For those considering the XSPerformance BBK
This is all based on memories from when dinosaurs roamed the earth and a few details may not be exact.
I’m pretty sure when Yamaha was designing the 650 they had every intention of the bike being capable of being stretched to 750. In fact I think the 650 probably would of been a 750 except for the cachet of the British twins and the forthcoming TX750.
My experience with 750 kits ranges back to 1976 and the wiseco kit. The setup I had in Old Brown was the 10 to 1 CR. Kit, stock cam and BS38 carbs.
I had ridden the stock 650 for about 9 months when it started to smoke on trailing throttle. Most my buddies had done the BBK with VM34 carbs and those bikes would run away and hide from me so I figured had to go into the top end anyway so why not.
Contrary to what I’ve read on the forums I think the BBK is smoother than the stock setup especially at lower rpm. I suspect the vacuum carbs had better velocity through them due to the increased air flow.
The other change I made was a 32 tooth rear sprocket which cruising at the double nickel of the time put the rpms in a better harmonic range.
All and all the BBK made for a much better bike.
The race bike engine was a 10.5 to 1 cr with VM34 carbs, 2 into 1 Hooker Header, pretty wild cam and some clean up of the ports.
It was a beast. Push start only. Even with the cam it still had good low end grunt but could pull 8300 rpm in 5th and was a blast to ride. With a 36 tooth rear it would loft the front end going from first to second.
The take away from all this is both engines were reliable and a noticeable improvement over stock.
This is all based on memories from when dinosaurs roamed the earth and a few details may not be exact.
I’m pretty sure when Yamaha was designing the 650 they had every intention of the bike being capable of being stretched to 750. In fact I think the 650 probably would of been a 750 except for the cachet of the British twins and the forthcoming TX750.
My experience with 750 kits ranges back to 1976 and the wiseco kit. The setup I had in Old Brown was the 10 to 1 CR. Kit, stock cam and BS38 carbs.
I had ridden the stock 650 for about 9 months when it started to smoke on trailing throttle. Most my buddies had done the BBK with VM34 carbs and those bikes would run away and hide from me so I figured had to go into the top end anyway so why not.
Contrary to what I’ve read on the forums I think the BBK is smoother than the stock setup especially at lower rpm. I suspect the vacuum carbs had better velocity through them due to the increased air flow.
The other change I made was a 32 tooth rear sprocket which cruising at the double nickel of the time put the rpms in a better harmonic range.
All and all the BBK made for a much better bike.
The race bike engine was a 10.5 to 1 cr with VM34 carbs, 2 into 1 Hooker Header, pretty wild cam and some clean up of the ports.
It was a beast. Push start only. Even with the cam it still had good low end grunt but could pull 8300 rpm in 5th and was a blast to ride. With a 36 tooth rear it would loft the front end going from first to second.
The take away from all this is both engines were reliable and a noticeable improvement over stock.
Mine originally said Florida too. When I changed the FL to KS the sales tax went away.
