.50 piston clearance

[malvaro]

Hi guys: do you know? whats the clearence between the pisto .50 and the cilinder? please help me.

[sheefreak]

Hi guys: do you know? whats the clearence between the pisto .50 and the cilinder? please help me.

 

That is way too big of a number. .50 is a half inch. You need to be in .003 to .005 or sixish.

[malvaro]

Hi: thanks for your help, the new piston's iam gonna put are 64.50mm, i just need to know between 64.50mm and the cilinder the measure.

 

thanks.

[spurdy]

Hi: thanks for your help, the new piston's iam gonna put are 64.50mm, i just need to know between 64.50mm and the cilinder the measure.

 

thanks.

 

0.003" - 0.005" or 0.0762mm - 0.127mm

 

SP

[blowit]

0.003" - 0.005" or 0.0762mm - 0.127mm

 

SP

 

 

 

Those numbers are precisely how cast pistons get a bad name. Forged pistons will require .003" but cast pistons will require only .002-.0028" clearance. If you setup cast pistons at .005", they may fail quickly.

 

 

Brandon

[spurdy]

Those numbers are precisely how cast pistons get a bad name. Forged pistons will require .003" but cast pistons will require only .002-.0028" clearance. If you setup cast pistons at .005", they may fail quickly.

 

 

Brandon

 

Sorry man, didn't even consider someone running cast pistons. I've always used Wiseco forged pistons and thought most people did as well. Cast pistons don't require as much of a gap due to the process of manufacturing them. Since they are molten and poured into a mold the grains of the metal are allowed to equally settle where as a forged piston is pressed into shape and the grains of the metal are very irregular and produces a lot of internal stress in the metal. A forged piston will swell more when it is heated then a cast piston will.

 

I should have asked which pistons he was using before I gave the tolerances from wiseco. My bad.

 

Shannon

[malvaro]

Hi guys, iam gonna use oem Pistons are those are cast or forget? please help.

 

 

 

 

 

Sorry man, didn't even consider someone running cast pistons. I've always used Wiseco forged pistons and thought most people did as well. Cast pistons don't require as much of a gap due to the process of manufacturing them. Since they are molten and poured into a mold the grains of the metal are allowed to equally settle where as a forged piston is pressed into shape and the grains of the metal are very irregular and produces a lot of internal stress in the metal. A forged piston will swell more when it is heated then a cast piston will.

 

I should have asked which pistons he was using before I gave the tolerances from wiseco. My bad.

 

Shannon

[hercalmighty]

Hi guys, iam gonna use oem Pistons are those are cast or forget? please help.

 

OEM is cast. What size are you looking at? .50mm or 0.050" over stock?

[malvaro]

64.50mm 0.50mm yamaha oem thanks for your help.

 

 

OEM is cast. What size are you looking at? .50mm or 0.050" over stock?

[spurdy]

64.50mm 0.50mm yamaha oem thanks for your help.

 

 

 

 

I was going through the assembly of a top end for a buddy last night and noticed the clymer service limit on oem pistons is 0.002" - 0.006". So it seems that the clearance for the cast piston has a lower minimum being at 0.002" and a maximum of 0.006" before needing rebuilt without failure.

 

SP

[malvaro]

ok guys, finally I bought wiseco M series Piston kit so,

piston to cilider clearance its 0.003" any suggestion with the rings? and the holes i need to make to lubricate the pistons?

 

thanks Mariano Alvaro

 

I was going through the assembly of a top end for a buddy last night and noticed the clymer service limit on oem pistons is 0.002" - 0.006". So it seems that the clearance for the cast piston has a lower minimum being at 0.002" and a maximum of 0.006" before needing rebuilt without failure.

 

SP

[hercalmighty]

The rings should be about 0.010-0.012 ring gap. If you have stock cylinders you dont need the oiling holes. You only need those if you have an exhaust bridge.

[malvaro]

yes iam with that stock cilinder, thanks for your help. what exactly exhaust bridge?

 

The rings should be about 0.010-0.012 ring gap. If you have stock cylinders you dont need the oiling holes. You only need those if you have an exhaust bridge.

[hercalmighty]

Most dirtbikes have a dual exhaust port. So there is a little piece of metal that separates the two ports. That little bridge heats up alot faster then everything else so it will expand faster. So to help with that you put a couple holes in the piston for oiling.

[malvaro]

thanks I got it!!

 

Most dirtbikes have a dual exhaust port. So there is a little piece of metal that separates the two ports. That little bridge heats up alot faster then everything else so it will expand faster. So to help with that you put a couple holes in the piston for oiling.