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Post by 190mech on Dec 6, 2010 21:08:26 GMT -5
Ive noticed some engines over the years that had a hole(s) below the bottom ring that connected in some way to a boost or transfer port.Reading in another forum, the thought of this port is to expel the trapped mixture from under the piston to be used for combustion and also allowing that flow to cool the underside of the piston.I hear it is popular in the desert race bikes that run wide open for hours on end..Just thinking out loud ,wondering if that mod might be made on a 2T scoot???
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Post by 90GTVert on Dec 6, 2010 22:31:26 GMT -5
Sounds like it may work. The only (intentional) holes I've heard of are supposed to be for oiling.
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Post by 190mech on Dec 7, 2010 5:24:17 GMT -5
Its written of in Bells book around page 40,trying to figure out just where to position it.If you think about it a scoot is like a desert racer,wide open most of the time....
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Post by 90GTVert on Dec 7, 2010 7:24:19 GMT -5
He says it's of particular benefit to desert racers, but it sounds like it could benefit any engine if it works as it's supposed to. Sounds like a great use would be on aluminum kits where the piston really gets hot easily. Everything he spoke of seemed to want the port to correspond with a new port cut itno the cylinder though. I could have misunderstood though, I'm still half asleep. This is definitely a completely different idea than the oiling holes I mentioned. They are supposed to line up with high wear areas on the cylinder wall and aren't actually supposed to let any charge in or out to any ports, especially avoiding hot exhaust gases. It's concerning a different engine, so the mesurements are prob of no use, but more info here in the photos... www.ytcn.nl/archief/index.php?dir=Kieltz_pistons/ |
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Post by 190mech on Dec 7, 2010 10:16:54 GMT -5
Im thinking a hole thru the piston and rear boost port wall thats steeply angled to flow with the mixture exiting from the case...
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Post by 2strokd on Dec 7, 2010 10:43:54 GMT -5
hhhmmmm :idea: good idea
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Post by 190mech on Dec 7, 2010 18:27:38 GMT -5
Here is one Lyn Garland uses on his RD350/400 road racers;  This machine uses a wide slotted boost port like this;  Dont see why that idea will not work if a hole is cut in the barrel to the rear boost port,when the piston is at BDC,all lines up.... |
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Post by 90GTVert on Dec 7, 2010 19:05:48 GMT -5
I get it with a setup like that shows, but do you think it would really do much if it's just a hole that lines up at BDC?
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Post by 190mech on Dec 7, 2010 20:55:10 GMT -5
Not so much for power,just to cool the piston top with a fresh charge moving under it each stroke..
Maybe 6mm tall and 12mm wide?
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Post by 90GTVert on Dec 7, 2010 21:51:19 GMT -5
Sounds like it could be worth a shot.
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Post by 2strokd on Dec 8, 2010 8:41:32 GMT -5
heck yeah! Even on a stocker it be worth a shot huh?
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Post by 190mech on Dec 11, 2010 19:49:12 GMT -5
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Post by 90GTVert on Dec 11, 2010 21:32:13 GMT -5
That's waht I figured you were doing, but thanks for the illustration. Looks like you made it work out nicely. Plan on going through with it on the scoot?
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Post by 190mech on Dec 11, 2010 22:05:21 GMT -5
Next time the 103 jug is off I'll do it just to see how it works!  |
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