Autolite 3922 vs 3923

[jerngina]

What is the right plug for 2001 R115GS. Been using 3923 for years. Just starting to get occasional pinging with almost 90,000 miles.

[Andy VH]

I have run the 3923 and 3924, both with no issues. I think the lower the number the "hotter" the plug. A hotter plaug may be better suited to lots of city riding.
If you are gettting pinging now, it could be carbon buildup on the piston crowns.

My 94 R1100RS has over 127,000 miles on it with no pinging issues. But twice per riding season I run a bottle of Seafoam or Chevron-Techron through the gas. When I look in the spark plug hole with the piston at TDC, I can still read a small casting detail on the piston crown.

Another old trick from years ago, is to run Marvel Mystery Oil, like about a pint, in a full tank of gas. Supposedly, the solvent derivatives in the Marvel oil clean up carbon deposits in a running engine. I have on occasion used Marvel oil in my gas with no ill effects.

[jimabmw]

Autolite's last number indicates heat range and the higher the number the hotter the plug.

[alien_hitchhiker]

So, if I'm consistently running a bit richer than the manufacturer intended (due to a Techlusion 259), would my engine benefit from a hotter plug?

I've been using APP 3923 plugs with a moderately tuned Techlusion for tens of thousands of miles. Everything else is stock. Currently 61K on the odo. The bike runs beautifully though a bit of dark 'soot' accumulates at the tail pipe. The plugs - when I pull them - are always pale grey. I almost always run premium gas.

Any opinions?

[breyfogle]

She plugs - when I pull them - are always pale grey. I almost always run premium gas. Any opinions?

IMHO, if the plugs are a pale grey, they are fine. No need to change plugs.

[Andy VH]

I agree. I use the Autolite 3923 plugs with a Techlusion in my 94 R1100RS with a modified stock exhaust, and I get the same sooty residue at the outlet. My plug color was a bit dark though, so I have dialed the Techlusion back a bit.

[jerngina]

I can definitely see that the 3923 is the mate for the R1100's. I am having trouble finding anything in writing that says the 3922 is the plug for the R1150. If it is only a heat range difference for the 3922-24, I may get a pair of each to see if there is any difference in the occasional ping. Thanks for all the input prior and aft. (the bike is in Germany, so I find it easier and less $$ to bring parts over)

[R100RS]

This PDF on the Honeywell/Autolite website indicates that the 3923 is the correct plug for the 1150:

http://power-21.com/HoneywellPower21i/RelatedInfo.aspx?b=A&f=Autolite/Motorcycles.pdf

[2BikeMike]

This PDF on the Honeywell/Autolite website indicates that the 3923 is the correct plug for the 1150:

http://power-21.com/HoneywellPower21i/RelatedInfo.aspx?b=A&f=Autolite/Motorcycles.pdf

Too bad that's only half correct for the dual plug bikes.

[jerngina]

That is what I have been looking for...

[R100RS]

Too bad that's only half correct for the dual plug bikes.

The OP's 2001 model is a single spark. For dual spark models, they spec the 4164 for the other plug.