piston holes?

[78250r]

hello i have a new big bore kit with a wisco piston the shop and instructions say i need to drill lube holes on the the exhaust side to compensate for the exhaust bridge and add extra lubrication is this a super big deal i have a machinest to do the drilling im wondering how exact i have to be thanks

[togup]

I have never heard of that ,youll get more results if you post under a specific atv forum

[IcutMetl]

Try posting in the TRX250R forum; there are sure to be guys there that can give you a definitive answer. I remember when I bought a Wiseco piston kit for my 'R, it came with the same instructions, but also gave basic dimensions if I remember correctly. My Wiseco piston already had the lube holes in the piston from the factory; in the later model cylinders, there was an exhaust bridge; I believe it was to reduce piston/ring wear and reduce the chance of ring snag as the piston passes over the exhaust port. When a cylinder is bored/ported, the builder will "relieve" the exhaust bridge (remove material from cylinder in bridge area), but the piston should have holes in it so that some of the fuel-oil mixture from the crankcase can find its way up from the bottom of the piston, thru those holes, and onto the bridge area to cool and reduce wear.

I'm looking at my old Wiseco piston right now; it's a .020" over piston from my '88 motor- with using only calipers, the holes are approx. .062" in diameter, centered in the piston, the first one being 1.985" up from the skirt on center, the second being 2.375" from the skirt on center. I would imagine that for this application, +/-.005" would be more than close enough. What will your machine shop guy charge you? I have a milling machine with a digital readout and all the goodies; more than capable of doing it for you if you like- it's a VERY simple operation.

http://i220.photobucket.com/albums/dd173/wlksjstn/pistonholes.jpg

[78250r]

im not sure i have to do moch up and then take it in shouldnt be to much thanks for the offer but im going to try and stay local as possible i just got my top end back from a three month stay down south my piston is actually for a suzuki rm the guy that built my engine frankenstiened it but i guess the set up is a poplular one anyways like i said its a wiseco piston the instructions call for three holes can i get away with just two?

[IcutMetl]

No problem, I'd stay local if I were you too. I've never heard of an RM piston in a 250R, only a YZ, but I'm sure there's a reason. I would personally stick with whatever Wiseco says.

[78250r]

ya its something to do with the stroke i think the strokes im interested is the kick start down stroke{right before the engine starts} and the two strokes the piston makes to give me power to go im getting pretty sick of starin at this thing

[tommygunnz]

I just had to drill the holes on my 87 LT250R wiseco piston there's instructions on that green paper that comes in the box you'll need a drill bit that is specified in the instructions and tape measure.

[j4duncanr]

yes just as the pic of the piston you should drill the holes and the green paper in wiseco box explains how to.what it does is provides lubrication esp at longer high rpm running.not doing this procedure will result in stuck galded piston.because the exhaust side (duh)runs so hot.its not hard to do.

[j4duncanr]

yes just as the pic of the piston you should drill the holes and the green paper in wiseco box explains how to.what it does is provides lubrication esp at longer high rpm running.not doing this procedure will result in stuck galded piston.because the exhaust side (duh)runs so hot.its not hard to do.

[78250r]

thanks for the replies i sold this quad dont hang me out to die but im going to try and get a kxf this spring dont worry ill get another 250r project soon but i just want to to ride to the pump and go {yes in my town you can ride to gas station haha}