Vacuum At Petcock...Carb Sync

[Steve K (IA)]

OK.  Had my tank off to change vacuum lines.  Bought a Digi Sync and ready to use it.  

One of the lines I replaced was the petcock to #6 with a hose I bought from Redeye that has been in my toolbox for two years.

Ready to sync the carbs, disconnect the hose to the petcock.  Attach my Mity Vac and it won't hold vacuum.  Can get down there and suck on the hose.  I could keep up at it all day and the air is free flowing through the hose.  Can taste/smell a bit of gas.  

I know the petcock works.  The last time I went for a ride, I didn't get far when the bike started to run like crap.  Remembered I didn't turn the gas on.  Turned on and all was good.

While I had the tank off, it was in the off position and never leaked.  

Ideas?

Thanks, Steve

[longrider]

I synced the carbs on mine about three weeks ago.  Ran into the exact same issue with the petcock.  When I pulled it apart the diaphragm had a small tear in it.  The engine has enough vacuum to pull it open but it will make #6  run lean    At idle it wanted to run only on five.   The petcock and carb sync sure smoothed mine out.

Warren

[Steve K (IA)]

I synced the carbs on mine about three weeks ago.  Ran into the exact same issue with the petcock.  When I pulled it apart the diaphragm had a small tear in it.  The engine has enough vacuum to pull it open but it will make #6  run lean    At idle it wanted to run only on five.   The petcock and carb sync sure smoothed mine out.

Warren

    
You've got to be Kidding me!

Warren,

Thanks for the tip. 

I tore into this project because it started running like crap.  It's on it's 16th season and the vac lines hadn't been replaced.  I figured that was the problem.  What I took out looked like new and had me thinking that the vac lines that I was replacing were good.

So, if the petcock diaphragm won't hold a vacuum, # 6 had to be causing the problem I experienced. 

Well, need to get a cover set and a fuel line quick disconnect ordered.

[longrider]

The cover set can be removed and replaced even if there is a bit of fuel in the tank.  I place a cloth on the bench and tip the tank forward.  It will stand firm.  Remove the cover set and replace. When you are done lay the tank carefully on the bench with the petcock about 2" off the edge.  Use a slightly larger hose and a small can to catch fuel..  pull a vacuum on it with the petcock in each position.  You can verify fuel flow and be sure it shuts as it was designed.

Warren

[hubcapsc]

More than once I've set my tank on its nose and a siphon took effect, causing
gas to flow from the vent at the back of the tank. Careful doing this
inside the garage. There's an article in shoptalk that mentions this and
I think they say if you're careful to close off the vent (put your thumb over
it or something) while you're tipping the tank on its nose, the siphon won't
set up... but still be careful doing this inside... the gas doesn't start
coming out right away, so don't be fooled into complacency...

-Mike "one of the only good things about not having an inside to work on my bike..."

[Steve K (IA)]

Thanks guys.  I was wondering if the cover set could be changed without removing the petcock.  I'm pretty upset I'll be taking the tank off again.   

[Jess from VA]

So you have to pull the tank and the petcock to change the coverset?

Isn't there a way to vice grip (or something) the fuel line and change it with the tank on with gas in it?

[Steve K (IA)]

So you have to pull the tank and the petcock to change the coverset?

Isn't there a way to vice grip (or something) the fuel line and change it with the tank on with gas in it?

You can't get to the right side of the petcock where the cover is.  It's blocked by the frame.  Would be cool if it could be changed without removing the tank.  If you seen my previous posts today, R&R of the tank is one of the most frustrating jobs for me to do on these machines. 

I've got a cover set and fuel line disconnect ordered.  Hope that disconnect makes things a bit easier.

[Jess from VA]

OK Steve thanks. 

We've had a number of report of problems and some leaks reported from those fuel line quick disconnects.  I had two and was talked out of using them (may still be in my parts bin).

I've had the tanks off.  What I found most helpful (working alone) was getting the bolts out, then lifting the rear enough to get a 2 X 4 on it's edge underneath it (which is about as far as it will come up with the lines still attached).  That gave me enough room to fish around and get stuff unhooked without having to hold it up.  So many jobs require one more hand than I have available.  Got it all buttoned up, and it ran great, except the IS dash immediately started flashing low fuel at me, and it kept flashing until I unbolted and lifted the tank up again and plugged in the fuel sending unit again.  Grrrrr.  Of course, that wire slipped down out of sight during all the confusion.

[westnek]

I just did mine to a pingel and tilting the tank forward is ok until you bring it back to level or on bike position -gas runs out of vent pipe from bottom of tank  -so I tied a knot in a plastic hose until I got  things all connected on the bike then caught the fuel in a container and it stops running =sure scared me at first =but all ok now ,,until something else go's -i'll post my picture>>

take care folks ride safe allways

[xman]

Does anyone have the Honda part number for the cover set?

Thanks

[Steve K (IA)]

Does anyone have the Honda part number for the cover set?

Thanks

16953-MBZ-B51 COVER SET,rooster    $28.84 before shipping at Partzilla

[longrider]

As I said in my post above.  If you have only a Small amount of fuel in the tank you can tip it forward and remove the petcock. It would be a mess if fuel came out of the vent that's for sure