XS650 Crankshaft - ideas needed.

Heres a fancey engine , in pieces . ( hope they know where they all go :wink: )

by the famous War Criminal & inventor of the TIGER TANK , Dr. Porshe .

These poved to be overly sophisticated , particularly when the dirt got in them , and the MUD . then there was the DUST , and the odd Molotov Cocktail .
( co - incidently read REAL Molotov Cocktails have 10 % Ethanol . perhaps the Govts planning something . :lol: 8) ) ahem right. ANYWAY .
Not to Mention the Knebellwurfurs / Stalins Organs & the Odd T34 & T72 .
Which were much MORE BASIC . and Didnt BREAK .

So . . . Simplicity is to be encouraded . Strived for , even . If its not there it doesnt weigh anything & cant break .

or see youre local Hippies / silver smiths , & knock up a three bearing one piece Commando C'case for a known shaft !

while were there . . . :cry:



Bit Like A M/V , the Counts one . :wink:
( we digess :lol: :wink: bit of class , anyway . )

http://www.phoenix-crankshafts.co.uk/images/sump1.jpg
[url=http://www.google.com.au/imgres?q=W+O+Bentley+.+Crankcase&rls=com.microsoft:en-au:IE-SearchBox&biw=1280&bih=856&tbm=isch&tbnid=lVVoWb3a0MmRHM:&imgrefurl=http://www.phoenix-crankshafts.co.uk/steel-crankshafts.html&docid=tQ01g1XB_6Ur6M&imgurl=http://www.phoenix-crankshafts.co.uk/images/sump1.jpg&w=220&h=175&ei=enfjUZy4BYbRkQWv44GgCw&zoom=1&iact=hc&vpx=763&vpy=206&dur=93&hovh=140&hovw=176&tx=71&ty=70&page=1&tbnh=140&tbnw=176&start=0&ndsp=31&ved=1t:429,r:4,s:0,i]http://www.google.com.au/imgres?q=W+O+B ... 4,s:0,i:92[/url]

I think that a 59.5mm stroke is too extreme. My Triumph 500 was built out of 650 parts with a 63mm stroke and the long rods . It was severely lacking in torque and thus very difficult to ride well. It could have been OK with a 6 speed box. I rode it in later years with straight pipes and a 5 speeder and reasonable tyres , and it was much better than when I had it in the 60s and 70s. I was more thinking of a 750cc motor with an 84mm stroke crank assembled out of perhaps SR500 or TT500 Yamaha bits. I think that would probably cop 10,000 RPM.

acotrel said:

I think that a 59.5mm stroke is too extreme.

Click to expand...

From first hand experience it is spot on and trackable with a six speed gear box.

acotrel said:

I was more thinking of a 750cc motor with an 84mm stroke crank assembled out of perhaps SR500 or TT500 Yamaha bits. I think that would probably cop 10,000 RPM.

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84mm stroke and 10,000 rpm? I don't think so. Mean piston speed is too high.

89 mm @ 7,000 rpm = mean piston speed of 4,088 fpm
84 mm @ 10,000 rpm = mean piston speed of 5,512 fpm

You are really getting into the exotic area of maybe modern fuel dragsters.

See the link below:

http://en.wikipedia.org/wiki/Mean_piston_speed


For a Norton twin, given all the supporting infrastructure you have to work with, keep the mean piston speed at or below 4,000 fpm.