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open and shut case


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elmo

 
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open and shut case

Sat May 14, 2011 2:50 am » Post: #1 » Download Post

hey everyone just havin a bit of a grind and cleanup of me cases while its apart if anyone can see any problems or tips shoot away ill get some more pics up soon



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elmo

 
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Sat May 14, 2011 3:57 am » Post: #2 » Download Post

sorry had some trouble loading pictures hopfully they work now .
the blue lines are were ive removed larger amounts and the arrows on the last photo red is were i reshaped the edges of the main bearing holders and blue
is were i reshaped and smoothed .
i still have to port match the heads and reed carrier but its come alongway from the standard with casting marks evey were
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elmo

 
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Sat May 14, 2011 3:58 am » Post: #3 » Download Post

http://cid-091891bbbe80dea7.photos.live.com/self.aspx/nsr250%20stuff
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elmo

 
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Sun May 15, 2011 6:39 am » Post: #4 » Download Post

"bum"p"
surly someone here has had a go at cleaning up the ports and cases on an mc21 iv done heaps of single two strokes but this be my first go at a twin cylinder.
so im just wondering is there any major improvment with alot of time spent or am i better just to clean them up and chase ponys else were.
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chucky
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Sun May 15, 2011 1:40 pm » Post: #5 » Download Post

ive not done any or a mc 21 but my friend did my aprilia rs 250 when we raced it he just went over the cases and matched the barrels to the cases also keep in mind that if match the barrels to the cases mark each barrel so you know which is front or back so when you put it back together you dont mix them up
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elmo

 
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Mon May 16, 2011 12:21 am » Post: #6 » Download Post

ok thanks good idea
i found this old link witch eased my mind as iv pretty much done exactly what this guy did
exept filling the oil wells with quick steel .
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elmo

 
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Mon May 16, 2011 12:23 am » Post: #7 » Download Post

http://www.hm3.aitai.ne.jp/%7Eaichi/kaizou2.htm
http://www.hm3.aitai.ne.jp/%7Eaichi/kaizou4.htm
http://www.hm3.aitai.ne.jp/%7Eaichi/kaizou5.htm
http://www.hm3.aitai.ne.jp/%7Eaichi/kaizou6.htm
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nsrdownunder

 
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Mon May 16, 2011 6:12 am » Post: #8 » Download Post

The picture in the last link of the modified head . Fronty didn`t you chop a head in half and there was no room for this mod ? I am guessing there wouldn`t be much cooling going on in that head . It looks like they used a few rods
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elmo

 
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Mon May 16, 2011 10:49 am » Post: #9 » Download Post

yeh had a good laugh at that
lot of rods and effort for little gain
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Matt@TYGA
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Tue May 17, 2011 8:43 am » Post: #10 » Download Post

Study the pictures of the cases as there's a fair bit to learn from that. And to be honest you don't need to cut as much as he's done to get the results.

Matching transfer between cases and cylinder is a good idea. As is grinding all sharp edges and casting flashing. Grind a radius on all edges, corners and what have you. Fluid likes radii, not sharp edges.

Don't knife edge port entries. Transfer flow is subsonic so nothing gained.

Do match up the RC valve. Lots to be gained here.

Don't polish anything to a mirror finish.
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elmo

 
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Tue May 17, 2011 9:46 am » Post: #11 » Download Post

thanks matt iv'e pretty much done exactly as you said .
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Matt@TYGA
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Tue May 17, 2011 11:12 am » Post: #12 » Download Post

Well you're good to go then! Very Happy

With the heads, central plugs are good, but a pair of rear heads is almost as good. The stock front head will suffer detonation once you start getting mojo out of the motor.
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elmo

 
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Wed May 18, 2011 10:55 am » Post: #13 » Download Post

awsome thanks i have two rear heads just waiting on my crank as its getting new bearings
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elmo

 
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Wed May 18, 2011 11:04 am » Post: #14 » Download Post

while i got you MATT what will a full gasket and seal kit set me back for mc21 dryclutch include crank seals just rough idea will be good
Thanks
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