Piston rod too big

[DrywallDoc]

Bought a complete wiseco piston kit from ebay for 89 shipped. I new that was cheap but thought, maybe he ordered one too small, and Is just trying to get some money back. So i bought it only to find out today that the wrist pin rod diidnt go through. I had others laying around and all were too big. They wouldnt even go in a bit. Not even a tight fit, they were just to big. So i took out the dremel and "honed some out" on both sides. I got it to fit but was an extremely tight fit as i didnt want to take too much off the piston. My question is does that have to move inside the piston too or just the wrist pin bearing? The piston moves perfectly up and down the cylinder. Is the wrist pin rod just there to hold the piston on the crankshaft rod? Or is it suppose to move alittle freely with the wristpin bearing?

 

[speedyslyder]

sounds like red flags are dropping all over the place
are you sure there was no bur on piston

 

[Awk08]

I'm not following exactly what you did, but it sounds like a disaster in the making.
maybe asking around before you dremeled anything would have been a good idea ?

 

[DrywallDoc]

I figured worst case ill take it off and put a different one.i havent tightened the bolts. I made the hole just a tad bigger to slide the rod in. Everything is working like it should, piston moves freely and the piston rotates on the bearing. The only problem is the rod is in the piston tight. is it suppose to be a little loose? I know its suppose to slide in easy, just figured as long as piston moved freely in cylinder it would be ok.

 

[Blaaster]

The pin should be a thumb press fit in the piston .(interference Fit )

My concerns are, is the pin the correct size for the bearing.

Have you removed equal amounts all round ( chances are not if you did not use a sized reamer) will the pin be able to flog around in the hole after the piston has expanded.

I think your best bet would be to get a new piston with the correct size pin and bearing to match.

 

[DrywallDoc]

The pin should be a thumb press fit in the piston .(interference Fit )

My concerns are, is the pin the correct size for the bearing.

Have you removed equal amounts all round ( chances are not if you did not use a sized reamer) will the pin be able to flog around in the hole after the piston has expanded.

I think your best bet would be to get a new piston with the correct size pin and bearing to match.

I see what your saying, makes perfect sense. I took it out and installed a new piston kit. I also took pics of the faulty piston so yall can see. I noticed a couple differences between them. The first is it had two clip grooves on each side. As if 2 clips were going to hold the pin in on each side. Also the end of the skirts is different. The last two pics are from a good wiseco piston.

 

[Blaaster]

Some manufactures put an extra groove which looks like it is for a circlip, but it is to provide lubrication to the pin.

Some Pistons are made to have floating gudeon pins.

Notice that there is a hole through to the bottom of the boss.

Was that piston designed for a YFS200...

 

[DrywallDoc]

Some manufactures put an extra groove which looks like it is for a circlip, but it is to provide lubrication to the pin.

Some Pistons are made to have floating gudeon pins.

Notice that there is a hole through to the bottom of the boss.

Was that piston designed for a YFS200...

I have no clue if it was designed for it as i bought it in a wiseco kit. The kit did say blaster200 though. I did buy it off a second party off ebay. Looks like i got screwed.

 

[best]

I don't know, looks similar enough for manufacturing differences.
Companies have factories all over the world, some source from sub-contractors.
Not all look exactly the same, for various reasons.
I agree with Blaaster on his ideas.

I would have measured the bore to see if it was in tolerance.
Heck, if it wasn't I would have honed it out to fit. Much like you were trying to do.

Steve

 

[DrywallDoc]

I'm not following exactly what you did, but it sounds like a disaster in the making.
maybe asking around before you dremeled anything would have been a good idea ?

I agree. I just figured there was nothing i could do about it, but make it work. Im glad i asked before i tightened everything though. You guys talked me out of it.