Quote:
Originally Posted by Randall
So I ran the compression test.... <25 PSI....
I have made sure that all hoses are properly connected and checked for any additional leaks. It seems that a rebuild is in the near future? Does anyone have a tried and true technique for testing for leaks?
It is my understanding that I should have a minimum of 100 PSI for starting, and around 150 PSI for proper operation... Can anyone confirm this?
How about any good recommendations for a rebuild? I'm not looking for crazy power, just a quality rebuild.
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I have rebuilt a GY6's top end in the past, and had a similar issue as that. For your compression to be that low, its likely either a very bad leak between the cylinder and head [unlikely] or one of your piston rings has worn/cracked/ etc. I would lean towards a issue with the rings or possibly even the piston itself. But you only will know once you tear it down.
As far as kits go, I have this 72cc kit on my scooter and it runs great even though i have stock everything else [even the jetting] right now...its a very noticeable power increase over the stock 50cc and the kit was machined well. I do know that some people run the 80cc kits [advertised as 100cc] and thats fine, myself i am weary of that as i have heard they put wear on your crankshaft so i go with a 72cc kit due to that instead. Thats just my preference. Keep in mind that the kit below says it is a 80cc but that is just advertising, similar to how the "100cc" kits are really 80cc. The kit below has a 47mm piston/cylinder which = 72cc.
https://www.amazon.com/gp/product/B0...f=scootdawg-20
And if you need a great video on clocking the rings, this video is for a 150cc gy6 but the same ring clocking works just fine on smaller CCs and it runs great.