Evening fellow gixxer lovers.

I haven't been here for a very long time and thought I'd pick the experts brains

Almost 2yrs ago my little 400 broke down. Now I can't recall the exact 'breakdown' but basically going along around 60mph and bike died....don't recall any strange noises just rolled to a stop. Got Mr AA to recover the bike and got it home....wheeled it into the garage and never looked at it. I'm wanting to get in there next weekend and sort it out, now it could be something real simple or a major failure. Question is before I start fault finding what are the 'likely' issues or best areas to start looking? The bike rolls in neutral but click it into gear and the rear wheel locks up. I did try to bump it when it was first recovered but rear wheel just locks up. Sorry I can't be more specific but will know more once I start having a mooch. Any help appreciated on where I should start

The gearbox may be ok. If it's stood for ages the clutch will have become really tight, and needs the engine running to free off. Does it start in neutral? Or does it stall when gear engaged?
Need more description really..
Try sidestand switch + pickup coil/cdi for favourites for electrics.

The bike doesn't start at all, whether neutral or in gear. I'll get the battery charged/replaced ready to have a go at it the weekend. Looking back to 2014 when it broke down I found an old post and mentioned when it died there was a ticking when power went and rolling to a stop.....would that pin point to electrics maybe? As you say difficult with little info

Electrics don't = ticking. Maybe top end mechanical issue. Try and restart it and see if it fires up at all or on 3 cylinders.

Ideally you need to give it a full health check 1st. compression check, new battery, clean/new plugs etc

Maybe a bit basic info, firstly does your starter turn when you push the start button? If not check all your fuses, which I think you should anyway, if they check out, check and test your starter relay(solenoid some call it) if starter turns but no firing sound, check your side stand switch, bypass it just to test and see if there's any luck, then check your plugs first then your coils, you can even check the connections from your cdi to your coils with continuity tester. Steve

Trouble shooting an engine that wont go is a process of elimination.
Break it down to the three basic requirements for an engine to run:
1. Spark
2. A fuel/air mix of roughly the correct ratio.
3. Compression.

Which piece of the triangle are you missing? hopefully not more than one!

Need to be a little careful with this one as it could be a mechanical failure thats to blame , if a valve has gone bad turning it over will cause more damage.

first stick it in 6th and then see if it will turn over with a bump if its still locked then need to look at mech failure!

Ok so actually got to look at the bike today and as initially thought not good and broken valve smashed into head. Damage on end of spark plug confirmed damage so removed the engine and looked up through the exhaust port and oh dear. The engine is out the bike but not taken engine apart. The big question is.......repair or replace?

Ps. thanks for all the replies and info guys

I've done the same donkeys ago when my cam timing went out.
You will need a new head, and also suss out why it happened in the 1st place. To rebuild the head is a very expensive job, and nearly impossible to get right. Did you over-rev it?
You may also need to re-shell it (big ends), as when I rebuilt mine the big end shell on the same cylinder went in short order afterwards.

Sorry to doom monger, just passing on past exp.