49cc's on a Schwinn

indian22

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Dec 31, 2014
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FOG, I am surprised Rick did not chime in on bolt head stamps. They indicate the Grade/ Tensile strength of a given hex head bolt. If you use Grade 5 or 8 you are in good shape.
Tom
Lol, I try to contain myself from replying to every post Tom. I'd think the forum gets rather tired of my many posts. I'm kinda' like the nerdy kid in grade school that raises their hand to answer every question... oh oh oh I know the answer!

Rick C.
 

Tom from Rubicon

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Apr 4, 2016
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Here ya go Curt,
Stainless steel bolts are rated for corrosion resistance. Bolt strength is rated in PSI (pounds per square inch). A stainless steel bolt has the same PSI rating as a grade 5 bolt (125,000 PSI). A grade 8 bolt has a stronger rating with a PSI of 150,000.
Give me a grade 8 any day.
No stainless PSI but everything else.
https://www.almabolt.com/pages/catalog/bolts/proofloadtensile.htm
Tom
 

curtisfox

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Dec 29, 2008
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FOG

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I think I'm at the beginning of the end of my 1st build in that this chunk of stainless represents the last major piece of the puzzle.

DSCF0846[1].JPG


There's a carrier for the primary chain's rear sprocket in there somewhere. All I gotta do is find it ...
 

Tom from Rubicon

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It's like carving in stone, material has to be removed to reveal the desired object and now very old school what we do.
The new way is to generate a 3D modeled object with computer software which a 3D metal deposition "printer" replicates layer by layer to a metal object as near perfect as is able. To my thinking, Blacksmiths survive and Tool and Die Makers will be marginalized.
I enjoy your work but if you will please also post to …...
https://motorbicycling.com/threads/bike-builders-that-have-machine-tools-shops.64769/page-28
Thanks,
Tom
 

FOG

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The last piece of the puzzle for the primary chain is done but I ain't real thrilled with the result. The biggest chain available for pocket bike motors is 8mm and it looks a bit cheezy compared to the #41 on the final drive.

DSCF0848[1].JPG


It's a cheapazz chain too! I used the best straight edges I got for alignment but when I watch it track on the sprocket it's all over the place. And it's the same section of chain that wanders over to the other side every time around. Apparently it's a crooked chain? Who ever heard of that?

Oh well. Maybe it'll wear and straighten itself out over time. After hiding it with a chain guard I'll just run it and see what happens.
 

indian22

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Good comments all. FOG your carrier turned out well. 8mm chain, quality chain, I've used with as much as 6 hp on small go carts that though light, the carts were still heavier than a cruiser bike. They worked well for me as long as they are setup correctly and maintained properly the 8mm should serve well. My use was not racing just pleasure for myself and kids. Many of the scooter e-motors use the 8mm. I have a 2kw (2.7hp) and a 3 kw (4hp) that came with 8mm chain and sprockets. It's not uncommon to see 5kw e-motors on bikes geared through a 5 or 7 speed derail. cassette and bicycle chain and shifting creates cross chaining (not straight) chain lines and that's a true torture test for any chain. Like you FOG I'm not impressed by the Chinese chain and I have some quality chain and links in route. The chain charts show 1200 lb. for standard grade 8mm & 1600 lb. for 415, though many seem to despise the 415 I've never broken one on carts or bikes, again not racing abuse) and that's a lot of each and thousands of hours in service. I've lost quick links (my fault) but never had a break. Tom's got the handle on a great brand & the wax job, which I've not yet tried, but like the concept.
You're already aware of the importance of a "true" chain line and proper tension through 360 degrees of movement, not allowing excess slack or chain wander & eliminating any side thrust so I'd think 8mm up to the task of the pit bike motor and that's why they are so equipped.

I like your attention to detail and the bike is going to turn out great.

Merry Christmas!

Rick C.
 

FOG

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Well ... we got trouble in paradise guys. I've been howling about the cheap 8mm chain but the real problem is a cock-eyed motor mount. The crankshaft isn't perpendicular to the frame. That ain't gonna work!

