GT90 build. Dual spark head, cetrifugal clutch and pull starter.

xspade17x

Active Member
Joined
Feb 4, 2020
Messages
212
the title says it all I'm onto another build. Although I'm also putting a shift kit on this one :D whatcha guys think?? It's also going on a gas tank frame
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xspade17x

Active Member
Joined
Feb 4, 2020
Messages
212
Do you really want to know what I think? I see performance being way down, two spark plugs fighting for their life from a 6V coil.
What would you suggest to solve that issue???I really didn't know another way to get this functional so I'm all eyes (i would say ears but its typing not talking.)lol
 

GreasyChris

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Jan 3, 2019
Messages
1,303
I hate to be the bearer of bad news but the dual plug head is snake oil. Even if you were able to get both plugs to spark it doesnt add any performance. If anything performance will go down because the combustion chamber is now bigger lower your compression pressure. Also don't cheap out on a jackshaft kit order the sickbikeparts parts one. The extra bit of money will save you a ton of hassles. Heres a video on how to install your centrifugal clutch.
 

Vikingimike01

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Joined
Jul 1, 2018
Messages
1,396
I would not say the dual head makes performance worse. If it gives less compression, then yeah. But other than that, no, if you got strong enough spark for both.

But they work a lot better on bigger bore engines. 600+CC I'd say?? IDK. Probably even bigger.. I know some harleys have those.
But again those are designed that way and these engines arent.
This is so combustion happens faster from both sides of the head. Not going from the middle out, but from the 2 sides in.
 

Street Ryderz

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Joined
Oct 14, 2016
Messages
3,575
Dual plugs,
This is so combustion happens faster from both sides of the head. Not going from the middle out, but from the 2 sides in.

Not true! The flame front propagates outward in a semi circle shape and this process starts before full compression is achieved at the top of the up stroke as it takes some time for this to complete, the comp forces it to be faster NOT more spark.Dual ignition systems were designed for aircraft engines as a redundancy system to prevent in flight failures and later used by other engine manufactures to aid in emission control,in these cases the spark has a slight delay between them like the Dodge Magnum hemi for cylinder clearing.Our magneto (wire loop) barely produces enough current to fire a single good plug even with a better secondary coil,when tested spark strength if you're lucky may be around 40k usually just under at best where as a strong spark is considered to be well above that,now try to fire two plugs with that same current and it will be far less on each!
 

xspade17x

Active Member
Joined
Feb 4, 2020
Messages
212
Dual plugs,
This is so combustion happens faster from both sides of the head. Not going from the middle out, but from the 2 sides in.

Not true! The flame front propagates outward in a semi circle shape and this process starts before full compression is achieved at the top of the up stroke as it takes some time for this to complete, the comp forces it to be faster NOT more spark.Dual ignition systems were designed for aircraft engines as a redundancy system to prevent in flight failures and later used by other engine manufactures to aid in emission control,in these cases the spark has a slight delay between them like the Dodge Magnum hemi for cylinder clearing.Our magneto (wire loop) barely produces enough current to fire a single good plug even with a better secondary coil,when tested spark strength if you're lucky may be around 40k usually just under at best where as a strong spark is considered to be well above that,now try to fire two plugs with that same current and it will be far less on each!
Would it be possible to install the 12v magneto generator along side the magneto and instead of using it to power lights use it to assist the spark plugs? Would this at all make a difference.? And the coil I got is for a honda 250cc its 6v-12v not just 6v. I got the DIY boot and clip on adapters for the coil.
 
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