Topic: Fuel dripping after carbs rebuilt.....

[cb750k7]

Hi all.
Need a few hints to save time and labor 

Yesterday I have rebuilt my carbs with a Friend's help.
After a complete renewing the internals (jets gaskets etc) air blowing through all openings and synching all 4.

Murphy took charge and when taking the bike to a test drive,  the fuel went dry just before installing a fuel filter...

Topped the tank, and rode the bike for an hour.
When parked with the petcock left open,  I found a puddle of fuel under the bike.

Seemed to me that the leakage was from the overflow tubes.

My concern is if a some "sludge" from the fuel tank got to the carbs because I was running  "on empty" and I need to go through the whole ordeal again or is there a better way to diagnose the cause of the overflaw?

Today I found that the fuel is still dripping even though the petcock was "OFF".

And another factor is that the bike "leans" heavily to the left when parked on the side stand (the center stand is missing).

Any "magic" hints or to go strip the carbs all over again

Cheers,

Jona

[Cvillechopper]

Happens very often that the pins holding the floats in have gouges from being removed with pliers.  This can keep the float from moving as it should so it doesn't let the valve shut off when it is supposed to. 
Did you replace the float valve and seat?   If not, did you clean them well?  You could try tapping on the carb bowl lightly and see if that helps.  Often it will loosen the floats if they're not badly stuck.

Good luck.

[Stert]

i have had my random carbs start leaking fuel like that. i just open up the top of the carb that is leaking and run my fingers over that little needle and whatever else is in there.

sorry i dont know what anything is called, but my dad told me there could just be a little peice of dirt holding it open.

it has worked for me every time. sorry i couldnt be more specific.

edit: me doing what i explained is probablty just a long way helping what Cvillechopper explained above.

[silentone]

You could try tapping on the carb bowl lightly and see if that helps.  Often it will loosen the floats if they're not badly stuck.

I cleaned and put my carbs back in Sunday and had the same thing happen, fuel leaking out the overflow on one of the carbs.  I did what Cville suggested above and it worked.  I used the handle of a screwdriver and lightly tapped the sides of the bowl.

[mystic_1]

Today I found that the fuel is still dripping even though the petcock was "OFF".

This part sounds odd.  How much fuel flowed out while the petcock was off?  Disconnect the fuel line and make sure that off is really off.  If not, then you have a second problem - your petcock.

mystic_1

[cb750k7]

THANKS,

I will try and tap the carbs with a rubber mallet (gently..)

The pin was extracted very cautious,  not to leave any scratches and marks on it.

Will take a look at petcock tomorrow.

What kind of a fuel filter is recommended?  Where to install it?

Cheers,

Jona

[TwoTired]

If you still have the in-tank filter on top of the petcock and it is still in good condition, it is unlikely that anything significant made it to your freshly cleaned carbs.  How many fuel filters is enough?  I reason that one good one is enough.  So did Honda.

When refitting old float needles and seats, it is important to keep the same needle matched to the same seat.  Juggling them from one carb to the next means a break in period for non-rubber tipped float needles.
If you used new needles and seats, why?  Didn't the old ones work?  Maybe you should put the old ones back in?

Could you have put the floats in upside down?

Did you use the proper float height setting for your carbs. PD carbs don't use 26mm.

Did you check the float bowl stand pipes for cracks?

And another factor is that the bike "leans" heavily to the left when parked on the side stand (the center stand is missing).

Check your side stand pivot for wear and that the pivot bolt is tight, pinching the stand "fork" tight.

Cheers,

[Cvillechopper]

You can use any high-flow in-line filter.  Here's a sight with samples.

http://www.parkeryamaha.com/index.asp?PageAction=VIEWCATS&Category=1333

As for the petcock issue, you can first try snugging the 2 screws on the face down a little.  If that doesn't work, you will probably need to replace the seal.  It can be found many places.  Here's a link for reference.  They call it the dial seal.

http://www.crc2onlinecatalog.com/Index_Main_Frame.htm

I wouldn't use a rubber mallet to loosen the floats.  You want something that transfers as much vibration without having to use much force.  The back end of a solid handle screwdriver would work better than a heavy soft object.  If you can't get it loose tapping with that, you need to pull the bowl and take a look anyway.  The rubber mallet has too much inertia to be hitting your bowls with it.

[cb750k7]

TT
I replaced all parts because I had no idea of the bikes pat, (new to me) and the carbs were leaking a little and handled very rough .

The bowls were seated at 26 MM

How do I clean the inner filter? Have to take the petcock apart?

Just bumped in this thread,  http://forums.sohc4.net/index.php?topic=5410.0 will check on the float bowl stand pipes too.

Cvillechopper
Took your advice not to use the mallet,  the link you gave about the dial seal gives only the models 69' till '74.  Will they fit '78?

Thank you all for your help !!!

Cheers,

Jona.

[TwoTired]

The bowls were seated at 26 MM

Really?  What carbs do you have?  Do you have a choke knob at the bars?  Or, choke lever on the side of the carbs?  Do the carbs say PD on the side?

How do I clean the inner filter? Have to take the petcock apart?

