I think I found my fuel "leak" - close call

[Paladin]

Had a couple of minutes to devote to the bike today and,  based on suggestions from many of you (thanks!), I decided to check and make sure there wasn't gas in my cylinders caused by prolonged cranking with a suspected stuck float valve.

Started on the left side at #6. Removed the plug and stuck a clean piece of tubing down the hole into the cylinder attached to a hand vacuum pump. Sucky...sucky... nothing. Moved through all the cylinders doing this, rotating the tubing in the hole so the natural bend in it would hit all over the top of the piston to make sure there wasn't pooled gas. I spent several minutes doing this for each cylinder to make absolutely sure I didn't miss anything.

Hit paydirt in Cylinder #2:



Whew! Dodged a major bullet, there! Not a ton of gas, but enough to cause me serious grief if undiscovered.

I think its safe to say that #2 carb float valve was stuck. As suggested by a poster here, my "leak" was most likely gas coming out the vent tube for the left hand side of the carb bank. When I get around to pulling the carb bank again it will be replaced and I'm going to pay special attention to all the float valves replacing any that look/act marginal. In fact, I replaced 2 that looked obviously hinky when I cleaned everything last week. Might as well spring for 4 new ones so I don't worry about it in the future.

I'm sure the gas in the cylinder washed every bit of lubrication from the cylinder walls. Any suggestions for how to limit excessive wear for that cylinder (until regular lubrication kicks in) when I'm finally ready to crank her up? I hate the thought of the piston grinding away inside the cylinder for even a few minutes without some kind of oil.

[PhredValk]

You could dump a tablespoon of oil down the spark plug hole. It's recommended in the manual for winter storage, so it shouldn't hurt anything.
Fred.

[Paladin]

You could dump a tablespoon of oil down the spark plug hole. It's recommended in the manual for winter storage, so it shouldn't hurt anything.
Fred.

Thanks, Fred. I've done that with a syringe before when checking compression on old cars. Should be just the ticket.

[R J]

WOW MOM, you went to a long task on gettin the gas out of the cylinders.

It is much easier to pull all 6 plugs and hit the starter.   Watch to see which hole it sprays the gas out of.    Same result as your 1 hour job, compared to my 10 minute job.     LOL, but at least you know how to use a sucky sucky tool.    Loved that name.    Relax, I'm just a funnin with ya.

Dry cylinder, ya got an oil can, the old pump type, if so stick it in the plug hole give it a couple of squirts and turn the engine over, it will get enough oil on the cylinder to stop all the metal to metal friction.

You are going to be an expert carb puller here before too long.
Keep up the good work.

[Paladin]

WOW MOM, you went to a long task on gettin the gas out of the cylinders.

You are going to be an expert carb puller here before too long.
Keep up the good work.

  The sucky sucky tool was the best $20 I ever spent. Works every time and I don't even have to buy it dinner.

I'm hoping I can stop after two carb pulling adventures. You're right, though. I bet I'm much faster at it this time than the first time 

[Lonerbtw]

 Dont forget to check your oil. With that much gas in cylender for sure some leaked by rings to bottom end. Better yet dont check it just change it. Just for safty sake pull all plugs and put some oil down each hole. I like Marvel. Then turn it over for 3 or 4 cycles.
 Lonerbtw

[valkyriemc]

+1 You went to this much trouble, might as well do it all. Glad its working out.

[Tropic traveler]

Dont forget to check your oil. With that much gas in cylender for sure some leaked by rings to bottom end. Better yet dont check it just change it. Just for safty sake pull all plugs and put some oil down each hole. I like Marvel. Then turn it over for 3 or 4 cycles.
 Lonerbtw

Good advice.
When my '97 hydrolocked it put a bunch of gas in the oil!

[John U.]

Well, I know that messing with carbs has got to be getting old by now, BUT narrowly avoiding a hydrolock has to count as a good days work in anyone's book. I'd have to say you're way on the plus side of this problem. 

