Spark Plugs

[tool13x]

I just wanted to revisit the spark plug topic. I have seen a few posts out there about which spark plugs to use and it seems like most everyone agrees on the NGK BR9ES.
 I recently bought a 1980 Invader 440 which until today I thought was a 1979.  The '79 calls for a BR9EV which the BR9ES is a direct replacement for, but in '80 they switched to a BZ9EV which I cannot find anything to cross reference as a replacement.
If I am not mistaken, the R designates it as a resistor plug and the Z designates an inductive resistor.
As for the information I pulled off of the NGK website at   http://www.ngk.com/glossary/8/spark-plug/I  , you cannot use a standard resistor or any non-inductive plug in a system designed for an inductive-resistor due to the major resistance difference(40ohms as compared to 1000-5000 ohms.)
Sometimes I get a little carried away so please let me know if I am over thinking this, but what plug am I supposed to use since I cant find a BZ9EV anywhere?

[Tory944]

I  Run BR9EYA   (same heat range as the ES, but with the same/similar design as the EV's)   Tory

[rminier]

Wow, now you have raised my curiosity. Having owned a '79 Invader for many years, I have just used BR9ES plugs. (Tried the "expensive" BR9EIX and really could not tell any difference. They probably resist fouling better than standard plugs, if that is a problem. This year I ordered some BR9EYA's to try, due to several posts on here from people using them.
  That NGK site is really interesting. I do have several parts manuals for the Invader/Intruders. I had to look at the '79 vs. the '80 parts manual to see what might be different. Certainly you pointed out the spark plug change. The '79 Invaders and the '80 use the exact same flywheel, CDI box, Ignition Coil, etc. However, both the pulsar coil and the exciter coil on the stator change to new part #'s for '80, along with a change for the spark plug cap part #. Hmmmm. I have to wonder. Anyone else have any insight into this?

[Tory944]

  As I am sure you know, modern two stroke technology has not made "leaps and bounds" over the years (from a design standpoint), but what HAS come a long way has been the ELECTRONICS.  Even though Kawi uses a CDI ignition, there has been much improvement in recent years with the two/four stroke electrical "brains" of the operation.  I am sure there are others on here who can give more technical aspects of recent electronic improvements than I...   more timing advance/retard, etc.  The BR9EYA's have a "split electrode" (smaller firing point) which CAN "contribute" to better fuel mileage, quicker start ups, etc.  The EYA's are only a few bucks more than the standard ES plugs and although they won't show much/if any power gains...  I feel that for the extra cost (minimal) they are worth using.  Make the most of an adequate (at best) 80's electrical brain.  IMO.  Do you run low test fuel in your sleds or high test?  If you had the choice of BR9ES (standard) at $2.99 plug vs. $4.39 for the EYA's would you run EYA's?  I did...  Some fact here and "my opinion" for sure.

[kawhead]

i'm pretty sure the pulser/exciter change was a durability update....the plug cap changed in 1980 to no resistance copper wire ends,hence the plug change imo. i've always interchanged br9es /br9ev according to customer budget, i've gone to br9eya a few years ago.

[rminier]

I ordered a box of 10 BR9EYA plugs for 24 bucks from a very popular supplier online a few weeks ago, mainly because the split electrode does sound like a good idea. I now have 5 sleds (groan, just what I need in Indiana ) with the recent addition of a '82 Blizzard 9500. It's pretty convenient that 4 of my sleds (all but the'75 SnoJet) call for BR9 plugs. I'm wearing my plug gapping tool out because the recommended gap varies from .016 for the 9500, .018 for the MXZ, .024 for the Invader, to.028-.031 for the '83 Vmax. Oh well, if only all of life's problems were that simple.

[tool13x]

Thanks for all the input, Ive been calling around to dealers and parts stores and havent really made any progress in finding out why so many places are cross-referencing the BR9ES with the BZ9EV, although one dealership today said the B9ES was the updated part number for the BZ9EV. Im beginning to think its not as big of a deal as it seems, although logically the BR's should have a weaker spark because of the higher resistance. I do like the idea of using the BR9EYA  and I might go with those.  It just still bugs me about the claimed interchangeability between Resistant, inductive-resistant, and non-resistant plugs.  I will be making a call to NGK's technical support line tomorrow to hopefully get some satisfying answers. I'll keep you all posted.

[mswyka]

We have been using BR9EYA in all our sleds for the past 4 or 5 years and find that they are very reliable.

[foxspoiler]

just picked up 2 boxes (20) BR9EYA plugs today at Fleet Farm for 22.50

[mswyka]

That is an excellent deal.