General questions?

Redm777

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I have a flying horse motor 66cc. Runs pretty good and has around 500 miles. I'm wondering if it's worth upgrading. I am planning on getting an mz65 clone pipe. Currently, I'm on a 24-in cruiser with a 41 tooth sprocket, and I'm a 110lb pound rider I hit around 28 WOT. I am getting a CNC sprocket adapter with a 36 tooth. I was thinking would hit around 35? or do I need more upgrades.
 

Sidewinder Jerry

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I have a flying horse motor 66cc. Runs pretty good and has around 500 miles. I'm wondering if it's worth upgrading. I am planning on getting an mz65 clone pipe. Currently, I'm on a 24-in cruiser with a 41 tooth sprocket, and I'm a 110lb pound rider I hit around 28 WOT. I am getting a CNC sprocket adapter with a 36 tooth. I was thinking would hit around 35? or do I need more upgrades.
Here I'm going to assume you're running a 9:41 ratio. In order to do 28 mph with a 9:41 ratio on 24" tires at WOT your engine will be turning 5539 rpm. At that same rpm rate on 24" tires with a 9:36 ratio you'll be doing around 32 mph.
 

Redm777

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Here I'm going to assume you're running a 9:41 ratio. In order to do 28 mph with a 9:41 ratio on 24" tires at WOT your engine will be turning 5539 rpm. At that same rpm rate on 24" tires with a 9:36 ratio you'll be doing around 32 mph.
So turns out I have 44t sprocket. So when I get the 36 I’ll prolly go 35-38ish
 

Sidewinder Jerry

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With a 9:44 ratio using 24" tires to do 28 mph at WOT you must be turning 5944 rpm minimum. Changing to a 9:36 ratio would mean at 5944 rpm it would give you a speed of 34.2 mph. You'd need 26" wheels to do 37 mph at 5944 rpm using a 9:36 ratio.

If you can improve your engine performance with a 9:36 ratio using 24" wheels 6079 rpm would give you a speed of 35 mph; 6600 rpm would give you a speed of 38 mph. The 2 stroke regulars here can tell you ways to get this slight increase in performance.

What all this means if you want to go faster than 34 mph. You need a smaller ratio than a 9:36 or larger wheels or increased engine performance.
 

Mossy

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A higher gear ratio doesn't always mean greater top speed the motor needs the power to pull the tall gear...
 

Sidewinder Jerry

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A higher gear ratio doesn't always mean greater top speed the motor needs the power to pull the tall gear...
He's a 110 lbs; he could probably even go as low as a 10:32 ratio on 24" wheels, which would give him a speed of 42.8 mph at 5944 rpm. Granted acceleration will be greatly decreased.
 

Zak

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Let's say you had all the top end (cylinder/head/intake/exhaust) to run 20,000 RPM, hypothetically unlimited RPM. What would you consider your "redline" for a bone stock bottom end? I've never dug into the engine. I just don't see much bottom end (case and bearings... what else is in there?) talk in here. How far can you go on top before you gotta remember leg day?
 

Mossy

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The bearings c3 or deep groove the Ballance less resistance the effort in vibration stealing power... And running tuned for 20k...
Two stroke stuffing is what you want to watch... Street Riderz does the same thing with science and knows the parameters...
 

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