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Post by 90GTVert on Nov 22, 2012 19:53:21 GMT -5
You're prob getting less combustion chamber volume, so more compression. It's not a squish band style head, but that really doesn't make a big difference most of the time. In these 2Ts, high performance pretty much just means it's setup for good compression and they're always the squish style. Some have more fins for better cooling. Just noticed you said you didn't know how to check, so here's a vid about squish clearance. www.youtube.com/watch?v=ZUe0p0DqFCk
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Post by one1 on Nov 22, 2012 20:32:18 GMT -5
Ahh thanks. I'll probably have to do it like this since I don't have thick solder.
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Post by 90GTVert on Nov 22, 2012 20:57:19 GMT -5
Should work.
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Post by one1 on Nov 22, 2012 21:14:10 GMT -5
Wouldn't you have some slight angle issue on the piston to compensate for this way since the piston isn't perfectly tight in the cyl? Like with this way you'd get a reading that is actually more than it is when the piston is perfectly flat in the cyl and not being biased to one side, wouldn't you?
Seems to depend on if you are measuring on the side the pin rocks to or if you are measuring on the side the piston doesn't rock to (inline with the pin)...... but you'd have to know and be on the line. Did I miss that technical detail on where to place it in the video and I wasn't paying attention?
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Post by one1 on Nov 22, 2012 23:23:58 GMT -5
I photoshopped the lip on the old head to fill in the spot where it is countersunk and compared the size between the hole and the chamber to the new head and it looks identical to me. It seems that countersunk part is the difference in the 50 and 52mm. (things you know, things I am learning). So we accidentally bumped the compression up, kool!
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Post by 90GTVert on Nov 23, 2012 17:04:06 GMT -5
Some will tape a piece of solder all the way across the piston crown to check. If you aren't pushing the limits, it shouldn't matter.
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Post by one1 on Nov 24, 2012 16:38:53 GMT -5
Random thought, is it still 97cc at 52mm or is it 110cc? I guess the stroke would be the difference in the 52mm 97cc and the 110cc.
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Post by 90GTVert on Nov 24, 2012 19:05:11 GMT -5
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Post by one1 on Nov 24, 2012 19:08:02 GMT -5
Yeah but I don't know the stroke on the engine. (152fm Linhai, Yamaha) Oh well..... All I see for the 52mm is 110cc advertised everywhere so that's the only reason I even ask.
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Post by 90GTVert on Nov 24, 2012 20:02:26 GMT -5
It's most likely 89cc, max would be 96cc. That's 42-45mm strokes, the most common. I have a 110cc and that is a 54mm bore with a 48mm stroke. Both aftermarket parts. Advertisers love to say the engines are bigger.
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Post by one1 on Nov 24, 2012 21:07:36 GMT -5
Dunno, but I did manage to take a pic this time when I was in there and all the covers were off.
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