Spark plug cross reference??

suiteo

XS650 Enthusiast
Messages
83
Reaction score
0
Points
6
Location
Phoenix, AZ. U.S.A
I've been searching high and low on the internet for an equivalent to the NKG BP7ES, but can't seem to come up with any definitive, "use this spark plug" answers. What plugs have you guys used with success that can be picked up at the local auto parts store? Need to start the bike today and can't seem to find the spark plugs I took out a couple of months ago. Rather not have to order them, since I have no bike shops near me.

Thanks,

Jay
 
Cool link, thanks. Searching to auto parts store's webpages, I'm not finding anyone that stocks these equivalents. Shouldn't be this hard to get a spark plug locally. Sheesh....
 
didn't think the number for champion plugs was right, N7Y, I always used N7YC, knew there was a y in there somewhere, champion plugs always used to be alot more tolerant to being flooded, with Brit stuff when flooding the carbs to start.
 
You may want to consider changing over to 5/8 Hex spark plugs instead of the stock 13/16 because of the greater variety of new plugs that are available in the 5/8th hex style. Here is a quick guide to plugs that are compatible. They are all resistor plugs, as are all new design plugs.

NGK Stock

FR4 5155
FR5 7373 (Hotter)

NGK Stock

BCPR7ES
BCPR5ES 7496 (Hotter)

Bosh Stock

FR8DPX 4202 (Platinum)

Bosch Stock

FR8DCX 7557
FR10DCX 7563 (Hotter)

These are 13/16ths

AutoLite #63

NGK BPR7EIX Iridium

NGK BPR8EIX Iridium ('70 - '72)

I have tested all of these plugs with the PAMCO ignition, of course, and they all work great, but the Iridium plugs actually produced a 4% increase in gas mileage, which equates to better fuel burn and potentially greater power.
 
I completed a road test for the Iridium spark plug to check the gas mileage. Here are the results along with a comparative to other plugs and coils:
Summary of highway gas mileage using various coils and plugs. The 17-6903 coil is the new "Ultimate Coil" with the towers on the side.

Motorcycle:1981/H
Carbs: Stock BS34's
Exhaust: EMGO 27" reverse cones
Air Filters: Paper element replacements for stock filters
Fuel: 93 Octane
Ignition system: PAMCO 60 degree (except test 1 is 90 degree)
Plug wires: 5K caps


Test, Coil, Plug, MPG, % Increase, From stock, Main Jet

1, Stock, #63, 57MPG, 0, 0, 132.5
2, 17-6822, #63, 60MPG, 5.20%, 5.20%, 132.5
3, 17-6903, #63, 66MPG, 10%, 15.70%, 135
4, 17-6903, BPR7EIX, 69MPG, 4.50%, 21%, 135

Note: Same 60 mile test route for all results.
Same pump used to refill after each run.
The results for the Iridium plug are impressive. More than I would have thought for just a change of plugs. Of course, this means that more of the fuel is being ignited in the cylinder, so there will also be a corresponding increase in power as well. Because more of the fuel is actually ignited, you can feed more fuel with a larger main jet to further improve performance without sacrificing fuel economy. I installed 135 jets for the last two runs, as shown
 
Last edited:
Well spotted Jay, the link does give the correct Champion equivalent, I misread it, sorryfolks :bow2:
 
anything need to be done to convert to the 5/8 hex plug

i am tired of having trouble finding the original in stock

advantages or disadvantages of the switch
 
bk,

Nothing else has to be done.
The advantage to using 5/8 ths plugs is the greater availability and the lower cost, because these plugs are used in a lot of cars and are often on sale.
 
Back
Top