Topic: Sad day, finally got her running then locked up, help?? UPDATE

[fil]

Hey Guys, so this new to me project 78 cb750 K came to me running on barely two cylinders with some issues that I've been sorting out.  Got the carbs all clean and replaced the DYNA S that was faulty.  Finally got it hitting on all fours and sounding great.  Left it sit 5 minutes, came back to dial her in- do some timing adjustments, set idle, and go for test run and got nothing with the starter.  Hooked up a battery charger then noticed the kicker was stuck.  I can move the motor slightly with much force applied, but it's seized.  I've got a ton of hours into this thing and not thinking straight so thought I'd ask if any of you have opinions/ suggestions.  Thanks!

[VTCBike750]

I really have no idea where to start, but wondered if taking out the plugs, placing some oil into the cylinders, and trying to turn it may help. However, doesn't really solve what caused things to seize up in the first place. Probably start at the oil pump, make sure that is running properly, and change the o-rings.

Do you know if the engines ever been pulled? Maybe some gasket sealer blocking an oil port?

[fil]

Thanks adam, as soon as I got done typing I went out and did just that.  I can get it to turn over now (cooling?) but not right at all.  I would not be one bit surprised if something were gumming up the pump.  I have no history on it but found all four carbs had black RTV in every jet and orifice.  The fact it turns over now has me breathing SLIGHTLY better.  Thanks

[BeSeeingYou]

Where you running it for a length of time while stationary.  They can overheat so if you do that run a fan full blast aimed at the engine.  I had my XS650 lock up on me while riding in extreme heat 2000 miles from home.  After an overnight camping in the ditch she fired up in the morning.  It burned a bit of oil for a while that lessened over time and now 25 years later it's still running strong.  I never did tear down the engine.

[scunny]

pull your tappet covers and see if you have oil up top.

[dave500]

as scunny said look up top,,if you found rtv in the carbs any in the oil galleries is like cholestorol in your main veins.

[fil]

Good stuff guys,
Srust58  I would say that in these triple digit temps your suggestion to run a fan is a great one, especially while sorting out details.  However, I did not run it long enough to overheat really.  I will definitely pull the valve cover to check for oil. 

I just woke up (430 AM) to the realization that I bet there is gas in the oil.  Last thing I did before calling it a night was put a rag underneath the dynamo cover b/c all of a sudden there was an oil stream coming from the three screws in the center.  I already know the petcock is leaking since there was gas on the floor under where I stored it while fixing electrics.  Silly as it is, I wonder if the floats are in upside down?  Put them on as I found them but that was assuming they were on right... gotta remember if the "hump" is up or down.  I just hope the motor is not fried...

[KingCustomCycles.com]

It is less work, and less money, to find another motor rather than spend too much time chasing down problems.  I try to keep 2 or 3 on hand for just such an occasion.

[Scott S]

 Sounds like it could be hydro-locked if there's gas in the oil OR it could have run lean and hot if the carbs were gummed up and you weren't getting fuel properly.

[KingCustomCycles.com]

Oil thinned by excessive fuel will not lubricate, evaporate when exposed to combustion, and cause all sorts of mayhem.  It is a common problem with vacuum controlled petcocks.  So much so that most old bikes with the vacuum shutoff have either had it bypassed, or the cylinder it draws vacuum from is scored and low on compression.  The good news is you might have caught it early enough.  If it happens going down the highway, it locks just a tad tighter.  As a side note, aircraft used fuel dilution in the oil to lower the viscosity (thinner) for cold weather starting before muligrades were available.  The fuel evaporated during operation and left the thicker oil to do its job. 

[fil]

King, luckily this petcock is not vacuum controlled (should it be??).  I had one on a yamaha 650.  After several attempts to properly restore it I threw it-  Far - then replaced it with an aftermarket....

I'm leaving the office for home in a bit PRAYING the motor is hydrolocked.  Going to drain the pan, pull plugs, keep my fingers crossed it's free and kick then try to go from there.  Getting that far seems far, but planning on new petcock and figuring out why it would flood back in motor. 

Pray to the God's of two wheel steel for me!

[KingCustomCycles.com]

No Honda SOHC I know of had a vac petcock.  Just one God, and he is looking after us, always.  He just wants you to learn something here, and look to Him for the answers.

[fil]

meant no religious disrespect.  Something a few of us here (around my garage) say when thrashing on a bike, not really serious about it.  Thanks for your input.

[fil]

OMGoodness she's free!  drained fluids- yes there was gas, pulled plugs, let her soak in penetrating fluid and she kicked over, rough but turned.  Soaked another few minutes, tapped the starter and slung crap 25 foot across the garage.  Back to no resistance. 

I NEVER thought a honda would take me through the emotional roller coaster that my BSA or Triumph does.  In 24 hours I went from full celebration firing strong on four cylinders for the first time to catastrophic lock up tears to joy for just kicking over.  wow...

Time to regroup, check for oil up top, and start all over with remote controllable fuel source.  Any other ideas?

[VTCBike750]

Nice! What did you use for penetrating fluid?

Next? Check compression?

[fil]

PB Blaster...Only because it was easily accessible and works for most "easy" jobs.  Kroil is a better product, no kidding ATF (tranny fluid) and acetone is amazing.  I've acquired a Seized Harley Sprint, a triumph single, my bsa and a panhead that have been free'd using the above.  none were torn down until way after they were running for a while.  I've got a fairly good "finger gauge" for compression, at least to get bikes running.  An actual test is definitely on the list for tomorrow, thanks

[grasscutter]

No Honda SOHC I know of had a vac petcock.  Just one God, and he is looking after us, always.  He just wants you to learn something here, and look to Him for the answers.

Both my SOHC CB650's do.  1981, 1982.

[fil]

Today I changed the oil & filter verified there was oil up top via valve covers, filled an auxiliary fuel supply, closed my eyes hit go and it roared back to life.  Was again back on all fours smooth.  I'm hoping it was just hydrolocked due to fuel leak.  I'm not 100% though and wondering if it could have wet sumped, been filled, and continued to leave oil i sump.  I'll keep an eye on that, for now I'm moving on...

To fixing timing side stripped screws and more importantly figuring out the broken center bolt going through timing advance and pickup.  Any suggestions appreciated...

thanks