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Post by earthman on Oct 14, 2018 11:11:54 GMT 1
What do you think chaps, good or bad idea and will they be available for an LC in the future I wonder??
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Post by rigga on Oct 14, 2018 11:33:22 GMT 1
Watched that the other day, interesting concept indeed.
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Post by Tobyjugs on Oct 14, 2018 12:29:20 GMT 1
Well explained, but the porting on the standard RD barrels are very different.
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Post by bezzer on Oct 14, 2018 14:29:14 GMT 1
The machining would have to be extremely accurate, to get the piston heights equal in a twin cylinder engine, if using what is effectively a threaded insert. Interesting theory though, especially the weight saving.
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Post by muttsnuts on Oct 14, 2018 14:52:34 GMT 1
I can see several issues with this, not least of which what stops the piston rotating round on the thread, so the piston ports move from the inlet port, thereby stopping the engine from working, also, the insert, it protrudes/blocks the piston ports, so again reduces/stops the inlet charge from getting where it needs to be, and last but not least, the piston crown relies on the cool petrol/air charge coming in to keep the piston crown cool, this insert effectively blocks that from happening, so will probably result in piston melt down on prolonged runs. Neat idea, just needs more development - just saying like !!!  |
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Post by earthman on Oct 14, 2018 15:55:28 GMT 1
I can see several issues with this, not least of which what stops the piston rotating round on the thread, so the piston ports move from the inlet port, thereby stopping the engine from working, also, the insert, it protrudes/blocks the piston ports, so again reduces/stops the inlet charge from getting where it needs to be, and last but not least, the piston crown relies on the cool petrol/air charge coming in to keep the piston crown cool, this insert effectively blocks that from happening, so will probably result in piston melt down on prolonged runs. Neat idea, just needs more development - just saying like !!! Good points you make there. |
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Post by dusty350 on Oct 14, 2018 15:56:12 GMT 1
Don't big 4 strokes have buttons that fit in the ends of the gudgeon pin ? Surely if there were no other pockets on the piston, the buttons would seal the side of the piston off completely ?
Dusty
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Post by liffy16 on Oct 14, 2018 18:16:32 GMT 1
Yes nice idea but i don't think it would work in the real world
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Post by ypvs400 on Oct 14, 2018 18:17:21 GMT 1
Don't big 4 strokes have buttons that fit in the ends of the gudgeon pin ? Surely if there were no other pockets on the piston, the buttons would seal the side of the piston off completely ? Dusty Yes and they have been used in two stroke race bikes for years plus you dont need to fit gudgeon pin circlips with this method. |
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Post by Tobyjugs on Oct 14, 2018 18:31:49 GMT 1
Just spoke to a friend who is part of a four man team. They want to get 27.5 hp from a 50cc engine. They have tried a similar design and got a small increase in power, after further testing they put the increase down to the gudgeon pin not flexing as much. This is of course a tiny piston revving to 18000 rpm so the over lap may not be as important.
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Post by bare on Oct 14, 2018 18:55:38 GMT 1
Addled Nutter TBH.
I have a couple of CL Combat 2 strokes.. Yeah I know.. but state of the art nonetheless.
Out of Russia mid '90s featuring NO wrist pin holes.
The wrist pin assly screws into the piston and calibrated shims are fitted betwixt wrist carrier assly and piston crown.. to ADJUST timings.
And it worked ...to well past 30,000 Rpms
Clever those Russkies.
That said the design proved no more effective and arguably more problematic (carrier tends to unscrew with ugly result) than 'normal' wrist pin/piston designs
Consequently that design lived for only 2 seasons before being dropped.
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