Rebuilding engine

[The Rookie]

Looking at rebuilding the engine in my daughters bike, for those who missed the other thread it was burning so much oil it went from full to empty in about 130miles and the piston and bore are lunched, I need to check the big end and main bearings as well before deciding whether to repair or not, so any how to guide links, workshop manual links etc much appreciated...

[Vivo]

Or buy a new engine. Everything brand new including CVT. costs around 400 USdollars..

[The Rookie]

Bike not worth it.....besides what's the point, may as well rebuild it.

[The Rookie]

OK, conrod all seems good so it's just a barrel and piston job, also found it's lost a lot of oil as the breather valve has broken (the one in front of the engine to the right).

Both circlips out the piston, gudgeon pin not moving, does it need some force?

[Vivo]

You could push or pull but damage the conrod and bearing if you don't have a support. Also, whacking it out might also swell it and likewise damage the conrod. You can take it to a shop with a press. 
Whack it out and just buy the assembly if you happen to damage the conrod....

[zombie]

Use a "C" clamp to drive a same size socket thru. A larger socket will act as a cup/sleeve on the opposite side. No worries about the piston. Before you install the new piston you can drill a 3/32" hole in each pin boss so that will not happen again

[The Rookie]

Cool, sockets and G clamp I have!

[The Rookie]

OK the pin is still stuck in the conrod, the holes in the piston wouldn't help as the piston is free on the Pin, is the pin an interference fit in the rod - if so why the circlips....

Can't get much leverage with a clamp, may try a hub puller next!

[The Rookie]

Hub puller worked, small piece of circlip had snapped off and were stuck in the groove, so pin now out, conrod OK, so rebuild time, anyone got some info on torques or cam timing, most the rest I think I can figure out.

[jezyg]

Got these from the AG50 service manual.

Valve clearance 0.04mm
Oil needed for a rebuild 0.85 litre
Idle speed 1900 rpm +/- 100rpm
Cylinder head bolt 0.7-1.1 kg-m
Cam change tensioner slipper bolt 0.4-0.7 kg-m
Cylinder head flange nut 1.2-1.6 kg-m
Valve adjusting locknut 0.07-0.09 kg-m
Oil bolt 1.1-1.5 kg-m
Oil filter screen cap 1-2 kg-m

Hope that helps a little 

[The Rookie]

That's great thanks Jezy, now just need to know how to set the cam timing!

[jezyg]

Turn the flywheel so that the “T” mark on the flywheel aligns with the index mark on the crankcase. Keep the round hole on the camshaft gear facing up and align the punch marks on the camshaft gear with the cylinder head surface (Position the intake and exhaust cam lobes down.) and install the camshaft onto the cylinder head. Install the cam chain over the camshaft gear.

[The Rookie]

Thanks for that, most that I can figure, but where do I see the T on the f/wheel, is that through the hole in the front of the clutch housing?

[jezyg]

Thanks for that, most that I can figure, but where do I see the T on the f/wheel, is that through the hole in the front of the clutch housing?

I think it is through the hole in front of the clutch should index mark on the crankcase and just align the two up.

[zombie]

The timing marks are on the flywheel. The right side of the engine.
This is my favorite explanation...  http://ebay.globaldc.com/scooterparts/borekits/100ccGY6/install/bbk.html