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Post by speedy1125 on May 1, 2011 0:28:52 GMT -5
well i ordered the hoca 50mm piston and ring set. went back to what was on it for now.
Modify:
PFS ships to me fast since i am in NC they are in GA
Might just wait. The head isnt torqued down yet . might just wait for the new piston
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Post by 90GTVert on May 1, 2011 6:51:15 GMT -5
Ah, now the ring around the piston makes sense. With clearances that close, I'm surprised you weren't getting a bunch of detonation. I guess the combustion chamber is plenty big with the 50mm kit. Is it misaligned or just too small of a diameter? Looks like it only hits on 2/3 of the piston's circumference.
If you do ever go back to 47mm, I'd probably stay with the stocker. You had good results with it. Then you would still have a spare or could sell off the other.
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Post by lshigham on May 1, 2011 6:53:15 GMT -5
I had that problem with a 47mm BBK sold to be used with the stock head, it crushed the piston and trapped the rings, causing a rather large oil cloud like you describe.
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Post by speedy1125 on May 1, 2011 7:32:03 GMT -5
Ah, now the ring around the piston makes sense. With clearances that close, I'm surprised you weren't getting a bunch of detonation. I guess the combustion chamber is plenty big with the 50mm kit. Is it misaligned or just too small of a diameter? Looks like it only hits on 2/3 of the piston's circumference. If you do ever go back to 47mm, I'd probably stay with the stocker. You had good results with it. Then you would still have a spare or could sell off the other. Yeah it looks like not enough material was taken out of the head. I bet i could do it with a dremel. |
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Post by speedy1125 on May 1, 2011 7:45:05 GMT -5
would have been a great day for a ride too. I broke my carb spacer so I couldnt go ride even if i did put the stock 47 back on  |
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Post by speedy1125 on May 1, 2011 7:55:02 GMT -5
Ah, now the ring around the piston makes sense. With clearances that close, I'm surprised you weren't getting a bunch of detonation. I guess the combustion chamber is plenty big with the 50mm kit. Is it misaligned or just too small of a diameter? Looks like it only hits on 2/3 of the piston's circumference. If you do ever go back to 47mm, I'd probably stay with the stocker. You had good results with it. Then you would still have a spare or could sell off the other. Its too small of a diameter. I need to take a dremel to it. www.partsforscooters.com/169-203_50mm_Piston_Kit?sc=11&category=735HOCA makes good parts right? |
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Post by speedy1125 on May 1, 2011 8:48:15 GMT -5
I wonder if i stacked up 3 or 4 base gaskets if that would help this clearance issue
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Post by reveeen on May 1, 2011 14:00:37 GMT -5
Sure looks like something isn't quite square?
I wonder if i stacked up 3 or 4 base gaskets if that would help this clearance issue
I would *think* so (but something isn't square, be it the block deck, the cylinder, the crank, or the rod), yes, a couple of extra base gaskets should be a quick and dirty "fix".
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Post by speedy1125 on May 1, 2011 14:35:51 GMT -5
Sure looks like something isn't quite square? I wonder if i stacked up 3 or 4 base gaskets if that would help this clearance issueI would *think* so (but something isn't square, be it the block deck, the cylinder, the crank, or the rod), yes, a couple of extra base gaskets should be a quick and dirty "fix". Just sloppy head work it looks like to me. CORRECTION: Lasted 400 miles. |
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Post by speedy1125 on May 1, 2011 15:41:29 GMT -5
Used my Ingersol Rand super gun with a borrowed 1-1/2" 3/4 " drive socket with a 3/4 to 1/2 adapter...spun it right off.  MODIFY: I ordered a 1000rpm contra spring thats why im taking the clutch apart. |
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Post by rocketdog on May 2, 2011 6:47:38 GMT -5
Sorry to hear that your having trouble Speedy. I don't really have any first hand experience with Hoca, but all of the pistons that I have seen are like the one you have pictured. With the exception of Airsal's.  I think the base gasket idea is a sound one. Now the question is, how many? If I can find my notes on the compressed thickness I'll share them. It looks like the piston actually hit the flat part of the cylinder head that surrounds the combustion chamber. Is that the problem? RD |
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Post by speedy1125 on May 2, 2011 6:56:26 GMT -5
Sorry to hear that your having trouble Speedy. I don't really have any first hand experience with Hoca, but all of the pistons that I have seen are like the one you have pictured. With the exception of Airsal's. I think the base gasket idea is a sound one. Now the question is, how many? If I can find my notes on the compressed thickness I'll share them. It looks like the piston actually hit the flat part of the cylinder head that surrounds the combustion chamber. Is that the problem? RD Yes thats the problem I was thinking 3 base gaskets. |
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Post by rocketdog on May 2, 2011 16:36:47 GMT -5
Depending on how much piston to cylinder head clearance we need. Steel rod cast piston V8s about .040 inch. Small four cylinder engines a bit less. I don't really know a firm number. I found the specs for a 47mm base gasket. Compressed 47mm base gasket-.5mm or .020 inch. Three should be plenty. Hope that helps.
RD
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Post by speedy1125 on May 3, 2011 7:17:10 GMT -5
thanks RD
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Post by speedy1125 on May 3, 2011 7:57:54 GMT -5
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