New 4stroke Build.

I recently demotored a Schwinn trike I built for my wife. Thought she might enjoy it. Should have known better. Was looking on youtube at bike camper vids when I saw this Briggs bike. I got inspired and had a 24” collecting dust. I like 24s. So came up with this. Finished it yesterday, and have been shaking it down since. Its stretched 10” and sized to fit a Briggs at some point. Its now running on a 142F.

I have a bike trailer I need to dust off and use, so this is built around trailer pulling. Looks mean nothing on this build, but I kinda like it.
So far it works great, shifts well and cruises nicely. Very pleased with the first impressions. The little 142 is well up to the task. Have more to do to it.
 

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Chainlube

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It is sized for a Briggs 3hp in the future, just have to move the primary drive to the other side.
I put a 80cc on a mini bike, mounted the piston vertically for that 4t thumper look. It's a 3hp.
 

Cannonball3

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Sidewinder
Regarding our discussion in the Huasheng ignition thread.
Max torque is where an engine can do the most work, after all thats what they are built for for the most part.
HP generally happens at higher rpms with the torque curve dropping. Torque gets it all rolling, not HP excepting electrics. Once the torque reaches a max and begins to decline HP then begins to build and the engine begins to build to its max. So for practical use most engines are designed to optimize the torque curve. Riding down the road in an average 5sp car you are in OD in the fat of the torque curve. Punch it and its no rocket. But climb hills it will. Kick it down a gear or two and off it goes rising above the torque curve into HP.
So this is exactly what this bike demonstrates. Both 6-7 are in the fat of the curve, a nice place to operate. Once you rev it out of the fat power begins to drop until either it cant begin to make HP or it begins to and starts to rev out.
Thats why we down shift.
Riding around at high rpms puts you in to HP which we all like, but its not a place we live at. I much prefer
to stay around the bulk of the power and save wear and tear on engine parts.

We all ride for different reasons. My Minarelli is a mid 50s ride. Turns bazillions of rpms to do it. Its fun. But I built this bike to be more practical. There is not a lot of HP here thank goodness it makes decent torque for what it is.

I know you are the forum guru on shifters, and have great experience with them. I appreciate that! But we ride differently. If I wanted to redline every gear Im sure I could get the bike much faster in the higher gears. I prefer to short shift it at around 5500. The gearing is spot on for that. I just dont need/see a reason generally to do otherwise.
 

Sidewinder Jerry

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Sidewinder
Regarding our discussion in the Huasheng ignition thread.
Max torque is where an engine can do the most work, after all thats what they are built for for the most part.
HP generally happens at higher rpms with the torque curve dropping. Torque gets it all rolling, not HP excepting electrics. Once the torque reaches a max and begins to decline HP then begins to build and the engine begins to build to its max. So for practical use most engines are designed to optimize the torque curve. Riding down the road in an average 5sp car you are in OD in the fat of the torque curve. Punch it and its no rocket. But climb hills it will. Kick it down a gear or two and off it goes rising above the torque curve into HP.
So this is exactly what this bike demonstrates. Both 6-7 are in the fat of the curve, a nice place to operate. Once you rev it out of the fat power begins to drop until either it cant begin to make HP or it begins to and starts to rev out.
Thats why we down shift.
Riding around at high rpms puts you in to HP which we all like, but its not a place we live at. I much prefer
to stay around the bulk of the power and save wear and tear on engine parts.

We all ride for different reasons. My Minarelli is a mid 50s ride. Turns bazillions of rpms to do it. Its fun. But I built this bike to be more practical. There is not a lot of HP here thank goodness it makes decent torque for what it is.

