[Johnny 5]

I had great success with my home port job on the stock dune 150 head. Christmas 2010 I borrowed my brother in laws dremill with a long bit a little bigger than a pencil lead in size. I removed the valves by putting a rag in the combustion chamber and using a socket to push the retainer down with a magnet in the center of the socket to remove the keepers. Wear safety goggles because a retainer keeper can take your eye out if it flys. I put duct tape strips on the valve seats to be safe. The intake spacer was offset from the head port so that was matched up first by opening the spacer to the head. The rough edges in the ports were cleaned up. Basically any bumps or flaws from the casting were removed. I left the intake port rough and polished the exhaust and the combustion chamber. To polish the port I used small pieces of red scotchbright pad on the dremill cut off wheel atachment. The scothbright pieces would not last long but got the job done. I didnt open the port diameters just removed the rough spots and smoothed out the transition and the back side of the valve area that was cut out and looked unfinished due to mass production of these heads. Lapped the valves with some compound by using my cordless drill and a piece of vacume hose on the valve. Not too much just enough to reseat the valves.
The first trip it made a huge top end difference and would pull all the way to max rpm.
Before the engine would flatten out at mid to high rpm.
I tried a 120 jet from a stock 114 and it bogged. Went to a 117.5 and ran perfect, with a uni filter and stock modified muffler with a little bigger tail pipe tip,3/4 inch.
I was willing to give it a shot because if the head got damaged it can be replaced for 50 bucks stock or get a performance head for about 100 bucks or more.

When we put the 39t rear sprocket on the blue dune it hurt the top end pull but would climb with 2 riders alot better.

If you dont feel confident dont mess with the head. I have been messing with small block chevys and dirt bikes for 23 years, the buggies for 8 years and have broken bent scracthed stripped cracked NOS melted pistons over built under built broken rocker arms and have had a blast doing it.

I cant leave a perfect running motor alone without modifying it for more power, or at least trying to get more power. My Dad would tell me that it was engineered by the manufacture and all I was doing was messing it up. Some times he was right, but not always.

Merry Christmas all you buggy builders and Jesus loves you.