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The RMV125 - CR125 Conversion for 99-05 RS50

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mattology
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Joined: Thu Sep 05, 2019 11:36 am
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The RMV125 - CR125 Conversion for 99-05 RS50

Post by mattology » Tue Sep 17, 2019 5:52 am

A long long time ago, in a city across the bay, I purchased my first RS50, and realized that while it was a ton of fun, there were major shortcomings in the transmission department.

While I would go on to swap in a new motor with a working transmission to ride around to class and back, the seed had already been planted into my mind that a motocross 125 engine with its incredibly durable transmission and much more broad spread of power would be an absolute riot in a lightweight bike like this.

Thus, the Racing Moto Vassallo 125 was created...

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Modifications include:

Chassis & Body:
* works style frame modification - polished upper spars, weld line added, bead blasted lower, T5 heat treated frame halves
* swingarm braced and modified to accept Honda CR125 motor swingarm pivot mounting location including oil impregnated bronze bushings
* front cradle modified to accept Honda CR125 motor and Aprilia RS125 radiator
* swingarm spools welded on for rear paddock stand sliders
* rear subframe modified for Honda CR125 motor intake clearance and removal of passenger supports
* oil tank and battery box delete to make room to mount Zeeltronic PDCI-11 ecu
* Xero billet chain adjusters
* Aprilia RS125 radiator
* AF1 Racing billet upper triple clamp
* Front fairing headlight replaced with carbon fiber cap off for track use only


Brakes & Controls
* Brembo RCS15 front master cylinder with stainless braided line
* Braketech Axis Cobra SS 320mm full floating front rotor (custom designed joint venture between myself and Jeff at BrakeTech)
* EBC HH FA194 front pads
* Ti front brake hardware
* stockish? who knows? rear pads ( i don't use the rear brake much at all, and when i do, i land on my head)
* 1991 CR125 throttle assembly & throttle cable
* 1991 CR125 clutch lever & clutch cable
* SATO RS4-125 adjustable rearsets with GP shift lever configuration
* 3d printed carbon fiber reinforced nylon peg sliders
* Woodcraft billet aluminium clip-ons


Engine and Driveline:
* Honda CR125 motor - 91 Cases, 99 Swedetech Stock Moto Cylinder, 6-speed transmission from 91 and 95 model year parts
* Phathead racing billet cylinder head for CR125 with RSA tech cylinder insert designed and manufactured by me taking cues from Jan Thiel and Frits Overmars information sharing on Pit Lane and KiwiBiker
* 2007 Honda CR250R Mikuni TMX38 TPS Equipped Carburetor equipped with Solenoid power jet for faux EFI on the fly
* 3d printed carbon fiber reinforced nylon Fibonacci inspired intake horn with Uni filter
* CNC billet intake designed by me for use with VForce reeds for Honda RS125 / Husq CR125 reed block (Fits Honda CR125; pn# V301C)
* Honda NX4 RS125 B-kit expansion chamber, custom modified to fit RMV125
* DLR Silencer for Aprilia RS250 challenge bike
* 428 chain conversion with custom 428 RS50 sprockets from Rebel Gears
* Swedetech billet O-ring exhaust manifold
* Swedetech J-arm shift linkage
* Swedetech engine covers
* Swedetech stator cover
* Rising Sun Cycles drill start setup
* Snugulator chain roller setup


Electronics:
* Zeeltronic PDCI-11 digital programmable ignition with power jet solenoid control
* Electrex UK Stator with charging coil
* Trailtech RR150 adjustable DC full wave rectifier and voltage regulator
* Aim sports MXL Pista datalogging dashboard
* Autometer LED shift light (it sucks, it's not bright enough, I never even see it going off)
* Aim sports LCU wideband O2 sensor
* Aim sports GPS05 GPS and Inertial measurement unit
* Dynojet quickshifter, enabled via Zeeltronic
* Full custom wiring harness utilizing Deutsch DT & DTM connectors
* Lightweight sealed battery


Suspension & Tires:
* DNM MT-BAG rear shock with 800 lb rear spring, adjustable rebound and damping as well as preload
* Dual compression and rebound equipped forks utilizing two Marzocchi rebound legs
* RaceTech Gold Valve cartridge emulators
* RaceTech Springs (AF1 High Performance Fork kit for RS50's)
* Martin77 / Mattology custom fork preload adjusters
* Sava 17" Slicks F001 95w / R001 115w
* front axle drilled for thru-bolt to mount Sato axle sliders

and now, some video:

https://www.youtube.com/watch?v=3NiJxNjSmqI

https://www.youtube.com/watch?v=1c28A9KV2Bs

https://www.youtube.com/watch?v=IlwLuMh3U10

https://www.youtube.com/watch?v=2bGprzosStc

https://www.youtube.com/watch?v=YL-CDZE-QK0

https://www.youtube.com/watch?v=VuTQ1CYOOxw



Hope you enjoy it, let me know if you have any questions, like if you want to build one yourself :)
Last edited by mattology on Tue Sep 17, 2019 9:50 am, edited 1 time in total.
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jkv357
Posts: 228
Joined: Fri Dec 01, 2017 6:47 am
Location: WI
Replica: '99 GPR EBE-075
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Re: The RMV125 - CR125 Conversion for 99-05 RS50

Post by jkv357 » Tue Sep 17, 2019 8:01 am

Thanks Matt!
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toratora
Posts: 3161
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Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
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The RMV125 - CR125 Conversion for 99-05 RS50

Post by toratora » Thu Sep 19, 2019 11:02 pm

Nicely done Matt.
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