Topic: Heavy gas stench, but no leaks found?! CB550

[putnaja1]

Hi All,

The saga continues..  I just took delivery of my 550, and it came from about 6 hohurs away in an enclosed van, properly tied down, etc.

The bike funked up my garage with a powerful gasoline stench..  I've had bikes indoors before, and a little/some gass smell is to be expected.  BUT, this one smells as if there is a leak, but I can't find any!  Looked under the carbs on the top of the crankcase, no puddles..  No puddles under the bike.  Felt all around the fuel tank and petcock- no leaks.  No leaks around the carbs (maybe 1 airbleed screw was a tiny bit moist looking, but no standing fuel anywhere)..

The bike seems to run okay- I had it out for about a mile around the block, all cylinders are firing, and it will idle after it warmed up..  It's probably not been run much- the gas in the tank is an unknown quality- but doesn't smell stale at all..  It took a few minutes of running on choke before it would idle/run okay without choke, but it's probably been sitting, so I suspect this is not a problem so much..

Anyways, it didn't seem so bad this morning, so maybe it was just from the gas sloshing around in the tank during the bikes transit, and me taking the gas cap off to look in the tank to inspect for rust.  Is there anywhere else gas could be pooling if there was a hidden problem (even though the motor seems to run fine?)  Like gass pooled in airbox, or even worse, in the oil?  I'm gonna change the oil tonight, so I guess I'll know sooner or later if it's that.

Any ideas?
Jason

[csendker]

If you don't know the age and/or quality of either the gas or the oil, change them both.  The gas maybe old and varnish-ifying; heavy smell = lots of volatiles = lots of leftover gum?  Also, if you're running really rich, the smell may be more pronounced. 

[cb(r)]

just to add the the previous post.  check if there is still a gasket on the gas cap.  if so then take bike outside, start it up, shut off the gas,  let it die out.  make sure the room you are storing the bike is free of fumes.  put bike back into the room and let set.  if the fumes come back then the problem is b4 the shut off.  if they dont come back then on to step N0. 2

[csendker]

check if there is still a gasket on the gas cap

Good idea.  While these have vented gas caps, you shouldn't get too much odor coming back through the air vent.  Now if your cap gasket was MIA...

[Paul]

Just on the off chance that the carb overflows are blocked (hence no leak) and the fuel is flowing to the carbs (Bad petcock / petcock left on, + incorrect floats, Jet O-Rings perished) there could be a slight chance of the fuel filling the carbs and A. going into the air box / filter and B. into the head.

Check the oil just to be sure.

[TwoTired]

Any weep, however small, in the fuel system will stink up the garage quickly.  If there is any whetted area on petcock, hoses, carbs, that's where the odor comes from.

There is also a foam engine oil breather filter element at the bottom of the air box.  This often neglected device can plug up and stink pretty bad with both oil a gas odors.  I've seen a couple that contaminated the air filter, too.

The will always be some gas odor from the machine.  Both the fuel tank and individual carb float bowls are vented to the atmosphere.  Standard garage design has outside ventilation near floor level to keep fumes from building and reaching explosive levels.  The ventilation holes have been known to be plugged by people wishing to keep their garages warmer.  However, this is unsafe practice if you are still putting vehicles inside it.  You may wish to check out your garage venting system.

Cheers,

[Bob Wessner]

Standard garage design has outside ventilation near floor level to keep fumes from building and reaching explosive levels.  The ventilation holes have been known to be plugged by people wishing to keep their garages warmer.  However, this is unsafe practice if you are still putting vehicles inside it.  You may wish to check out your garage venting system.

Good points, great ideas.. too bad they didn't think that way 65 years ago. 

[TwoTired]

There could easily be local building codes about garage venting.  Here in CA, a lot of homes have their hot water heater in the garage, whose burns come on at unpredictable times.

I'd bet the building codes were changed AFTER an explosion.

[78_SaltLick]

If you lift up the seat, and remove the air filter is there a strong gas smell coming from there? I know when i removed my air filter for the first time, there was a real strong gas smell coming from that hole.

