Hydraulic lock symptoms?

CDNCBX · Post by **CDNCBX** » Tue May 13, 2008 11:17 am

Has anyone ever had the unfortunate experience of hydraulic locking on the older models? I have a '79 and I waited a few hours before shutting off the fuel valve after riding. The next time I tried to start it, the motor only turned about a 1/4 turn then stopped. I tried again - but only heard the solenoid click. At first I thought it could be the starter, but also understand that hydraulic locking could have been the culprit.

Could there be a bent rod from that 1/4 turn caused by the starter motor while there was a lock? Or is the starter just stuck/engaged? The rear wheel is locked when in gear - and the bike can't be push-started. (battery is fully charged).

I am plannig to take it in, but wanted to let the mechanic know what the issues may be so he knows what to look for....any clues?

Thanks in advance - again!

EMS · Post by **EMS** » Tue May 13, 2008 11:28 am

Are you saying that the engine is stuck? You may have a different problem. If you had a bent rod, the engine would probably still turn, even run. You could diagnose that yourself by trying to see how high piston No 1 comes in the cylinder on an upstroke. But if you can't turn the engine over, it is either seized or you have a mechanical block somewhere.

CDNCBX · Post by **CDNCBX** » Tue May 13, 2008 12:01 pm

Yes, the engine is stuck. We tried to push start - but the rear wheel is locked. I was thinking that maybe the starter is still engaged (never disengaged from the time I tried to start it). So was thinking of pulling it out and seeing if the engine would then move.

I'm not an experienced mechanic (that is why I thought I'd take it in). The bike worked perfectly the last time it was riden (by a friend) - but because I was not riding it, the fuel valve remained open for 3 hours after the ride finished. (Hence I also suspected hydraulic locking when the starter would not turn the engine).

I suspect a mechanical block as you suggest - so I thought I'd start with the starter (no pun intended

I did smell fuel when I removed the plug from the number six cylinder - which brought to mind the hydraulic lock scenario...

Thanks for your reply - I'm hoping that I have not damaged the bike.

daves79x · Post by **daves79x** » Tue May 13, 2008 12:23 pm

Remove all the plugs NOW. If it is gas filling a cylinder, it will come pouring out and then the engine can be cranked with the starter to clear the remainder. It is not likely you bent a rod just with the starter. Rods bend when the bike fires on a couple of cylinders when one is full of gas.

If you find gas in a cylinder, measure down from the top of the plug hole in that cylinder to the piston. Then measure the other cylinder that rides with it (1-6, 2-5. 3-4). You can tell if a rod is bent as the piston will be measurably lower.

Then change your oil, reinstall the plugs and start it up. A bent rod will have a deep knocking sound that wasn't there before. If all is well - find and fix the leaking float valve and turn your gas off every time you park the bike overnight.

Dave

Terry · Post by **Terry** » Tue May 13, 2008 12:31 pm

In re: " If all is well - find and fix the leaking float valve and turn your gas off every time you park the bike overnight."

Make that (everytime you shut the motor off) if you have the original carb plumbing, not just overnight. I live on N 2nd St near Hedding and 1st. Where are you?

CDNCBX · Post by **CDNCBX** » Tue May 13, 2008 1:07 pm

Thanks all for the info... I will remove the tank and ALL the plugs and make the checks you recommend.

Terry, I'm at Camden and the Almaden Expressway in the Almaden Valley. We should get together for a ride - once I have this thing fixed

I may end up taking it in if it goes past the plugs - I don't have the experience and don't want to tinker for fear of making things worse.

Thanks again.
Persi

alimey4u2 · Post by **alimey4u2** » Tue May 13, 2008 2:13 pm

If raw gas has been leaking into the cylinder, don't forget to replace your oil as it is now contaminated....

Ooops, looks like Dave has covered this in a previous reply, however I will leave this intact as a reminder...

daves79x · Post by **daves79x** » Tue May 13, 2008 3:24 pm

Forgot to mention - if you crank the engine with the plugs out and gas has come out of a cylinder - make sure the kill switch is 'OFF'. You'll have a fire going if not. The spark will jump around from the caps.

Dave

CDNCBX · Post by **CDNCBX** » Tue May 13, 2008 4:28 pm

Thanks all for your tips! Especially about the kill switch!! I'd hate to start my bike on fire

alimey4u2 · Post by **alimey4u2** » Tue May 13, 2008 4:32 pm

CDNCBX wrote:Thanks all for your tips! Especially about the kill switch!! I'd hate to start my bike on fire

Excellent advice from Dave, you could have 6 flame throwers..

.

bobber · Post by **bobber** » Wed May 14, 2008 7:41 am

Also try, once plugs are out, removing r/h crank cover and rotating engine in reverse via the crank with a 17mm wrench.
Curious too about valve timimg... may be something to check before trying to force it to turn that the timing chain hasn't jumped and a piston is up against a couple of valves.

Rick Pope · Post by **Rick Pope** » Wed May 14, 2008 8:01 am

I don't think turning the engine backwards is a good idea. The cam chain tensioners aren't meant to have the strain......

EMS · Post by **EMS** » Wed May 14, 2008 8:20 am

Rick Pope wrote:I don't think turning the engine backwards is a good idea. The cam chain tensioners aren't meant to have the strain......

I would agree with this. I think that is the reason, Honda says in the manual, you shouldn't do this. Especially the secondary cam chain tensioner could be pushed loose.

bobber · Post by **bobber** » Thu May 15, 2008 7:49 am

EMS wrote:
Rick Pope wrote:I don't think turning the engine backwards is a good idea. The cam chain tensioners aren't meant to have the strain......
I would agree with this. I think that is the reason, Honda says in the manual, you shouldn't do this. Especially the secondary cam chain tensioner could be pushed loose.

So what about when the valves are adjusted?
I'm not saying to turn engine complete 360 degrees, which can be done properly with no issues, however it would quickly identify some possible culprits to be looking for.
Engine shut down and initial start is when valve timing jumps. Trying to force an engine with an unknown problem to turn via electric starter or push starting can cause much more damage than turning by hand, where you can "feel" the rotation.

EMS · Post by **EMS** » Thu May 15, 2008 10:12 am

bobber wrote: So what about when the valves are adjusted?
.

I think it is exactly for this procedure, where the manual says "do not turn the engine backwards". I don't have the manual here...