SXR Help ID these pistons.

[Mike W]

Tore down my SXR 800 motor but need help to ID these pistons. They have an “A” stamped on the top and “ART” molded in the casting inside the skirt. They measure 81.5mm so I’m sure they’re not stock.

 

[user_error]

Did you measure from the bottom of the skirt? If they really measure 81.5mm, they are not Sxr pistons because Sxr cylinder bore begins at at 82mm and can be bored to 85mm typically. What cylinder did these come out of?

 

[Mike W]

Did you measure from the bottom of the skirt? If they really measure 81.5mm, they are not Sxr pistons because Sxr cylinder bore begins at at 82mm and can be bored to 85mm typically. What cylinder did these come out of?

Stock 800 cylinders. I measured the top of the piston. Just measured the bottom of the skirts and they are 81.80mm.

 

[Harbor]

81.80, may be 82 or so collapsed. Try remeasuring the cylinder bore at the bottom of the sleeve, with just the tips of calipers and see what you get..

 

[Big Kahuna]

Basically same as ProX

 

[Mike W]

81.80, may be 82 or so collapsed. Try remeasuring the cylinder bore at the bottom of the sleeve, with just the tips of calipers and see what you get..

Ok, 81.99mm. So, stock bore and pistons. Perfect.

 

[WFO Speedracer]

ART is who makes the OEM pistons for Kawasaki, they are a Japanese manufacturer, also pistons are not going to measure the same as the bore size, they will always be smaller, the difference between the bore size and what the pistons measure at is your cylinder to wall clearance, in this case .20mm or .004 in, nothing is collapsel nothing is wrong there unless the taper or out of round is out of spec.

 

[Harbor]

ART is who makes the OEM pistons for Kawasaki, they are a Japanese manufacturer, also pistons are not going to measure the same as the bore size, they will always be smaller, the difference between the bore size and what the pistons measure at is your cylinder to wall clearance, in this case .20mm or .004 in, nothing is collapsel nothing is wrong there unless the taper or out of round is out of spec.

I did not feel comfortable the measurements since the piston was measured at the top first, so I directed him to measure the cylinder in the least
worn area and he was able to answer his own question.

 

[WFO Speedracer]

I did not feel comfortable the measurements since the piston was measured at the top first, so I directed him to measure the cylinder in the least
worn area and he was able to answer his own question.

The reply was more for the rest of the guys here but yes you were correct it has to be measured at the bottom of the skirt as pistons are tapered.

 

[Mike W]

The reply was more for the rest of the guys here but yes you were correct it has to be measured at the bottom of the skirt as pistons are tapered.

I always left my engine building to the experts so I never dealt with this kind of thing. Being that I’m retired I better start doing the repairs myself so I appreciate the good info.

 

[WFO Speedracer]

Also the only way to truly know the condition of that cylinder is by using a bore gauge, A caliper will only measure the bore at one spot, it has to be measured in many spots on both the X and Y axis to determine taper and out of round

 

[MTRHEAD]

Stock pistons