[wizard -vrccds#125]

Pulling the carbs is the right way to go. I just pulled mine on the Project bike. 98 with 10K it has been sitting along time. I was hopping I didn't have to, but milage dropped to 30. Took about an hour. I have 2 sets on the shelf ready to go ( all rebuilt and bench set ). Will have them in in them in tomarrow. The set I removed can be rebuilt when I have the time !           

[MarkT]

Good work on catching the leakdown before it broke the starter / gears.  Good thing to do for future prevention, install a dan-marc valve.  Inexpensive, stops float valve leaks.  See http://www.horseapple.com/Valkyrie/Tech_Tips/Fuel_Shutoff/fuel_shutoff.html

[Paladin]

Good work on catching the leakdown before it broke the starter / gears.  Good thing to do for future prevention, install a dan-marc valve.  Inexpensive, stops float valve leaks.  See http://www.horseapple.com/Valkyrie/Tech_Tips/Fuel_Shutoff/fuel_shutoff.html

Hey, that's pretty slick! I think I like that better than the pingle swap. What size inline fuse did you use? 2 amp?

Thanks!

[Ricky-D]

Mark, when you say it will "stop float bowl leaks", you are mistaken!

The electric shut off will stop gas flow which in turn will limit what can get into a cylinder when the bike is sitting with a leaking float assembly.

But the electric gas shut off has no bearing on a leaky float bowl assembly.

I know what you meant, just wanted to correct the misconception.

***

[MarkT]

Mark, when you say it will "stop float bowl leaks", you are mistaken!

The electric shut off will stop gas flow which in turn will limit what can get into a cylinder when the bike is sitting with a leaking float assembly.

But the electric gas shut off has no bearing on a leaky float bowl assembly.

I know what you meant, just wanted to correct the misconception.

***

What I meant was, it should stop hydrolock through the leaking float valve path.  If you have a leaky float valve and a dan-marc installed, it will only leak until the level of gas in the bowl is drained to the outlet level, wherever that is.  It won't continue indefinitely because it's not getting more gas from upstream.  I don't know the quantities on this, but I suspect ther may not be enough gas in a float bowl to overfill the CC of the combustion chamber with piston at TDC, so cranking would not result in the piston slamming into a volume of incompressible gas and busting the starter train.  Just my guess without the numbers available.

If the vent path - the vacuum to the petcock - is really a path for gas leakdown if the diaphram fails (which some have said), the dan-marc won't address that.  And I haven't addressed it either.

[MarkT]

Good work on catching the leakdown before it broke the starter / gears.  Good thing to do for future prevention, install a dan-marc valve.  Inexpensive, stops float valve leaks.  See http://www.horseapple.com/Valkyrie/Tech_Tips/Fuel_Shutoff/fuel_shutoff.html

Hey, that's pretty slick! I think I like that better than the pingle swap. What size inline fuse did you use? 2 amp?

Thanks!

I don't know.  It's a while ago.  Whatever the watts of the dan-marc is / 12, X 2 .  Maybe 5 amps.  Higher than needed, but only gonna open with a true short.

[michaelyoung254]

What I meant was, it should stop hydrolock through the leaking float valve path.  If you have a leaky float valve and a dan-marc installed, it will only leak until the level of gas in the bowl is drained to the outlet level, wherever that is.  It won't continue indefinitely because it's not getting more gas from upstream.  I don't know the quantities on this, but I suspect ther may not be enough gas in a float bowl to overfill the CC of the combustion chamber with piston at TDC, so cranking would not result in the piston slamming into a volume of incompressible gas and busting the starter train.  Just my guess without the numbers available.

If the vent path - the vacuum to the carb - is really a path for gas leakdown if the diaphram fails (which some have said), the dan-marc won't address that.  And I haven't addressed it either.
[/quote]

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What about placing a 2nd electric shut-off valve in the vacuum line to the carb? The Dan-Mark states that it can be used with Propane, Natural Gas, and air, so if it will stop these, it surely should stop vacuum. (Just make sure to install in a direction whereas the vacuum pulls the needle shut and not open. Seems to me that that would solve the problem of a leaky diaphram.