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Just grind it out and have someone TIG a new lump there to drill and tap for a shiny new screw.  Suzuki use those plates to direct oil to the gearbox shafts.  Without them they get no lube and we all know that lube is a necessary part of life in a transmission

There's a guy in the UK with a 380 which he fitted a set of RG250 gamma cylinders and gained their crankcase reeds and extra ports.  he says his revs to 12,000 and make 55 or so rear wheel HP.

He has a connection to Barry Hart of Barton motors who made the Sparton 3 cylinder water cooled 500 which was in limited production back in the day.

The Motoworks bike originally had chambers with what appear to be 3 convergent cones but the one for sale now has a single cone and what look to be very large diameter stingers.

There is some incredible work in that Motoworks bike for sure.

I am pretty sure that the batteries I use are LiPo.  I use RC/drone batteries from Turnigy.  Admittedly I don't run in MotoAmerica but I will have to look at their LiFePo4 batteries as replacements.  With a 4s (4 cells) their LIPO is 13.2v and the LiPo is 14.8 volts which I like for the fatter spark energy.

They do get very inflated over time though, so when this square brick becomes fat and blaoted I will change to LiFePo4 and get a new charger to keep it all in one piece.

Try a set from Mikes XS.com.  Great price.  And yes to the smaller PVC tube for spacers to set pre-load.

I have corresponded with him on facebook.  He had an interesting GT750 tracker there a couple of months ago.  Hi crank videos look promising but I have a local two stroke guy near me with his own machine shop.  He's a two stroke expert that worked at Johnson and then at Aaen in Racine, WI so he knows his stuff and builds and races hydroplanes.  Before that I sent all my GT750 cranks to Bill Bune Enterprises and my Yamaha TZ and RD cranks to Rick Merhar in Ohio.

It's nice to have choices though.

That was an interesting video, but the one on the BMW sidecar they too racing was more impressive in many ways.  Some amazing shots of Ari Henning hanging out the side of the chair at Shannonville.  I know it's not a two stroke, but a great video none the less.

I read an article years ago that IIRC concluded that 2 ring pistons made more power below something like 9,000 rpms and single ring made more power above that point. 

The idea of running a single ring in a two ring piston has been tried many times but no one that tried it, that I know of, has ever published the results.  I would imagine that if the piston has relatively thick rings, like one from that era, then ring flutter would be an issue and so would sealing if a ring is removed.  If the piston in question had thin rings - say 0.8mm to 1.0mm, then a single ring on a 2 ring piston would probably be OK as long as the ring land diameters were suitable.  I suspect that on a single ring piston they may be different.

Key thing in this instance, is that we are talking about a DS2 which won't rev very high before the clutch comes off and didn't make a huge amount of power, so why add to its stress and unreliability. If the OP is making a stronger crank, they could probably also find suitable 56mm pistons. 

Anyone remember how many rings in a TD1 piston? I suppose I could check the parts book if I could remember where I filed it.

Derek Pickard raced a DS2 Asama racer ie race kit back in the day in Australia but I have no idea if he's still around or what pistons he used.

I would hypothesize or guess that the frame tube is much lighter gauge that the average street bike frame. That bike isn't very heavy, fortunately, so you might get away with adding  a half tube to that bottom rail and weld the stand to that "outer tube" to spread the load.

What year/model?  I might (long shot) have a set in my stash.

Would also need to pre-heat the block and probably cut away a lot of metal just to get in there. I would be more tempted to machine in and press in an insert and ignore the rest of the pits.

What year/model?  I might (long shot) have a set in my stash.

It is fixable,  but will probably cost much more than finding a replacement cylinder.

Thanks for that info on sheet thickness.  I think it tells me to use 20 gauge for street chambers and 22 for lighter applications.

You might check teh length of those two sections to see if they are the same where they join. It is possible that one file is incorrect. BTW, I once had a good look at a really nice set of pipes that worked well and I realized that one cone was reversed on both pipes. Minor discrepancies don't seem to make a whole lot of difference at street levels of performance for some reason.

I have Bassani and jemco pipes and both have a step at at least one of joins. I suspect they would make slightly more power without those steps but not enough to make it cost effective for them to be perfect.  When I worked on a kart header pipe some years ago, the design that worked best was one which was closest to a smooth transition like a curve rather that sharp changes in direction or section.  I don't have software or the time to see if a continuous curve would work much better and if so by how much compared to different cones.  That's where hydro formed chambers might have a slight advantage.

Beautiful welding for sure.  Why do the last sections look like they are a size too large?  It almost looks like they are a step larger than the next smaller ones.  Probably an optical illusion.

And welding 22 gauge is super hard not to blow through.  Are pipes usually 20 gauge or 22?  I measured a few different pipes recently and metal thickness almost seemed to be 21 gauge which wouldn't make sense.

I remember that picture but couldn't find it when I was looking the other day. 

That exhaust is a mess for sure.  The small pits are not an issue but it would be best to have that floor welded or machined to take a spacer to replace the damaged metal.

I doubt that damage is from a crash.  It looks to be eaten away by caustic soda or someone put an oxy torch in the port to burn off carbon.  Either way it should be repaired or replaced. if anyone can repair it it's probably Josh at Bill Bune Enetrprises.

Thanks SoCal.  That's useful info.