Topic: Solved, **unacceptable mostly fuel nonsense

[BomberMann650]

Either my hearing has improved suddenly, or bloo is making some extraneous noises since the rockerbox replacement.

So I double check the cam chain, got it to quiet down some, but still hearing some top end nosie.

Thought maybe exhaust leak, checked torque on manifold nuts, still noisy.

Considered timing a suspect, made a small adjustment, less noisy, but still noisy.

Most interesting phenomena, is placing a hand against the cam covers seems to mellow it out.  Maybe my hand is just absorbing the sound?  Haha

I set my valves pretty damn close to spec, wondering if I'm jist a little too tight? 

I don't believe I overtorqued the cover bolts and screws, and the new cam was clean of debris and turning free when I swapped it.

What could I be overlooking here?

[calj737]

 What bike? If its a 550, it could be the rocker shafts are worn and are wobbling within the cover 

[Phinn]

Carb sync. I had a similar problem with a new noise that I thought was an exhaust leak  (esp. at idle) and it was an imbalance in No. 3.

[DaveBarbier]

What bike? If its a 550, it could be the rocker shafts are worn and are wobbling within the cover 

Haha, he replaced his early (74?) 550 valve cover with a later style to get the rocker shafts with the pins. His original one was toast, a lot of play in the shaft bores. I don't recall if he used his original cam with mating rockers.

Bomber, if you suspect exhaust leaks use a bit of hose as a stethoscope to listen around the exhaust ports. Did you use new exhaust gaskets?

[flybox1]

Carb sync. I had a similar problem with a new noise that I thought was an exhaust leak  (esp. at idle) and it was an imbalance in No. 3.

+1

[BomberMann650]

I had the syncronization dialed last summer.  Does it ever change?

I figured I'd be replacing exhaust gaskets with my next oil change.  I know MAC says you can do oil filter changes without header removal, but it's a tight fit and sure to make a mess if you don't.

In an unrelated series of events, can't seem to stop my #4 carburetor from spilling gas, pretty consistent fuel loss going on.  Adjusted float level yesterday but it's still a problem.  I know my petcock is a dripper, but 4 is the only carb that's over filling!!

Havent had that problem in a long long time.  This is getting frustrating, It seems you can't fix one thing on this bike without suddenly needing to address three NEW problems....

Oy vey

[Phinn]

I had the syncronization dialed last summer.  Does it ever change?

... In an unrelated series of events, can't seem to stop my #4 carburetor from spilling gas, pretty consistent fuel loss going on. 

I wouldn't assume they're unrelated.  An excessive fuel level in a bowl can cause that piston to run rich, which means that you likely have unburnt fuel being drawn out of the exhaust valve.  If you get enough fuel, you get a backfire, which is a fuel combustion occurring in the exhaust pipe instead of the chamber where it belongs.  That's why mine sounded like an exhaust leak -- I was getting a mini-combustion in the pipe where it turns downward.

[BomberMann650]

I had the syncronization dialed last summer.  Does it ever change?

... In an unrelated series of events, can't seem to stop my #4 carburetor from spilling gas, pretty consistent fuel loss going on. 

I wouldn't assume they're unrelated.  An excessive fuel level in a bowl can cause that piston to run rich, which means that you likely have unburnt fuel being drawn out of the exhaust valve.  If you get enough fuel, you get a backfire, which is a fuel combustion occurring in the exhaust pipe instead of the chamber where it belongs.  That's why mine sounded like an exhaust leak -- I was getting a mini-combustion in the pipe where it turns downward.

I understand that.  It's just odd because this lil bike had run like a top on the last ride before rockerbox replacement.

It's not unusual  on the occassion where I run the carbs low for service, the float might stick open after putting it back together.  NORMALLY, I can shake the bike and it stops.  Been that way for months, sat thru the winter without spilling gas. But now, I've been dealing with this leaky carb for 3 days, it just continues to leak, the other three don't. 

Really wish I had a replacement for my replacement petcock

[DaveBarbier]

I had the syncronization dialed last summer.  Does it ever change?

