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Will any piston perform better with holes drilled in them

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I've read where Wiseco pistons need to have 2 or 3 holes drilled in the exhaust side, to help cool down the motor. Why doesn't wiseco drill the holes in them before selling them? Does this work on any other pistons? Which piston is considered best? One of my friends swears by wossner pistons, another says wiseco. I usually just use oem. Kind of liking the wiseco racers elite, but do they need to be drilled.

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The holes don't cool down the whole motor, they put gas and oil on the exhaust bridge to help keep it cool.  There is no performance advantage.  As far as pistons go, the wossner and wiseco pistons are both good pistions, I don't think you can go wrong with either of them. The reason Wiseco doesn't pre drill some pistons is because they use the same piston in a lot of different applications and some of them don't have an exhaust bridge so you can't have holes with no exhaust bridge.  As far as drilling all pistons.  I wouldn't recommend drilling a cast piston(OEM pistons are cast), if you buy a forged piston, I would recommend the holes. 

Edited by frdbtr
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Depending on how fast you are :ride: seriously if you're on the gas it won't last a hour without holes drilled.  What I've noticed these days pretty much just oem Honda pistons come not pre drilled.  Just did this 07 couple weeks ago. This engine came with tranny problems but I did the piston while was apart. 

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I rode 3x per week for years, raced B class up until 2011.  Won a lot, but was never A class material though.  I never ever ever drilled holes in the piston.  In the 70s, yes.  Haven't felt the need on a modern water cooled nikasil plated CR250 or 125.

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5 hours ago, mxaniac said:

I rode 3x per week for years, raced B class up until 2011.  Won a lot, but was never A class material though.  I never ever ever drilled holes in the piston.  In the 70s, yes.  Haven't felt the need on a modern water cooled nikasil plated CR250 or 125.

I do it as a precaution, especially with the 02-07 250 motors which have a bad habit of cracking the exhaust bridge.  :) 

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"Do it" only if your year/make/model has a exhaust bridge. You can have the same piston fit/run/perform ex in different years/makes/models & one may have the exhaust bridge & others don't. Also the location of the bridge(s) from model to model isn't always going to be the same either. This is why they (Wiseco) dosen't pre-drill the holes from the factory. The directions that come with the Wiseco pistons tell you all you need to know about how to & if you need to....

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I had an 07 CR250 previously and put a new piston in it. It did not last 5 hours and the piston was damaged just like the one pictured above. I then replaced that piston and drilled the holes, and rode that bike for multiple hours with no more problems.

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On 2 stroke sled motors I messed with with holes in the piston skirts to cool both sides on the exhaust port and along side the transfer port windows. Typically whare pistons usually scored

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5 hours ago, ASP1227 said:

I just got a ProX piston for my ‘86 cr250. Should I drill it?

Yes for sure

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4 hours ago, ASP1227 said:

Ok, how exactly do you do it? What size bit and stuff?

This was another guy I helped and when get home I'll send it from wiesco 

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So when I drill it I drill all the way thru the wall of the piston right?

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3 minutes ago, ASP1227 said:

So when I drill it I drill all the way thru the wall of the piston right?

Yes just follow that step by step or this. My measurements easy to understand and close enough :thumbsup:

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