets & have the correct resistance.

[H2RICK]

Back in the 70s, I used Kmart car coils after one of the bike magazines had an article about them. If my memory is correct, they worked quite well but were hard on the points.

Thanks for jogging my memory on that factoid, jabcb. I remember laughing at the time thinking "Why would Kmart have better coils than the OE items ??". Much, much later I learned the sad truth. I don't suppose that Kmart currently sells the same coils though, unfortunately.......although there are lots of modern substitutes to be had.

[T350guy]

I was just comparing my 74 GT 750 owners manual to my 77 and the 74 states plug gap to be 28-32 whereas my 77 states NGK or Nippon Denso to be 24-28.

Ian

[jabcb]

The Kmart coils were just generic coils for cars that had points ignition system.
They used around twice the current of the typical bike coils of the time, which is why they were hard on points.
The current draw created another problem in that many bike alternators didn't have enough output for the additional load.

Modern high performance coils are much better than those Kmart coils were & they don't draw additional current.