Topic: Big Trip, Day 2: Fail. Need Help.

[B.O.X.N.I.F.E.]

Day two of mine and a buddies big loop of the midwest ended in failure today. We made it from Little Rock, AR to Tulsa, OK.

My little 550 ran like a sewing machine. The bike in question was the buddies CX500. The bike is getting about 12 mpg. We've replaced the plugs, caps, stator, pulser, tested the coils, all good.

The conundrum is the plugs are reading cold. How can a bike run somewhat lean and be gulping fuel? I checked and the main jets are in place.

Sent from the hotel lobby. Here's ole reliable:

[Gorms]

Just a guess but could you be draining gas from the float bowls while your riding with the petcock on?  The gas has to be going somewhere.  If you think that could be it, tape a plastic bag to the drain tubes and see if there is gas in it after some miles.

[bistromath]

you mean the plugs are reading lean, right? how does it run? is it pulling strong? gorms suggestion is good, too. check the spark you're getting, just to be sure. is it running on all four?

[NickC]

Running lean= inefficient. Thats why mileage is so bad. MPG is more of a measure of efficiency

[B.O.X.N.I.F.E.]

Running lean= inefficient. Thats why mileage is so bad. MPG is more of a measure of efficiency

A little more info...

The right cylinder was running super rich. Like gas dripping from the header gasket rich. So we put in a smaller main and leaned out the air/fuel screw. That leaned it out, but the massive fuel consumption has remained the same, if not worse. The other cylinder has stayed slightly lean the whole time despite tuning attempts.

The bike is blowing a lot of white smoke. Oil level was a little high, so we drained it and changed the oil. Oil level is now good, still blowing white smoke.

[bryanj]

CX is one of the few Hondas that need a NEW air filter regularly, blowing through dont work

[B.O.X.N.I.F.E.]

CX is one of the few Hondas that need a NEW air filter regularly, blowing through dont work

brand new filter!

[Hush]

The oil you removed from the sump, did it smell of gas and was it rather thin?
My partners 400 Suzuki has just done this to us, the float valves have rubber "O" rings around them, these were 28 years old but looked OK until I took one out and it crumbled to dust.
The gas was seeping past these and running through the carbs into the airbox and the engine valves eventually filling the sump!
I replaced the "O" rings and problem solved, could gas be being lost at night when you park up?
If you are starting with a fresh tank during the day and still losing so much then it aint what I suggested.
How does the CX run? does it run well or a bit under powered? could be blow by if the rings/pistons have high wear.

[750goes]

1. Check you valve clearances - it's simple to do on the CX - but if it's blowing lots of white smoke from the RH cylinder then the exhaust/inlet valves may not be opening or sealing properly.

2. Is it really clattery/noisy ??

3. Check both carbs by undoing the drain valves, and flushing through some fuel... then remove the float bowls and check the floats pins, as one may be broken causing the fuel to just pour through the system when running, or jammed open somehow.

4. Have you checked both carb inlet pipes/tubes for integrity - these often have cracks and won't seal properly.

5. Is it using any water - white smoke v steam ??

Hope you get it sorted out quick for the sake of your trip..

[B.O.X.N.I.F.E.]

Hey guys, heres whats going on

Did a valve adjustment - no stuck valves. Oil does not seem thin, but smells gassy to me. Dropped both bowls and all seems kosher to me. No dropped jets, float valves working, floats actuating up/down without taking on gas.

We're going to see if there is a shop that will let us borrow a compression tester. What PSI difference will indicate severe blow by in a cylinder? I believe the right cylinder was about 20 psi below the left, obviously a little out of whack.

The bike does run. It can keep up at highway speed, has a dead spot around 30mph if you pull hard, doesn't do it if you ease up. The bike pulls ok, seems to be running a little rough, but not awful.

[bucky katt]

shouldnt be more than a 5% difference i believe.