Valve settings

[Jacklagace]

Hi all, I’m new to this, I got a gio x31 250cc 2010 and I try to set the valve, but there is no mark or T for tdc. Also is that normal that a move the timing chain almost out of the sprocket (cam) I try to set the valve but I got no compression at all. The bike ad a problem before it’s stall on road my nephew as it and he said it was smoking (black) and it’s stall.

Thank you

[Plump Kibbles]

Could you start it before the post?

Black smoke usually means a clogged air filter OR running too rich.. or both.

The timing chain - I'm not exactly following what you're saying about that. Shouldn't have to touch the timing chain - turn the engine till the piston comes up in the cylinder, you can pull the plug and use a light or a (clean) stick or rod or something that fits to see the movement or the piston head through the plug port. That should be TDC - check, check, check before buttoning up everything though - I opened my valves too much due to incorrect TDC placement and got the 'ticks'. You can also use your finger to feel for the compression through the plug port as well. Close off the opening for the plug with your finger and turn the engine. IF there is absolutely no compression at all, the bike will not run - but if there is actually compression issues, that would be internal and I wont be of much help.. I've not had to do any compression diagnostics..

I am hoping for you that it is NOT internal issues...

[JerryHawk250]

From what I'm reading you have a CB250 with a overhead cam. You should have no slack in the timing chain. It's possible the cam chain tensioner failed and allowed slack in the chain and has jumped a tooth or two nd is out of timing. Do not remove the valve cover to adjust the valves. Just remove the two round caps on the valve cover to adjust the valves.