200cc Tecumseh Build

Here's the new throttle linkage:
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So this method of transmitting power did not end up working. The chains were constantly out of alignment, and the left side sprocket had problems because it was out too far. This time it works, I got rid of the right side sprocket and used only the left one, connecting the chains to the biggest and smallest chainrings.
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As you can tell, the clutch is now on the other way, so the chain can get much closer. The reason I wasn't able to do this before was the permanent key inside the clutch. The shaft wasn't long enough for it to reach the key way when put on backwards. To solve this, I started the engine to get the shaft spinning like a lathe, then used an angle grinder to make more of the shaft 3/4 diameter. Now the clutch sides on further, and the key reaches.
 
The chain tensioner is made out of a skateboard wheel I carved out. Works great because there's already bearings in it. The engine is moved all the way to the right side and can't go further, so the chain from the clutch to the jackshaft still doesn't line up, but the tensioner moves the return path of the chain so it never comes off, and always stays tight. The downside is that the bike can't be rolled backward or the chain comes off, but it rides great with no problem and the skateboard wheel doesn't make any sound.
 
In the first picture there is a small bicycle chain going from the jackshaft to the wheel. As you might guess, when I accelerated uphill it snapped. I still had more of that #41 roller chain since it came in a 10ft pack, so I replaced the bike chain with that. I used the bike chain at first because I wasn't sure if the larger one would work with the small chain ring on the jackshaft, it was from a multi speed bike without much room in between gears. Turns out it works fine, now the bike is reliable. Still no foot pegs yet
 
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That thing looks like fun, must sound cool too.
This engine is rated at 6.5hp, and the bike does fly, it can cruise at 30mph just above idle speed. Takes off from a stop just fine. Accelerates extremely fast, but there's alot of vibration if you take off too quick. I'm going to wait until the frame has some more support before I open it up, there's not even footpegs yet. This engine also has a cast iron flywheel that weighs like 30 pounds, not sure how that affects the performance. Does anyone know if this is legal to ride on the street, (in California) . I've heard it has to be under 49cc.
 
I finished making a new muffler and some foot pegs for it. For the footpegs, I took apart the bearings where the cranks go on an old bike, then took out just the shaft. I cut the shaft in half, and used some pipe as a sleeve to extend the width, then welded it. Next I welded the shaft to the bottom bar of the frame, and bolted in the cranks and pedals. The pedals spin but the cranks are in a fixed position slanted slightly foreward.
The muffler is just some pipe and a baffle aiming backwards, the old one blew the exhaust gasses right at your leg.
I rode it about 5-6 miles just going about 20-25 mph and no issues, it runs great. sounds better with the less restrictive muffler.
Ill post pictures tomorrow and maybe get a video if the rain stops
 
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Jasanabia said:
Does anyone know if this is legal to ride on the street, (in California) . I've heard it has to be under 49cc.
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It is not 49cc - It is 2.0 gross hp. Since you have 6.5hp and no pedals, your motor bicycle is illegal to ride on the street in California . There are several threads posted on this forum of the legal requirements.

Get that chain lined up before you throw it and really hurt yourself. Last thing you need is the chain whipping off at 30+ miles per hour into your spokes or onto your body. If you can't move the engine any farther over, then redesign your mount. The chain needs to be lined up straight, sprocket to sprocket.

Good Luck,

Chris
AKA: BigBlue
 
BigBlue said:
It is not 49cc - It is 2.0 gross hp. Since you have 6.5hp and no pedals, your motor bicycle is illegal to ride on the street in California . There are several threads posted on this forum of the legal requirements.

Get that chain lined up before you throw it and really hurt yourself. Last thing you need is the chain whipping off at 30+ miles per hour into your spokes or onto your body. If you can't move the engine any farther over, then redesign your mount. The chain needs to be lined up straight, sprocket to sprocket.

Good Luck,

Chris
AKA: BigBlue
Click to expand...
Thanks, I didn't expect it to be street legal. I'm reluctant to change the design so the chains line up because it works so well right now. I rode it 5-6 miles with no problems. Since the tensioner moves the return path of the chain so it lines up, the chain can't come off. I can understand the danger of a chain flying off especially when your moving at a high speed.
A bicycle derailleur works by not having chains aligned
 
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So today I was riding it and came up to a stop sign, took off and the engine spewed out a huge cloud of smoke. Kept riding it and every time I took off from a stop it made a big cloud. My dad said it was a blown head gasket, but I didn't feel any difference in performance and no lost compression. I took off the head any way here's some pictures
 
The head gasket was fine, I think I may have accidentally put some two stroke fuel in it. Got it back together and it runs fine.
With this gear ratio the governer kicks in at about 50mph. It hits a power band at about 35mph and takes off.
 
Ill try to make a video if I can figure out how to mount a camera to a helmet or something
Has about 20-25 miles on it, just riding around the neighborhood.
It would be nice to have a cvt, even with a big engine the acceleration from a stop is not as good as it could be. Taking off quickly makes the engine shudder a bit and the clutch gets real hot. Top end suffers too because the rpms just max out and you slow down when you let off the gas like downshifting in a car. Makes this cool popping sound though like backfiring or something , not sure what it is
A friend told me it would be safe enough to remove the governor so ill probably just do that
 
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