Another new project bike build! 125cc

nidyanazo

nidyanazo

New Member
Well it's a motorcycle, but you guys will probably like it. This is a street legal CA plated Aprilia RS50 (Gran Prix replica) that I'm swapping a motocross race motor into.

http://www.youtube.com/watch?v=F7wcdJ0Furo

It's going to be under 200LB and have about 35HP to the tire..

Anyone who has ridden a 125cc two stroke dirtbike knows how much these motors love to be ringed out!

So here's the start, My bike before I took the engine out.


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Here I was still deciding on what engine to go with..
‪Start of RS50 engine swap project‬‏ - YouTube

A quick riding video with the stock (modified minarelli 70cc engine)
‪Aprilia RS75 onboard run‬‏ - YouTube

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Here's the donor bike I bought for the project. It's a 2000 YZ125
Rides great, pops wheelies with ease.

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Just ordered this Arrow expansion chamber and kevlar silencer..Will cut it up and use the 'header' from the FMF pipe that came on the YZ to make the exhaust fit..

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Well today's the tenth day working on this project, with an average of about 4 hours per day. I'm expecting the arrow pipe to arrive on thursday, at which time I'll take the bike to prime fabrication and have them weld it up, and lengthen the kick-starter and gear shift (it's gonna be a GP shift pattern!!).. Tomorrow I'll get the radiator plumbing all set, the new sprocket is on the wheel and I have the 520chain all ready. Just need to shorten it the correct amount. Things are really heating up!





 
Man there is too many Crickets lol.

I followed this thread this is gonna be a fun bike for sure! I have been in Auto mechanics/construction/Bodywork etc all my life. I ''never ever'' get tired of seeing watching or doing these type's of projects. Really looking forward to the maiden voyage. (^) Since my S6T and S6S I have quickly grown very fond of these italian beauties. Thanks for sharing.
 
Got an onboard video coming in a few mins..
Unfortunately found out my fuel line was kinking up and starving the engine of fuel at high rpms. Fixed that with better fuel line, ant the bike feels great.
Tops out at at a speedo indicated 85mph, so more like ~78mph.. Could def. regear a few teeth smaller on the rear sprocket. The tires are shot so I was pretty haired on going too quick, so with some good sticky rubber I can tell it's going to be excellent. I got a racetech progressive spring kit ready to go on
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a properly fitted K&N in the mail... The VFORCE reeds need to get installed..Got a new clutch kit coming because it feels like its slipping a bit...
..Guess thats all for now..

Here are a few more pics of the bike as sits today..

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