On my continuous journey of tuning intake and exhaust for the 700cc project (https://www.xs650.com/threads/700cc-kit-with-a-shell-1-cam-in-a-78xs650e.65405/#post-819839) I have stumbled on what this motor may be capable of by removing the 26” commando mufflers that I bought for the project. Here in the latest iteration.
I have removed the airbox and substituted it with UNI pods. The headers are 1.75” which were sleaved down with Torque inserts at the exhaust port and 1 3/8” TPOs from MMM. I ran out of mains and running lean, but even when I fix that I don’t think the performance will be better than what I got with the stock air box and stock headers in the link above. But look at what happened when, for the hell of it, we removed the commando mufflers
Quite incredible…. Look at that mid-range... The bike is lean above 6K and had I had 145 or 147.5 mains on hand with me, the top end would have kept climbing. So now I would like to rethink what I use for the mufflers and welcome knowledgeable suggestions. If anyone has had experience with 18” cone engineering megaphones (straight through or the quitter version https://www.mikesxs.net/18-in-stain...html?fits-motorcycle=Yamaha/XS650/XS650E/1978) or the https://www.mikesxs.net/17-2-in-sta...html?fits-motorcycle=Yamaha/XS650/XS650E/1978
Or emgo/heiden tuning 17” with removable core. Appreciate your feedback. Maybe I need two sets of mufflers, one for the week and the other for the weekend
Here is the dyno sheet for reference: we did not rig up a way to hold the sniffer as it was late in the day and I was way over my booked time. The main on here is 142.5
here is the run with mufflers:
I have removed the airbox and substituted it with UNI pods. The headers are 1.75” which were sleaved down with Torque inserts at the exhaust port and 1 3/8” TPOs from MMM. I ran out of mains and running lean, but even when I fix that I don’t think the performance will be better than what I got with the stock air box and stock headers in the link above. But look at what happened when, for the hell of it, we removed the commando mufflers
Quite incredible…. Look at that mid-range... The bike is lean above 6K and had I had 145 or 147.5 mains on hand with me, the top end would have kept climbing. So now I would like to rethink what I use for the mufflers and welcome knowledgeable suggestions. If anyone has had experience with 18” cone engineering megaphones (straight through or the quitter version https://www.mikesxs.net/18-in-stain...html?fits-motorcycle=Yamaha/XS650/XS650E/1978) or the https://www.mikesxs.net/17-2-in-sta...html?fits-motorcycle=Yamaha/XS650/XS650E/1978
Or emgo/heiden tuning 17” with removable core. Appreciate your feedback. Maybe I need two sets of mufflers, one for the week and the other for the weekend
Here is the dyno sheet for reference: we did not rig up a way to hold the sniffer as it was late in the day and I was way over my booked time. The main on here is 142.5
here is the run with mufflers:
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