Topic: MY MOTOR IS LOCKED ??? - I"M SMILING LIKE A CHESHIRE CAT

[750goes]

Well this just about takes the cake, I won't beat about the bush - here are the symptoms and possible causes - let me know your thoughts and any other possibilities - I start tearing it apart in the next few days..

Riding around in 1st and 2nd gear - and I know its running rich - but running on all 4 at least...
the bike falls over on a tight left turn - very lightly and bumps the concrete - no damage - scratched the top of the clutch switch

start it again - do a few more laps of the car park all things normal - then doing a right hand turn it STOPS

NO strange noises before, no smoke, no cam chain or primary noise evident

I go to start again and the kick start is jammed solid - will not turn, try the electric start - it engages then does nothing..
push it back to the unit -

put on cetrestand - check oil - plenty
check gearbox -yes it selects first and second ok and locks up the back wheel - I cannot turn the motor by turning the back wheel when it is in gear.
back in to neutral wheel spins fine backward/forward

try kick start and electric start together - get half a kick only - it is then LOCKED UP TIGHT AS A FISH BUTT

took out tappet caps - plenty of oil
took out plugs 1 & 4 - sooty black (no oil)

tell me something  - I know its not going to be good...or probably simple

Cam chain ?? or something else more horrible

Whats the checklist to discover why my motor is locked ??

[MRieck]

Excess fuel in the cylinders causing it to lock up. Pull all the plugs and kick it. Only thing I can think of quickly.

[750goes]

Thanks mrieck  -  Pulled 1 & 4 plugs - cannot move it one mm ??

 

[scondon]

    Can you back the motor up at all? Pull the points cover and fit a wrench around the large nut and try to spin the engine in the opposite direction. Don't force it too hard since the timing shaft is not meant to take heavy torqueing. Might not work after all the attempts to kick it forward.

   I've never had a motor sieze but I've had a few apart. Bent valve hitting piston? Cam chain or primary chain jumping the sprocket?  Not sure what it takes to have a piston sieze to the cylinder but I wouldn't think low speed riding would do that.

  Hang in there 750. Take it slow and methodical. If you need a teardown so be it, worse things have happened, though I'm sure you'd much rather be riding at this point

[nickjtc]

When it fell over did it bend the gear shift lever/mechanism? Could something have locked up inside the transmission??

[750goes]

Scondon  & Nickjtc thanks for your replies, will look into those couple of things in the next few days,

at the moment I am still trying to calm down..........will take a few more drinks I think.........

and I'm sure going to take a few photos and post the results of my explorations in the next week or so..

will probably be spending some money too I think at least on a head & base gasket for starters...

keep up the replies guys I need all the support I can get...#$%* #$%* #$%*..........still obviously upset.......

[bryanj]

First check nothing jamed in sprocket, then check gearchangr mech (next cover in). Rather than use the nut on the points end take off the alternator and use the bolt in there

[750goes]

bryanj

have not checked but I don't think anything is jammed in the sprocekt as I can select neutral  easily enough and the rear wheel turns freely, and it can be pushed ok with no strange noises from the gearbox of things grinding away .

will also check behind the sprocket cover for anything not looking right

probably take off the alternator and try to turn the motor

will add this to the list of possibilities - thanks

any more thoughts - anyone

[bistromath]

well, pull the 2&3 plugs, be sure it's not fuel-locked as mentioned above.

[MRieck]

well, pull the 2&3 plugs, be sure it's not fuel-locked as mentioned above.

Good idea. 1&4 rise and descend together...they could be at bottom dead center with 2&3 at top dead center with one of them on the compression stroke (both valves closed). If you have a lot of fuel in there...you said it was way rich which also could be caused by leaky float valves....it will lock soild. I've seen it happen. If you try to turn the engine over with a large breaker bar etc you can break a rocker arm or worse. For future reference you can turn the engine over from the right side of the engine (much easier than removing the generator cover).

[scondon]

If you have a lot of fuel in there...you said it was way rich which also could be caused by leaky float valves....it will lock soild. I've seen it happen.

   Just curious, Mike. Does this happen because there is too much in the combustion chamber to compress? Piston can't make it to TDC because of too much pressure?

[Gordon]

If it were locked up because of fuel in the cylinders, wouldn't the fuel slowly leak past the rings allowing the engine to turn after sitting for a little while? 

[nickjtc]

If you have a lot of fuel in there...you said it was way rich which also could be caused by leaky float valves....it will lock soild. I've seen it happen.

   Just curious, Mike. Does this happen because there is too much in the combustion chamber to compress? Piston can't make it to TDC because of too much pressure?

Fluids are to all intents and purposes, incompressible, so if the combustion chamber is full of fuel, and that piston is on its compression stroke (both valves closed) the piston cannot travel upwards. If the issue is forced than catastrophe could occur.

Yes, given time, the gas should drain into the crankcase, but that would depend on the condition of the rings on that piston.

[Boomologist]

I have layed a few bikes on their sides and never had one get a hydraulic lock.
If you think that 2 or 3 has a fluid lock turning off the gas and letting it set would allow the fuel to drain out into the crank case. But if a carb was flowing that much fuel it would run out the carb throat once the cylinder was full, or on a compression stroke, and you would see it.

