Wolframore
- Joined Jan 21, 2019
- 2,609
Back in my day, both the exhaust and intakes ports in the cylinder were changed from a round hole to one that was more "D" shaped and some times also raised to change timing. Transfer chambers were polished to aid flow. Piston port engines were few and far between. Most were reed valve engines, and we used "stuffers" in the crankcase to raise the primary compression. This was on gokarts and mini bikes, most using either a McCullough or Power Products engine.Porting for 2 strokes is completely different than 4 strokes
Not too sure about that. Sthill saws I don't think have reeds but do have piston ports If I remember correct.Window pistons have to be used with reeds.
Yes in the cylinder wall, with the flat side toward the head. When I say flat ,they did have a radius in the corners. The rings were kept from rotating in even stock engines back then by a pin in the gap.Were the D ports in the cylinder walls? If so with the curve on top? It is one way to increase duration and give the rings a gentle close. Too much duration and the power band shifts losing low end torque. I like Suzuki’s method of having an adjustable port which changes with RPM. Its an ingenious way to keep low end power while opening up at higher RPM. I believe it changed from 178-204 degrees.
Some Stihl saws have reed valves, they might be so small they’re easy to miss. I like the windowed pistons as it helps cool the engine, but if you don’t have a reed it will push fuel back to carb.
The real old type Shils did use reeds, but when they changed to the modern MS series saws they did away with them.I would love to see those engines.
I don't know about that. Before I went to the Stihl's I had Mac's, Poulan's and Craftsman's(most made by Poulan). Besides not having the same amount of power they didn't make as high of RPMs as the Sthils. This was on saws with similar or the same CC's displacement. I always thought the Stihl name was pure "hype" advertising, but after using one that a friend had I was a believer.Stihl has some very cool design. Some get rid of transfer ports in the cylinders and add them to the pistons. You would need to stuff the heck out of the crankcase to run that top end.
Good article, I wonder if it will take off? Looking at a $30 K bike which is about the cost of a new trike. Impressive stuff though. I thought Alexa was smart but this new bike is really smart.
I wonder why they didn’t just do direct drive.
My local dealership also has try it days. Not sure if they have a new Live Wire for us to check out up close and personal. My next HOG chapter meeting is Friday the 4th so if I remember I'll ask the dealership.My Harley Dealer here in Orem have a training track for people who want to learn and get a Drivers License. I’ll bet they would let me ride one on the Track.
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