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 Post subject: Spark Plug Help - Twin Plug Heads
PostPosted: Sat Jan 13, 2018 12:24 pm 
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Joined: Sun Nov 10, 2013 8:44 pm
Posts: 6
Couldn't find any previous thread but may have been user error. I purchased a reversed head from Jan at Redfox and sent front head to be converted to twin plug and be ported and gas flowed. What I don't have is any idea of what spark plugs to run. I am running 900ie cams and the bike is a track only and carbs choice is still under discussion with with my very talented engine builder. I asked Jan for suggestions but received no response.

Any suggestions appreciated.


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 Post subject: Re: Spark Plug Help - Twin Plug Heads
PostPosted: Sat Jan 13, 2018 1:36 pm 
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Joined: Sat Oct 29, 2011 3:38 pm
Posts: 425
What diameter is the plug hole?


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 Post subject: Re: Spark Plug Help - Twin Plug Heads
PostPosted: Sun Jan 14, 2018 1:17 am 
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Joined: Thu Oct 14, 2010 11:23 am
Posts: 1156
You did not mention compression ratio, or pistons, or what carbs you are using, or any change in the ignition system you will use.

But, usually, with dual plugs you can expect to retard the ignition by 4 or more degrees from stock, and run leaner jetting (than before).

Why not just keep it simple, start with stock plugs, and see how it goes? D8EA ngks, or RA6HC champions work on my 750 and 900 engines. Both have big carbs, race cams, high compression pistons, and stock igntions.

MikeV


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 Post subject: Re: Spark Plug Help - Twin Plug Heads
PostPosted: Fri Jan 19, 2018 6:11 pm 
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Joined: Sun Nov 10, 2013 8:44 pm
Posts: 6
Thanks for responses and suggestions. Spark plug diameter is 12mm. The bike is running a 944cc kit, carb choice is still open. Sorry can't be more specific than this. Temperature range for plugs was my idea of a starting point.

Thanks


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 Post subject: Re: Spark Plug Help - Twin Plug Heads
PostPosted: Fri Jan 19, 2018 8:46 pm 
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Joined: Thu Oct 14, 2010 11:23 am
Posts: 1156
Start with something “known”, stock. Sometimes called a “given” in certain tests questions.
Trying to change eveything at once is an invitation to chaos. Incrementalism sometimes works.

No one has an your to your answer because everything you are doing is new.

Now, for another glass of red wine. Ciao, MikeV


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 Post subject: Re: Spark Plug Help - Twin Plug Heads
PostPosted: Fri Jan 19, 2018 9:47 pm 
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Joined: Sun Nov 10, 2013 8:44 pm
Posts: 6
Wise words Mike. Thanks alot.


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 Post subject: Re: Spark Plug Help - Twin Plug Heads
PostPosted: Sat Jan 20, 2018 3:59 am 
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Joined: Wed Sep 11, 2013 7:13 am
Posts: 172
You're not going to run it flat out from the start, are You ?
As Mike stated with a (for me new and lovely word :D ) "Incrementalism" : since there are so many unknowns, better play it safe, rich and cool. And slowly turn the heat up ;)

And isn't it possible that Jan knows some basic starting point ?

ciao
ducadini

_________________
Nego i ricordi peggiori, richiamo i migliori pensieri


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 Post subject: Re: Spark Plug Help - Twin Plug Heads
PostPosted: Tue Jan 23, 2018 12:54 am 
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Joined: Fri Jun 24, 2016 2:38 am
Posts: 45
Location: New Zealand
Please share some pictures when you get the heads back. Ports, combustion chambers, plug holes. All the juicy fun stuff :D


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