xbr 500

[guest1830]

 Got a spare XBR500 and was thinking of converting to 650cc......Anybody know anything about the 650 conversion .....have original Honda xl650 crank and bearings, barrel,piston and rings, oil pump, clutch plates and springs...just need help/advise on what to do and what needs modified....

[SteveC#222]

Don't think you can go to 650cc with the original XBR cases as there isn't enough 'meat' at the crankcase mouth to bore out for the barrel. Most only go to 600cc (XL600 barrel/piston) which is a pretty straightforward swap.  If you want to get 650cc the easiest way is to fit the complete 650 Dominator engine with the clutch basket and primary drive swapped for the XBR ones to make the gearing right.

[guest564]

On my 600 conversion I ran the XL600 clutch and primary, with the extra torque it ran the higher gearing no problem and the chain/swinging arm clearance is better than running a smaller sprocket on the rear.

[guest1830]

ok here we go..stripped xbr500 down to casing...the "original" Honda 650 crank, barrel, and piston all fit with enough room to put a fat lady in also... everything turns freely, with nothing connecting with what it should not...Yes the skirt on the 650 is smaller,as the 650 crank is bigger, which allows the room....Still checking the head out to see if it can be used....Anyone done this before as imput would be helpfull

[JOOLZ]

Most people who convert to 650 just use the whole NX engine unit. If you have put the 650 crank in the XBR and there are no clearance issues then I cant see a problem.  If the barrel fits in the case then no problems with that, and the XBR head should bolt straight on with the added benefit of higher compression. I dont know anyone who has done this conversion, but it looks like it will work ok. Hope that helps a little

[guest1830]

thanx Joolz
"good minds think alike"....just hoping the compression doesnt blow the head, and it turns over ok...However all the parts were purchased from Honda and they reckon it can be done, got them cheap when purchased another Xbr. The previous owner bought them years ago to do the conversion, but never got round to it and the bike stood for over 20 years. Only has 5000 original miles. Going to leave that engine intact. Iam doing the conversion on one of my other xbr"s, that has over 90 thousand on it. If all works well should be fun....Always fancied something between the XB and my Vtr...Hopefully all goes well....Thanx again for the imput, especially from someone who knows there stuff..cheers karen

[guest564]

What year model was the 650 crank from? from what I understand the earlier cranks fit, later ones don't, I bought an NX650 bottom end less crankcase and the crank was way too wide to fit the XBR cases. The 650 eats crankcases in race tune.