I know you are the forum guru on shifters, and have great experience with them. I appreciate that! But we ride differently. If I wanted to redline every gear Im sure I could get the bike much faster in the higher gears. I prefer to short shift it at around 5500. The gearing is spot on for that. I just dont need/see a reason generally to do otherwise.
Before when I had the LandRider I originally was using a 3x7 Drive system. The problem was there was a cadence adjustment screw on the LR auto-shift rear derailleur. Which affected the shift rate depending on the chainring size. I eventually went to a 1x7 Drive system. The reduction was 49.21\1 to 18.82\1 I lost a little off the bottom of the reduction range and a little off the top of the reduction range. I had set the cadence adjustment screw so that when using the throttle if the engine rpm dropped below 5500 rpm it downshifted and if it went above 7500 rpm it upshifted. For the most part, the bike worked great. Then I gained a lot of weight. When encountering 30% grade hills, I had to provide a lot of pedal assist to maintain max torque rpm, even though the bike had shifted automatically to its lowest gear. If I didn't at least maintain max torque rpm I could start smelling the clutch burning. My clutch engages around 4200 rpm. The reduction simply wasn't low enough for what I was asking it to do.

With these small 4 strokes, 6800 isn't the redline. It's the max hp rpm. An 8000-9000 rpm range is the redline. This is why when I'm at full throttle I'm in the highest gear which keeps me between 6000-7000 rpm. If I drop below 6000 rpm I downshift; if I go above 7000 rpm I upshift. My engine is 12 years old. Unless I'm coasting downhill. I never let my engine drop below 5000 rpm when using the partial throttle. When you gave the 5,6,7 speeds I was assuming you were at full throttle. Going above the max hp rpm is only going to give you a little speed increase for that particular gear. When you said the speeds decreased in 6 and 7, it suggested engine strain; that it was in a gear to high to maintain max hp rpm.

The Sidewinder is far superior to the LandRider. Its reduction range is 66.79\1 to 16.25\1. Though I've lost 50 lbs. I haven't encountered a hill yet I can't hit 7000 rpm at full throttle, even when pulling a loaded trailer. Cyclists have found it is more efficient to use a lower gear with a higher cadence than it is to use a higher gear with a lower cadence. Still, there's a balance point there a sweet spot so to say. What I'm trying to point out here is instead of upshifting to drop your speed and rpm you'd be better off staying in 5th gear and throttling back to drop the speed and rpm.

One thing I quickly learned when going to a 1x7 Drive system was how much quicker the chain and rear freewheel cogs wore out. I was going through 3-4 chains a year and having to replace cogs at least once a year. That's why I said the benefit of 5 cogs will reduce the wear on them and the chain vs 7 cogs. You may even want to consider a 4 cog setup. Something like 34,28,22,18. That'd reduce your cross-chaining a lot.

With the Sidewinder, I've practically eliminated cross-chaining with my color-coded sequential shifting system. Which all can be done with the left hand. Though I now use a Shimano HG71 chain it's still doing great after 2 years. The chainrings and rear freewheel are in great shape as well.

IMG_20220824_132527.jpg
 

Cannonball3

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I really do appreciate your knowledge on multi speed drives and taking the time to respond!

I think one thing that hasnt been mentioned is I am on 24” wheels. That changes the overall reduction greatly
when we are discussing the drive trains gearing. What a 29:1 lowest ratio is to me is way lower than what it is to you. All 7 gears are usable on my build. As I said locking out 6-7 would mean cruising in 5th approximately 1k higher in rpms. Something I dont want/need to do. I have been developing the bike on the 3/4 mi long causeway of our island before venturing out to the streets. I think once on a long run the 6-7 speeds will climb a bit, the power is there.

Grubee lists the redline on the unlimited ignition to be observed on the 144f @ 6800. Sounds right to me. I believe
I have found the sweet spot for this build considering my terrain. Clutch wear is a non issue as its all in before 4k. I cant make it slip lugging it down til it hits the upper 3ks. Above that it just pulls as best the engine can being loaded like that.
Maybe its not clear that I am only using the 28t front ring as a driver. No cross chaining. So 28/34 is my low. Next is 28/28 a 1:1, all ratios from there are overdriven. As I remember 7th is as high as 11:1. That is doable due to 24” wheels.
That would be a tall ratio on a single speed 26”.

So wrapping this up, what I'm doing is similar but different from what you are doing so its apples and oranges. You speak from building an entirely different and most useful bike with a wide range of ratios available.
I have just built a neat little motor bike with a 7speed transmission, that in my mind works very well and suits what
I need to a “T”.
 
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