Fuel in crankcase

[ricko600]

Went on a ride up Angeles Crest Highway to Newcombs Ranch for breakfast. Bike was on center stand with fuel petcock off. Started fine and away I went. Stopped at Newcombs, put bike on side stand and left petcock "On". Had breakfast and talked shop for about 90 minutes. Started bike without incident and rode up the hill about 20 miles then back down to freeway. Running down freeway at 75 and 5,000 RPM the bike started to lose power. I backed off and took the next off ramp, pulled in clutch and bike died. I coasted to a stop then tried to restart. It started by wouldn't rev and sounded "loaded up". I parked it and opened the oil filler plug and had a "gusher" of fuel and oil. I capped it off and called my friend - the owner of the bike, he doesn't ride and let's me ride and maintain it.

So it's back home on my trailer.

1. Could a stuck float valve fill the crankcase in 90 minutes while I was eating breakfast? I guess if #1 was at TDC and didn't fill and hydro-lock it could have filled. It started and ran fine for about 50 miles before bogging.
2. More importantly, what would you do next? Drain and refill crank case and drain and refill again? How do I assess any ring and/or bearing damage?
3. If it runs fine, should we just run it and ALWAYS close the petcock when the engine isn't running?

Thanks again.

Eric
PS - the owner is thinking of draining it and making a static display piece....

[Gearheadgregg]

not sure it could fill the crankcase that fast with stuck float, it would had serious Hydro lock it would have been hard to turn over motor, ? did you check the Oil that (Day) before your ride ?...not the day before, Does your bike have a vacuum Diaphragm Petcock ? if it does put a vacuum pump on the vacuum line and check to see if it holds, I own a Honda Valkyrie and they have the Vacuum Petcock also many owners are Blowing the starter gear Off when trying to start even after sitting for 1 hr...Fuel runs through the Split Diaphragm into the Vacuum Line and down the Carb vacuum Port straight into the cylinders with out having a Stuck Carb Float

[steve murdoch icoa #5322]

Yikes.
After a couple oil and filter dumps maybe something as simple as an oil pressure gauge could inform you of any damage.
If you have to repair the clutch, start looking for one from a Prolink.
Looks like you have received good advice in the other threads.

[Gearheadgregg]

1979 does not have vacuum petcock my bad

[ricko600]

I didn't check oil before I rode. My bad. No it doesn't have vac petcock. I thought same thing - if it was flowing for 90 minutes it would have hydroed UNLESS it was flowing into a cylinder that was at TDC and got past rings straight into crankcase. Could happen I guess but seems pretty small odds all that would happen.
Maybe petcock is letting fuel through when off. I'll check that.

Anyway back to "what to do". Changing oil a couple of times and starting it isn't likely to do and further damage - if it's done its done - so I'll give that a try today.

How do I hook up an oil pressure guage? I'll search posts unless someone can easily point me to something.

Thanks again.

[daves79x]

Continuing from the other thread - the crankcase likely filled over some time with the petcock 'on' or leaking through. Other thing to service is the airbox catch bottle under the battery box. You likely pumped a lot of crankcase fluid out the vent and into the airbox. The bike likely smoked like crazy during this time also due to a lot of this blow-by being sucked into the carbs.

I would certainly put an individual drain on #1 and turn the gas on to see if that float valve is sealing at all. Others can leak causing this also, due to the design of the bowl drain system, but #1 is the most likely to cause this. If you have any question about the carbs' integrity, I'd get them off again and check them out and only reinstall them when they can sit for 24 hours under pressure without leaking or weeping.

Dave

[cbxmel]

Surprised you did not get a bent con rod(Or have you?) as acknowledged fault on the 78/79 1000Z with Honda supplying vac tap under warrenty. Many owners did not take up the offer of free vac tap so yours sounds one that slipped through the net. Ouch!!

Good luck if you decide to check out the inside of the motor.

Mel UK 1876

[CopperCollar]

That just brings tears to the eyes. If the oil was that diluted I would suspect bearing journals overheating.

One could drain the oil and refill it, run the bike and listen for main and or rod journal knocks....hmmmm.....gut feeling would be to split the cases and look at the journals.

Mike

[daves79x]

Mel:

We did not get that recall option here in the states. Never heard of a vacuum petcock retrofitted to a '79 until you folks in GB started talking about it.

Dave

[cbxmel]

Thanks Dave,

Will dig out the worksheet from Honda and show you what it looked like just in case of interest. Peter Broad who founded the Uk club with myself and a few others had the famous 'fuel lock' when he parked his bike on the side stand in late 78 and did not turn off the gas tap. Ended up with bent rod which had mponuted on a display plinth as warning to others. Bike was still under Honda warranty as only a few months old.

cheers mel 1876

[cbxmel]

Hi again Dave,

Here is the instruction sheet which came with the vac tap the owner decided to fit themselves even the dealer would need it!

cheers Mel 1876 ps see next post for rest of sheet.

[cbxmel]

Here is part one!

[EMS]

Yes, there was a retrofit for the 79s with a vacuum petcock. And these are probably the installation instructions. But there was no recall replacement by Honda under warranty that I am aware of. I bought my 79 new in Germany in 1978 and I never heard of a recall petcock replacement and my bike was serviced by the dealer throughout the warranty period. It still has the original plain petcock. I always turn the petcock off on any bike I can do so. Even on my '81.
I don't know what Honda did if you had hydro-lock within the warranty period. Maybe they accepted it as a design flaw and picked up the bill and as part of the repair installed a vacuum valve.

[cbxmel]

Yes Mike,
I know Peter Broad's bike was done under the warranty as several others I have been made aware of were. I used to stock the vac kits with the instructions when I ran cbx services for five years. After around three years Honda would no longer accept claims under the warranty for this design fault or whatever you want to call it. I know my 78 which was not sold until November 1981 having languished in a Honda main dealers since October 1978 was most certainly fitted with the vac kit when it was sold as I am the second owner and the original buyer made a point of advising me it had been fitted before sale.

cheers mel 1876

[EMS]

Mel, I think this is a matter of semantics. In Germany (and probably here in the U.S.) Honda did not offer free vacuum kits for anybody who asked. If you had a problem due to hydro-lock or else, Honda probably accepted a warranty claim and repaired it and also installed a vacuum valve. But there was no general retrofit offer, like the one for the 469A advancer, for example.
If this would have been something Honda had a service bulletin about which would have initiated an automatic replacement, most CB1 CBXes would have a vacuum petcock. They do not. At least not outside the U.K.