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I'm having trouble using Gunson Colortune spark plug with my RB30 head.
Basically the central electrode sparks onto the body of the head inside the hole instead of sparking inside the combustion chamber.
Wrapping central electrode with piece of rubber tube and inserting a rubber sleeve inside the spark plug hole wasn't able to stop the spark either.
What should I do to get this Colortune thing to work with the RB30 head?
I can see the deep hole on the spark plug hole is the reason for easy spark leak, but Gunson should have come with a ceramic coating around the electrode to prevent that, just like normal spark plugs.
Please have a look at the pictures to get a picture of what I'm saying.
Any ideas to get the thing to work, will be appreciated.
P.S.The Gunson spark plug gap appears to be around 1mm or so. Not too far from stock 0.8mm requirement for RB30 spark plugs. I don't think I can adjust the Gunson plug gap without damaging it. Gunson plug is obviously way shorter and and the spark ignites good 1-2cm away from the location where it happens with a stock spark plug. I'm not sure whether that helps, but I'm guessing it's requirement to be able to see the combustion colours clearly through the sight glass ring of the Gunson plug.
BTW, my RB30 is dual fuel and I used the colortune plug on LPG.
Last edited by dom14; 26th November 2016 at 01:50 PM.
I wonder why the spark happens from more resistant & longer path outside the spark plug when it can happen from the least resistant & shortest path inside the spark plug from the tip of the electrode!!!??
I know nothing about them, but did read this on the net
"Spark plug reach is the distance between the end of the spark plug threads and the seat or sealing surface of the plug. Plug reach determines how far the plug reaches through the cylinder head. If spark plug reach is too long, the spark plug will protrude too far into the combustion chamber and the piston at TDC may strike the electrode. However, if the reach is too short, the plug electrode may not extend far enough into the cylinder head and combustion efficiency will be reduced. A spark plug must reach into the combustion chamber far enough so that the spark gap will be properly positioned in the combustion chamber without interfering with the turbulence of the air-fuel mixture or reducing combustion action."
I would take a guess the plug is 2 short 2 be doing anything useful............. but I'm know mechanic and not at all mechanically inclined
Time is never wasted when your wasted all the time
I know nothing about them, but did read this on the net
"Spark plug reach is the distance between the end of the spark plug threads and the seat or sealing surface of the plug. Plug reach determines how far the plug reaches through the cylinder head. If spark plug reach is too long, the spark plug will protrude too far into the combustion chamber and the piston at TDC may strike the electrode. However, if the reach is too short, the plug electrode may not extend far enough into the cylinder head and combustion efficiency will be reduced. A spark plug must reach into the combustion chamber far enough so that the spark gap will be properly positioned in the combustion chamber without interfering with the turbulence of the air-fuel mixture or reducing combustion action."
I would take a guess the plug is 2 short 2 be doing anything useful............. but I'm know mechanic and not at all mechanically inclined
Yeah, the colortune plug I bought is ok for motorbikes, but perhaps not so for RB30.
It still doesn't explain the spark mayhem though.
Why does the spark happens outside the plug, instead inside at the tip of the electrode where it suppose to happen?
Something's wrong with the colortune plug or the way I do it.
These are the video of "spark leak". It appears it only sort of happens when the engine's on idling.
It also appears it does it more on petrol than on LPG.
First one is petrol and second one is LPG.
This is video with silicon sort of rubber ring around the place where I think the spark leak happens & with a high impedance ignition lead. First one is the normal ignition lead. Second one is the high impedance ignition lead. Both videos have the silicon rubber insulation ring around the gunson plug extension where the spark leak happens.
Does the combustion colour look ok, in terms of rich/lean mixture?!!
I'm also revving/pumping the accelerator to see what colour the combustion produces.
It appears to be burning lean during accelerator pumping!
As you can see the spark leak happens regardless of low or high impedance ignition lead.
I reckon you’re largely talking to yourself on this. I may be wrong but suspect that most here have never seen a Gunsons Colourtune. I’ve still got one in a drawer out in the shed, would’ve bought it around 35 years ago (in the UK) & used it to tune Triumph twins. Never had the spark leaking issue, but always found use to be a bit of a fiddly process. Can you buy them today in Oz?
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I reckon you’re largely talking to yourself on this. I may be wrong but suspect that most here have never seen a Gunsons Colourtune. I’ve still got one in a drawer out in the shed, would’ve bought it around 35 years ago (in the UK) & used it to tune Triumph twins. Never had the spark leaking issue, but always found use to be a bit of a fiddly process. Can you buy them today in Oz?
Yeah, you can. It's around $100 or so locally. I thought that's bit too dear for a spark plug with a sight glass built into it.
So, I orderd it from UK for $50.
I actually ordered it for the little bike, but was told it's good for tuning any engine.
Cross sparking kinda baffles me a little bit.
I have to find the real reason behind it, hence the reason I keep posting what I do here.
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