head gap. help!

meatgrinder · Jun 24, 2013

So I just received my kit a few weeks ago, a 66cc powerking slant head. Upon inspection, saw the head & the jug not quite "close" to each other. after a few search here in the forum, read that by replacing the acorn nuts will solve the problem. So basically threw out the acorn nuts and replaced them with normal nuts. But it seems that after replacing the nuts, it still doesn't close the gap between the head and the jug (still not torqueing the head) but I tighten them not much but just enough to check if it will close the gap. Is this ok if I start the engine with this gap still wide? :-||

Here's a pic:

Toadmund · Jun 24, 2013

For the most part the gap looks somewhat normal, it's the ridge on the head that makes the gap.
BUT! If in doubt, which you should be, you should lap the head and the cylinder on a piece of sandpaper on a flat piece of glass or something.

Head lapping

meatgrinder · Jun 24, 2013

Thanks for the quick reply toadmund! That is what im planning is to lap the head for a better fit. But before trying to sand the head, would i be able to get away by using a rtv high temp silicone to close the gap?

biknut · Jun 24, 2013

That's an interesting intake manifold. The cylinder casting looks pretty good too. What brand of motor is that?

Venice Motor Bikes · Jun 24, 2013

That gap is normal! Don't worry about it.

mew905 · Jun 24, 2013

meatgrinder said:
Thanks for the quick reply toadmund! That is what im planning is to lap the head for a better fit. But before trying to sand the head, would i be able to get away by using a rtv high temp silicone to close the gap?

Yes, I dont run a headgasket at all, using only Permetex Copper silicone as a sealer (I dont have any new gaskets and they all seem to leak anyway). I only wait an hour or two for it to dry before I try a test run too (I'm not trolling, I'm dead serious), as long as you dont get too much in the cylinder, you'll be fine, it'll cook off any excess, but yes, looks like bad casting burrs on your head, a quick lap procedure should fix that easily.

Kioshk · Jun 24, 2013

Like the man said: THAT'S NORMAL! Don't sweat it, and DON'T go over-sanding and over-tourquing it.

meatgrinder · Jun 24, 2013

Thanks for the help guys! Really appreciate it. Maybe i'll just torque the head bolts correctly and forget about the gap!

Bikenut- yeah the intake manifold is somewhat different to what I normally see on ordinary ht engines. And the motor brand is "powerking"

-Ryan

biknut · Jun 24, 2013

meatgrinder said:
Bikenut- yeah the intake manifold is somewhat different to what I normally see on ordinary ht engines. And the motor brand is "powerking"

-Ryan

Thanks for the reply. I've built one bike from a PK motor, but it didn't have that manifold. That one looks better then the normal ones. It did have pretty good looking castings though.

Huffydavidson · Jun 26, 2013

Who did get the PK from?

biknut · Jun 26, 2013

Huffydavidson said:
Who did get the PK from?

Pirate Cycle sells them.

Huffydavidson · Jun 27, 2013

I know pirate sells them. But who did he get his from? Not where can I get one.

biknut · Jun 27, 2013

Huffydavidson said:
I know pirate sells them. But who did he get his from? Not where can I get one.

He bought it from Pirate Cycle. That's how I know they sell them. That was back in October though.

truckd · Jul 7, 2013

PK 80's are all I run and I've never seen that, lap the head and cylinder, I also use copper spray casket on my head & base gaskets and never had a leak.

bill2781 · Jul 7, 2013

how much torque should a person have on the head bolts?

SuperDave · Jul 7, 2013

bill2781 said:
how much torque should a person have on the head bolts?

Specs say 120 inch/pounds, if you're using a FOOT/Pound wrench it's 10 Ft/Lbs (12 inches in a foot, 120 / 12 = 10). Don't overtorque the fasteners on these motors, they are soft aluminum and will pull the threads if overtightened. Loctite is HIGHLY recommended.

mapbike · Jul 8, 2013

truckd said:
PK 80's are all I run and I've never seen that, lap the head and cylinder, I also use copper spray casket on my head & base gaskets and never had a leak.

none of mine have a gap like that but I wont argue about whether it is OK on that engine or not, also I use the K&W Copper Coat on my head gasket and I've never had a leak, I've never even had to re-tighten my head nuts.

bill2781 · Jul 8, 2013

thanks super dave I gota keep that in mind

Jeckler · Jul 8, 2013

Am I the only one that can see daylight between the head and jug in the 2nd pic? I'm not talking about the 1/2" gap between the fins either.

mapbike · Jul 8, 2013

Jeckler said:
Am I the only one that can see daylight between the head and jug in the 2nd pic? I'm not talking about the 1/2" gap between the fins either.

The gap you speak of is exactly what we are all discussing.

I can easily see how some engines could have this gap and it not be an issue, if the raised area around the combustion chamber of the head that compresses the head gasket is thick enough it would cause the head to sit up like it is showing to do in the pic shown in this thread, as long as the head gasket is compressed down evenly and torqued properly there will not be a leak and then there is no problem.

The fact that I shave all of my heads down several .001'ths on all my engines may be one reason I dont see anything like that with any of mine and maybe the raised sealing area of the head is just much thicker on some engines.

as long as it seals good there is no problem just like several have already said here.

Map

head gap. help!

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