Stater chain getting stuck

[Greenlander]

Hello fellow FJ owners,
Recently my 84 FJ occasionally lock up when starting. It will fire the first cylinder with a puff of smoke coming out from the first header pipe then stops with a loud clunk. Then starts up a bit rough at first then normal once warmed up. Someone here posted the same problem and he would put it in gear off the stand and move bike to work it free. He was worried that he would eventually cause the chain to snap or the guide to break off and cause damage so he had it replaced. I Have noticed more noise from the chain since mine started to get stuck (5 times so far). I was told by Randy that these chains rarely breaks so my question is: can I mitigate the stress on the chain and the chance the guide or oiljet will come off and cause serious damage, by bump starting it in 2nd gear down my driveway which I did twice successfully ? OR is a breakdown right around the corner? I'm on a budget so hoping to avoid having to split the cases.
Any constructive input will be greatly appreciated.
Cheers, Hans

[TRoy]

symptom sounds exactly like what i experienced many years ago. due to hydro-lock.  carburetor needle valve/seat leakage causing gas to seep into cylinder when bike is parked.

[TRoy]

...if so, there's likely a some gas seeping past the rings & into the engine oil too. check see if the oil smells like gas, if so fix the carbs , fuel system & change the oil

[Pat Conlon]

I think TRoy is on to something here...hydro lock from a leaking petcock.
I don't recall ever hearing of a "locked up" starter chain.
Stretched chain, yes. Noisy chain, yes, but a locked chain? No.

[ELIMINATOR]

If the crankcase had enough fuel in it to cause a hydrolock, surely bump starting it wouldn't work?

[Pat Conlon]

If the crankcase had enough fuel in it to cause a hydrolock, surely bump starting it wouldn't work?

Correct, if the crankcase is full you're SOL, you're going nowhere, however if just 1 cylinder is full, or partially full, a locked starter can be a symptom.




Consider this a PSA: Check your petcock. If it dribbles, fix it...or you will bend your rod.....
(where's Klavdy when you need him?)

[Greenlander]

symptom sounds exactly like what i experienced many years ago. due to hydro-lock.  carburetor needle valve/seat leakage causing gas to seep into cylinder when bike is parked.

Yes you hit the nail on the head! About a month I noticed a discreet smell of gas after having the tank off the week prior. Turns out I hadn't properly secured the clip on the gas line at the petcock,causing a slight leak that dripped on the vacuum hose and then onto my unipod by 2ND carb. I secured the gas line but didn't clean the unipod. I took out the spark plugs from cylinders 1 and 2. I found #2 sooted from running too rich so it appears the gas only leaked into that one. I do detect a whiff of gas when sniffing the oil but not strong so I'm thinking it was only leaking at the petcock and not at the carb as well. So I will clean and treat the unipod,change the oil and see if that works (with fingers crossed)
Thanks for your advice. Another great example how helpful this forum is to FJ owners.

[Greenlander]

If the crankcase had enough fuel in it to cause a hydrolock, surely bump starting it wouldn't work?

yeah that would eventually cause a bent rod or valve if I started doing that. Thanks for your input

[Greenlander]

If the crankcase had enough fuel in it to cause a hydrolock, surely bump starting it wouldn't work?

Correct, if the crankcase is full you're SOL, you're going nowhere, however if just 1 cylinder is full, or partially full, a locked starter can be a symptom.




Consider this a PSA: Check your petcock. If it dribbles, fix it...or you will bend your rod.....
(where's Klavdy when you need him?)

Whao! A bent rod! I would be SOL indeed. That got my attention. (Welcome to Hydro lock 101 Hans)
I've never heard of it before but it surely is the right diagnosis. I Think you're right that it's only on one cylinder so hopefully no serious damage other than further stretching my now noisier starter chain .
I will do as suggested and go from there.
BTW why is it named a "petcock "? Where did that originate? In a whorehouse maybe?
Go niners, Hans

[Sparky84]

a leaking petcock

Is it much of a job to replace the petcock?
Any special sealant or just take unbolt old and install new and relighting!

My tap leaks when turning it, which only happens on the odd time I need to set it to prime after playing with carbs.

Cheers
Alan

[FJmonkey]

Easy to replace. Just use the new gasket that comes with it.

[Sparky84]

Easy to replace. Just use the new gasket that comes with it.

Thanks,
Just do the bolts up tight or is there a torque setting.
No loctite required on bolts?

Cheers
Alan

[FJmonkey]

If I remember correctly bolts are JIS (looks like Philips). Not easy to measure torque, so nice and tight. A proper JIS bit is recommended. Or change the fastener for a different head type. A medium thread lock is ok. The gasket compresses and helps naturally with holding the threads. 

[Greenlander]

If the crankcase had enough fuel in it to cause a hydrolock, surely bump starting it wouldn't work?

Correct, if the crankcase is full you're SOL, you're going nowhere, however if just 1 cylinder is full, or partially full, a locked starter can be a symptom.



Update; So when I took the tank off to check for leaks and clean  Unipods,I found a slight seepage at the elbow of the petcock. Even though it is safety wired I could twist it and timed a drop every 4 minutes which was enough to cause hydrolock when parked a couple of days with #2 piston near the top.
So I tapped it back in tight and not a drop after two hours  I then cleaned the Uni's and was surprised how dirty they were. I switched from KD's last October! It's likely because 40%of my commute is through the burnscar from the fire last thanksgiving.
Took it for a ride and wow what a difference cleaning the filters made. She now runs crisp and responsive as after a tune up  So I suspect the petcock was leaking all along but only affecting the second cylinder and when it started turning over slow I thought I had a weak battery. With a new battery it would occasionally do it still but that didn't alarm me as being the first symptom of hydrolock because she was still running good.
Researching the problem I found a article advising you just tap the starter button to hear if any movement,if nothing don't depres it because of the stress involved on the internals,which is the loud clunk. At that point pull the plugs to force the gas out carefully,reinstall and be sure to check oil for gas in it as well before riding.
I'm Changing the oil today just for good measure and also to check for metal particles.
Thanks again for everybody's input.
Cheers, Hans

Consider this a PSA: Check your petcock. If it dribbles, fix it...or you will bend your rod.....
(where's Klavdy when you need him?)

Whao! A bent rod! I would be SOL indeed. That got my attention. (Welcome to Hydro lock 101 Hans)
I've never heard of it before but it surely is the right diagnosis. I Think you're right that it's only on one cylinder so hopefully no serious damage other than further stretching my now noisier starter chain .
I will do as suggested and go from there.
BTW why is it named a "petcock "? Where did that originate? In a whorehouse maybe?
Go niners, Hans

[Motofun]

I was always taught to keep my CBX on the center stand.  Reason being if you left it on the side stand for a long time AND float valve leaked (petcock being open) it would fill the number one cylinder.  The CBX was an in line 6 with the #1 cylinder hanging way out to the left.  It would bend the conn rod and hole the piston.  Voila....the infamous "hole in one"!