I figured I'd be replacing exhaust gaskets with my next oil change.  I know MAC says you can do oil filter changes without header removal, but it's a tight fit and sure to make a mess if you don't.

In an unrelated series of events, can't seem to stop my #4 carburetor from spilling gas, pretty consistent fuel loss going on.  Adjusted float level yesterday but it's still a problem.  I know my petcock is a dripper, but 4 is the only carb that's over filling!!

I don't recall how often the manual says to perform a carb sync, but yes it does change over time. And obviously if you have to remove the slides/needles for whatever reason.

I think I have a MAC 4-1. I use a plastic bag covering the pipes right under the filter housing to direct oil into my basin. Works fine.

Fuel spilling from the overflow tube? Debris stopping the float needle from seating, stuck float, crack in overflow tube. Also make sure the bowl drain screw is snug.

[DaveBarbier]

Really wish I had a replacement for my replacement petcock

Is this a riveted petcock or does it have screws? Even the riveted ones can be drilled out and replace the rubber bit. Then just tap and use screws to close it up. I've never done this though, just heard of a few membwrs here that have.

[Stev-o]

I had the syncronization dialed last summer.  Does it ever change?

I figured I'd be replacing exhaust gaskets with my next oil change.  I know MAC says you can do oil filter changes without header removal, but it's a tight fit and sure to make a mess if you don't.

In an unrelated series of events, can't seem to stop my #4 carburetor from spilling gas, pretty consistent fuel loss going on.  Adjusted float level yesterday but it's still a problem.  I know my petcock is a dripper, but 4 is the only carb that's over filling!!

I don't recall how often the manual says to perform a carb sync...

Every 3000 miles as part of the tune up.

[BomberMann650]

Really wish I had a replacement for my replacement petcock

Is this a riveted petcock or does it have screws? Even the riveted ones can be drilled out and replace the rubber bit. Then just tap and use screws to close it up. I've never done this though, just heard of a few membwrs here that have.

It's a screw front petcock - and there is a single o-ring behind the face plate.  Would replacing that o-ring put enough squeeze on the plastic cone to stop the drip?

[DaveBarbier]

Really wish I had a replacement for my replacement petcock

Is this a riveted petcock or does it have screws? Even the riveted ones can be drilled out and replace the rubber bit. Then just tap and use screws to close it up. I've never done this though, just heard of a few membwrs here that have.

It's a screw front petcock - and there is a single o-ring behind the face plate.  Would replacing that o-ring put enough squeeze on the plastic cone to stop the drip?

I don't know this petcock, more familiar with the 'rotary phone carriage' style seal, but that o-ring is how it seals as you turn from 'on' to 'off' to 'res'. Might just need an o-ring. If you don't get OEM, it has to be Buna N or Viton to resist fuel.

Edit: there should be a spring washer in the assembly somewhere. Just a thin curved washer. That may have just lost it's 'spring'. Could try bending it a little more severely and putting it back together.

[BomberMann650]

Really wish I had a replacement for my replacement petcock

Is this a riveted petcock or does it have screws? Even the riveted ones can be drilled out and replace the rubber bit. Then just tap and use screws to close it up. I've never done this though, just heard of a few membwrs here that have.

It's a screw front petcock - and there is a single o-ring behind the face plate.  Would replacing that o-ring put enough squeeze on the plastic cone to stop the drip?

I don't know this petcock, more familiar with the 'rotary phone carriage' style seal, but that o-ring is how it seals as you turn from 'on' to 'off' to 'res'. Might just need an o-ring. If you don't get OEM, it has to be Buna N or Viton to resist fuel.

Edit: there should be a spring washer in the assembly somewhere. Just a thin curved washer. That may have just lost it's 'spring'. Could try bending it a little more severely and putting it back together.

I'll look into that.

I've noticed I can push in the lever ever so slightly by hand. 

