Benly 150cc Cylinder Head Strip and Paint

[Smithers]

Old Honda cylinder heads are super easy to work on. They look really complicated at first because they are compact but when you break it down... it's like building a set of Legos.

Todays goal:

• Disassemble the Benly cylinder head

• Inspect the internals for wear

• Have the head dipped in solvent or bead blasted

• Degrease and tape off openings

• Paint the thing

This morning I took it to my buddies engine shop and asked him if the guides looked ok and had him do a quick inspection. Everything looked great to him so I proceeded to find the best way to strip it for paint. He said he would just bead blast it in order to get the crud out from the cooling fins. I didn't want to waste his valuable time screwing with my little project so I thanked him and headed to my next destination.

I arrived at my friends transmission shop and I began taping off the head to prep it for the sandblasting cabinet. About halfway done and my friend walks up and takes a look at my little project. He asks me why I wasn't putting it in the cleaning tank first. I said, "WHAT? You have a tank to dip this in? Why didn't you tell me that a long time ago!!". So I ripped off my tape and headed to the other side of the shop. What I saw was a thing of beauty! A very large red steel cabinet that is large enough to climb into. They mainly use it to stick transmissions in to have them cleaned automatically. When the door shuts a sprayer rotates around the part inside and sprays it with high pressure, BOILING hot solvent!! AWESOME!!

Please excuse the Sprint Mogul 6800 pictures. I only had my cell phone on me for pics. =]


10 minutes later the cylinder head is COMPLETELY clean! I was shocked. Every single crack and casting depression was clean all the way through. That machine is worth it's weight in gold! I was in too much of a hurry to snap a pic of the magic solvent machine but here is a shot of the head on my buddies mechanic tool roller. Looking pretty!



I've already taken the valves out and the springs are still putting a little pressure on the rocker arms. The valves MUST come out before you try and take the arms and cams out because they preload the assembly so much that you can't move the rockers. The next step after they are out is to push the rods out that act as the pivots for the rocker arms. First take the clips off from the ends. Then simply find something like a punch that is the same diameter as the rod and tap it out from one side to the other.





And there you have it. The cam, rocker arms and valve springs basically fall out on their own.

[Smithers]

The next step was to clean out the really tiny holes and cracks even more. When you really get close you can find more and more dirt and all needs to be scraped and cleaned. Then in order to get a perfect hard finish from the paint you need to make double sure that the surfaces are degreased. I basically used a third of a can of carb cleaner to remove all the oil and residue. I try and get these steps done as fast as possible as this work is pretty miserable.



Time to tape off the holes! I have 3m paint tape but it's expensive! Electrical tape can be had for really cheap and it's nice and stretchy. It also sticks to metal much better. Start taping and use a new blade on your razor or exacto knife to but around the curves and edges. Make sure the temperature of the chunk is nice and warm (throw it in the oven if you have to) and do your best to spray deep in the cooling fins without causing your paint to run. =] If the alloy is cold the paint will run easily so warm up your head. Play it safe by using a very light first coat without covering the surface too much. You want to be able to see the alloy through the paint. Then come back 4 minutes later with a heavier coat which will stick to the primer coat much better than the raw alloy of the head. A third coat a few minutes later will surely give you good coverage. Follow up with 2 coats of clear if you want that showroom shine.



I let the color coat dry for a day before I put the clear on top. I wanted to make sure the paint dried completely before sealing it with the clear. On all of the other parts I let the clear adhere to the silver paint when it was tacky.