xr250l electric start conversion


  1. I'm stuffing a CBX e start in my 92 XR250l and having some problems with deciding which is the proper left mainshaft  bearing.  The OEM bearings for a XR250l come with a seal on one side.  The attached pic shows the mainshaft bearing on my XRL with a bearing seal but the CBX bearing has no seal.  I am wondering if the CBX has no seal in order to allow lubrication to the e start gear which the XRL doesn't have.  Both crankcases have an oil passage on the bottom that allows oil return to the sump.  Any comments will be appreciated.
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  3. Oh right, intro.  First bike was a SL100, (bought new), this was my gateway drug to a rebuild of a H1 when I was 16, (blue metalflaked the frame - hey, it was the 70's).  Coupla more bikes then a hiatus for 30 years.  Picked up a 78 CM400 5 years ago, hey this is fun!  Ended up with a XR400 and a ZRX1200.  Found the ZRX too inviting in the 200 - 250 kph range and sold it.  The XR400 was a beautiful bike but too big and heavy for me in the single track / tight woods we ride.  Picked up a xr250L but found kicking it over made me piss blood.  Hence the search for an e start conversion.  Sourced a CBX bottom end and also had my kidney out, so I can kickstart and not bleed but the estart still seemed like a good idea.  Also, still like the street so I've got two GT550's a T500 and a RZ350, (wifes bike) in various states of rebuild.  Also have the 2 strokes version of a Thumper, a 76 TS400, but I think my wife wants to upgrade from her TW200 to it.  We'll see after she kicks it over though.

Well into it, so not likely to stop now. But a 250 making you piss blood starting is just plain wrong.

 You can start a properly tuned 250 with your hand. (literally).

If it's not 1st or 2nd EASY kick, you need SETUP work, not e start. (but COOL!!)  ;)

Thanks for the reply,

Well, the bleeding was from a nasty kidney tumour, the kicking just brought it to my attention, hmm, I guess that XR saved my life in a way.

As far as starting, I did a bunch of mods, snorkel removal, XRR carb, 280 kit, XRR header, unifilter, so I'm still sorting that.  It started easily with the estart but I found the engine running hotter than before.  I started messing with the jetting thinking it was too lean and hadn't really got that sorted before I tore it down again to replace the leaky countershaft seal.  That's when I noticed the discrepancy in the bearings, I've got the bottom end in the frame but want to figure out whether or not I should pull off that main bearing seal before reassembly.

Here's a pic of the start of my build, well with the XR250L partially torn down and the CBX engine with the e start.


The CBX250 is a late 80's and the 250L is a 92. I'd started to look for a CBX engine to do an estart conversion and found they were few and far between. After much internet searching I went to Supersport in Langley and he had this engine sans head sitting on his shelf.

The frame was nasty looking so I touched it up with a spray bomb. But covering up rust didn't seem right so I stripped it, the brush on stripper kinda worked but a can of aircraft stripper used repeatedly with rinses in between did the job, (eye and breathing protection and do it outside is a must).







For the frame I used a product from KYB coatings, it's 4 stages comprised of stripping, rust protection, primer and paint.  I liked the idea of being able to use a brush and do it indoors.  Funny, the primer was a thing of beauty but the final coat of black had wrinkles in it.  It's solid now that it's dry though.


I wanted to keep the XRL crank since the CBX has a shorter stroke and putting a 280 kit in would only give me a displacement increase of 15 cc.  Unfortunately the CBX crank is required for the longer shaft on the flywheel side to accomodate the e start gear. 




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