How Do I . . . Prep My Motor

Parts NeededTools Needed

Topic:                           How to prep and paint your motor

Expertise Required:      Intermediate

Estimated Time:            Hard to tell

Tools Needed:               Various scrapers and cleaners, metric thread cleaning kit (or taps)

Inspection, Cleanup and Prep:

At this point you need to look at a couple of things that could be show-stoppers. Inspect the piston skirts closely. If you see any cracks, it's game over. You either have a sloppy bore or a twisted crankshaft (or both)

Also, look to see if any of the bearing alignment pins are missing. If they are - look to see if they are embedded in the top of the pistons and/or in the head. This isn't catastrophic, but if you see damage in either area, you need to look and see if any of the pieces did any damage to the edge of the pistons and/or ring lands.

Finally, take a look and see if they rings are stick or are trying to stick a little anywhere. If there's a tight spot, it'll be a problem area later, you you might dodge the grim reaper for a while.

Note: If your bearings look like someone attacked them with a chisel, that's called "brinelling" and it's not great. Not fatal, but you might need to use some Loctite bearing strength sealant on the bearing shell at assembly time.


Clean block with parts washer, or whatever de-greaser you have. Get everything really degreased. Use a toilet brush and run it though the cylinder bores lots of times. If you have a smaller bristle brush, run it through all of the intake ports too. Don't forget to degrease the lower half of the block and the bolts.

Then, rinse both the block and the lower half in Hot Water and DAWN DISHWASHING LIQUID. Not any other brand. Don't argue. Have some kind of oil ready to wipe down the bores with. I use 2-stroke fogging oil - works great.

Rinse parts thoroughly and use compressed air to blow everything dry. You need to put some oil on those cylinder walls within the first minute or 2 after removing from the DAWN. They will rust that fast. Seriously - only 1 or 2 minutes. Be prepared!


Remove the old seals from the holder and press in new ones while the block is drying thoroughly. Also, remove the old rings from the pistons. BE CAREFUL - they can be quite sharp. Put the new rings on the pistons and get them lined-up correctly. Use a tap and go through all of the large 10mm threads (main bolts). Then take compressed air and blow them clean.

If there is any residual 1211 or assembly sealant, be sure to get it all off now - and use Acetone or something to get gasket surfaces ultra-clean.

Take a minute to lube-up the pistons with the new rings. A little fogging oil works good here - or 2-cycle oil. Then install the bearing C-rings back into the block. Make sure they seat correctly.

Take all of the seals and pack them full of waterproof grease - being sure to make sure the center lips are greased good.

Bolts - take the time to get them ultra clean and chase the threads if possible. If you don't have a tap-and-die set that fits this thread, use a wire brush and get the bolt threads ultra-clean.


Joomla templates by a4joomla