Warped Head

[steef]

I got a 80cc slant head from zoom bicyles. It's blowing one head gasket right after another. Six so far. Now I have discovered that the head is warped. I have looked every where and all 80cc zoom slant heads are out of stock. Need to know what heads are compatable with this motor.

Thanks for any help, Steve

[2door]

Before replacing your warped one I'd suggest you try a little home-brew machine work. Use a good flat surface, glass is good, lay down a sheet of 150 grit sandpaper and start rubbing the head on it. You'll be able to see where the high and low spots are immediately. Keep working until you have a uniform surface, concentrating on applying even pressure, then start with a finer grade of paper until you get down to about 200 to 400. You have then lapped the head and, unless the cylinder is also warped, your head gaskets should seal correctly. I'd also suggest sealing the head gasket with some brush on silver paint. The older the paint the better. There are head gasket sealers but I've never found one that worked any better than old, almost dried up, silver paint. Let us know how you make out. One more thing...if you have acorn nuts on the cylinder studs make sure thay are not bottoming out and not allowing the head to be tightened. I like to replace all acorn nuts with hex, just to be sure.
Tom

[Blakenstein]

My head has been kind of warped for a long time...don't know if I got any hope left

[Pablo]

All the cheap Zoom slant heads are warped.......the Chinese, they are consistent at some things.

Anyway, it's super easy to follow what 2-door says. I just use some picture frame glass, wet sandpaper for the final 2 grits. Then I wash the head really, really, really well.

I use a new head gasket, and INDUSTRIAL aluminum spray paint - seems to have enough aluminum - on the gasket. Just hang it, spray it well, let it cure a bit and carefully assemble and torque. Never had a leak this way.

[robin]

Originally Posted by Blakenstein

My head has been kind of warped for a long time...don't know if I got any hope left

LOL good one i wonder sometimes if many on this forum are--most people view it odd to have a motorized bicycle when sometimes for the same money you can have a motorcycle.

[PaulFlorida]

I just came back from a test run with my new slant head. About twenty miles in, I stopped to check things over, and yup it's warped a little. I'm using the thin head gasket from SBP too- The compression is through the roof! Tremendous torque up hills, doesn't rev out as far though. I had to lapp my stock head and I had no problems with it since. Time to do this one.

[steef]

OK, Been really busy with work and school so it's been hard to find time to work on the bike. I thought Tom's idea about sanding down the head was fantastic cause it never occured to me that I could fix it myself. Scince my time has been hard pressed, I took the lazy man way out and took the head to a machine shop and had them shave it down for me. I did seal the gasket with some silver paint, I did'nt have any old paint so I had to use new. Now it's running great and seems to have a little more torque. thanks for all your help. Will see how long it stays running this time.
Steve