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« on: February 03, 2017, 11:04:07 PM »
The key I stress, which ever piston you get, either one needs to be set up proper by the bore man.
Wiseco has had that pin problem in the past, but that problem is long gone. Wossnor went through that same problem as well, with one of mine & I was lucky enough to get a replacement free. They as well have solved that pin problem.
Problem with the pin, with just a hole drilled in, once the pin is pressed into place & piston in an engine & running, pressure was building up & pushing the pin out of place, so what they did, after the pin hole drilled in, there was a little V notch put into the hole to let the pressure out, pin problem solved.
A forged piston, for any & everybody using the engine, bore to piston clearance needs to be set at 0.0030, or else they will end up seizing the engine.
Now for a pro like rider, been on 2 strokes for many years & that rider going to break the engine in a proper way & then heat the engine to the proper temps before blasting off on it, knowing full well the jetting is spot on before they ever put their foot on that kicker, then the piston to bore clearance maybe can be set up a bit tighter, but that operator has got to be strict each & every start up to detail.
Now a cast piston, most know that the cast piston dont grow as quick from the heat as the forged pistons do, so the bore man can set them quite a bit tighter piston to bore clearance than a forged. A cast piston, like if that same pro like rider was going to be operating this engine, bore could be set up as close as 0.0010 with the same attention to detail from the rider just like with the forged.
Pretty much the difference, between the two types of pistons so far as durability, is dependent on the bore clearance it is set up at & the attention paid to the carbs jetting & the care that the operator will provide for that engine.
Compression wise, the forged piston, can stand quite a bit more higher compression than the cast & for a good amount of time/use. Not saying the cast piston cant survive fairly high compression, just that it wont last as long if hammered on regular. I've seen many in high compression set up, the piston would crack right across the top of the wrist pin & engine still running ok, just not like as when first built.
There have been engine builds, where the cast piston set up tight, compression not to high & it out live the forged pistons. There are many riders/racers out there will have nothing but a cast piston in their engines. To each their own I guess you could say, but with either piston, the bore man is the most important part alone with the person tinkering on the carb jetting.
Neil
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