No fuel getting to top of piston

Wilder777

New Member
Dec 7, 2017
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Hey, new here, I've had the bike since Feb. and constantly have strange problems. It's the GT7 model, before it was a bad cdi problem, no spark, fixed that great spark, nothing, dry plug, so I take the top end apart, snapped bottom ring was the problem, no scoring or other problems. New rings, new gaskets, cleaned everything up, new tank, but still plug is dry, verified gas in carb, on Reed valves, and past. Take apart again and there is gas in the crankcase, new gas, cause I sprayed starting fluid in carb. I don't see how it's not getting to the intake tubes on sides, there not wet, nor is the top of the piston, great compression, I'm on a steep hill and it stops me easily towards the bottom without brakes applied, any ideas?
 

Wilder777

New Member
Dec 7, 2017
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I thought it was compression, because I kept the old gasket for the crankcase on last tear down, but put new one on this last time and the compression is really strong now. I'm lost, think I'm going take entirely apart and check crankcase?
 

crassius

Well-Known Member
Sep 30, 2012
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you won't know compression without doing a test - if reeds are stuck, compression will feel OK in cylinder but be low at intake so reading will be low - same with crank seal blown - piston pushes hard but no intake pressure, so reading low
 

crassius

Well-Known Member
Sep 30, 2012
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depends on how much wear is on cylinder - I'd try the rings, but if they don't seat, I'd buy a new motor rather than a new cylinder - these motors are OK for what they are, but have metal that can warp out of shape just because someone looked at it cross eyed

I get guys that do serious port work, then can't get it to run - t-gauge on cylinder shows it isn't even close to round anymore.
 

Greg58

Well-Known Member
May 1, 2011
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Crassius probably hit right on your problem, with a broke ring a lot of the compression was bypassing the rings into the bottom end, which could have pushed a crank seal out. The left side seal is not as wide as the right and blows out easier.
 

Wilder777

New Member
Dec 7, 2017
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Mag seal already came bad, got a new one put gas resistant rtv around outside, and wheel bearing grease in the center can't even smell gas there.yeah I tried putting new rings in the old cylinder,but its definitely not seating, got a new cylinder and rings I'm the mail. Anyone had this happen?