Pistons Pistons Pistons!!!

[Quickonstep]

Ok.. first off.. if you dont know, please dont answer, im just looking for knowlagable engine builders. Comments are welcome, just dont act like you know when you dont.

Ok, has anyone ever had any problems with locator pins coming out? i was thinkin of top pinning the piston in the R motor, just for safe keeping.. in boat motors, its the only way to go.. those buggers will come out but ive never had one come loose goin through the top.

Another thing is radical cut pistons.. here is some i did for my boat motor.. and wondering if it would be worth cutting up one for the r...

These pistons lost almost 250 grams if not more (cant remember exactly) and all weight within 1 gram of each other.

http://home.comcast.net/~kottonmouthkings1979/pistons.jpg

Jesse

[Derrick Adams]

Sorry.. No "knowlagable engine builders" here. LOL

[Quickonstep]

LOL amazing.

[Mr. Sandman]

If you're talking about the wrist pin coming out, I've never had a problem and neither has anyone else I know that owns an R. As for cutting the piston, on a big bore, you may want to lighten it up to help with the revs or you could lighten the flywheel.

[Quickonstep]

no, if the wrist pin comes out, then maybe i shouldnt be building engines lol.. im talkina bout the LOCATOR pin.. the pin that goes in the ring groove that sets the ring to where it needs to be.. those little pins can come out and reck your engine.. i was thinkin about just removing the stock pins and pinning it down from the top

Jesse

[Mr. Sandman]

Ok, I follow you now, but I haven't had that problem either, knock on wood.

[Quickonstep]

i was thinkin of doing one for the R but the porting is way different on the R jug than it is on a marine motor..

Jesse

[OldSchoolin86]

Man I've built a ton of motors for bikes, trikes, and quads and have NEVER had one of those come out. I wouldn't really worry about it.

[RideRed250R]

when i had my R pinned out for 5 minutes down sand high way and i mean full throttle LOAD AND FAST and when it blew i didnt lose one and i burnt a whole int he piston and killed the intake skirt (came off)
adam

[RideRed250R]

also the boat motor has the lake (cool water) constantly flowing threw it were the R's watter is alittle hotter so u could worp a piston by taken to much out of it on a 250R
adam

[a-camp]

I wonder why wisco has never done that ? They might have spet alot shooting that idea down. Built 100s of top end as a Sea Doo tech.( 8 years hate them now) Never lost a pin. seen a rod flip over and go through the bottom of the case and then out the side knocking the carbs off.

[RideRed250R]

thats a sight i would love to see LOL
a-camp u seen everything!
adam

[Quickonstep]

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

[a-camp]

Did not use to many Wisco pistons in Sea Doos . Stock was much better.Ive only done 10 or 15 in bikes.I will keep my eye on that . I have no reason not to believe you .

[jeswinehart]

okay a-camp ,,,, i ain't for the life of me figured out what you are talking about here . pins , circlips ,,,, educate me or bring me up to speed or what ever,,, have not heard the term "pins".
i certanly am no pro at re-builds but want to learn about this ,,, please.


john

[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