Bowl levels are the same, sooooo.....

[Scud]

Alright, I checked gas levels in each of the float bowls by draining individually and they are exactly the same. #1 plug still looks like I just took it out of the box after 200 miles (white and clean, no carbon whatsoever, not even on the circumference).

I cannot see, or feel any airleaks at both the airbox side or intake side of #1 carb. Spraying a little carb cleaner does not increase RPM's.

Any ideas?? I am worried about holing a piston. Exhaust pipe on #1 is not turning blue or gold so I guess that is good.

This is a 1980 and does not have the intake manifold gasket where an air leak would show a lean condition.

Confused (again)...

Scud

 

[KEITH KRAUSE]

Even a lean running plug should have some amount of carbon on the rim.
The plug would stay new looking if the cylinder wasn't firing at all. You're sure the cylinder is firing?
It should be obvious if the bike's running on 3 cylinders. But I have to ask because as I said, even a very lean burning plug will show some carbon around the rim even though the electrode and insulator look clean.

 

[Scud]

Very good point Keith, I do always feel the exhasut pipes when I am trouble shooting a problem like this and even though #1 is slower to warm it eventually does and warms at a rate similar to #4.

I am truly at a loss for this one...any other suggestions?

Scud

 

[mike J]

If your pipes are turning blue that's a sign of the motor running rich. A rich mixture will continue to burn in the head pipes causing the bluing. A lean mixture has all the fuel burned by thr time it get to the exhaust actually lowering exhaust gas temp. Also leaving the choke on too long will blue the pipes as well. Mike J

 

[mark m]

If your pipes are turning blue that's a sign of the motor running rich. A rich mixture will continue to burn in the head pipes causing the bluing. A lean mixture has all the fuel burned by thr time it get to the exhaust actually lowering exhaust gas temp.

Actually, that is backwards. The rich mixture runs cooler and is done burning by the time it hits the pipe. The lean mixture burns slower and is still burning as it leaves the chamber, causing bluing of the pipes.


Mark

 

[frosty5011]

If your pipes are turning blue that's a sign of the motor running rich. A rich mixture will continue to burn in the head pipes causing the bluing. A lean mixture has all the fuel burned by thr time it get to the exhaust actually lowering exhaust gas temp. Also leaving the choke on too long will blue the pipes as well. Mike J

blue = lean !

 

[mike J]

Sorry guys but I have to say your wrong. Richen the carb or retard timing will all lead to blue pipes. I used to work in an engine shop shop with a Superflow 901 dyno. Rich mixtures equal hotter exhaust gas temps. Mike J

 

[flyingace]

I agree they are wrong. Lean mixtures burn faster and hotter - there's a higher % of air (oxygen) in the mixture. That's why lean mixtures create pre-ignition and piston crowns with holes in them. As to pipes turning blue - higher ignition temps from a lean mixture could certainly cause that.

 

[dpep]

I am interested in the debate over which mixture extreme makes your pipes run hotter. I don't think there is any disagreement that a lean mixture makes your engine run hotter. I believe that is because there is more gas that does NOT get burned and carries away heat. That unspent fuel passes through and out the exhaust serving as a) liquid ccolant b) wasted energy $, or c)air pollution, depending upon your perspective and priorities.

 

[KEITH KRAUSE]

Gas acts as a coolant. It has too. More gas in the mixture will lower the temp'.
As for pipes bluing, I know for a fact that lean mixtures create the worst bluing simply because of my experience with jetting. The pipes turn gold first and if the mixture is lean enough, the pipes turn blue. The quality of the chrome and metal thickness matters a lot, but lean mixtures burn hotter.
I have HEARD people say they left the choke on and blued the pipes. But I haven't seen this happen in front of me.

 

[KEITH KRAUSE]

Very good point Keith, I do always feel the exhasut pipes when I am trouble shooting a problem like this and even though #1 is slower to warm it eventually does and warms at a rate similar to #4.

