Quote:
| Originally Posted by bradders but as he said many times it was down on power  the space where the pipes go up thru the shock is very limited and if you looked at his, it had one side much larger than the other. Take a lot of dyno work, messing around and cash to sort that right unless someone got lucky the M620 doesnt have a hoop tho and I know you can fit a 916 shock so just wondered if there was more space, not got the bike home yet so cant just go have a look, but seems those that know think not |
Paul, you could definitely do underseat, and it would work. It looks the nuts and saves a lot of work in an off (of which I had too many). My old B bike had 50-51bhp with the single side exhaust and went down to 48-49 with the underseat and rebuild. However, it isn't that straight forward. I have no direct comparison to the two exhausts with exactly the same motor. In addition, bhp isn't the whole story. Torque is the pulling power, and mine definitely pulled (at times) as well as Senna/Sorted/Ghost/Hugh's bikes, who were all amongst the strongest engines. With (only) 65bhp you should be able to get an underseat exhaust made up to expel the gases fast enough.
I don't see how it would be any harder than on my B bike... the front pipe came under the engine and through the swingarm, then connected with a short pipe from the rear cylinder before meeting the silencer. I don't see why that couldn't be done on a 620. The main technical "problem" with this set-up is that to keep a nice balanced motor the theory states that you should have equal length headers that provide the same flow/backpressure to each cylinder. Obviously this is impossible.
29-Nov-2011, 10:45 
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