forged or standard ?

[mnpes]

Not being a Metallurgist or Chemist just a Technician :biggrin:
Could someone answer a question for me regarding forged pistons ~ standard pistons ?

During a span of 37yrs both thrashing and sensible riding ( 2-strokes ~ yam - lam - suzuki - kawasaki - yamahas up to 500cc)

Never once had a pin drop from a standard piston only very occasionally from a forged piston

Lads now including myself using Pump fuel (5% ETHANOL + Quality Oil ) Riding the same speed/distance and engine setups
Having pin problems with forged pistons not standard ones
Mr recommends you change their forged piston rings and check the pins every 1500mls ( )

Is it the Ethanol or other additives/abrasives reacting with the metal structure of a forged piston rather than the silicon based standard pistons ~ Causing the pins to drop or a manufacturing fault ?

As the present additives were not used on the pistons I had drop pins years ago

[soullad]

Good call
let the debate begin

[fred]

I've always run piston ported motors. Only ever had ring peg probs twice,both were forged pistons. First was wiseco suzuki 205,peg fell out after about 5k miles my fault for lack of maintainence.
2nd was wearing of peg on mb piston,ring went over peg,and into exhaust port,this was 200 miles after re ringing a piston that'd done 1000 miles. this was a few years ago,mark put it down to super plus unleaded. never used it since. No probs since,but i do tend to re ring mb pistons every 1000 miles,or so.
Used to run honda 205 pistons for 10 rallies a year,plus work and back in the 90's,and re ring every year-18 months. Never had a problem with these pistons,except needing a rebore every couple of years. Shame they only did 3 sizes. Pretty sure honda used cast pistons.
Next year i'm going to try a goetze piston. But if this is not up to it will have to use a mb piston.
Until someone brings out a cast piston with 1mm wire rings,there's not much choice if using piston ported motors with 16mm gudgeon pins.