250/400 Spark Plugs

[Kip Kern]

Any recommendations for spark plugs for the 73/74 250's and the 74 400 would be greatly appreciated.  Bikes will be used as museum pieces, "putters" not racers.  Would like to stay away from Champion if possible.  Thanks

 

[fischercycle]

Hi, Kip I have the bosch 260 through 310 half 1nch reach maybe that will help, also the champion gold platinum also the baru 240 to 310 same as bosch the pink one.also good to see your still involved.  JAKE FISCHER

 

[Dave Withrow]

Kip,
  I've been running NGK B9HS plugs as a standard plug and B8HS when I needed a hotter plug.  My '74 400 does well with them.

 

[Kip Kern]

Thanks Guy's, I appreciate the feedback,  it is always nice to be able to count on friends!

 

[tlanders]

Kip,

I thought that the NGK B8HS plugs was the standard ( Barry Higgens) except for the Mint 400 which should use a B9HS, I read somewhere, opposite to what Dave said. I have been using the B8EG plugs however for racing. They have a much stronger spark but they are long reach. So I put 1/2" high spacers between the plug and the head to make the long reach plugs end up at the same point in the cylinder as the short reach ones do. At first I was concerned about the fact that I only have one plug gasket between the plug and the spacer and there is none between the spacer and the head, but so far I haven't had any leaks. Sure wish I could remember where I read about the colder plug for the 400.

Teddy

 

[Steve Minor]

Don't know if it helps or hinders, but my Penton owner's manual that says Bosch W-290 for the Mint 400.......

 

[tlanders]

DUH - Dave did say the B9HS was standard for the Mint 400. I read his message wrong. Sorry Dave.

Teddy

 

[Knute]

Hey Guys,

I spoke with an engineer at NGK at the beginning of this race season and he recommended their VX series of plugs.  These are NGK's best motorcycle plugs, featuring a "fine wire platinum center electrode and a tapered ground electrode" for maximum efficiency, making them ideal for older ignition systems as well.  I used the B8HVX in our 250 and 400 race bikes and didn't change a plug all season.

As far as originality goes, one of my old manuals mentions the Bosch W 290 T 16.  Would this have been the original plug Kip?

Kent

 

[Kip Kern]

I think that is correct Kent.  The old Bosch numbers are no longer available, they changed all of their numbers to new ones, I'll have to recheck the changes!

 

[Kip Kern]

OK,  Bosch W3AC or NGK B8HS = 100/125 Penton
     Bosch W3AS or NGK B8HV = 175/250/400 Penton

This is what I found so far!

 

[tlanders]

What's the difference between HS and HV? Teddy

 

[Frenfroe]

H=short reach
S=standard electrode
V=fine electrode (platinum)
and
VX=new super fine electrode

 

[tlanders]

Thanks. Our local cycle shop thinks the B8EG is the best plug for racing and doesn't like the platinum ones. I wonder what the difference is between the VX and G?