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Dirt Bike Brands - Other
Will two strokes come back?
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[QUOTE="DougRoost, post: 1181720, member: 23019"] Piston ring sealing and piston slap is of course true for any piston engine, being it 2T, 4T, or diesel. In fact, it's up to the oil ring to apply and scrape the oil film off the cylinders in a 4T engine, as anyone who's ever had a engine with worn rings and the resulting excessive blow-by is well aware of. As a long-time car hotrodder, I can also tell you that a key design point for performance 4T camshafts is overlap and duration. This is how many degrees of crankshaft rotation that the intake and exhaust valves are both held open. When combined with a tuned header, it's the exact same idea of a 2T with expansion chamber adding a supercharging effect by using the exhaust pulses to further scavenge the cylinder and draw in additional air-fuel charge via the intake valve. In the current crop of racing 4T dirtbikes, you have this camshaft design coupled with the very small skirted pistons, so they, too, pollute. The other engine design we haven't talked about is the rotary or Wankel. I used to have an RX-7 and it's a great, smooth engine. The owner's manual actually warned you to check the oil level often since if you're not using oil there is a problem. This is because they had a pump to spray a fine mist of oil on the combustion chamber walls. This obviously affected emissions but it illustrates again that all these mechanical engines require lubrication where metal is in contact with metal. [/QUOTE]
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Dirt Bike Discussions By Brand
Dirt Bike Brands - Other
Will two strokes come back?
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