new piston install

[FLAWLESS]

I'm having trouble installing my piston.
The ring compressor seems to grip the piston before the ring and I can't get it into the block. I've got a 12 thou ring gap too.

Also do I need to install the piston into the block before I attach it to the conrod. It looks a little difficult.

Cheers
Justin

 

[jaguar]

Best way to do it is install the piston/rings into the cylinder and then lower it into place (eyeing the connecting rod location thru the piston pin hole) and slide in the piston pin and then put in the retaining ring.
It's the safest for the rings. Otherwise there's always a chance you'll damage them. Once using the other method the top ring actually rested on top of the locator pin instead of to the side of it and it really gouged my cylinder.

 

[FLAWLESS]

Thanks Jaguar,

Did you have any trouble getting the rings compressed?? to fit into the bore, they seem to not wanna go.. Maybe I need a better compressor.

 

[outrgus]

DON'T FORGET TO OIL THE RINGS WITH 2 STROKE OIL, THIS ALWAYS HELP WITH THE PROCESS.

 

[GreenPeace]

The one ring is thicker than the other. Make sure you have them right way round.
I never use a tool to install new rings. Install the rings in the piston, make sure the ring ends match the lip in the piston groove. Get your Mom to help you and install the piston from the bottom of the barrel ( the barrel is taper at the bottom). Compress the first ring with your fingers and slide it into the barrel and then the second. Easy job...Dont brake your Moms nails thougn..

Good luck

 

[jamin326]

ring compressor what's that, i've never used one of those things, use my own two hands simple, hold the rings compressed with one hand and slide the jug down over them with your other hand, done and attach the piston to the connecting rod first, you should be able to compress the rings by hand without much trouble, do apply two stroke oil to the piston and inside of the cylinder

 

[canyncarvr]

You aren't trying to compress the rings over the locator, are you? The pin that's set into the piston?

Otherwise, the rings should easily squeeze into the bore with your fingers.

As noted, put the rings on the piston, one pin clip in, the piston in the bore then put the whole mess over the studs. Line up the pinhole, put in the pin and insert the second clip.

Note!! Be sure to have the crankcase protected with a towel or somesuch so when you drop the dang circlip, it won't fall all the way to the bottom of the cavity!!

Rings are supposed to be the same thickness (on the 'H' model, anyway). Marks up...although that's kind of a given with the ring type. If one ring has marks and one don't, put the one with markings on top.

After you get the piston started, use your fingers thru the intake port to ensure the rings get smoothly past the port.

DO NOT reuse pin clips. If you are installing a wiseco, make sure the pins 's-n-a-p' into place.

Did'ja get it done by now?? All set?

 

[FLAWLESS]

yEP, all in now, thanks guys. I put the piston in from the bottom, by squeezing the rings with me fingers. I then used some occy straps to hold the block above the conrod. In my haste I forgot to install the gudgeon pin bearing, and I stuffed one of the pin clips pulling it out. I re-used my old wiseco pison clip, which is only a year or so old anyway not bent or closed in, and it was as hard as the new clip to put in, and it did "twang" into place so should be cool... I'll start it tonight..

 

[seancza]

This is great info. I'm just going to replace the piston for the first time.

One question, the service manual shows a special tool to pull the piston pin.

Is this necessary or can you just carefully poke it out

thanks for the help

 

[srhill]

Re: Do I need special tool to remove piston pin? No.
I pushed mine through I believe with a 3/8" drive extension.

Question: What is a "occy strap"?

Flawless, I know you want to get the beast started but using the old clip is just asking for trouble. I don't know about you but I would stay 'puckered' everytime I road it.

 

[canyncarvr]

The pin can usually be removed with your pinky. The extension idea is just fine, but just cuz it's metal don't get the idea that means you can pound on it!!

You wouldn't do that.......right?

After you take the clips out (and throw them away), a bit of massage to the hole not covered by the pin will enhance easy removal. Some scotchbrite or an exacto knife scooted around the hole (your crankcase is stuffed shut with a clean towel, right? Said that already.) will get the pin out with zip.zero tbl.

If you like tools and have trouble, a large c-clamp and a couple of sockets used as spacers will work just fine.

You have the crankcase stuffed shut with a nice clean towel, don't you?

 

[FLAWLESS]

Schrill,

An Occy strap has hooks on each end and the strap part is elastic. I used it to hold the block up. I taped the piston to the block. Then I could pull down on the elastic, and position the gudgeon pin easily. I did the whole job on my own easily.

RE:- The clip, well its spring steel, it was not deformed in any way, and really it just sits in a groove. The clip expanded to sit neatly too. I know its not good practice, as removing them can damage them easily, but since its expanded in its groove, I'm happy with it.
I'll tell you guys if it f$#@ks up though. But really its got no-where to go.
They are kinda dodgey anyway, theres only a bees dick of pin holding that gudgeon pin anyway, there is no load on it.

Cheers
FLAWLESS (hopefully !!)

 

[FLAWLESS]

Oh by the way Guys, I did start her up last night. Started first pop, really stoked.
I used about a 30:1 mix for the first tank, no more than half throttle, should be run in now and back to 50:1.
Sounds heaps better, starts easy, can't wait to open her up..

Thanks for everyones help..

 

[canyncarvr]

Not to throw too big a pail on this parade...

You'd be surprised of the forces the clip undergoes at piston speeds you get from 8000rpm! That's part of why the rec is not just to use new ones, but to place them with a specific orientation.

Yeah...I know it's not the speed, but inertia that's the issue.

re: Got no where to go?

You don't wanna know.........:( You likely won't be surprised to find out how far it can go.

Here's hoping!! (hopefully, as you say).