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  #7881  
Old 03-25-2015, 12:28 AM
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mapbike mapbike is offline
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Default Re: what did you do to your motorized bicycle today?

I also got a little more of the port work done on the jug that will be going on the engine I'm building for the Yellow Schwinn I started on last year, I got clutch cover cleaned up, mag installed on engine and a couple other things done.

Got a late start today but Got a few things done so I'm happy..

Jug before I do a little more work after dark.
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  #7882  
Old 03-25-2015, 10:57 AM
BOYGOFAST BOYGOFAST is offline
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Default Re: what did you do to your motorized bicycle today?

Today I'm in the process of evaluation , the term "Spooky Tooth" is now to be test the piston in my 66 cc is bout to undergo a surgery that will leave one cylinder ring and remove all the skirt with exception of a tooth to block off the front / exhaust port included will be drilling out some of the weight of the connecting rod with a 5 mm diameter drill bit.Have it reassembled and turning a smooth 0- 6000 +rpm in a few minuets or so .. SPOOKY TOOTH .
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  #7883  
Old 03-25-2015, 10:50 PM
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Davezilla Davezilla is offline
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Default Re: what did you do to your motorized bicycle today?

I've tried the single ring and the end gaps are pretty wide on these as it is so getting decent compression was a problem, I did get it to work and it felt nice and strong but lost compression after just a few short rides. Now if you can find a different piston with narrower ringlands and a 1mm wide ring with enough metal on the ends to set your own gap it would work, but so far I've only found chrome rings in these sizes which would tear up the nikasil plating in the cylinder in short order...
Also cutting too much off the skirt can allow the piston to rock inside the bore excessively before the engine warms up and this piston slap can accelerate wear considerably... Keep a close eye on things while you're doing your testing. And finally... when you did your cutting on the piston make sure you leave a smooth radius on everything to prevent cracking, the piston also needs a certain amount of metal to support it's self or that "tooth" could crack off... Again, keep an eye on that as well.
If you got some pics of the piston and can take a little constructive critisism myself and a few others can tell you if it'll last or show you how to make the cuts so it won't self distruct.
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  #7884  
Old 03-25-2015, 10:52 PM
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Davezilla Davezilla is offline
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Default Re: what did you do to your motorized bicycle today?

Map... those transfers are looking really nice... How much more do you plan on doing to this one?
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  #7885  
Old 03-26-2015, 12:45 AM
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mapbike mapbike is offline
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Default Re: what did you do to your motorized bicycle today?

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Originally Posted by Davezilla View Post
Map... those transfers are looking really nice... How much more do you plan on doing to this one?
I have to finish matching the ports perfectly to the transfer area in the case, then Im gonna get the exhaust port to a mirror finish after I widen it just a little bit more, Im not gonna remove anymore from the top of the exhaust port since its already a little higher than some of the other jugs I have, and the intake port is actually a little low than some of the other jugs I have, intake port is about where its gonna be I think, just nice and clean and jot to shiny for better atomization of the fuel before it goes into the crankcase.

Tranfers in jug are nice and high already so no ramping of the piston really, I may put a shallow slot angled back toward intake just to help direct charge away from exhaust as much as possible, Ill post some pix of how I plan to do it once I get it done, this will be experimental and will only be a slight modification just to see how it works, I dont need big sloping ramps just something to aid in directing charge toward intake without taking to much of my compressuon potential away.
This is my Id'y anyhow.....lol!
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  #7886  
Old 03-27-2015, 12:02 AM
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Davezilla Davezilla is offline
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Default Re: what did you do to your motorized bicycle today?

Same thing here since it was slow at the shop today, I took the new jug I got off ebay and did some massive porting to it, knife edged the transfers at the bottom andnat the bottom of the transfer opening, cut out the casting ridge and did some simple aiming of the ports. The exhaust port is now a massive 28mm wide and I widened the intake by 2mm on each side then lowered the floor of the intake by 4mm. I'm not gonna mess with the exhaust roof until I can get a bottom end since I need the piston in place to set the timing and duration... I could do that by measuring how far down from the deck the port roofs are but if I need to shave any off the base or šant get a 40mm stroke bottom end or if anytghing else comes out different it would throw the timing off so I'll wait on that part.
Since I'm doing the exhaust a lot larger than my last one I'm going to have to make a short header adapter to connect the kx pipe to the cylinder by using a stock kx flange header.
On the intake side I'll be using the 18mm mikuni carb so this engine will be able to breathe a lot better than my current setup. I may go ahead and set this one up with a reed valve if budget allows but for now the plan is to stay piston port.
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  #7887  
Old 03-27-2015, 11:23 AM
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GoreWound GoreWound is offline
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Default Re: what did you do to your motorized bicycle today?

I stuffed half a brollo pad into my exhaust to try and quiet my bike somewhat, think I over did it, lost about half my power.
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  #7888  
Old 03-27-2015, 02:08 PM
curtisfox curtisfox is offline
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Default Re: what did you do to your motorized bicycle today?

Brillo pad is full of soap use steel whole,prolly half as much LOL..actually stainless scrubber from dollar store is more coarse .........Curt
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  #7889  
Old 03-27-2015, 02:25 PM
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mapbike mapbike is offline
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Default Re: what did you do to your motorized bicycle today?

Quote:
Originally Posted by GoreWound View Post
I stuffed half a brollo pad into my exhaust to try and quiet my bike somewhat, think I over did it, lost about half my power.
Yep back pressure like that will wipe out the power of these little engines, like curtisfox said a stainless steel or ever pure copper scrubbing pad like can be found at dollar stores and such is your best better as baffle material to quiet i5 down some, but just be aware that even a small amount of it in the pipe will cause you to loose some power since it restricts flow.
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  #7890  
Old 03-27-2015, 04:02 PM
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GoreWound GoreWound is offline
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Default Re: what did you do to your motorized bicycle today?


that's what I used, probably shouldn't have called it a brillo-pad, but you know it's like kleenex. I ened up stabbing it wil some wire untill it loosened up, seems to have helped greatly!
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