Any of you guys seen a 4,5 or 7 cylinder H2?
seen one at Barber, I think it's a 5 cyl. Also a Z-1 V-8!
Any of you guys seen a 4,5 or 7 cylinder H2?
You just keep it on the pipe, don't let it fall off. Throttle control is a lot more predictable that way. Slam the down shifts and over rev it into corners, no valves to float, ya know. Come off the corner on the pipe. That's the trick. But, then, when you got over 100 hp at the right wrist, it's still intimidating, I reckon. It's a far cry from a 125, put it that way.I never got to ride more'n a 250 two stroke except for street RDs which don't count.
I know when David Green (a friend from the past who's no longer with us) won the Daytona 250 novice pro race in 81, he was given expert status in 82 and eligible for F1. He had no problem with money, dad ran "Durwood Green construction" in the Houston area and David got any toy he wanted, paid cash for a Ferrari 308, that kind of rich.So, for 82, he bought a TZ750 and an ex-euro RG500 Suzuki production racer. When he got 'em to TWS at a "test day" (we didn't have track days back then) both those bikes scared him so bad, he sold 'em and bought a new TZ250 for the season.
I never got to ride one, but I think I'd been like David, would have scared me to tears, cry like a girl.
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Actually, Eric, you were a far faster rider than David was. How David won that Daytona race, I'll never know. I could run with the guy at Oak Hill and I had half the motorcycles he had. I think he realized he didn't have any business on a 750 and that it would hurt him. I'm sorta glad I never got a chance to try one.I think that day at Daytona, David must have pulled something out I never saw in him before or since, but he beat a guy named Donny Green that day, fast rider out of California, and a 16 year old fast kid that went on to set 250 class records in AMA, Rich Oliver. That race was David's 15 minutes of fame.
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So, we can all sit here and awe at what we might do with a motor like that, but I don't know about myself. I might be more than a little intimidated by that much power in a 2 stroke.A man's got to know his limitations.
The stock CR500 scares me, so I think I'll pass.
So, John, when you kill yourself on that thing, can I have your SD-R?![]()
Leave the tuned pipes off of a two stroke and you will be amazed at how broad the power band becomes. I once rode my H1 with only the header pipes on it, no mufflers, and the engine pulled much harder at the low rpms without that big hit in power at 6000 rpm.
The last thing you want on an observed trials bike is an engine that has an on off switch for a throttle, guess what type of engine is on most trials bikes.
It's not just the pipe tuning, but also port tuning and intake tract tuning that dictates the power band of any two stroke. It's all about port time/area. For a grasp of the fluid dynamics of it all, read "Two Stroke Tuner's Handbook" by the late Gordon Jennings. Far too complicated for a post on a BBS. Now days, there are computer engine flow modeling programs that will do the math for you. You must measure port areas and timing and make the inputs, but it will draw power curves for you, including pipe tuning and intake tract tuning. Buddy of mine has such a program and it's pretty danged impressive. He built my KX motor using it. I sorta wish we'd left it stock, though. We built it for the big tracks of CMRA and I wound up using it mostly on TMGP kart tracks over the years. Friggin' peaky with those radical ports on such tight tracks. You really have to have the gearing right and keep it up on the pipe everywhere, but do that and it flies.It is a big handful in traffic, though. It's a lot of fun. It'll get little power wheelies and will actually power slide the rear out of corners on kart tracks, like a motoGP scaled WAAAAAAY down. LOL!
Yes, the porting has to agree with the tuned pipe's rpm. But take the tuned pipe (expansion chamber) off and run the exhaust straight out of the port like a chain saw and the engine makes much less power, however, it will be equally unpowerful at all rpms. The big hit when the engine comes on the pipe will be gone.
Two strokes can be quite torquey if they are designed that way, ever ride an old Jawa 350 or a Suzuki GT 750?
Most people would probably go faster with a more mildly tuned engine on the average race track. A mildly tuned engine helps you be fast on the slowest part of the race course where you spend the most time. To understand the concept, consider riding two miles going 10 mph for the first mile and 30 mph for the second mile. Your average speed is not 20 mph but only 15 mph.
If your goal is to average 20 mph on that two mile run, you could either go 10 mph for the first mile and ride the second mile at the speed of light, or you could increase the speed of the first mile to 15 mph and finish the second mile at 30 mph.
How bout a 700 cc two stroke trail bike!
http://hellforleathermagazine.com/2008/04/atk-confirms-2009-700-intimida.html