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Post by MAReames on Apr 27, 2011 2:02:33 GMT -5
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Post by 190mech on Apr 27, 2011 4:40:17 GMT -5
No,the barrel diameter is too large,the crankshaft stroke is 39(50cc) and 42(90cc),even if you ground out the cases for the barrel to fit,the shorter stroke would make the port timing waaay off..
Thats a 50mm bore cylinder,a stock 90cc uses a 52mm bore...
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Post by lshigham on Apr 27, 2011 5:52:13 GMT -5
Not to mention the 4mm squish you'd end up with.
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Post by 90GTVert on Apr 27, 2011 6:37:18 GMT -5
I tried it long ago before I knew anything about 90cc motors, or much about 2Ts in general really. At that point, lots of websites were saying you "may" need to clearance the cases. I figured there was a shot it would fit. The only way these big kits are likely to work is if you have a 1E40FM rather than the more common 1E40QMB. That's pretty much a 90cc motor, with a 49cc bore. 49ccscoot.proboards.com/index.cgi?board=yamajog&action=display&thread=352 |
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Post by reveeen on Apr 27, 2011 6:40:08 GMT -5
Or the wrist pin that may, or may not fit (10mm vs 12mm).
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Post by MAReames on Apr 27, 2011 13:40:32 GMT -5
So whats is the biggest I can go with out modifing the casing? Also just so you know I have 12mm pin.
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Post by reveeen on Apr 27, 2011 14:21:45 GMT -5
Without splitting the case: 70cc
But keep an open mind, you may pull the top end only to find the bottom "needs" a crank. I know it's a PTA, but you should pull the cylinder before you consider ordering any parts.
By the time you buy a cylinder, crank, bearings, seals, and gaskets it may be cheaper (and faster) to just swap a 90 in there.
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Post by MAReames on Apr 27, 2011 14:59:02 GMT -5
I already got it apart the crank is fine. I bought this engine because it had a recent 70cc kit on it but the guy that installed it didn't deburr the jug and it scraed the piston so bad that the rings got weld at the bottom by the exhaust port.
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Post by reveeen on Apr 28, 2011 20:14:22 GMT -5
The "trouble" with having a 12mm piston pin is:
The traditional Minarelli engine in the 50cc variety has a 10mm piston pin. When you buy an "economy" cylinder kit for a Minarelli with a 12mm wrist pin the assumption is you have a stroker crankshaft in there and the port timings are a bit different (or not optimized for the short stroke engine). So it falls to you to: 1) decide upon the desired port timings, and 2) adjust the cylinder accordingly.
What I'm trying to tell you (I guess) is: whatever you do here, it is not "plug and play" (for maximum benefit), you are going to have to pay attention.
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