Motorized Bicycle Aftermarket Spark Plugs

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Down_South

New Member
Aug 28, 2008
140
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North Carolina
OK, so I've done some research on spark plugs and have listed every brand from around the world that has a plug for these 2 stroke bike engine kits. My goal is to make a list that anyone can use no matter where they live. Feel free to add any other plugs that have the physical dimensions of 14mm diameter with 1.25 Threads Per mm and 1/2" reach ( 12mm and .472" reach is acceptable). Heat range and resistance can vary but the physical dimensions should remain within above specs.

Spark Plug:
Accel - 0453
AC Delco - R44F
Autolite - 4123, 425, 275, 4093, XS4093
Beru - 14R-7BU
Bosch - WR6BC+, WR7BC+
Champion - L82YC, RL82YC, L86C
Daytona Maxfire - 61490
Denso - W20FPR-U, IWF20
E3 - E3.32
Eyquem - 775SX
Motorcraft - AER32
NGK - B6HS, B7HS, BP6HS, BP7HS, BPR6HS, BPR7HS, BPR6HIX, BPR7HIX
SplitFire - SF265F, SF412C <--- both discontinued - Shucks!!
Torch - E6TC, E6RTC

Also, for those of you who are looking for a "shorty" plug for a tight fitting engine, I managed to find some 3/8" reach plugs that will fit just fine in the stock heads that came with 1/2" reach plugs.

Autolite - 2974, XST2974, 254, XST254 ( The 254 has a solid terminal bud that won't work with the stock cap, if this is a problem, use the 2974 which has a threaded terminal bud. )
NGK - BM7

I've attached a picture of the stock Chinese plug that came with my engine. The picture shows a clear cross reference to a NGK BP7HS. I really learned a lot about spark plug companies while making the list. I haven't heard of some of them until now.

DISCLAIMER: Not responsible for any damages. Double check my info before buying and make sure that the new plug matches up with the stock plug that came with your engine unless you're using "shorty" plugs. Have fun and ride safe.
 

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Down_South

New Member
Aug 28, 2008
140
0
0
North Carolina
Guess you haven't heard the old saying, "Pistons, the breakfast of Champions!" :D
Yep, I have a John Deere tractor that uses the Champion 71 (RC12YC) plug and I switched over to the Autolite 3924. I like to get out the DMM/DVOM/Ohm meter and check plug resistance. The Champion 71 measured in at 15.1K and the Autolite 3924 measured in at 4.82K, so I use the Autolite. Too much resistance can fry the ignition coil.
 

Degoragon

Member
Apr 7, 2019
33
19
8
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Question, Anyone try a Champion CJ7Y or an Autolite 255? It's for a short frame (24" wheel) cruiser bike. I was wondering if either of these short plugs would be good for a 66cc "Slant Head" GruBee Skyhawk GT5? I am in the midwest US.