Ive got an 80cc motorbike engine and im needing a new base gasket (the gasket that the bottom of the cylinder sits on) and ive seen 49cc gaskets for like 2 bucks but then an 80cc gasket for about 5 bucks..is there a size difference?
49cc or 80cc base gasket size?
- Thread starter copmagnet80cc
- Start date
There is usually more distance between the studs with the larger jug. The smaller gasket most likely isn't going to fit!
Usually?
most likely?
here's a definite answer:
A 48 cc base or head gasket has less distance between the stud holes than a so called 80. Stud holes are 6mm too and yes the opening is smaller as well.
Yes, there are so called 80's with 6mm stud holes too.
Your penny pinching substitution ain't gonna work.
You can buy "80" base gaskets for $2
i make my own gaskets out of quality gasket paper by tracing the old ones onto it, gasket paper is cheap even the good stuff ~!
i make most base gaskets at 1.5mm thickness then deck down the jugs to make the proper squish clearance, the thicker gasket raises the jug thus raising your transfer and exaust and intake port, then just port and polish the exhaust wider and the intake downward and wider and your transfers should be where they need to be just clean them up. some jugs are ported all over the place depending on quality though and may actualy neeed thinner base gasket ! and port corrections ! i toss those in the trash and get new ones lol
also you can use copper sheets of varrying thickness for gaskets that last forever if you have the means to cut it and punch the stud holes correctly
the best set up would be a .5mm copper head gasket and a nice oil/gas resistant blue fiber paper base gasket that is 1.5mm thick, it adds a tottal of 2mm hight to your 47mm bore, and will raise your jug up at least .5mm and require the top of the jug to be decked down at least equaly or even more to gain compresion and good squish clearance and deck hight
some people run with no base gasket as a feeble atempt to gain compression without doing work ... yeh you will gain comp but it will lower your transfers and exhaust ports and cause a huge drop off in power and torque production, what good is a high comp motor if the port map is all wrong ????
i make most base gaskets at 1.5mm thickness then deck down the jugs to make the proper squish clearance, the thicker gasket raises the jug thus raising your transfer and exaust and intake port, then just port and polish the exhaust wider and the intake downward and wider and your transfers should be where they need to be just clean them up. some jugs are ported all over the place depending on quality though and may actualy neeed thinner base gasket ! and port corrections ! i toss those in the trash and get new ones lol
also you can use copper sheets of varrying thickness for gaskets that last forever if you have the means to cut it and punch the stud holes correctly
the best set up would be a .5mm copper head gasket and a nice oil/gas resistant blue fiber paper base gasket that is 1.5mm thick, it adds a tottal of 2mm hight to your 47mm bore, and will raise your jug up at least .5mm and require the top of the jug to be decked down at least equaly or even more to gain compresion and good squish clearance and deck hight
some people run with no base gasket as a feeble atempt to gain compression without doing work ... yeh you will gain comp but it will lower your transfers and exhaust ports and cause a huge drop off in power and torque production, what good is a high comp motor if the port map is all wrong ????
Last edited:
The good barrels don't need to be raised and a standard base gasket will give good tr port timing.
The 38mm stroke barrels with a 40mm stroke crank need to be raised around 1.5mm to get the transfer port timing closer to 120.
I prefer to make a copper base gasket and use a thin paper gasket under it as the thicker paper base gaskets compress to much.
The 38mm stroke barrels with a 40mm stroke crank need to be raised around 1.5mm to get the transfer port timing closer to 120.
I prefer to make a copper base gasket and use a thin paper gasket under it as the thicker paper base gaskets compress to much.