I have any number of excuses for this and here's one. :) Look at this itty bitty sprocket.

DSCF0849[1].JPG


How do ya put a straight edge on that little bugger?

Another thing that led me down the path is the motor's overall length. I can barely get an air cleaner on between the seat post and carb, and meanwhile out front the pipe wants to run into the downtube. That's where the current configuration pretty much needs to be and I thought it was straight.

But, with failure, always comes the opportunity for improvement! And that's a good thing cuz I fail a lot!

Since I started this endeavour I've learned the pocket bike guys get these little motors all wound up with pumper carbs. Which are a lot shorter than that Mikuni I put on there years ago. That'll let me move the motor back at least an inch and probably allow for some amount of offset to get the primary chain tucked in a little tighter too. What we have here is an opportunity to "Refine the Design!"

I'm also gonna gut my spare motor out for mock up. A long bar thru the crankshaft holes will tell the perpendicularity tale. I'll get it straight this time.

So ... I thought I was at the beginning of the end. Turns out I'm back to Square One! Mounting the motor was the 1st thing I did. :)
 

Tony01

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Nov 28, 2012
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Well ... we got trouble in paradise guys. I've been howling about the cheap 8mm chain but the real problem is a cock-eyed motor mount. The crankshaft isn't perpendicular to the frame. That ain't gonna work!

I have any number of excuses for this and here's one. :) Look at this itty bitty sprocket.

View attachment 103205

How do ya put a straight edge on that little bugger?

Another thing that led me down the path is the motor's overall length. I can barely get an air cleaner on between the seat post and carb, and meanwhile out front the pipe wants to run into the downtube. That's where the current configuration pretty much needs to be and I thought it was straight.

But, with failure, always comes the opportunity for improvement! And that's a good thing cuz I fail a lot!

Since I started this endeavour I've learned the pocket bike guys get these little motors all wound up with pumper carbs. Which are a lot shorter than that Mikuni I put on there years ago. That'll let me move the motor back at least an inch and probably allow for some amount of offset to get the primary chain tucked in a little tighter too. What we have here is an opportunity to "Refine the Design!"

I'm also gonna gut my spare motor out for mock up. A long bar thru the crankshaft holes will tell the perpendicularity tale. I'll get it straight this time.

So ... I thought I was at the beginning of the end. Turns out I'm back to Square One! Mounting the motor was the 1st thing I did. :)
Yes I know this feeling. I feel like that with my electric schwinn build. When I built it up I used the frame as the jig for the rear. Of course being electric and hub driven it doesn’t need to be straight as long as the front and rear axles, and head tube are flat and parallel to each other. FOG just fake it till ya make it. Might take some or a lot of heat, bending and twisting, and you’ll get there. My builds always looked best from the side or quarter view, never dead on the back or from top, LOL!
 

Tom from Rubicon

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Angle aluminum is a good straight standard FOG. I am going to use 1/4x2x2 aluminum L stock for the engine mount of my Bike Berry Huffy. As you have discovered, precise engine output sprocket location is the critical to everything going down stream in the driveline.
Tom
 

indian22

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Dec 31, 2014
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FOG I use a sizeable flat plate with a hole in it to replace the small output sprocket to line things up, or drill a hole (for the output shaft in a length of angle iron to run back to the rear sprocket, either one gets you real close to a perfectly straight chain line.


Rick C.
 

FOG

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When last heard from I was re-mounting a crooked motor. Got that done, but then I wasn't a bit happy with the way the primary chain was hanging way off the side of the bike. Visions of the chain sawing on my leg came to mind. Offset required, so I'm doing it again! For those who are keeping score this is the 3rd time ...

In the picture you can see by the air cleaner how much I've moved the motor over. And can you imagine how far out the primary chain was? It was horrible.

DSCF0857[1].JPG

I've also been playing with chain guards. This is my 2nd attempt and who knows? I may do that again too. :)

DSCF0856[1].JPG