150cc GY6, Tear Down, Rebuild, PICS By mikey34 (Read 1,517 times)

[mikey34]

Hey guys, So I am rebuilding a 150cc Roketa, it's the bigger "Touring" body style. Big for a 150.

THE STORY: Driving WOT, 55-60mph, all of a sudden, I loose power, it drops down to 40, 35, 20(It also started making a metal on metal noise, AT FIRST it SOUNDED like a clutch, clutch looks fine... After I seen the good clutch, I decided to pull the engine, the bike WILL start btw, it needed throttle, but it WOULD start. However I hear extra noise out of the case... I ALSO, FOUND metal shavings in the oil plug. Quite a bit really, but the Rings on the piston look fine..

PICTURES SO FAR
CAM and ROCKER off


HEAD OFF


JUG OFF


Piston/Rings




I am just not sure where these shavings came from! I am wondering if one of the bearings is bad, Crankshaft, possibly blown crank seal... but I could hear SOMETHING rattling around in the engine when I would start it on the bike, and now I SEE NOTHING>>?!?!?!? Thanks in advance for any help guys...

P.S. the head gasket was Warped, I'm sure this is from him running it with NO OIL

[mikey34]

So far, I am thinking crank shaft bearings... I'm gonna go ahead and replace all Oil Seals and Gaskets, Rings. Does anybody know the best place to get bearings? I have seen videos over at 49ccscoot.com, and he names a couple brands, but not the best place to get them.
rich, anybody? Alleyoop
Thanks guys

[mikey34]

If anybody gets a chance to look at the Piston and Rings, let me know what you think, the jug LOOKS fine, no scratches or rough surface, but the rings Mainly the oil ring, looks like it has disintegrated. the UNDER side of the Rings look like they are the same size as the piston and the TOP side looks slightly bigger...? This could be where my shavings are from..

[Alleyoop]

The top end looks good really since you have it all out I would just put in all new rings. But the problem seems to be in the case if you heard some metal rattling around I would say bearings. If its the crank bearing just get a new crank.
Alleyoop

[mikey34]

Thanks Alley, I'll split the case tomorrow, see whats cookin in there, take some pics and see what you think too, I really think that's it, he ran it with out oil even on the dipstick for idk how long, when it died, it slowly lost power, and I heard a metal on metal noise, at first I thought clutch, but clutch was fine, when I would start it, it made a god-awful clanking noise when you rev it.

[Alleyoop]

Turn the crank by hand from either the flywheel side or variator side if its a crank bearing you will feel it grinding. So you took the right side plate off behind the stator and checked the Starter Clutch? I have seen some that one of the springs came out.
Alleyoop

[mxmatt]

I put $5 on it being your rod bearing. Happened to me last December.

[mikey34]

Thanks mxmatt, for some reason, my gut is tellin me that's what it is, but when I turn the engine by hand, It stops in 4 places, kinda like it does when you move it to top dead center? Could this be bad bearings?

Alley, I haven't taken the Stator/Flywheel or Variator off yet, I need a puller :/

[mikey34]

I can move the ROD in and out, WITHOUT the rest of the engine moving, so pretty sure this is my issue

[Alleyoop]

Yep if you can move the rod in and out the Rod Bearing is shot and NEW CRANK.
Alleyoop

[mxmatt]

Jun 25, 2014 8:57:16 GMT -6 mikey34 said:

I can move the ROD in and out, WITHOUT the rest of the engine moving, so pretty sure this is my issue

"I want my $5." Spoken in Better Off Dead paperboy voice!
Alleyoop , is right. You need a new crank. I lost men in nearly the exact same way you did in December. Depending on how mechanically inclined/curious you are, replacing it can be done. There are several YouTube videos and instructions on sites like this one to help you through it. The other alternative, and in hind sight I'd do this, is to buy a whole new motor online. I had a lot of fun rebuilding mine, but the time involved for me and the cost after making a few mistakes wasn't worth it. Pick your poison. 

[olivertwisted]

Haha... A "Better off Dead" fan! I got that, before ya even qualified it ! mxmatt