Engine building parts?

[David Baugh]

I suppose that's possible, Martin, but it didn't do that until I changed the flywheel. I concluded that it doesn't have enough inertia to keep the rpm's steady. The critical frequency seems to be 3200 - 3400 in first gear only. It doesn't take much to upset it. I've seen high-dollar race cars react similarly.

Dave

[Craig Richter]

David, this "bucking" used to happen occasionally with my sand buggy when I was cruising back to the pits. Problem with light flywheels is they not only spin-up faster, but they decelerate faster too. Can be hard to hold an RPM with light throttle. Push in the clutch, blip the throttle, things get better. When in doubt ... Gas it!

[David Baugh]

Thanx, Craig. That's precisely the condition I'm talking about .... and my standard solution, as well. There are basically three ways to end the abuse. Power out of it, chop the throttle, or the "clutch & blip". The third seems to be the least violent and easiest on the 60 yr old crankshaft. It can also be executed with more elegance.

There are a lot of small, trendy historic towns around here with 25 mph, 2-lane main streets and narrow sidewalks with brick storefronts. At 32-3400 rpm, the speed is about right, the exhaust is singing, and the shriek of my pie-plateless fan echoes off the buildings into the street. People are looking to see what's coming, when .... There it is, a manhole cover. Instantly, the whole scene erupts. But I can save it with the clutch and throttle blip and still get a round of "thumbs-up", because this ain't my first rodeo. Clutching her tiny dog to shield him from injury, my lovely wife of 50 yrs tells me to "knock it off". Sheepishly, I reply, "aw Honey, I was just showin' off". And isn't that why we dump all that time and money into these things and drive 'em in the first place? Where else can a 73 yr old gentleman find gratification like that?

Dave

[Martin Benade]

I never would have thought a light flywheel could cause that. I'll have to add that to the long list of things I don't know about. And David, that is a harmless vice. Keep it up!

[David Baugh]

Maybe it's one of those things you have to experience. But from my perspective, under the right conditions, a relatively lightweight rotating mass can become very unstable. I just have to be sure to catch it before it trips my inertia-activated roll-over switch.

Dave