[putnaja1]

Bingo!

1st things first- I was scared after reading about the gas cap gasket, but was happy to find mine has it's gasket, and it's in good shape.  Next, I tried the shut off the fuel petcock trick, and ran the motor until it consumed what was in the float bowls..  Still stinks.

Then, I took off the airbox lid, and removed the air filter element- the bottom of it *REEKS* like gasoline!  I turned it upside down, but no fuel leaked out- maybe this problem happened before, or I do know that when the bike was moved via box van, the fuel petcock was left on..  Would this make fuel eventually leak or splash into the airbox?  I have a new element on the way anyhow (getting my tune up parts together), so hopefully this thing won't smell so pungent once the air filter is replaced.

Jason

[78_SaltLick]

there is a sponge down in there on the bottom, or at least there should be. Mine was completely soaked with old gas/gook and almost disentegrated. I replaced the air filter and that sponge and the smell went away. Why would gas be in there in the first place?

[78_SaltLick]

nevermind, i should have read twotireds post to begin with, hes the master.

[techy5025]

Almost all the early airboxes suffer with some form of gas leakage.
In my case it looks like a backfire or something caused a burn spot.
It almost looks like paint stripper that melted the plastic. Also, I see
no evidence of anything that resembles a "sponge" in the bottom...
just the filter itself. Is this something that was added K1 and up with the
new airbox design. 

It's clear though that by some process raw gas finds it way into the
airboxes.

Jim

[Mopar_Tony_SF]

I have the same issue with my CBX.  Stingks up the garage bad fr a half day or so.  No leaks. 

Fumes are coming out of the airbox.  Once enoughfuel evaporates out of the carbs, smell goes away.  Befre I park it, I run it with the fuel off for a few minutes and the smell goes awat quicker.

[TwoTired]

Also, I see
no evidence of anything that resembles a "sponge" in the bottom...
just the filter itself. Is this something that was added K1 and up with the
new airbox design. 

You're kidding right?  This thread was about a CB550.  There ARE a few differences between the 550 and 750.
I'd be happy to send you some foam if you're feeling left out. 

Cheers,

[dusterdude]

tt,you`re a most benevolent fellow.

[putnaja1]

So, is there anything to this sponge that is special?  Couldn't I just make my own outta a kitchen sponge?  I'm not sure I should pay Honda the 4 bucks for one..

Anyone replace theres with non-factory parts, of the household available variety?

Jason

[TwoTired]

It is an open cell foam 1 Cm thick, that withstands gasoline and oil vapors and allows air to pass through it.
Does your kitchen sponge have these traits?
 I predict that you will spend more than $4 of your time trying to track down and verify the proper specifications to an alternate foam element.
Your call...

If you are complaining about spending $4 on your bike to keep it operational, I predict a dire future for your machine.

And, then other people wonder why dealers don't fully support these old bikes.

[putnaja1]

Hahahahaha

OK, you got me being a cheapskate- although it aint money that's the problem, it's getting time to go to the shop, order, then waiting while it comes in, then going to the shop to pick it up, etc.  That's the part that is a pain..  But, you are right- I just need to do the right thing..
Thanks for the reality check!  :-)
Jason

It is an open cell foam 1 Cm thick, that withstands gasoline and oil vapors and allows air to pass through it.
Does your kitchen sponge have these traits?
 I predict that you will spend more than $4 of your time trying to track down and verify the proper specifications to an alternate foam element.
Your call...

If you are complaining about spending $4 on your bike to keep it operational, I predict a dire future for your machine.

And, then other people wonder why dealers don't fully support these old bikes.

[Bob Wessner]

Jason,

I don't know how far you are from your local dealer, but for me it's 14 miles round trip, each trip. You might consider doing it on-line with someone like ServiceHonda. Even though they now have a min. ship cost of $9.00 it's not that much when you consider two round trips (order and pick-up). The current IRS deduction per mile is $0.44 per mile and you know that's low compared to reality particularly in light of current $3.00/gal. gas. My dealer takes 5 days, someone like ServiceHonda can have it at your door in less time than that.