Topic: Engine locked up after drop?

[PatrickZ]

Hey brain trust,

I'm struggling to figure what happened with my (rebuilt) 1975 CB550. It's been running fine this year. Wife accidentally bumped the bike with the car and it fell over on its left side (side opposite the kickstart). I looked it over, nothing obvious happened to it beyond some scratches on the handlebar grip.

A few days later I tried to start the bike with no joy. The kickstart is locked up completely, won't budge the engine. The electric starter sounds like it's really struggling to turn the engine, though the battery is always on trickle charge and is full up. I stopped messing with the starter after a couple of tries, if something is stuck, I really don't want to force it and break it.

Bike rolls fine on neutral and in clutch. When in gear, I can rock it back and forth a bit as is normal. And again, bike's been running fine before that.

I'm really at a loss as to what would cause an engine to lock up like that, if the bike's been tipped over. Any thoughts from folks on what I should check?

Thanks in advance for your help!
P

[pjlogue]

Remove the spark plugs and see if it will turn over with the kick starter.  Keep your face away from the spark plug holes while turning it over.

-P.

[jgger]

^^^^This is great advise. The thought being when it was tipped over an open intake valve would allow fuel to free flow into that cylinder. The needle seats and floats don't work very well laying on their side.

Also make SURE the kill switch is in the OFF position and the key is also in the OFF position. If you are spitting raw fuel out of the plug holes one little spark will ruin your day.!

Good luck.

[newday777]

Exactly my 1st thought as reading the description. Did it set on it's side for a while??
Hyro-lok. Liquid does not compress. All plugs out before you kick it over or use the starter
If liquid is in the cylinders, all 4 plugs out, then spin over with the starter, kill switch off so no spart. The starter will clear the liquid out of the cylinders. Then start it up.
Report back.

[PatrickZ]

Thanks guys, really appreciate the advice. Makes sense and I'll try it out shortly away from any ignition sources!!

Cheers
P

[C317414]

After you get it started, change the oil.  Some of the gasoline sitting on top of the pistons may have made it's way past the rings.

[BenelliSEI]

And report back. Never heard this one before?

[Tracksnblades1]

Where exactly did the car impact (bump) your bike ?

[PatrickZ]

So short answer, no joy yet. Might be recurring hydrolock?

Longer answer: I took out the plugs, pushed on the kickstarter to crank the engine, and got it moving again (note, no gas actually shot out from the plug holes). But when I put the plugs back in and crank the engine (with electric starter or kickstarter), it cranks a few times, almost starts, but then becomes increasingly difficult to crank. I tried this a few times where I take the plugs out, crank, repeat. But every time it seems like the engine refloods and re hydrolocks.

Could it be possible that one or more of the cylinders keeps flooding? Could the cause be something else? Any advice on how to troubleshoot?

Thanks folks!

[denward17]

Any gas flowing out of overflow tubes?  The bump could have caused a carb float problem.

[BenelliSEI]

If a carb is overflowing enough to fill a cylinder, fuel should be flowing out the bottom of the airbox too.

[scottly]

So short answer, no joy yet. Might be recurring hydrolock?

Longer answer: I took out the plugs, pushed on the kickstarter to crank the engine, and got it moving again (note, no gas actually shot out from the plug holes).

If no gas came shooting out of the plug holes, the motor was not hydro-statically locked!
Since the bike fell on the left side, have a look at the alternator cover: if it hit the ground hard enough, it may have shifted to the point of the stator rubbing against the rotor. This wouldn't be the first time this has happened. 

[Tracksnblades1]

So short answer, no joy yet. Might be recurring hydrolock?

Longer answer: I took out the plugs, pushed on the kickstarter to crank the engine, and got it moving again (note, no gas actually shot out from the plug holes).

If no gas came shooting out of the plug holes, the motor was not hydro-statically locked!
Since the bike fell on the left side, have a look at the alternator cover: if it hit the ground hard enough, it may have shifted to the point of the stator rubbing against the rotor. This wouldn't be the first time this has happened.

Exactly..👍

It goes back to where was the bike bumped?
 How hard did it get bumped?
 How hard did the bump make it land?

He posted the kick starter was completely locked up..
Starter can barely crank it with a charged battery… was it bumped on the clutch housing? Kick starter shaft? points cover..?

