What replacement spark plugs do you use? (chinese 2-stroke)

srdavo

Well-Known Member
Joined
Nov 4, 2006
Messages
3,161
here is the list I compiled a couple years ago.

NGK B6HS & B5HS
Champion L86C
Champion CJ7Y low profile ( I like these)

Autolite 425
ND W2OFS_U
Bosch W9EO

The plugs in bold print are the ones I have personally and successfully used.
does anyone use any of these?
has anyone found more to add to the list?

I want to confirm my list, but NAPA only carries the 1st three .
thanks
Dave
 
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OldPete

Guest
One should not use plugs that place threads inside the combustion chamber for two reasons.

1- The thread/s can fill with carbon and start damaging fragile aluminum cylinder head threads when removed. It can get so bad the plug threads go into a bind at removal.

2- With extended heavy load on a hot day the thread that is exposed inside the chamber can glow just enough to induce deadly detonation. This leads directly to a holed piston or a piston seizure. Bad stuff for sure.

(I have seen a seizure cause by a Heli-coil plug hole repair that was hanging into the chamber by half a thread.)

Solution? Use an old gasket along with a new one or use a solid copper ring to space the plug out enough. This is the only image I could find on a quick search. Called index washers. They are used to place to open side of the plug gap directly at the incoming air charge when the plug is tightened.



srdavo, delete this if you wish. :cool:
 
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gone_fishin

Guest
my ngk b6hs is exactly the right length on my dax70.

can anyone confirm any of the other numbers? we wanna make sure the manual is correct.
 
H

Herrmanator8

Guest
!!!!!!!!!!!!!!!!!

I have an 80cc bike motor that i bought from kingsmotorbikes and it came all stock and the spark china plug is stock. Is the stock spark plug the right length, id like to know whats the best/highest performance spark plug i can get and it must be the right length because i dont was and engine seizure or any other problems in addition to the ones i already have. so can someone please tell me what i should get plz, and maybe some good advicel.

Thanks, Jon Herrmann
 
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Guest

Guest
NGK B6HS OR B5HS are the best direct replacements.

I have fitted an Autolite 4093 with no problems, but haven't checked to see if it goes into the cylinder at all.
 
M

MotorbikeMike

Guest
spark plugs

I have not messed with these in years, but I can tell you that I remember that not all of the heads are threaded the same depth, and in many cases the orig plug is actually too short,. Mike
 
O

OldPete

Guest
Re: spark plugs

MotorbikeMike said:
I have not messed with these in years, but I can tell you that I remember that not all of the heads are threaded the same depth, and in many cases the orig plug is actually too short,. Mike
Every home-brew mechanic should have one of these, they can be had in plastic, from Harbor Freight for <<$10. A vernier caliper w/depth gauge.


 
G

Guest

Guest
...or take the head off and screw your plug in and see where it ends up.
 
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jol

Guest
I got a NGK B6HS as spare, but use the one that came with the motor
 
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