Two plugs - Neccessary?

[Grow Pattern]

I made a dual plug head for the OS 1.40 and for the 1.60. I also ran two Mintor 1.60's.

I know before I type what follows I may well draw some fire, but after two years of using twin-plug-heads on different motors I am personally convinced that they are a total waste of money and time.

If you are using a twin plug head to fix a "problem" there is probably a better fix!. 

I went through over 60 plugs of all types. I still have a can-full of them in my van. Constantly, I saw the lower or rear plug fail, It always ran better with the center plug working but you had to reset the carb. One argument is the engine keeps going if you lose a plug. The reality that I experienced is that there was a big loss of power and often overheating when one plug went out. Twin plugs change the ignition timing of the engine. Two plugs of the same type, A-3 "F"etc. or mixing rated plugs all interfere with the timing and design of the motors combustion.

Of course there are a whole bunch of folks that are happy with two plugs and are convinced that they are the way to go. I say enjoy and I'm glad for you, really!

My 1.40's, and I say mine whether I still own them or not, run like watches on one plug. My OS 1.60's run great on one plug. The FI or Mix-carb versions, it makes no difference, if you set the carb correctly and use the right volume of pipe, they run great.  I literally  gave up on my 1.60 Mintors, especially after I was informed by the supplier that I did not know what I was doing with 2-cycles!  I acknowledge they could well have been right, but there was no available information to fill the vacuum of why and what was the reason that they did not work. (Ironically enough the factory agreed basically with my findings and changed the guts of the product) The upgraded piston and liner ran better but they still kept killing plugs at a much higher rate than a single plug set-up. 

But I digress. The twin plug does give a lower idle and does help through transition on a tuned pipe. However if your engine will not run at an acceptable idle on one plug something else is amiss. For example. wrong plug, wrong fuel, idle mixture is off, bad bearings, tight ring/liner etc. Similarly on transition problems. I have noticed that quite a few so called tuned pipes do not have much of a tapered cone to the main body of the pipe. Mix carbs and double plugs might get you through these issues, It's your choice.

Regards,

Eric.
  ----- Original Message ----- 
  From: Rodney Tanner 
  To: discussion at nsrca.org 
  Sent: Wednesday, April 20, 2005 2:48 PM
  Subject: Re: [SPAM] Re: RE: OS mixture question


  Hi Ron,

  Eric H, or Dean P would probably be the best people to answer that.

  I forget how many variables back I changed to the 3M heads. My basic take would be that they give a smoother mid range on an ESD pipe, are less sensitive to pipe setting, lower the compression - so run cooler, without affecting the top end performance. 

  Rodney


  Ron Van Putte <vanputte at cox.net> wrote:

    On Apr 20, 2005, at 8:11 AM, Cameron Smith wrote:

    > Are you supposed to change em? Seriously I change both plugs about 
    > every 3 to 5 cases of fuel. Sometimes I just rotate the center plug to 
    > the back position then replace the center plug. I replace ANYtime the 
    > engine deadsticks or acts to much out of character. Most times they 
    > are still good.
    >  A buddy checked my idle the other day on my NEW Single plug (STOCK) 
    > head & it also Idles at 1K. Gotta luv it!

    I've got to ask this: Is there any real difference in the way an OS 
    1.40RX runs with the Mintor 1.40 head 'extra' plug in the 'front' or 
    'rear' position? I know that Lance says to run it with the 'extra' 
    plug in the 'rear' position, but I theorized that there would be better 
    fuel ignition if the 'extra' plug was in the 'front' position, as far 
    away from the exhaust as possible. I've been running mine that way and 
    the engine runs fine.

    Ron Van Putte
    >       
    >                                       
    >  
    > -----Original Message-----
    > From: discussion-request at nsrca.org 
    > [mailto:discussion-request at nsrca.org] On Behalf Of 
    > Jim_Woodward at beaerospace.com
    > Sent: Wednesday, April 20, 2005 8:57 AM
    > To: discussion at nsrca.org
    > Cc: discussion at nsrca.org; discussion-request at nsrca.org
    > Subject: Re: [SPAM] Re: RE: OS mixture question
    >  
    >
    >
    > Hi Rodney,
    >
    > Why are you changing plugs every 30 flights?  That get pretty 
    > expensive in the long run.  Is the engine running lean?  I've seen a 
    > few other using the 3M head and OSF plugs, and not having to change so 
    > often.
    >
    > Cameron, how often are you changing plugs?
    >
    > Thanks,
    > Jim W.

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