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  1. O

    Wobble-plate axial engine design project.

    The Duke mechanism seems to have solved this problem. this requires a synchronising wobble mechanism to locate the wobble plate, and a crossed-pin universal-type big end. the motion at the pistons ends up in a single plane relative to the piston. The synchronising mechanism looks like rollers...
  2. O

    Details of performance two-stroke engines.

    Well, I am back down to more average levels of cash on hand, so no buying tig welders or bigger lathes for me! However, for my bench engine, it is possible to get quite good power from older style barrels, and it will keep me going for quite a while catching up on all the planned alterations...
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    watercooled 50cc two-stroke.

    New layout for header pipe curve and lead-in to the chamber. The first part is an extension of the head port. Question: are there good reasons why this is too tight a curve? the inner radius is about the same as the tube diameter. In some fluid apps, I seem to remember that the inner curve...
  4. O

    watercooled 50cc two-stroke.

    Photos of the reed block with bypass: This is probably easier to make out than the drawing. The other reed block is the original. I may use half of this with the butterfly valve, as the reeds in the carbon fibre unit seem to be much stiffer, and may not work as well. The idea of the reed...
  5. O

    watercooled 50cc two-stroke.

    Update on Two stroke mods: Development of the combined reed valve with bypass. The core device has been completed. I am now working on the clamping plates and the carburettor adapter. Photos to follow. It occurs to me that I can eliminate the bottom reed valve set for very little breathing...
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    watercooled 50cc two-stroke.

    Latest progress on engine and addon parts: 05-07-22 The engine is now fully dismantled. It looks like there is a rear inlet passage over the flywheels and under the barrel bottom. This means the valve block would be better twisted 90 degrees from where I was originally planning, with the...
  7. O

    watercooled 50cc two-stroke.

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    watercooled 50cc two-stroke.

    Reed valve assembly with bypass: This is based on the 125 Yamaha reed valve block. It is further spaced out to fit a 30mm butterfly valve in the middle, and the centre petals are removed. The objective is to discard crankcase compression once the engine gets on the pipe. The pipe suction is...
  9. O

    watercooled 50cc two-stroke.

    Start of engine mods: I have done these barrel porting changes. The double line show old and new port edges. Basically a bit of a blueprint job. Transfer ports flow limits may be raised by a couple of percent. If the simulation suggests it, I can make the secondary boost ports deeper and less...
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    watercooled 50cc two-stroke.

    The engine has arrived! However, it seems to be about 63 cc one, not 50cc. This is probably not a problem, as I can factor down the power to the 50cc standard. 50 cc is 79% of 63cc , so the 30hp aim rises to 37.8 hp. I don't know what hp standards everyone is using, Dutch appears to be ps or...
  11. O

    watercooled 50cc two-stroke.

    Ideas for grafting on new partial exhaust manifolds: If I can find mating surfaces 5mm wide, and enough depth to take an m4 screw, I can bolt up form-fitting aluminium blocks, and seal both the water-jacket and the exhaust with silicone gasket sealer. If the gap is under 0.5mm, the sealant...
  12. O

    Loading on grubscrews.

    I have been looking at multiple grubscrews. If I use grade 10.1 grubscrews, I think having a grubscrew section shear stress of under 200 MPa (29000psi) is a good indication that it will not drag through the shaft material or come loose. You can go over the yield point of the shaft where the...
  13. O

    watercooled 50cc two-stroke.

    I have had a look at some of this. I am intrigued by the 2-layer exhaust and transfer setup that Frits- I think- is suggesting. I have the Janbros pdf and spreadsheet, as well as engmod2T. I had a further look at the KTM50 LC engine, and it is very similar to the RVRT port setup, so the barrel...
  14. O

    watercooled 50cc two-stroke.

    Corrections for the RVRT Zundapp, by Rob Van Rossem. The one that did 24.6 ps (pk) at the rear wheel was a rotary inlet valve engine, and the Malossi RVRT barrel has secondary exhaust ports which are sharply angled into the main port. There is probably not enough material to do this on the KTM...
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    watercooled 50cc two-stroke.

    Alternative inlet boost system: If it turns out that bypassing the reed valves at around the effective rpm range of the pipe, is a good thing, then the leaves in the reed valve can be propped open by a central blade in each reed opening. This could be activated by a moving cylinder outside...
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