The filter is accessed by removing the petcock.  It fits into the tank outlet and goes around the tube in the petcock.  They can be difficult to remove without damage, particularly if there is rust in the tank.  If you can find a bolt that just barely fits into the hole, screw it in about 1/8 to 1/4 inch and pull out the filter.  It has a pretty fragile membrane and can be damaged by almost any tool.
However, the beauty of the Honda filter is that you don't usually need to clean it.  The sloshing of the fuel in the tank clears the filter for fuel flow, but still prevents the crud from reaching the carbs.  Unless there is something sticky in your tank, you should be able to flush out particles from the filler hole.  Do you see any rust inside?

Here's a new one and a damaged one from a very rusty tank that refused to come out quietly.

[silentone]

The bowls were seated at 26 MM

http://www.motorcycleproject.com/motorcycle/text/specs.html

Clicky the linky.  Find your carb and readjust your floats per those specs.

[cb750k7]

The bowls were seated at 26 MM

http://www.motorcycleproject.com/motorcycle/text/specs.html

Clicky the linky.  Find your carb and readjust your floats per those specs.

I know that the bike is a K8  but the engine is '76...

choke lever on the side of the carbs
The floats are correct at 26 MM.

TNX

[silentone]

The bowls were seated at 26 MM

http://www.motorcycleproject.com/motorcycle/text/specs.html

Clicky the linky.  Find your carb and readjust your floats per those specs.

I know that the bike is a K8  but the engine is '76...

choke lever on the side of the carbs
The floats are correct at 26 MM.

TNX

I didn't know that.  Nevermind then.

[voraciousc]

I am not sure if you mentioned this or not, but are your floats in good shape.  If they are eroded or damaged, they will not float like they should.  I currently have one that does this and if I turn off my bike and then turn off the petcock, I will have a small pool of fuel every time.  To check to see if it is your petcock that is leaking you can always shut the fule off while the motor is still running.  After a minute of two shut off the motor and see if it leaks.  If it does your petcock will need to be rebuilt, if it doesn't your petcock is just fine and the problem is in the carbs.

[Roach Carver]

if you have brass floats take the one of the carb that is overflowing and shake it . If it has fuel in it then it is BAD. otherwise, either float is not set to the right height or trash is in the seat.

[cb750k7]

if you have brass floats take the one of the carb that is overflowing and shake it . If it has fuel in it then it is BAD. otherwise, either float is not set to the right height or trash is in the seat.

UPDATE:

I guess that the floats are not brass,  anyway they are black....

I double checked the petcock and seems that it functions good,  it has to be aligned very accurate to "STOP" any small deviation and it leaks...

after knocking with a screwdriver handle on the bowls, (did not fix the dripping) I decided to take off the overflow tubes which apparently had to do it first thing,  and found that only one carb,  (the second from left when seated on the bike) is dripping.

Took the bowl off and found that the floats are not jammed.

Could it be that a small grain is stuck in the needle seat?  If yes,  is there an easy way to blow it out without dismantling the whole carbs again?

I would like to thank you all again for your support and advices,  this forum means a lot to me.

Cheers,

Jona

[Cvillechopper]

You should be able to pull the float pin and drop the float and valve with the carbs in the bike.  Just go slow.  Very much sounds like something could have gotten stuck in the valve.

[Dave Wyatt]

Close the petcock a few seconds before turning off the engine and park it on the centerstand.   Thats how I handle my weepy carb gaskets, but yours is the overflow, so that's something else.  You might try lowering the float a MM to see if that helps.  Could be the needle isn't seating quite hard enough.

[Aaron J Williams]

Check your overflow tube for cracks while you have the bowl off.

[cb750k7]

Check your overflow tube for cracks while you have the bowl off.

Hi,

Did that,  (accordind to the FAQ thread),  no visible cracks.

Will take out the floats and check the needle today.

TNX

[neil10]

Go basic  check where the fuel is coming from
amazing how many spots can leak
if overflow bowls, take bowls of gently push floats up and down to relase possible muck
Make sure filter is clean  and installed
look in tank  to see condition of tank might need clean

[cb750k7]

UPDATE:

After taking your advise,  I took off the drain pipes and found that #2 is the only one that is dripping fuel.

Since I did not have the time or the place to take off the carbs again,  I tried to adjust the floats height until the overflow will stop dripping and succeeded,  but got a new issue,  #2 started "burping" which indicated of fuel starved cylinder....

So today I managed to meet with my mechanic friend and he adjusted the floats correctly and the "burping" stopped.

I installed the HONDAMAN's electronic ignition ,  (thanks again Mark) and I really could feel the difference.  The bikes starts immediately and runs more strongly. 

i do need your advise about idling RPM's,  after warming up it rises to about 1500.  Is it normal?  I would like it to be 1200 RPM.

THANK YOU ALL.


Jona

[mystic_1]

You should be adjusting your idle with the bike fully warmed up.  That means it will be too low while warming up, which is why a lot of choke mechanisms also bump up the idle speed using a little cam.

mystic_1

[twisted bastard]

May want to make sure the float was not bent out of position during the rebuild and reassembly. Its kind of tight when the float is in the upper position and drag on anything will cause it to stick before the needle is pushed closed.