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Posted

Took my new pistons and cylinder to a new shop to get the cylinders bored. Started discussing banshee mods porting and such. One of the guys in the shop tells me you need to put the motor togather with out the head and when the piston is all the way down see if the port openings are completely open if not mark the piston and take it back apart and grind the top of the piston in the area that was marked until you get all the ports completely open. He said it is usually 1mm or less

So he saying to notch the top of the pistons so you get full flow .

I really do not want to grind on a brand new set of pistons.

So what do you guys think? Is he crazy or what.

 

Thanks

Tim

Posted

personally, i wouldn't grind on any new piston for any reason. that's just asking for a disaster to happen. i'd rather have the porting corrected to match the stroke & pistons.

Posted

I have been here since 2003 and never heard anything like this, I'm not going to start grinding on new pistons!!!!!!!!!!!

We just ride trails we do not need the fastest machine just a good dependable one.

Posted
Took my new pistons and cylinder to a new shop to get the cylinders bored. Started discussing banshee mods porting and such. One of the guys in the shop tells me you need to put the motor togather with out the head and when the piston is all the way down see if the port openings are completely open if not mark the piston and take it back apart and grind the top of the piston in the area that was marked until you get all the ports completely open. He said it is usually 1mm or less

So he saying to notch the top of the pistons so you get full flow .

I really do not want to grind on a brand new set of pistons.

So what do you guys think? Is he crazy or what.

 

Thanks

Tim

 

 

 

Sounds like you got some bad advice. Grinding on the top of the pistons is not all that bad if you know what you are doing but he probably did not tell you this will change the port timing too?? I would not recommend making any port changes unless you know what is going on there and sounds like you are best to assemble as is. Many machine shops have " an idea" what is going on but port timing is critical in them. Notching the pistons is a 40yo method of "poor man" porting but also good for testing theories because used pistons are always cheaper than new cylinders and easier to cut.

 

Brandon

Posted

piston notching was very common back in the day, in fact alexander Graham Bells book two stroke tuning mentions it a bunch of times, it has draw backs though like changing the integrity of the piston, could cause a grenade. i would just go with a reputable builder.

Posted
piston notching was very common back in the day, in fact alexander Graham Bells book two stroke tuning mentions it a bunch of times, it has draw backs though like changing the integrity of the piston, could cause a grenade. i would just go with a reputable builder.

 

 

Yeah, it's talked about many times in that book...

Posted

yeah well that idea was acceptable in 1965 but youd be way further ahead to have the cylinders sent out and professionaly ported by somene who uses a porting program and with many years exepriance

there is no replacment for doing it the right way .

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