[killer454]

i bought a 2000 400ex a few weeks ago to rebuild and just took the old piston out and it is a weisco 10-1 std bore.

the problem is they put the arrow on the piston to the exhaust port,that is not right.the only damage to the piston is all on the carb side of the cylinder and piston.

my new piston has an arrow and according to the manual it points toward the carb-is this right?

the manuall says the that the (in) mark should point to the intake side of the cylinder so i guess the arrow would do the same right?

can anybody tell me for sure?

 

[Helmut]

The arrow on a Wiseco piston is supposed to point toward the exhaust.

 

[killer454]

i bought a namura 11-1 it has an arrow to which way does it point?

i tryed to findout but no luck at their website and have looked on here with no luck either.

can anybody tell me which way for this piston?

 

[Helmut]

i bought a namura 11-1 it has an arrow to which way does it point?

i tryed to findout but no luck at their website and have looked on here with no luck either.

can anybody tell me which way for this piston?

I'm pretty sure that the arrow points toward the exhaust on all pistons. If it has an arrow, it points toward the exhaust. If it says "in", it points toward the carb or intake.

 

[killer454]

ok that makes since,im going to have to becarefull on this build because im going by the manual and was not expecting this problem between oem piston and aftermarket.thankyou for the help im taking it to a guy to bore it out tommorow and will ask him to just to be sure,but you sound like you are right.arrow to the exhaust side of the cylinder,thanyou very much for the help.

 

[Helmut]

You're welcome.

 

[TRX2fiveO]

The Namura kit I bought to put in the 250EX I just rebuilt had "IN" stamped on it but they are a 2 valve engine too so I guess that's the difference??

 

[killer454]

yes it must be the 4 valves,my new piston has an arrow just like the old weisco piston.

how do you like that brand piston?

 

[shadetree]

as helmut stated..if you use a after market piston..and if it has a arrow..it has to face the ex. if it has '' in '' stamped on it..it faces the intake side of the cylinder.