wont start now

[wpbfrider_11]

Had my bike for a couple years now bought it brand new out of the show room and rode it everywhere its a 2009 got it with 0 miles now has over 17k I have always done the maintenance myself.

Well one day I was riding and the spark plug shot out of the engine but luckily the threads were still there so I put it back in and kept riding then it happened again about a 1000 miles later but the treads were shot so I parked it till I got the time to rethread it so I took the head off did a new head gasket too wasn't to hard I put it back together and triedstarting it up it sputtered a little bit and would fire but die instantly. I checked for spark have good spark. Cleaned the carb so should be getting fuel. Tried starting it again and same results so I checked the timing and I had the cam timing backwards so I changed it. By backwards I mean when the marks are supposed to be lined up they were but the cam was upside down I think the technical term would be 180° off. But after changing it I still get a sputter like it is trying to fire but now it doesn't even fire.

I don't know if there is something I'm missing or if the engine is just at the end of its life

[raul10141964]

check the valves adjustment

[JohnC]

Probably not what you wanted to hear, but you could have installed a helicoil in the old threads without disassembling anything...

What does the spark plug look like after you try to start it? Is it black? Wet? Dry?

+1 on checking the valve adjustment.

I'm pretty sure the GZ250 fires the plug once for every revolution of the crankshaft ("wasted spark"), so having the cam out by 180 degrees (360 on the crank) shouldn't matter. Does it behave the same now as it did before you changed the cam? How's the compression?

[wpbfrider_11]

Checked and adjusted valves well atleast the exhaust valves they were really tight had to back off the adjuster a lot just to get the tinniest of the feeler gauges in. It started raining so never got to the intake side but gave it a quick crank and after a couple tries it fired up and stayed running as long as I was holding the throttle but died as soon as I let off so I think I'm going to check the intake valves when it stops raining if that ever happens.

Also I know I could of done the rethread on the bike but I had a leak at the headgasket so I figured might as well just do it all and the leak turned out to be the little bolt between the headers vibrated out so good lesson learned should go over the bolts every couple months