Piston is hitting head on new rebuild help please

• Piston is hitting head on new rebuild help please
  Posted by Rytie77 on 18 Jun, 2013 13:41
• Hi iam new hear I just had my motor redone I get it home and start putting everthing back together I put the kick start push down on it and goes up and stops in pull head and it moves up and down put head on no nuts and the piston hits head can I run to base gaskets and what will that change thank u
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• #1 Reply
  Posted by MotorGeek - Jerry Hall on 18 Jun, 2013 14:09
• Quote from: Rytie77 on 18 Jun, 2013 13:41

  Hi iam new hear I just had my motor redone I get it home and start putting everthing back together I put the kick start push down on it and goes up and stops in pull head and it moves up and down put head on no nuts and the piston hits head can I run to base gaskets and what will that change thank u
  

  
  There is a reason why the piston is hitting the head.  Do not just start stacking gaskets to stop the piston from hitting the head.  There may be other problems.
  
  Did  you talk to the guy that rebuilt the engine?
  
  Was the head milled?
  
  Do you have the wrong piston?
  
  Was the connecting rod changed?
  
  Was the cylinder base or head gasket surface machined?
  
  Did you bore the cylinder?  If so how much was it over-bored?
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• #2 Reply
  Posted by Motoman991 on 18 Jun, 2013 14:52
• ^^^Mr Hall covered everything.
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• #3 Reply
  Posted by Dezsled on 18 Jun, 2013 15:44
• With each question Jerry asked, it points to different aspects of the engine to look into. So if you can help him pin it down you'll be riding again a lot sooner
  
   
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• #4 Reply
  Posted by Rytie77 on 18 Jun, 2013 16:18
• Thank u for responding ok has a new hod rod crank was bored over not sure how much and not sure if it was milled I called the guy who built it and no call back but I put piston all the way down in the stroke and it looks like its perfectly level with the exhaust port
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• #5 Reply
  Posted by MotorGeek - Jerry Hall on 18 Jun, 2013 18:12
• Quote from: Rytie77 on 18 Jun, 2013 16:18

  Thank u for responding ok has a new hod rod crank was bored over not sure how much and not sure if it was milled I called the guy who built it and no call back but I put piston all the way down in the stroke and it looks like its perfectly level with the exhaust port
  

  
  Does the edge of the piston rise above the top of the cylinder when the piston is at top dead center?  If so, is the hole in the head gasket large enough for the piston?
  
  If the piston will go through the head gasket is the step in the head at the outside of the squish band larger than the piston?
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• #6 Reply
  Posted by Rytie77 on 18 Jun, 2013 19:27
• It does not hit gaskit the edge of piston comes out of the cly a little but then drops back in the cly
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• #7 Reply
  Posted by LT250RWV on 18 Jun, 2013 20:35
• Get us some pic so we can see what your talking about.Pics help us help you.
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• #8 Reply
  Posted by Stpltn250r on 18 Jun, 2013 21:25
• get some calipers and measure the bore of the dome and the bore of the cylinder.
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• #9 Reply
  Posted by Rytie77 on 19 Jun, 2013 07:51
• The piston pots out of the cly then drops below
  
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• #10 Reply
  Posted by MotorGeek - Jerry Hall on 19 Jun, 2013 08:08
• What is the piston size?  What is the number on top of the piston?
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• #11 Reply
  Posted by Rider414 on 19 Jun, 2013 09:27
• Nice looking Jug - 
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• #12 Reply
  Posted by Dezsled on 19 Jun, 2013 09:37
• The finish on those cases looks killer too
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• #13 Reply
  Posted by Rytie77 on 19 Jun, 2013 09:48
• Piston number 9328e.  Top number bottom 571m06850
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• #14 Reply
  Posted by Rytie77 on 19 Jun, 2013 09:53
• Thanks guys have a lot of time in this thing hope to have it running soon here is the hole quad
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• #15 Reply
  Posted by Stpltn250r on 19 Jun, 2013 11:40
• you could measure from BDCto the top of the sleeve. i bet the cyl has been milled way to much on the top. did you pc the cylinder? looks like a custom dome is in order. from my cell phone the piston looks to be out the hole by .060. thats alot!
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• #16 Reply
  Posted by MD2smoker on 19 Jun, 2013 11:46
• On a good note, that chassis looks awesome!  Cant wait to see this completed!
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• #17 Reply
  Posted by Rytie77 on 19 Jun, 2013 13:08
• Thanks hope it will be done soon yes it is pc hole quad is pc the motor is holding me up were would one get a custom dome
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• #18 Reply
  Posted by Stpltn250r on 19 Jun, 2013 15:54
• now im on a computer and it doesnt stick out as much as i thought. the liner was making me think it was sticking out further than what it is. do you have an oem head or do you have a pro design?
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• #19 Reply
  Posted by Rytie77 on 19 Jun, 2013 16:08
• I do not will a pro design
  Help or i can try to find a head
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• #20 Reply
  Posted by WestTexasKing on 19 Jun, 2013 16:29
• The first picture appears to show the piston sitting above the sleeve, I've looked at it numerous times trying to see if it was just an optical trick, but I think that's where your problem is.
  Try this....
  -Get some thick grease and smear it thinly all over the top of the piston (make sure you get all the way to the very edge of the piston!).
  -Install head with gasket and snug the nuts down (don't torque).
  -Bring the piston up until it hits the head.
  -Remove head and observe where the grease was left (or where the grease was squished off the piston), this will tell you where the piston is hitting and can give us more info to diagnose your problem.
  -Take a picture of any findings and post here, then wipe the grease off to prevent spark plug fouling later on.
  
  One of the things it will tell us is if the piston is hitting the head or the head gasket, another thing it will tell us is if the head itself is cut correctly or not (well, partially anyway).
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• #21 Reply
  Posted by Rytie77 on 19 Jun, 2013 17:08
• Ok I will do that when I get home I did throw a another base gasket on just to see if it would help with the head just siting it didn't I tighted it down and it would just hit
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• #22 Reply
  Posted by Glamisrider on 19 Jun, 2013 18:10
• Rytie,
  There should be a number 86mm through 89.5mm on the top of the piston, what is that number?
  I assume this is a weisco?
  
  Also what is the max diameter of the head gasket your using in MM (use digital calipers $10 a Harbor Freight).
  
  If the pics shown are TDC it does not look like your piston is coming too far out, could just be the head, has it been modified or is it stock?
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• #23 Reply
  Posted by Rytie77 on 19 Jun, 2013 18:27
• This is what's on top Piston number 9328e.  Top number bottom 571m06850
  I bought it like this but had it bored and new piston I didt ask them to modified it at all
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• #24 Reply
  Posted by Dezsled on 19 Jun, 2013 18:45
• The last 5 digits tell you the size ... 08650 = 86.5 mm
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