Hopefully that can stop the drip and stopping the drip will stop the overflow

Still funny it only overflows on carb #4

[BomberMann650]

This is the petcock style in question

[BomberMann650]

All that gas overnight

[BomberMann650]

Update, evidence of overflow in other carbs drain tubes.  Focusing attention to petcock.  Again

On the bright side, my four wheeler has a half a tank of premium now!

[DaveBarbier]

You do realize that you have two issues, right? The petcock shouldn't leak but even if it did, on functioning carburetors it won't leak out the overflow tubes.

Debris stopping the float needle from seating, stuck float, crack in overflow tube. Also make sure the bowl drain screw is snug.

Also worn float needles.

[BomberMann650]

You do realize that you have two issues, right? The petcock shouldn't leak but even if it did, on functioning carburetors it won't leak out the overflow tubes.

Debris stopping the float needle from seating, stuck float, crack in overflow tube. Also make sure the bowl drain screw is snug.

Also worn float needles.

Yes, I'm aware I'm dealing with a nearly complete system malfunction here.

But I can try $6 worth of ace hardware fixes on the petcock today...carburetor disassembly/cleaning/inspection/repair/replacement -- that will have to wait til payday... 

And I'm having the damndest time tracking down oem honda carb parts for the 69A's

[DaveBarbier]

Gotcha

BUUUT, diagnosing why the carbs are leaking shouldn't cost anything You can even drop the bowls to do most tests while the carbs are still on the bike. Just sayin'!

[BomberMann650]

Gotcha

BUUUT, diagnosing why the carbs are leaking shouldn't cost anything You can even drop the bowls to do most tests while the carbs are still on the bike. Just sayin'!

Yeah, I had the bowl off the offending carb the other day, when I did a float level check and adjustment.

That float level adjust didn't stop the leak, and ultimately came back to haunt me while I was trying to keep up with the guys and their BMW's again.

Float trouble was the theme of that days ride, one feller had his float bubble burst and sink on his beemer.

But I digress.

I will be dropping the bowl and setting the float level to the 22mm mark (again)

And if I can find some jet brushes I'll give the float needle housing (pardon my terminology) a healthy scrubbing.

In other news, I rebuilt both of my 75 supersport petcocks and they seem to be holding water.  Installed one on the tank and set it over a pan to see if it passes gas or not.

Oh the punamity!

[onepieceatatime]

Check the overflow tubes on the carb bowls. I have read where others had a problem with their carbs doing the same thing, and the tubes had tiny cracks in them.

[BomberMann650]

Check the overflow tubes on the carb bowls. I have read where others had a problem with their carbs doing the same thing, and the tubes had tiny cracks in them.

The thought occurred to me.

I'm just running out of time to do stuff before work, and it's getting uncomfortably warm beneath my shade tree.

But I have two petcocks now that don't seem to leak....knock on wood

Removed some oxidation from inside the pcocks with emory cloth, then polished em with the cotton tip on my dremel.  New stiff springs and fresh o-rings seem to have done the trick!

[DaveBarbier]

Are the o-rings you used Viton or Buna N? If not and they're just regular o-rings they won't last and will swell and turn to goo.

Check the float levels with the clear tube method. Don't just set the floats and forget. Just because they're set at the proper height doesn't mean the right fuel level is in there.

When you have the carb bowl off you can easily remove the float and drop the float valve and have a look to see if it's damaged.

You've got a few easy tests to do but if you're comfortable with just doing a fix of the petcock then that's cool.

[BomberMann650]

Are the o-rings you used Viton or Buna N? If not and they're just regular o-rings they won't last and will swell and turn to goo.

Check the float levels with the clear tube method. Don't just set the floats and forget. Just because they're set at the proper height doesn't mean the right fuel level is in there.

When you have the carb bowl off you can easily remove the float and drop the float valve and have a look to see if it's damaged.

You've got a few easy tests to do but if you're comfortable with just doing a fix of the petcock then that's cool.

I was able to get Viton o-rings at ace and they fit!

Last I had the little springy conical thing in my hand, it seemed intact.  The brass in these carbs are in better shape than the bodies