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    Cylinder Pressure vs Cylinder Size?

    I "designed" my own cylinder head for this little 40cc motor I'm using and figured my 1st clue to if I got it right would be a compression test. Uh-oh. Only 75 psi. Even after I oiled up to simulate the rings being broken in it only got up to 95 psi. Based on past experience below 100 psi they...
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    Curiosity about centrifugal clutch

    I can understand that. It'd make me a bit nervous too. :) FWIW, I've known people that have ditched the key on a flywheel to get optimum ignition timing. Taper's can definitely hold that. Not the same thing tho.
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    Curiosity about centrifugal clutch

    Assuming we're talking about a tapered shaft and sleeve a normal amount of torque will jam the tapers together. You'll probably need a puller to get them apart.
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    Engine problem thread for the Corvid 19

    Looks like it got too hot and seized the piston. At an elevated temperature the piston expands to the point where it gets too big and more or less gets stuck in the bore. They can even lock up completely. I know this from an RD400 that locked up on me at 75 mph. That was a slide for life. Once...
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    Frame adjustment question

    If you spread it from the dropouts it will come right back to the same place when you tighten the back axle up. What you'll need to do is lock the dropouts in place somehow before you spread. The back wheel itself won't work. It'll just be in the way. 3/8" all thread and a metal tube cut to the...
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    Bike builders that have machine tools/shops

    I always like to pressure test my 2 stroke motors. When properly sealed they should hold 5-10 lbs for a few minutes. But my little pocket bike motor don't want any part of that! Uh-uh. Total fail! It's leaking all around that piece of plastic I cut down for an insulator. It's only .200 thick...
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    More Problems! Why?//fpoq

    No experience with one on me, but there are seat posts with suspension available. Google up!
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    Bike builders that have machine tools/shops

    I got too messin' with my Round 2 effort on loose screws to see what 10 degrees might look like and realized, " we don't need no stinkin" 10 degrees"! More like 2 or 3. So I did some skim cuts at ever increasing slight increments and scored! The top portion got a little thinner but that's fine...
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    Old Guys Simplex moto-peddle bike

    Not long ago I punked a male pit with some small rocks. Couldn't hardly believe it but my 1st shot hit him in the nose! The rock bounced back at my feet so I fired again but he was already backing up so I missed. By the time I picked up another pebble he was jumping a fence to get back in his...
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    Bike builders that have machine tools/shops

    I almost got an intake! But not yet ... It's that angle that's messin' me up. When you rotate a surface to an angle the dimensions change. I need to figure out how to deal with that. What got me on Round 2 was the spigot's too low and now the carb's hitting the frame where it used to clear. It...
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    Old Guys Simplex moto-peddle bike

    I pedal just about every day which means getting chased by a dog now and again. The thing is, I can't out pedal a reasonably fit full size dog! So I don't. What I do is stop and get off the bike. Then we either get acquainted or have a confrontation. That part's up to the dog.
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    New to Whizzer

    Wish I could help because that's a good lookin' bike! There is a sub-forum dedicated to Whizzers where you might poke around for more info. https://motorbicycling.com/forums/whizzer-motorized-bicycles.8/
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    Bottom end leaking oil

    It's probably your carb. I say that because usually there's not enough fuel left in the bottom end to puddle the floor. It could be leaking into the intake and into the bottom end but most times it's the float bowl overflowing because of a leaking needle and seat. Just my best guess.
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    Bike won't run

    The windowed piston is something your reed valve needs to function at full potential. Piston port motors don't have a window because the piston itself opens and closes the intake port. The reed valve does that job in a reed motor so a window is needed to more or less get the piston out of the way.
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    Stumbled on this Speedway racer and thought I'd share...

    I was at a practice oval with my dirt track Pinto back in the day when a guy showed up with a Speedway bike and needed help starting it. I shoved for all my skinny butt was worth but that wasn't working. So we switched places and got it fired with me on it. Not having brakes kinda freaked me out...
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    Old Guys Simplex moto-peddle bike

    Rick, the recent Supreme Court decision to give the Eastern half of Oklahoma "back to the Native Americans" piqued my interest. I don't know what to think of it! Is this symbolic or is there some substance to it?
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    Bike won't run

    Motor mods need to be balanced so they can work together. The porting and big exhaust would have a tendency to lean out your motor by increasing air flow, which means the speed carb is probably jetted for those conditions. What you are describing sounds like a motor that's way too rich. You more...
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    Bike builders that have machine tools/shops

    Wow! That is tight! I believe aluminum grows 13 u" per degree. A 10 degree swing means 130 u" or .00013"? 10 degrees and you're done! I was working some steel crankwheels one day with about a 3 " dia and watched the tenths shrink away as they cooled. Lost a thou.
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    Old Guys Simplex moto-peddle bike

    I got stranded on my old Yamaha in the middle of a 20 mile dirt road thru the mountains up to Big Bear. Forgot to check the oil tank and seized it. My fault. With no oil available for 10 miles in either direction there wasn't anything left to do but leave it on the side of the road and start...
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    Do you consider this front mount safe?

    Joe wasn't talking about your rear mount. He was thinking you could delete the rear plate off of the front mount and get a better fit. You should at least try it.