I am truly at a loss for this one...any other suggestions?

Scud

It's kind of hard for me to get past the logic that even a weakly firing cylinder will leave some carbon on the outer rim of the plugs. I have to go by what you say, that the plugs look brand new and are clean everywhere. :? :?
I'm not sure it's carburetion either. It does sound like the spark is weak and is at least part of your problem. Did you say you swapped #1 plug lead with #4? What happened? Did you try another plug just to be sure it's not a bad plug? Back to basics?
Can you take a compression test first? I would.
If it passes a compression test, and the plug lead swap keeps the problem at the same cylinder, then I'd remove the carbs and check them correctly, starting with the float levels. Then a complete cleaning and o-ring check. Check the mixture screw setting at that carb and compare. Bench synch the carbs, followed by a vacuum synch.

 

[flyingace]

Scud,
There's some confusion on my part from incomplete information. Is this a continuation of another thread?

If not, I don't know if your bike is running poorly, not running or what. All I know is that one of your plugs look like new. What's the original symptom(s)?

 

[Anonymous]

Mike J,

If you go to your local flying club, and get in a plane with an exhaust temperature gauge, when you're flying around, and lean the mixture (airplanes have manual mixture control because of the altitude changes they make) you will notice that as you lean the mixture, the temperature in the exhaust rises- to a point. Then it cools out just a bit, then the engine stops.

Not to be argumentative, but lean=hot.

-istp :wink:

 

[BuffB]

Discolored pipes DO NOT come from mixture being too rich.

In fact, as a certain rider from Holland once told me: discolored pipes come from:

..........................NOT ENOUGH POLISHING!..........................

 

[Scud]

Hey Guys,

I have been guiding fly-fishermen on the South Fork of the Snake river the last few days getting up early and home late and am just now gettin back to this.

Thanks Keith and flyingace.

First Ace,

Symptoms:

Number one plug looks just like I took it out of the box after long and short rides, idling for five minutes or thereabouts makes no difference. Exhaust pipe number one gets warm just a little slower then four but does get warm... :? This tells me that it is firing right?

I performed a synch (Carbtune) a month ago and all are very close, like within .10 inche or less (very close to even).

Keith-

I have not swapped #1 and #4, will do on my next day off.

I did buy a new plug and it looked the same..like new after fifity miles.

I do not have access to a compression tester but will look.

I did a carb dip two years ago and at that time replaced all o'rings (thank you Robert Barr) at that time. Also if you remember (Earl...), I oredered a carb kit and the pilot jets were larger in the kit hence making me run rich and fouling plugs (all last summer... :roll: ), I replaced with original jets and now all are tan with the exception of number #1 at this time.

Carb setting on number one.... I will check the number of turns...again on my next day off (Saturday more then likely).

Again, sorry for not keeping up and thanks for the information.

Scud

 

[flyingace]

Sounds like you are inferring that there is no gas mixture getting to cylinder #1. I can't think of another way that a plug would look like new. That would mean you are running on three cylinders, and it would run like SHI*. I have to ask the same question as Keith - can you tell if it's running on all 4? If not, disconnect plug wire #1 and see if it runs any different.

 

[Scud]

Like I mentioned in two previous posts....exhaust port #1 DOES get warm after one to two minutes of starting, to me this would mean that there is some sort of heat being generated via the spark plug igniting an air fuel mix and then pushing it out the exhaust pipe....right????

The thing is is that she does not run like SH.., she purrs :-k

Scud

 

[flyingace]

Sorry I can't help. I can't wrap my mind around a plug that looks like it never fired with an engine that purrs. But there are far more knowledgeable GSers than me in this forum, so don't give up.

Ace.

 

[KEITH KRAUSE]

Well, I'll just wait for the results after swapping #1 lead with #4. That will narrow it down.

 

[Scud]

Thanks Keith, that will be tomorrow more then likely.

Scud