[bryanj]

Remove the alternator cover and see if it it turns by hand DO NOT turn it with starter or kick as if it spins it will spit the oil gallery plug out and pour oil all over the floor

[PatrickZ]

Hey folks,

Quick responses & comments to your thoughts:
1) The bike was bumped on the rear wheel, and then fell over on its left side, i.e. on the left handlebar and alternator cover. Bumped very slowly (like 5 mph) while the car was being parked. Bike fell down seemingly not too hard, the only visible damage is to the left handlebar rubber end. Picked back up after 2-3 mins.
2) I'm not seeing any gas coming out of the overflow tubes.
3) I'll take the cover off the alternator and spin it by hand later today. But I don't think that's the issue, because I know that if I take the plugs out, I can get the engine to turn again freely.

Cheers,
P

[ekpent]

Strange. I crashed a 750 once and broke the stator cover. Fixed the bike all up with new gas tank, handlebars and other goodies. Stator cover was one of the last things to go on. Installed. Went to try and start and engine got stuck. Found out after all that that I had bent the end of the crank !  Dang !  No clearance and had to replace that also.  Oh the joys 

[smee]

Hey brain trust,

I'm struggling to figure what happened with my (rebuilt) 1975 CB550. It's been running fine this year. Wife accidentally bumped the bike with the car and it fell over on its left side (side opposite the kickstart). I looked it over, nothing obvious happened to it beyond some scratches on the handlebar grip.

A few days later I tried to start the bike with no joy. The kickstart is locked up completely, won't budge the engine. The electric starter sounds like it's really struggling to turn the engine, though the battery is always on trickle charge and is full up. I stopped messing with the starter after a couple of tries, if something is stuck, I really don't want to force it and break it.

Bike rolls fine on neutral and in clutch. When in gear, I can rock it back and forth a bit as is normal. And again, bike's been running fine before that.

I'm really at a loss as to what would cause an engine to lock up like that, if the bike's been tipped over. Any thoughts from folks on what I should check?

Thanks in advance for your help!
P

Do you have a little boroscope? You can look in the plug holes to see if you have any oil/fuel in there. I suppose you'd see it with the plugs out and cranking the engine over.


If you take off the points cover, can you freely spin the motor using the hex nut?

Another thought for the stator side. Any crack to the case at all? Underneath the cover is a washer and dowel that connects the start motor cog to the crankshaft cog. Perhaps the fall caused this to get bumped off axis and somehow got bound up.

[BenelliSEI]

CAUTION using the points hex nut. Easy to damage, or bend it. Don’t even try with spark plugs in, and if you feel any resistance, stop.

[PatrickZ]

Hey folks,

So I've been working on the bike for the past few weeks, and I still haven't gotten it to run.

I removed the stator cover and confirmed there's nothing cracked or bent in there, and the stator rotates in the shaft without any impingement.

The key symptom is that when the engine locks up, I take out all 4 plugs, and after some coaxing, I can get the kickstarter to rotate again freely. I put the plugs back in and connect them, try to start the engine, feels like it's close to starting but never does, and then locks up again. I then have to remove the plugs to get it turning again. There's no gas shooting out the plug holes when I turn it, there's a small amount of gas that comes out the overflow tubes.

I'm at wits end with this. Any thoughts on what to try next?

[scottly]

there's a small amount of gas that comes out the overflow tubes.

You stated before that no gas came out of the overflow tubes, IIRC?
For now, leave the fuel petcock turned off when attempting to start the bike: if fuel is coming out of the overflows (all, or only one or two?), the float bowls are full of gas, and the motor will run for a while before the bowls run dry.

[PatrickZ]

Thanks Scotty. You are correct, very little to no gas coming out of the overflow tubes.

I'll try it with petcock off and see what happens.

[Don R]

 I'd try it with the petcock off and a dash of starting fluid. I hate to play the devils advocate but is it possible that it hydrolocked after the spill and when you tried to start, it bent rings or a rod?

[Tracksnblades1]

Hey folks,

So I've been working on the bike for the past few weeks, and I still haven't gotten it to run.

I removed the stator cover and confirmed there's nothing cracked or bent in there, and the stator rotates in the shaft without any impingement.

