head gap. help!

Yup, I agree. That gap is totally normal as folks have already pointed out. If you take the head off and examine the way the gasket seats you'll see what Mapbike is explaining, and he is correct.
 
Just My opinion I'd take it off and get a Dax Head if yer budget is small, if you can afford a CR Machine or Pooch 70cc hi hi comp Head shoot for it, I'm picky and always try to avoid a problem later by fixing it now.
 
Here is a couple of pic's of the PK80 I just finished building today, notice the copper coated gaskets and heat ventilated outer fins, this is a sleeper, 3.5 HP stock out of the box after mods and rebuild, 5.0 HP I have a few power options I'm considering after fit fabrication, I'll keep that a secret for now.
By the way the 1st pic is pre fit and head was not bolted down straight so don't think the piston mod is cut wrong
 

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truckd said:
Here is a couple of pic's of the PK80 I just finished building today, notice the copper coated gaskets and heat ventilated outer fins, this is a sleeper, 3.5 HP stock out of the box after mods and rebuild, 5.0 HP I have a few power options I'm considering after fit fabrication, I'll keep that a secret for now.
By the way the 1st pic is pre fit and head was not bolted down straight so don't think the piston mod is cut wrong
Click to expand...

Thats a really nice looking engine, does it have a better balanced crank in it?

Looks like you did a good job on that build, hope it runs fast and for a long time for ya.
 
Yes! the crank is balanced with a quality German lower bearing and Japanese wrist pin bearing, the reason I posted these pic's was to show the copper coated base and head gasket, to bad it isn't done at the factory and 12ft lbs torque on automotive grade head bolts.
 
This gap must be there. It must be there because you have a twenty thousandths of an inch ring around the bottom of the head. This ring causes the head to basically "float" allowing the head to warp and leak. In my twenty years of turning wrenches, I have never seen something so stupid. I sanded mine down on a piece of glass and still have sixty-five thousandths between the piston and the squish band (needs at least .050 to be safe) on my GT-5. I always had oil running down the fins before, now there are absolutely no leaks around the head and it runs much, much better. If someone can explain why this ring is on the head, please enlighten me.
 
Because their Chinee engineered DAH !!!

Head was lapped just over .050 same as jug then HEAVY! HEAVY! copper coating on both base and head gasket, some run 2-head gaskets just to solve the leakage, I think the main problem with these engines are that we try to over think the re-engineering of them, 5,000's here .0211 mm there a micron here and a 15,000 of an inch on that. these engines were not designed by someone with a real engineering degree, the real engineering starts when we break them down, correct all the wrongs that Wong didn't care about on the assembly line and re-build em right.

I have seen vid's of these engines being cast in some ones basement tied with a rope strapped onto their back and peddle'd to a shabby factory where they're assemble'd then sold on Ebay to you, the guy who expects perfection, material quality and top notch engineering for $129.00
 
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Can you find a link to that video? I've seen a few on youtube (Grubee Sky Hawk) factory. It's neat to see how they are made. To me it's a marvel they actually work as well as they do..
 
I will do my best to look for it but I will admit it was about a year ago.
 
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I'm still looking for that link, I stumbled on it about a year ago, wonder if my memory is still any good enough to remember where LOL!
 
Never saw that one before, sure makes you think hard about what brand yer buy'n
Thanks fer sharing that BA
 
This is an old thread but currently relevant. . I'm dealing with the same thing today . what scares me is it is almost a backfire but not a pop. More of a whoosh and I think mostly under a climbing load. Help please. I'm stopped at 7/11 and don't want to ride back home like this. I have made a few different extra head gaskets of various thicknesses. From coke can to aluminum siding
 
If you hear air leaking the head gasket is bad or the head is warped, you need to sand the head on sandpaper taped to a thick piece of glass, you can do the same with the cylinder. After sanding use a new head gasket and torque the head to 10-12 foot pounds, torque to 5 pounds in a x pattern the move up to 10-12 depending on stud size. 6mm torque to 10, 8mm torque to 12.
 
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