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I bought a 1999 polaris trail boss 325 2 stroke from a guy who bored it 40 over to a 400. I need to know what iridium spark plug do i need to buy to replace the standard plug. If anyone can help I would appreciate your time an advice. Thanks
 

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I bought a 1999 polaris trail boss 325 2 stroke from a guy who bored it 40 over to a 400. I need to know what iridium spark plug do i need to buy to replace the standard plug. If anyone can help I would appreciate your time an advice. Thanks
Boy did he ever see you coming! Polaris did not make a 325 two stroke. The 325 was introduced in 2000 and was a four stroke.

Now that's bad enough in itself, but a .040 over bore on the 325 engine would take it from 324.93 cc to 333.31 cc - it's impossible to BORE a single cylinder engine and gain 75 cc (depending on the starting displacement) - a 1000 cc single cylinder might gain 75 cc, but not on a .040" (1 mm) overbore. An engine with a 110 mm bore and 100 mm stroke would be 950.33 cc - bored .040" it would be 967.69 - a 17.36 cc gain in displacement.

I just recently sleeved and bored a Honda TRX400EX to 89 mm (a 4 mm - .160" the 440 kit) which made it a 435.48 - it then got a stroker crank installed chainging ths stroke from 70 mm to 74 mm - this increased the displacement to 460.37.

In 99 the two stroke engines were 250, 300 and 400 cc - the 400 was liquid cooled while the 250 and 300 were air cooled. They all used a BR8ES NGK spark plug - the Iridium version is BR8EIX

Find out what you have got there before you screw it up!
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