Electric start project
  • rcthirty
    Posts: 7
    Joined: Sat Sep 21, 2013 8:18 am

    Electric start project

    by rcthirty » Wed Apr 30, 2014 6:51 am

    A couple of months ago I bought a Service Honda Junior R from one of the members here. Service Honda makes special Honda conversions, among them the "Junior R" which is a CRF250R engine in a CRF150RB frame. I actually wanted the Junior X which is Service Honda's electric start model (CRF250X). I bought a 05 250X motor off eBay along with a wiring harness and some missing electrical components. After installing the engine I had to find locations for the electrical components like relays, rectifier, battery and starter solenoid. That was the toughest part. The rectifier is up under the front number plate but all other components had to be located in the sub frame. A small Lithium battery is in the air box. Brackets I had to fabricate and the wiring harness was stripped and shortened or lengthened to the components locations. After all was done I gave it a test as seen in the video. What amazes me is how quick it started with the untested eBay motor. I don't know how to embed videos on this forum but here's the link.

    https://www.youtube.com/watch?v=RSqg8jj2ZZ8

    I still have to do some jetting as the Carb is a 40mm not the CRF250x's 37mm. Still.. this thing starts so fast you can hardly release the start button fast enough. I wonder if a battery powering the coil would make the 150RB start as fast ?
    2008 Service Honda Junior R
    2007 CRF-150 RB (sold)
    2009 Suzuki DR-650 with FI
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    riddler9
    Posts: 1096
    Joined: Thu Apr 22, 2010 12:09 pm

    by riddler9 » Thu May 01, 2014 8:14 pm

    Nice project. Did you do anything other than the X motor and electrical - suspension, frame enhancements, etc.? What did you do for exhaust? How does the weight compare to the 180 lb SH build?
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  • rcthirty
    Posts: 7
    Joined: Sat Sep 21, 2013 8:18 am

    by rcthirty » Fri May 02, 2014 4:57 am

    According to Service Honda, the dry weight of the Junior X is 180 lb dry. That sounds a bit optimistic to me.Although in riding it feels the same as my 150RB. Of course the 250X motor is a torque monster compared to the 150. I still have my CRF-150RB as seen in the background of the video. I had set that up with a flywheel weight and stage 1 torque cam which made it better but nowhere near the 250X motor.
    I think the Junior R or X use the Stock CRF150 chassis except for changes to the engine mounting so there are no enhancements to frame or suspension. I weight 120 lb and find the stock suspension acceptable.
    It looks now like I'll be keeping this and selling the CRF150RB. :D
    2008 Service Honda Junior R
    2007 CRF-150 RB (sold)
    2009 Suzuki DR-650 with FI

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