Spark Plug

[tmc3c]

What are some of the types and heat range plugs being ran in a 250 ? I have a 76 250 with reed valve and I was wondering if the heat range plug being ran in this bike would be the same as one without a reed valve motor ? Also I am in S.C. so I am close to sea level.I am running a ngkb8h but it is wet after riding,I have just regrounded my ignition and soaked my exhaust tip in Muratic acid and water and I am draining the gas and going with fresh gas,so this is why I ask about the plug cause it will be replaced also !! Thank You Guys for your time on this!![^]

Thomas Carmichael

[tmc3c]

I had forgotten that I have asked this same question on 8/24 but the main thing I need to know at this point is: Does the reed vavle motor use the same plug as a bike without a reed valve ? And I promise I won't ask about it again,unless I have another brain fade[8]

Thomas Carmichael

[Larry Perkins]

Thomas,

Raced a reed 250 motor for a season and found that a NGK B9HS was best for MX and a B8HS for cross-country.  However if you are riding it at ISDTR from what I hear it is pretty open and I would go with the 8HS.

Larry P

[tmc3c]

Thank You Larry ! Is the the b9 hotter than the b8 ?

Thomas Carmichael

[wildman]

Here's my take on spark plugs, use what works best. Sounds simple, but you must be able to "read" them. I find often a hotter than recommended heat range works well, as well as a projected tip, in this case probably a NGK BP8HS or BP7HS. The higher number on NGK the colder the heat range. A nice brown color is what your looking for, and you should check it after some wide open running, don't idle, just shut it off and read the plug. Main jet size comes in here as well as overall carberation. My point is try a hotter plug and then check it. Its unlikely to burn your piston quickly and may result in a lot cleaner running bike that doesn't foul plugs. For example, my RMX came with B8EGV high dollar platinum that would foul every time I stopped. B8ES, cheaper still fouled. Then per Eric Gorr, noted tuner. I tried NGK BP7ES, 1 plug a year, nice brownish black color, even at the sand dunes wide open.
You might also try some champion plugs sometimes they are like a half heat range different. Hope this helps, Dan Pagel

1975 250 Cross Country, 1974 175 Jackpiner, 1975 125

[tmc3c]

Thank You Dan !! I will be on my way to the cycle shop in the A.M.!!!

Thomas Carmichael

[Larry Perkins]

The lower the number in NGK the hotter the plug.  You want a hotter one for slower speed.  I believe this to be correct.

Larry P

[tmc3c]

Say a 7 for tight woods and a 8 for mx ?

Thomas Carmichael

[firstturn]

Thomas,
  I use to run a hotter plug for tight woods and then a colder plug for MX.  See Layy's post.

Ron Carbaugh

[Larry Perkins]

A 7 is too hot for a 250 motor.  Use a 8HS for woods and a 9HS for MX or open fast running.

Larry P

[tmc3c]

Thanks Larry, I have been running a 8 for the woods but the plug has been wet after riding and now I have made other changes and will try the 8 again and see what it looks like after a ride.I soaked my exhaust tip in muratic acid & water and it turned the water brown and I moved the ground wire to a better ground and I drained the fuel and will go with fresh gas.The motor is "new" Kip Kern built and the reeds are new and the carb has been in and out of so many times that I can do it all by feel now, so I hope this solves my problem.Thanks Again for your Time and Trouble!!

Thomas Carmichael

[Larry Perkins]

No trouble and very little time.  Good luck!

Larry P

[tmc3c]

Ok Gang,let me ask another question and I will be quiet:I went today and bought a new plug and I didn't look at the reach of the plug and when I went to install it I found that it was a long reach instead of the short reach of the one I took out"ngkb8hs" Now for the question part: Did my 250 motor come with a short reach plug or is the longer reach the correct one in the first place? NGK B8EV. Thanks Guys.

Thomas Carmichael