The key symptom is that when the engine locks up, I take out all 4 plugs, and after some coaxing, I can get the kickstarter to rotate again freely. I put the plugs back in and connect them, try to start the engine, feels like it's close to starting but never does, and then locks up again. I then have to remove the plugs to get it turning again. There's no gas shooting out the plug holes when I turn it, there's a small amount of gas that comes out the overflow tubes.

I'm at wits end with this. Any thoughts on what to try next?

When you take the spark plugs out, how do you coax it to free it up ?  Oil the cylinders ?

When finally coaxed to turn over freely, will the starter turn it over freely for extended cranking time ?

Is the engine oil diluted with gasoline? Does the oil have a gasoline smell ?

[newday777]

Hey folks,

So I've been working on the bike for the past few weeks, and I still haven't gotten it to run.

I removed the stator cover and confirmed there's nothing cracked or bent in there, and the stator rotates in the shaft without any impingement.

The key symptom is that when the engine locks up, I take out all 4 plugs, and after some coaxing, I can get the kickstarter to rotate again freely. I put the plugs back in and connect them, try to start the engine, feels like it's close to starting but never does, and then locks up again. I then have to remove the plugs to get it turning again. There's no gas shooting out the plug holes when I turn it, there's a small amount of gas that comes out the overflow tubes.

I'm at wits end with this. Any thoughts on what to try next?

When you take the spark plugs out, how do you coax it to free it up ?  Oil the cylinders ?

When finally coaxed to turn over freely, will the starter turn it over freely for extended cranking time ?

Is the engine oil diluted with gasoline? Does the oil have a gasoline smell ?

Definitely not enough information given to us PatrickZ.

When you removed the stator cover, did you kick over the motor or use the starter to confirm the motor spins over as it should, while the cover is off, and again after you put the cover back on, plugs in and out? How many rotations do you do on the motor? Many? Or few? You are not using the starter to spin it over with the plugs out?? The starter will spin it over faster to clear out any liquid gas than the kickstarter will. Liquid gas will not compress in the cylinders with plugs in and can bend valves and conn rods.
Have you insured the carbs are not overflowing?

You say you have pulled the plugs, what is the 'some coaxing ' you have to do to get the motor to Kickstart to rotate over again freely?
Do you not use the starter?
What is the battery voltage before and while you try to start it?
Have you been keeping the battery on a tender to keep it fully charged up?
Have you checked the battery connections are tight?
Have you load tested the battery?

[PatrickZ]

Hey guys

Really appreciate the good questions. Responses below.

When you take the spark plugs out, how do you coax it to free it up ?  Oil the cylinders ?
Rock the bike in 1st gear, back in neutral, and pressing on the kickstarter 

When finally coaxed to turn over freely, will the starter turn it over freely for extended cranking time ?

 The kickstarter will turn freely forever with the plugs out. When the plugs are in, the electric and kickstarter will turn for maybe 15 seconds, and then rapidly lock up.

Is the engine oil diluted with gasoline? Does the oil have a gasoline smell ?

Not sure. What's the best way to check that, dip something into the plug hole? Or where the dip stick is?


When you removed the stator cover, did you kick over the motor or use the starter to confirm the motor spins over as it should, while the cover is off, and again after you put the cover back on, plugs in and out? How many rotations do you do on the motor? Many? Or few?


I used the kickstarter and confirmed it rotates fine with the plugs out. With the plugs in, it locks up after about 10-15 engine turns. Or about 10-15 sec with electric starter.


You are not using the starter to spin it over with the plugs out?? The starter will spin it over faster to clear out any liquid gas than the kickstarter will.


I was advised not to use the electric starter as any spark could ignite any gas or fuel. But if it's safe to do it without the plugs I'm game to try that.


 Liquid gas will not compress in the cylinders with plugs in and can bend valves and conn rods.

That's why I've really tried not to use the electric starter much. Once I get it spinning freely without the plugs, I don't hit any resistance in the turns, so I don't think I've bent anything yet.


Have you insured the carbs are not overflowing?

This could very well be the issue, if something is unseated. But I'm not seeing gas coming out of the overflow valves if that's the case. Is there an easy way to check this?


What is the battery voltage before and while you try to start it?
Have you been keeping the battery on a tender to keep it fully charged up?
Have you checked the battery connections are tight?
Have you load tested the battery?


Battery is connected to a tender constantly and is at 13.5V. Again I had no issues with the battery prior, and that should affect the kickstarter turning or starting the bike I would think.