OMC Cross Charge Mod questions

[930turbo]

Port timing is unchanged.

[930turbo]

Cylinder base & piston skirt mods complete;

[Umassot50]

looks good. im doing something similar starting with a 115 block. adding some 135 exhaust parts. I will also be filling the inner port wall in the area your showing to give it some arc to match the shape of the removeable outer covers. high temp epoxy will work there. will fill right into the round bottoms of the ports too so the lower port edge will be flush with the piston top at BDC. an arced inner port wall in a two strokes works far better to increase port velocity and directional control. my block is below. will detain the transfer work when i get too it.

[Riverman]

That's more material to remove than I thought. How did you lay it out? Did you just touch off the top and go down the 1.375"?

[930turbo]

I clamped the block to the mill using the exhaust machine surface as reference to square it up. The I started from the split line surface and went down the 1.375". Then some quick math on the piston determined the scallop needed to be .905 from the base. I used a 2" hole saw (very high tech ) to make the cut.

[930turbo]

The next step is lube coating on the piston skirts and ceramic coating on the crowns and cylinder heads. Two-stage reed are in route. I'll balance the pistons and end-balance the rods. I think that's about it.

[930turbo]

Back in the day, I spent countless hours stuffing the block on my Force 85 triple. I did the same thing you mentioned. Actually when finished the transfer covers were epoxied in place so I could smooth all surfaces. I used marinetex as the filler. It worked.

[930turbo]

Dry lube film applied to the pistons.

[930turbo]

Ceramic thermal barrier finished. Tungsten burninsh on the rings & wristpins.

[930turbo]

Ceramic thermal barrier on the cylinder heads and thermal barrier on the exhaust collector. All coatings thanks to Jan @ Power-Coat

[Cavit8]

Indeed, thanks a million Jan!

[Umassot50]

should i ceramic coat this?

[930turbo]

I like it! Let's see the other side.

[930turbo]

I've successfully twin plugged a Porsche 914 type 4 & a Triumph Bonneville 750. Significantly less spark lead was necessary on both counts after the modifications.

[Freddie Webb]

I have a pair that look real similar that are set up for methanol.