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Hole in the head !
Posted: 10:20 pm Dec 12 2007
by johnkdx220
I'm getting ready to ship the 220 head and carb to RB. Here is a pic of my head!
Looking at the before and after pictures in CC's photo album, I notice that his stock engine head is different. CC's head doesn't have a hole in it!
What is this?
Posted: 10:41 pm Dec 12 2007
by Indawoods
That's something they do special for Canadian bikes....
Posted: 10:47 pm Dec 12 2007
by johnkdx220
I got it Inda! Its meant for installing a pre-heat winter spark plug!
Posted: 11:33 pm Dec 12 2007
by scheckaet
isn't that where you put the SPARK PLUG?
or maybe you have a special, limited edition: 220 and 1/2 cc
Posted: 11:48 pm Dec 12 2007
by GS
Lowers the compression ratio, just a smidge, so that our neighbors to the south can keep up, eh?
Flame away !!
Posted: 11:53 pm Dec 12 2007
by thebleakness
You guys have it all wrong...
It's so that they can stash alittle of their legal mary-jane inside so their buddies following will get high.
Posted: 11:57 am Dec 13 2007
by fuzzy
That's a new one. Positive this head hasn't been off since the factory put it on? Could be an accident from when they machine the combustion chamber.
Posted: 12:19 pm Dec 13 2007
by johnkdx220
fuzzy wrote:That's a new one. Positive this head hasn't been off since the factory put it on? Could be an accident from when they machine the combustion chamber.
The head has been removed before to install a Wiseco kit (of course). I just never had the chance to compare it with others. I'm wondering what RB would do with this? (other than removing the legal mary-jane inside)
Posted: 02:21 pm Dec 13 2007
by fuzzy
I'm sure if it's not included in where he machines it will be left. You could have it TIG'd, and then re-cut but It's not worth worrying about.
Posted: 04:22 pm Dec 13 2007
by GS
Apparently that 'legal' mary jane is pretty bad and not worth stashing....or burning....well at least the gov't-grown-approved stuff anyway.
Posted: 05:54 pm Dec 13 2007
by RBD
It is part of the machining process.....
If you look at a KDX 200 head, the entire combustion chamber and squish area are cast into it's shape.
When you look at a KDX 220 head you see that the entire combustion chamber and squish band are machined to it's shape.
If you have not guessed by now the 200 and 220 use the same casting and the only difference is the 200 head is uses the cast combustion chamber. The 220 head is a 200 casting and the combustion chamber is machined larger for the larger displacement of the 220 (the little dimple is part of the machining process).
OK...., now for the hard part for you to understand is, you really can not take a 200 head and machine it to a 200. WHY???? you ask, if the 220 head starts out as a 200...., why not.
The answer is that when the machine the spark plug hole and spot face it for the spark plug depth. the 200 head is machined deeper into the head because the combustion chamber is smaller.
So if you try and cut the 200 head to the 220 specs the spark plug would stick through into the combustion chamber about 3 to 4 mm, not a good idea.
Just a note, I have machined a 200 head here lately for a guy that want to experiment with high elevations 10,000 ~ 12,000 feet. I know this head will not work at sea level but at 2 mile high I think there is a chance. I have not heard anything back yet on how it works out.
Ron