Loss of power, torque. Sputters at full throttle

[jonathan180iq]

......What the hell is going on?

You guys are going to have to describe your valve adjustment process. This is a growing issue around here. Something's not right.

[pillowpants]

Anyone knows where I can find a new or used head cylinder?

[JohnC]

I'm gonna guess the valve adjustment is a complete red herring and, coincidentally, the stuck valve got unstuck in the process. It stuck again, this time hitting the piston.

[dual_uzis]

Hi, I'm just a new guy but I'll describe what just happened to me.

I dont work on bikes much, but I'm a 15 year Master Technician. I know my way around a wrench.

07 GZ250 came in for knocking/tapping noise and wouldn't start. Checked carby, boots, etc. Started fine on alternate fuel.
Pulled valve covers to find super, super tight exhaust rockers. loosened then up, assemble, bike starts beautifully, but still rattles.

Exhaust valves were being held open and the carby wasn't getting enough vacuum to start on.

check compression after valve adjust, still low, so I pulled the head off. Found the r/s exhaust valve seat had come unpinned from the cylinder head and was clanking round on the valve when the valve was opened. I'm not sure how it didn't bind up and break the valve off, maybe got lucky and caught it just in time. The head was beat up badly enough to buy a new one.

Research has shown me that bad valve seats are a common issue with this bike, maybe a suggestion to pull the head and re-do the seats would combat so many failures before they occur.

Sorry to hear about your bike.

[tnastvogel]

Your valve... broke off? Wow.

Ebay is where I would look first, then maybe a salvage yard, then probably a Suzuki dealer. Good luck.

Remember to support the cam chain from falling down into the case and have the piston on TDC on the compression stroke (the one after the intake stroke-watch the valves open).