DISCLAIMER: The modifications described in the following text are for educational purposes only. In no way do I recommend that you apply these modifications to your own motorcycle. If you do choose to go ahead and modify your motorcycle based on the information in this document you will accept all responsibility for your own actions. The author(s) of this document, and host(s) providing it for you, accept no responsibility whatsoever. If you are unqualified to make any of the changes described herein but are bent on doing the modification, seek out a knowledgeable friend or professional mechanic for assistance.

Instructions courtesy of Craig Mattless:

These mods sound complicated but, now I have done it once, it would be pretty straight forward to do it again. The CBR starter I used is a Mitsuba SM13 but it's case is approx 5-10mm longer so the steps are as follow;

Remove the old starter completely but keep it as you will need some bits from it.

Cut approx 7mm off geared end of new starter spindle, Sounds harsh but it works well, I used a mini grinder with thin metal cutting disc.

Remove the 2 long bolts which hold the starter together from both old and new starters - don't get the bits muddled.

Take rear section off the old starter which has correct fixing holes. You need to elongate these holes by turning them into slots. If you don't elongate the fixing holes enough the starter will prevent the engine case from sealing. I did this with a small circular file and it was easy. The CBR starter is longer overall so these slots need to allow it to move closer to footbrake side of bike by approx 7mm. You don't need to be too accurate as you can tighten the fixing bolts when everything else is fixed in place!

IMPORTANT. If you use the old brush holder the motor spins the wrong direction! I found out the hard way.

Remove the small nut from the live terminal on the new starter and remove the plate which houses the brushes.

The new brush holder needs to be trimmed to allow the 2 long bolts to pass through. I just marked it with a pencil and trimmed a small section out where the bolts touched using a junior hacksaw. 

Tip! There is a tiny single metal tab on the new brush holder plate which needs to be cut off to allow re-assembly! It becomes obvious when you try to put it back together. They are location tabs but the thing cannot move any way!

Re-assemble the CBR starter with old 'rear section' in place.

It seems a lot of effort but it works well and saved me £100 as the CBR starter was only £15 eBay.

Proper engineering drawing below

Craig
November 2010