If the engine was running and suddenly stopped I would suspect something else.
Two things come to mind here.
1. Have you checked your oil recently?
2. I had something like this happen. It was one cam bearing that wasn't getting oil and seized up. Locked up the entire engine.

[750goes]

thanks for the replies so far,, I will be looking at the motor sometime in the next few days when I can spend some time thinking through the problem and trying all the good suggestions being forwarded.

I will post more information about the problem and causes when I discover what it is.......hoping for just a broken camchain...

[MRieck]

If you have a lot of fuel in there...you said it was way rich which also could be caused by leaky float valves....it will lock soild. I've seen it happen.

   Just curious, Mike. Does this happen because there is too much in the combustion chamber to compress? Piston can't make it to TDC because of too much pressure?

Fluids are to all intents and purposes, incompressible, so if the combustion chamber is full of fuel, and that piston is on its compression stroke (both valves closed) the piston cannot travel upwards. If the issue is forced than catastrophe could occur.

Yes, given time, the gas should drain into the crankcase, but that would depend on the condition of the rings on that piston.

Agreed and a good explanation. But iff the petcock isn't shut off though gas will continue to bleed in and if the rings are in good condition.....

[bill440cars]

        Another thing to think about if the motor has developed (what I've been told years ago was) a
  "hydrostatic lock" and if the gas is allowed to eventually leak off into the crankcase, that could be disastrous. I've heard of car motors blowing their oilpans open and doing considerable damage to the motor, when they attempted to start it. Might ought to drain and flush the oil mixture. What do ya think?  If that's whats happening.               Later on, Bill

[750goes]

bill440cars,

will be doing a quick check and drain some oil tomorrow to see if there is anything metallic floating about or petrol,, but the bike was running ok before this happened - unless it sucked in a big mouthful of fuel just as it stopped I cannot see how it would be fuel related, but won't discount that until I can check it out..

will take out plugs 2&3 - have to borrow a plug spanner tomorrow

will also check to see if I dropped a valve - another possibility (hope not)

then if I find nothing indicating what it is -take off the sump/oil pan and have a little look around...

still crying - the beer last night did not help...

[nickjtc]

then if I find nothing indicating what it is -take off the sump/oil pan and have a little look around...
still crying - the beer last night did not help...

Do that first. It will tell you the most with the least effort.

What kind of beer? I find a 'thoughtful' beer helps in cases like this, such as Boddingtons Pub Ale, in the can, with the trivet.

[750goes]

nick

I drink anything that's cold and tasty - preferably OZTRALIAN called Tooheys OLD - or any old beer I find laying around being under utilised...and trying to collect dust..

I may drop the sump off - will see if I have time tomorrow - Wifes birthday coming along in two days - so have to be home early and not covered on oil - not engine oil anyway 

I'm starting to fell better than I was - thanks

[Jerry Rxman Griffin aka MuthaF'er]

I think you should have more beers first. Thoughtful beer is kind but COLD beer is better and the only thing better than COLD beer is FREE beer. This isn't likely going to be an easy situation. Hope it is, but..... Expect the worse and be very glad if you come out better. I knew I had "a problem" when mine locked up. Missed 2nd, 10,000 rpm +. Bang. It quit. Pulled clutch. Pulled over. Got off. Looked for oil leaks or holes in the engine. None. Good. Bad. Hit starter button. It didn't do anything but laugh at me. Tried kick starter. Yeah, right... "Oh #$%* get the trailer" time.  Pieces of aluminum in the muffler (75 750F) and air cleaner box. That damn valve had no mercy on my piston. It could be numerous things. Hope you don't find aluminum pieces when you start digging.

At this point I can feel your pain. I'm hoping for an easy solution for you but be prepared. I have 3 of everything top end if you need spares. On the other hand there is nothing wrong with added cylinder volume and Mike Rieck heads. If you gotta spend the money, do it right while you have it down.

    

[750goes]

thanks,

I will be trying the FREE beer this afternoon - DAUGHTERS BIRTHDAY (22 yo) - and trying to kill my future SON IN LAW who sold me the bike 12 months ago - it was $300AU

Will be hoping for something simple but if not - ce la vie (sorry for the spelling)...

Will do any and all the work required if I have to strip it down to the bare bones... but heres hoping I don't have to

Definitely feeling a bit better looking forward to a lazy Sunday afternoon - DRINKING and NOT DRIVING..

[scunny]

more beers for better ideas
just about to jump on my pushbike and go for a couple myself

[750goes]

scunny,

I may copy your approach  - but I think the mice ate my bicycle seat a few years ago...and I don't fancy really pedalling anywhere - unless it is downhill of course and I can get a lift home..

 

[bill440cars]

                   Hey guy, Here's hoping that it's not too bad. I've got a bad feeling about this but, I keep
          hoping for the best on this. I feel your pain, when something happens to my wheels (whether it
          be my van or my bike), I'm all out of sorts until it's resolved. Good Luck.    Bill