Piston slop - lmao

Okay, a little preface before I get into this. On one of my bikes for the past couple of weeks I've been fighting some grinding on my clutch cover. The slop in my large gear was causing the gear to 'grind' on the cover at high rpm. I could clearly see where it was hitting the cover. So instead of replacing the whole clutch unit(and those 57-3mm bearings), I got out the Dremel and had at it. Just to give the gear more clearance, I added a couple more gaskets for good measure.

But I was still hearing the grinding sound.... So I double checked my cover, which I permanent marker'd the inside(after dremel) so I could see if it was still hitting, but there wasn't a scratch.

Uh Oh...


Plus I was starting to lose power...



Double Uh Oh!!



So I decided to pull my head off and have a look:

Aww Crap! What are those dings in the head from!!??


So off the jug came......

Good lord almighty! There was a 'little' play in the wrist pin, and I say little like mount Everest is a molehill:

It spun from here:


To Here!!:



That ain't right, is an understatement.

So I got the wrist pin out with a little persuasion and...

The bushing was completely gone! And it still ran! Not well, but it got me home...



And all that play caused the piston to chew on the transfer ports:


And both sides of the piston:




I'm baffled that it still ran.





So anyways, I know I'll at least need to replace the top-end. But how much lateral play should there be in the connecting rod? I've got about a 1/4" side to side at the top. Should I just junk this engine? Or is it salvageable if I can get the bushing chunks out of the bottom end?

Here's the head pic that gave me justification to pull the jug:

Few hundredth, D'oh! Well I just measured and its only 3/16" play, but still... it friggin ran like that, boggles the mind.

Anyone have an extra engine kicking around? I'll pay for shipping and a couple boxes of beer for ya

I pulled the G-clips, all that was left is what you see in pic #3. I set the pin back in to show the amount of play it had. The bushing was completely disintegrated. Pics 1 & 2 show the amount of play. I'm still baffled it actually ran and got me home tonight.

It just goes to show the resiliency of these little motors.

1k if I was lucky, the 'grinding' was horrendous! lol I didn't push her because I wanted to get home without pedalling.

I would've went for just a top end, but there's 3/16" play at the top of the connecting rod. So it's only a matter of time before the bottom bearing goes too.

I got the engine/bike used off of Kijijji for cheap. Now I know why... when I got it- the bottom of the intake gasket was gone, and the plug was pure white. Who know's how long they ran it like that for... But I figure that's why the bushing ended up in the bottom end, lol.

Luckily scotto- hooked me up with a clunker of his, mounting bolts chewed and whatnot. but the internals are good, so I should be able to scavenge the top end and the crank to throw in this case. It should be on its way anyday

It ran great for a few weeks, then it ran better for a few days before it crapped out. Like my dad always told me "Engines always run better just before they die", so I'm inclined to believe the sentiment, even though the outcome sucks!

Oh yea, the last owner wasn't even aware that the bottom of the intake gasket was missing. So it was running 'mad' lean (ie. plug was white as paper ). I replaced the gasket after I got it and gave it a 'once over', but the damage was already done.

I don't really trust the bearings on the end of the crank either, they could crap out 20k after I change the top-end...

so...

The replacement case that's coming has had extensive work done on the rear mounting studs, so I could try it, but in the end I think that's unreliable compared to a decent case. Plus I've never cracked a case open before, so I'm looking forward to swapping the crank(and bearings) actually.

I wish I had the money for one of FourEasy's balanced cranks while I had the case open! But that's just not feasible at the moment.

Thanks for the interest and suggestions guys!

Oh hey, what's up with the Schwinn S-7 tires? Don't they make them anymore?

I found some here: Global Bikes Online- Low priced bicycle seats, saddles, tubes, tires, frames, cranks, bmx, mtb, lock, light and other parts and accessories , dunno if they're what you're looking for...

Hey juliman, Foureasy makes and sells balanced cranks(with real bearings) for around $100, drop him a line via pm for more info.