Yamaha g16 backfire

[willy d]

I have a g16 that run for a second then just cranks over then backfires..like it only firing sometimes?
I have cleaned the carb a cpl times..seems to be a fire issue..any help wld be great thanks

[cgtech]

You probably have a stuck valve. When you take the valve cover off to adjust the valves, the problem will be obvoius.... a pushrod will be "not where it belongs". If you find this to be true, removing the head will be needed.

You can just put "everything back in place", thinking the problem is fixed, but the problem will happen again tomorrow.

If you find the last things i said to be true, the next step is remove the head, remove the valves, clean everything REALLY GOOD, the intake & exhaust ports, the valves, the inside of the valve guides. Everything must be so clean that a Q-tip with rubbing alcohol comes out perfectly clean. It's that important. Then lube everything with just a little motor oil during reassembly. Use a new head gasket & a new valve cover gasket, dont reuse the old ones (this is important for long term success). And, cleaning your old valve cover gasket off will probably be an effing nightmare. (Wait, you have a G16, itll be easy) G2-G9 is the nightmare.

Hey, if it turns out the valves arent sticking like I suggest, sorry, at least the advice was free. I been on these yamahas for more than a decade, so I'm not just making this stuff up.

[willy d]

Ok wasnt valve issue..cleaned carb again..got running..lost spark again..checked with a spark tester and it has no spark..am I grounding out somewhere?

[cgtech]

At the front of the motor, down near the base, you will find a plug with 2 wires (blue & black). Unplug it, it's the circuit that grounds out the coil to kill the engine. With that plug disconnected, you should have spark all the time. If you dont, your TCI (coil) is bad.

Be ready to plug the wires back in, or stuff your thumb in the intake, just in case the carb is mis adjusted. There will be no way to shut it off.