#1 pipe cold

[Steve]

When you have your "cold pipe" symptoms, does it also sound like it's running on just three cylinders?

Just for fun and games, while it is idling, turn the mixture screw on #1 out another turn or two.

My son's 650L has one carb that need the screw out about 4 turns, while the others are about 2 1/4.

.

[egetron]

I'm not sure how to tell if if it's on three cylinders.

While it's running, if I unplug the spark plug of the cylinder in question, the engine does begin to gurgle and die out, albeit somewhat slowly. If I do the same with any of the other cylinders, it dies out immediately.

[tkent02]

That should tell you something. Normally a four cylinder GS will keep running just fine on three cylinders, although it would be a little rough. It will idle, and it will rev up, you can ride it around just fine, just has about 25% less power… More like 35%.

[Wallowgreen]

First thing to say is Tom and Steve know exactly what they're talking about with these kind of problems. But, here's my experience with his kind of problem take it as it's intended, just an extra data point.

I spent many, many months working a similar problem on both my 850 and 550 Kat. I stripped, dipped, sprayed and shot compressed air through everything about a bazillion times on both racks of carbs. I even took the set from the 550 to the lab at work to xray the bodies so I could visually inspect the micro bore passages inside them. All looked good and open as far as both the technician and I could tell. Then I wasted months looking elsewhere for the problem.

Then a set from a 550L that had the same part numbers for each individual carb came up for sale on fleabay for $35. I bought them, did the usual clean with my ultra sonic cleaner and put them on. Hey presto! Never had any problems since.

Same thing fixed the 850.

So while I concur with the clean your carbs routine, I've also found that some bodies just can't be cleaned good enough. I guess you can argue anything can be cleaned if done properly and maybe so. But at the end of the day I got fed up with taking carbs off, cleaning them and refitting them that I say just get a spare set, clean them and try them. See if that fixes your problem.

[almarconi]

I find it so tiresome to offer advice to some people on this forum. No matter what you suggest they already have a counter response yet their problem still exists. This thread is an example of this. No matter what is suggested the problem will not be fixed because the OP already has all the answers. Why bother to offer advice to people who already have all the answers and know how to solve the problem?

[tkent02]

I find it so tiresome to offer advice to some people on this forum. No matter what you suggest they already have a counter response yet their problem still exists. This thread is an example of this. No matter what is suggested the problem will not be fixed because the OP already has all the answers. Why bother to offer advice to people who already have all the answers and know how to solve the problem?

Sometimes I think they are trolling for someone to say, "It can't be fixed, you must go buy a shiny new motorcycle."

But I didn't get that impression from this guy.

[520eek]

I also feel that this op is wanting help also. I am in the same predicament with 1980 850G. I had posted some info in the general maint area but will post here. I was following along to hopefully gain some knowledge and try to figure out what is wrong with my bike.

[almarconi]

Bike has not been on the side stand... It's always on center stand. My petcock vacuum line is attached to #2

I synched the carbs with a vacuum gauge.

I really cleaned the **** out of the carbs. Full dip in Berryman's for 24 hours (I did this twice on #1 carb just to make sure). sprayed and poked out every imaginable crevice with carb cleaner and compressed air.

If I've changed plugs, swapped the 1 and 4 plug wires and the problem persists... can I rule out electrical as the problem?

No matter what is suggested it has already been checked and rechecked.


How can you sync the carbs if the engine is only running on 3 cylinders? Is the spark plug wet on cylinder 1? If not, do you have fuel in the bowl? Remove the bowl and move the float, gas should pour out.. have you checked?

Its pretty obvious that you are missing something otherwise your bike would be running on all cylinder and the pipes would be getting hot.

[egetron]

Man, almarconi, why so grumpy?

I saw your first post and I plan on checking my compression and spark as you suggested.

How do I determine a "healthy" spark? Is an orange spark necessarily bad? I think I may remember my spark being slightly orange.

I will also check to see if the spark plug is wet. I have checked in the past but remember not really being able to tell. Sometimes it seemed wet, sometimes it seemed dry. But I'll check again.

I did sync the carbs... why wouldn't it work if it's only running on 3 cylinders? Isn't the sync just measuring air pressure? The non-running cylinder is still pumping air right?

Not trying to be a know-it-all, I'm asking because I don't know!

[Big T]

How do I determine a "healthy" spark? Is an orange spark necessarily bad? I think I may remember my spark being slightly orange. !

White is great
Blue is good
Red is dead

[fastbysuzuki]

Hi
If you think you spark is on the orange side when you test it outside of the cylinder then it is likely to be weak or fail when it's under compression do you have or can borrow a colortune see link

http://www.carbtune.co.uk/colortune.html

That way you can visually see if your getting a spark under compression as well as the mixture colour.
Colortune are sold on eBay as well.
Hope this helps

[egetron]

Same problem persists

So I'm getting what appears to be a pretty good spark (blue/purple) on all four cylinders.

Also worth mentioning, when I run the engine, it reaks of gas. Which leads me to believe that a bunch of gas is going into the engine and not getting burned. When I take out the first cylinder plug, it appears to be WET... so could it still be a carb problem?

Thanks for all your help guys.

[chuck hahn]

DONT START IT if you even REMOTELY suspect fuel is in the oil. Find the source first. take both lines off the petcock and use some vacuum line..or whatever.. to run lines down to two clear soda bottles and let them sit for several hours or over night. This will let you know if the petcock is leaking and from which nipple. Do this in the normal ON position.

Second..never let the bike sit with the petcock in the PRIme position.

If the petcock isnt leaking, the next suspect is the floats and float needles. Inspect that the floats are in good condition, the float needles dont have wear grooves in the tips if they are metal and look for creased lines in the rubber of the rubber tipped style. Also see that the seats themselves dont look damaged where the tips poke in and make the seals.

Check float hts. wrong float hts may not allow the needles to shut off fuel flow..and that leaking fuel has to go somewhere....down the carb throats..past the rings..and into the crankcase.

WET plugs is an indication of the float hts being wrong, mixture screws set too far out, a choke plunger not closing all the way or having bad seats, weak ( although an existing ) spark. Just the top several things i would check before trying to run the bike.

[chuck hahn]

Oh and be sure the rubber plugs are over the pilot jets on CV carbs..if not they will flow tons of fuel and flood that particular carbs cylinder in seconds flat. AND just because they are there doesnt mean they are sealing right. If they are old and hard or have the indent in the tops from the carb bowls really pressed in them, i say replace them.

[egetron]

I suspect I do have a leaky petcock. I definitely need to take care of that. Could that cause my bike to not fire on all cylinders?

I have checked float heights. If I have a leaky petcock, but my floats are working properly, can gas still leak into the engine?

Just out of curiosity. How do I tell if there's gas in the oil? I've replaced the oil recently, and I couldn't tell by looking at it. Also, what happens if I attempt to run it? Could it explode?

And, for the almarconi's out there, when I ask these questions, I'm not trying to argue/question your judgment, I'm asking for my own edification!

Thanks everyone!