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1987 XR100R Project, a few questions for the gurus

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Well, I am a quad man myself, but the kids are wanting to get into dirtbikes/motocrossing. I have another post about a questionable purchase between the CRF70F and the DRZ/KLX110 above. Well now on the the 1987 XR100R project bike.

This bike was given to me by the brother-in-law so I have nothing invested in the start up. First question relates to jetting, I have already purchased the Wiseco 2mm over piston and had the cylinder bored, what jet size should I step up to on the main and pilot, I figure one size per .5mm, but I could be wrong, I really dont know where to start with the pilot, maybe up 2 sizes??? What is the factory pilot and main sizes?

So far I have dropped about $600 in parts and boring work just to find out that I have a bigger problem. Seems the shift shaft was bent and rebent so many times that it bored out the hole in the crankcase, beyond any possible repair that I can think of, especially running 11:1 compression, he had told me that it leaked a little oil going in, but I just assumed the seal was bad. Also it seems the ratchet shaft hole is in similar shape, but not as bad. I have thought about adding the air that clamps on to the end of the carb like the ones that bbrperformance sells. I did pick up a FMF Powerstroke 4 exhaust, replaced the fork seals, steering bearing, handlebars, grips, handguards, seatcover, front and rear brakes, cables, brake and clutch levers, fenders. Rear shock seems to be in good shape but it is 17 years old so a Works shock/spring of some kind may be in the future. My biggest concern is now the crankcase, I have sunk quite a few $$$$ in the bike to this point and would really like to avoid another $420+ for a new crankcase from the local Honda dealer, do I have any other options? Any suggestions on front springs or rear shock, this will primarily be ridden by 11 y/o who is only 4'9" and weighs about 90lbs. He has abused the 1986 XR80R I bought for him to learn on. Hopefully this will last him a year or two, or at least until his younger brother can grow into it. All suggestions greatly accepted.


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