Pistons Pistons Pistons!!!

[Quickonstep]

ok... here goes.. the circlip holds the wrist pin in place.. on the wrist pin is the piston obciously, the wristpin bearing and the rod.. on the actual piston there are the rings.. now the rings can only go one place.. what keeps them in place are locator pins.. those little locator pins can wiggle out and totally **edited** up a mota... top pinning them virtually eleminates that issue.

Jesse

**please dont type around word filters**

[Quickonstep]

here is a picture of a top pinned piston... you can see where the original location of the locator pin was.. and the new place.

Btw, you can just go take your piston and pull the pin out and put a pin through the top, its critical to go on the boost port for cooling reasons.

Jesse

[OldSchoolin86]

believe it or not, wiseco's are famous for pins flying out... i take the pins out, mill a hole into the ring valley, replace a pin, mill the piston head flat again, install.

Jesse

I choose not to belive, atleast in the bike, trike and quad world. I've done way to many to not have seen a "famous" problem.

[Quickonstep]

well.. now that i think about it.. your right, it happens at a higher rpm.. around 9k+ is where those pins start flying out.

Jesse

[OldSchoolin86]

well.. now that i think about it.. your right, it happens at a higher rpm.. around 9k+ is where those pins start flying out.

Jesse

Sorry, still not buying it. The some of the bikes I wrench turn 11k+. I'm just trying to help here sence you asked what we thought.

[short4stuff]

I have something to say, when you top pin it like that, are the ring gaps both right there?... they should be in different spots.. Do you know what I am saying? ...

[KASEY]

on a 2 stroke the rings are PINNED to keep them from turning and ending up with a ring end getting stuck in a port opening,,, i ,,in 30 years of building motors have never seen this happen ,,, so i would feel safe in sayiny not to worry,,,,

[Curtis-Tecate3]

I am with Oldschool & Kasey. I have never had an issue with the ring locator pin coming out. This includes 17K rpm kart racing motors.....

Curtis

[Quickonstep]

thats a good thing that it is not a problem... unfortunatly for us guys with boats and outboard motors specifically, its a major problem... and glad it could be cleared up.

Jesse

[Wickedfinger]

I'm with Oldy and Kasey on this one too - in my 20+ years of ATVing, I've never seen that happen. I will however say that with a multi-pistoned pinger like an outboard motor, the odds of something happening like that to a piston go up dramatically simply because of the fact that there are more of them to go wrong. That being said, I've also owned a Banshee and have ridden with them for years and years, and even with the chances going up 100%, I've never seen that ring issue being a problem with them either (however I do agree that it can happen). I personally would take the stance that modifying a piston like that by "drilling" and tapping in a pin in an uncontrolled environment like a garage with simple tools would only raise the chance that you might actually "weaken" the piston - probably by introducing cracks or something like that. You do have to remember that unlike in an outboard, a single cylinder ATV motors piston has to carry 100% of the engines power load, where a multi-pistoned outboard has 25% - 17% of the load distributed over 4 - 6 pistons. Just theory I guess, but its how I'm feeling. I just don't think its neccessary.

[RideRed250R]

i had a bass boat with a 175 horse johnson on the back twostroke motor and that thing turned HIGH Rpms and never had a pin come out only thing that broke on it was a linkage rod just had the bottom end rebuilt and ran for 10 more years and is still runnin the colorado river today! that thing would do 75 TO!
also if u see all the main high performance engine tuner's building unlimited RPM banshees look at the pistons they are using i know trinity uses wesico's on there 585 125horsepower banshee motor
adam