I Think My Engine Has Blown Up!

[angryfarang]

Gutted.

I started my Honda Hornet yesterday, well I tried to... The starter motor turned, then came a horrible crunching sound from the engine and it locked up. I hit the starter again, you can hear it turn and lock.

Any ideas what this could be? I know it doesn't sound good.

Cheers,

Matt.

[Spoonman]

Might be the start motor so pull it out and bench test with another battery and some jumper leads.

[angryfarang]

Thanks for the reply. Hopefully it's that and not the engine!

[VocalNeal]

How long was the bike standing without being run?

Could be hydraulic lock. Fuel has leaked past the carburetor into one cyclinder. Take all the spark plugs out and try again. If this is the case and fluid does come out of one cylinder check it to see if it is fuel or water. (Just in case)

Could be a stuck valve? Unlikely but if left for a very long time?

Side note:

Thinking your engine has blown up is like thinking you are pregnant. It either has or it hasn't, there is no middle ground. The fact that all the bits are still inside the engine and the floor is not covered in oil should be a key to the correct answer.

Edited January 7, 2013 by VocalNeal

[angryfarang]

Thanks for the reply.

The bike wasn't stood at all. I've been using it most days with no issues. I'm so busy with work no time to look at it, will probably be another 6 months until I have time... LOL. No worries.

[dave_boo]

Unless the starter is stuck in the engaged position, why don't you pull the plugs and push the bike whilst it is in gear. IF it is vapour lock that will clear it right up and if it is not will quickly tell you if the engine has major damage (as in you won't be able to move it).

[angryfarang]

Thanks Dave. I will give it a try. The plugs are a knightmare to get to, it's tank-off job.

Again, thanks for all the replies and help.

[floridaguy]

Possibles, stuck valve hitting a piston, seized piston (engine starved of oil), starter loose, dead battery (you would be surprised how many times.....)

Does it turn over but not start now, or not at all?

[angryfarang]

Battery is good (charged it the other day)

The starter starts to turn but locks up with a thud...

I might try to bump start it in second gear later, see if it starts up.

[floridaguy]

If the starter locks, it might have come loose. My truck did this once also. Also, check your grounds and power to the starter. The battery might be good but the juice isn't quite getting there.

[Familyonthemove]

I wouldn't try to bump start it 'till you know what the problem is ...... don't want to run a damaged motor or you'll do more damage. But it may only be a stuck starter dog.

Put it in a high-ish gear and try to push it - does the engine turn over? Take the plugs out to make it easier to turn over (even though you have to take the tank off - you'll learn a lot by turning it over with the plugs out and listening.

Or ..... If it has a centre stand - put it in a high gear and try to turn the rear wheel (if no centre stand - stick it on a heap of bricks)

[VocalNeal]

I'm so busy with work no time to look at it, will probably be another 6 months until I have time... LOL. No worries.

call your favourite bike repair place they will come and pick it up and hey presto..

[floridaguy]

I'm so busy with work no time to look at it, will probably be another 6 months until I have time... LOL. No worries.

call your favourite bike repair place they will come and pick it up and hey presto..

Ahhh, but that takes all the fun out of it!

[BSJ]

The timing chain has stretched so much the cam shafts have jumped a few cogs and now the valves have locked together and been smashed into by the pistons which has caused one or more of the compression rings to break and gouge into the cylinder wall. Attempting to start the engine now will only lead to further damage.

Or it could be a jammed starter dog!

[angryfarang]

The timing chain has stretched so much the cam shafts have jumped a few cogs and now the valves have locked together and been smashed into by the pistons which has caused one or more of the compression rings to break and gouge into the cylinder wall. Attempting to start the engine now will only lead to further damage.

Or it could be a jammed starter dog!

I'm maybe wrong but I'm sure the hornet cams are gear driven.

[VocalNeal]

So it was running fine and your rode home OK. Next time you tried the current problem arose?

The first question to be asked when trouble shooting is "What has changed?"

[angryfarang]

So it was running fine and your rode home OK. Next time you tried the current problem arose?

The first question to be asked when trouble shooting is "What has changed?"

The bike was just left overnight and started the next morning.

[VocalNeal]

1. Could still be hydraulic lock if you forgot to turn off the fuel tap?

2. Check the water level as this is another indicator of hydraulic lock. If low water has leaked into one cylinder.

As has been said put the bike in 2nd gear and try to push it. By push it I mean lean constantly on the bike as it moves forward. If the engine is free it should move forward slowly and you should be able to feel the compression of each cylinder in turn. If you can feel four compressions it is not an engine problem it is the starter or battery. If you feel something mechanical or solid then you need to, at minimum, remove the plugs and try again.

