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too bad

you either can have high compression or you can have pump gas
 

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hey guys im lookin for a high compression piston but i want to run pump gas and keep the stock bore
your very best bet is to run a fresh oem piston and use a single layer of the stock head gasket with some permatex copper spray on it....

you will gain almost a full point of compression... have perfect crank balance... and the combustion chamber shape will be perfect, the way yamaha designed it...

and best of all you will have tightened up squish clearance by .018".... that will add power and increase your tolerance to lower octane...

you absolutely will not find a pump gas piston setup that makes more power than that...and it will outperform almost every high compression piston setup too....
 

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your very best bet is to run a fresh oem piston and use a single layer of the stock head gasket with some permatex copper spray on it....

you will gain almost a full point of compression... have perfect crank balance... and the combustion chamber shape will be perfect, the way yamaha designed it...

and best of all you will have tightened up squish clearance by .018".... that will add power and increase your tolerance to lower octane...

you absolutely will not find a pump gas piston setup that makes more power than that...and it will outperform almost every high compression piston setup too....
Interesting free mod...
Do you think it is safe with European Fuel ? 95-98 Octane.
I will probably try. If i found something similar to permatex...
 

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Interesting free mod...
Do you think it is safe with European Fuel ? 95-98 Octane.
I will probably try. If i found something similar to permatex...
European 95-98 is comparable to American 91-93 from what I remember. They only use the RON number, and not the average of RON and MON.
 

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Discussion Starter · #8 ·
your very best bet is to run a fresh oem piston and use a single layer of the stock head gasket with some permatex copper spray on it....

you will gain almost a full point of compression... have perfect crank balance... and the combustion chamber shape will be perfect, the way yamaha designed it...

and best of all you will have tightened up squish clearance by .018".... that will add power and increase your tolerance to lower octane...

you absolutely will not find a pump gas piston setup that makes more power than that...and it will outperform almost every high compression piston setup too....
mixxer what do you mean by only use a single layer head gasket.
 

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One of the sticky threads on the top of the forum explains a lot about the single layer head gasket.
 

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the original head gasket is three layers... you just cut the riveted /stampoed section that holds them together...and you have 3 separate layers....

the outside layers are coated and those are the ones to use... not the middle layer of plain steel...

so you take one of the outer layers and hit it with a thin coating of permatex copper gasket spray... and that is all you need...

plus you have a fresh extra layer you didnt use... so save that for next time you pull the top end down
 
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