Engine won't turn - stuck.

[GDBD59]

Yesterday I balanced the carbs on my partner's recently acquired K1. 17k miles, tidy bike. I fitted a hose to the front cyl intake. I did not take the carbs off. Got the carbs set, & finished yesterday evening putting the airbox back on. I had to turn the idle speed down after finishing, but it seemed a little more difficult to start, so I was interested to see how it started this morning.

It turned over for a fraction of a second & then there was a solid clunk. The engine is stuck. I've taken out both spark plugs & took the starter motor off. No sign of any damage. I can't turn the engine with the back wheel, forwards or backwards. If I've managed to drop something into a cylinder it's happened fitting the airbox, but if so it's immediately got past a carb slide.....???


Suggestion as to what to do next?

[squirrel_hunter]

I've not experienced this myself but it sounds a little odd that it started and then wont turn over the following day even with the spark plugs out and turning the rear wheel. If the engine is suspected to be stuck then while I would think to test directly by turning the engine from the fly wheel as done to set the cams but that might not be the best thing...

If you were in the carbs then I'd go there and start looking. Take the carbs off and see if there is anything trapped in the inlets. Check that the hoses are all still correctly connected and the balance pipe is blanked back off. Do you have a bore scope or way of looking into the bores while the plugs are out to ensure that there is nothing in there? I'd also be tempted to take the valve covers off to see if there is anything obvious there in case there is a stuck or bent valve or the cam chains are still attached and tight. Hopefully this will be a simple fix to a simple problem but I expect you'll need to do a bit of time consuming investigations and take it slowly step by step.

[GDBD59]

I don't have a borescope. They can had be had fairly cheap I believe.....may have to get one. I basically agree with all you've said.

[redtrummy]

If something fell into a cylinder it would surely still try and turn over and you would hear about it. it was obviously in gear when you turned the rear wheel, and presumably you did try it in neutral on the starter motor? I presume the starter motor spins ok disconnected from the engine A locked gearbox would give the same symptoms . Keep us informed of progress.
Good luck

[GDBD59]

I went to see a Mech engineer who has a machine shop. He recently did a job on carbs. He's puzzled why the engine won't turn in either direction. He's wondering timing chain. He's suggested a couple of things to try.

[GDBD59]

The front cylinder intake was full of fuel. So when engine started to crank it filled the cylinder. I'm not sure why...

[Seeker]

Originally Posted by GDBD59

The front cylinder intake was full of fuel. So when engine started to crank it filled the cylinder. I'm not sure why...

If the seals on the vac operated fuel pump have failed and a float valve stuck in a carb it can do that.

[GDBD59]

Originally Posted by Seeker

If the seals on the vac operated fuel pump have failed and a float valve stuck in a carb it can do that.

Ok.....and in the context of earlier posts? I'm puzzled why only the front. And the bike ran ok (1st test since buying) until I 'messed' with it......

[Ruffy]

Originally Posted by GDBD59

Ok.....and in the context of earlier posts? I'm puzzled why only the front. And the bike ran ok (1st test since buying) until I 'messed' with it......

Possibly the float valve on the rear carb was in very good order, certainly good enough to block fuel passing under gravity.

Also, it's possible that the problem was there before you bought the bike and just hadn't been noticed. If the 'leak' is minor it might take some days for sufficient fuel to pass to cause a problem so if the bike was used regularly it would never show itself. Maybe the agitation from removing and re-fitting the airbox allowed more flow than 'usual'? (speculation)

From memory the front cylinder is lower than the rear and of course differently inclined, so maybe that just meant more fuel gathered there? (more speculation)

My last curvy seemed to have a similar starting problem occasionally but it was totally fine if the bike was used for day-to-day commutes - it usually only 'struggled' on Monday mornings if it had been stood over the weekend. (Battery & usual reg/rec possible issues were eliminated throught fault-finding!) Sadly I never fixed it fully because I was knocked off and the bike was scrapped. But I was considering just fitting an old fashioned on/off fuel valve on the tank outlet pipe that I could use for longer lay-ups - more a bodge than a proper fix though. Checking and changing seals on vac operated bits is probably the right answer.

[GeorgeRYoung]

Originally Posted by GDBD59

The front cylinder intake was full of fuel. So when engine started to crank it filled the cylinder. I'm not sure why...

If I understand correctly, you took out the spark plugs and tried to rotate the engine using the rear wheel (presumably in 6th). I'm puzzled why the fuel didn't squirt out the spark plug hole.


This phenomenon (called 'hydrolock' from hydraulic lock) is fairly common on Kawasaki Concourses, caused by a combination of crappy petcock and leaky float valves, and has been known to cause bent rods.