3. Batteries fail suddenly. Sometimes overnight. If the engine turns freely as above. Turn on the headlight. Does it go out when you try and start?

Do you have access to another vehicle and some booster cables? You could try that.

No time call a shop!

[Spoonman]

This Honda Hornet I assume it is a CB600 ?

If yes what year model ?

[BirdsandBooze]

The timing chain has stretched so much the cam shafts have jumped a few cogs and now the valves have locked together and been smashed into by the pistons which has caused one or more of the compression rings to break and gouge into the cylinder wall. Attempting to start the engine now will only lead to further damage.

Or it could be a jammed starter dog!

I'm maybe wrong but I'm sure the hornet cams are gear driven.

The Hornet engine has a cam chain and the tensioner is prone to failure so that is probably a good place to start looking.

[angryfarang]

This Honda Hornet I assume it is a CB600 ?

If yes what year model ?

This is a 250 Hornet. CB250FT.

[angryfarang]

The timing chain has stretched so much the cam shafts have jumped a few cogs and now the valves have locked together and been smashed into by the pistons which has caused one or more of the compression rings to break and gouge into the cylinder wall. Attempting to start the engine now will only lead to further damage.

Or it could be a jammed starter dog!

I'm maybe wrong but I'm sure the hornet cams are gear driven.

The Hornet engine has a cam chain and the tensioner is prone to failure so that is probably a good place to start looking.

250 Hornet cams are gear driven. So I presume there is no cam chain.

[angryfarang]

1. Could still be hydraulic lock if you forgot to turn off the fuel tap?

2. Check the water level as this is another indicator of hydraulic lock. If low water has leaked into one cylinder.

As has been said put the bike in 2nd gear and try to push it. By push it I mean lean constantly on the bike as it moves forward. If the engine is free it should move forward slowly and you should be able to feel the compression of each cylinder in turn. If you can feel four compressions it is not an engine problem it is the starter or battery. If you feel something mechanical or solid then you need to, at minimum, remove the plugs and try again.

3. Batteries fail suddenly. Sometimes overnight. If the engine turns freely as above. Turn on the headlight. Does it go out when you try and start?

Do you have access to another vehicle and some booster cables? You could try that.

No time call a shop!

Neil,

Thanks for the help. I'll have some time at the weekend to play about.

I'll try a new battery first, the local honda shop stocks one.

I'll also try to push it along in 2nd gear as you stated and see if the engine moves freely.

All the best,

Matt.

[VocalNeal]

Neil,

Thanks for the help. I'll have some time at the weekend to play about.

I'll try to push it along in 2nd gear first as you stated and see if the engine moves freely.

I'll also try a new battery first, the local honda shop stocks one.

All the best,

Matt.

Matt,

Sorted that for you!

[T_Dog]

I'd suspect a dead battery first.

[JSixpack]

It was merely your imagination. This kind of thing only happens to Chinese bikes.

[thaicbr]

The timing chain has stretched so much the cam shafts have jumped a few cogs and now the valves have locked together and been smashed into by the pistons which has caused one or more of the compression rings to break and gouge into the cylinder wall. Attempting to start the engine now will only lead to further damage.

Or it could be a jammed starter dog!

I'm maybe wrong but I'm sure the hornet cams are gear driven.

The Hornet engine has a cam chain and the tensioner is prone to failure so that is probably a good place to start looking.

250 Hornet cams are gear driven. So I presume there is no cam chain.

If its a detuned Cbr 250 4 cylinder engine ( which i think it is ) then I might have a starter motor you can buy. I will check tonight. Ok

sent from my Q6

Edited January 9, 2013 by thaicbr

[Lickey]

OP, put the bike in gear and try pulling it backwards, if the engine moves a bit, select neutral and try the starter,if it gives half a turn and the engine locks up, there could be some big problem in the cylinder head area,

[BSJ]

The timing chain has stretched so much the cam shafts have jumped a few cogs and now the valves have locked together and been smashed into by the pistons which has caused one or more of the compression rings to break and gouge into the cylinder wall. Attempting to start the engine now will only lead to further damage.

Or it could be a jammed starter dog!

I'm maybe wrong but I'm sure the hornet cams are gear driven.

The Hornet engine has a cam chain and the tensioner is prone to failure so that is probably a good place to start looking.

250 Hornet cams are gear driven. So I presume there is no cam chain.

If its a detuned Cbr 250 4 cylinder engine ( which i think it is ) then I might have a starter motor you can buy. I will check tonight. Ok

sent from my Q6

It may be gears driving the camshafts in the head if there are 2 separate cams but usual practice in Japanese engines is to have a chain drive both cams.

[transam]

I'd suspect a dead battery first.

Tend to agree. Try push start in 2nd gear, see what happens.