too lean or too rich?

[littlejohn2458]

So my buddy called me and said "hey i got a bike!" he said i got it for 400.00. was thinking Oh brother! well he brought it over. turned out to be an 82 gs1100k. good compression, good spark, carbs in a box taken apart, breaks in a box taken apart, valves in a box taken apart, and the wiring harness in a box snipped apart. after about 20 hrs of work and a few Domino's chicken kickers later, i put on the fuel tank hooked it up and BAM! its running good. as far as i can tell. Only thing is now when i take a temp gun to the exhaust pipes off the head, i get all different readings. #1-300 #2-200 #3-195 #4-280. that was after about 15 minutes of idling. i know i need to sink up the carbs but i do not have a sink tool. so i am using a temp gun on the exhaust pipes. does anyone know of a good temp to be running these at? i have the fuel needles set at 2.5 turns out. I know i need to get em all set at the same temp but does that seem too lean or too rich?
Thanks a ton,
John

[tkent02]

You need to adjust the valves, and synch the carbs first. It may not be a mixture problem, the hot cylinders may just be doing all the work. Really the carbs need to be cleaned, o rings replaced, all the neglected maintenance needs to be done before you run it much. These are one of the most reliable motorcycles ever, but only if they are maintained.

Letting any air cooled bike idle that long is asking for trouble, they need airflow to keep from overheating.

[littlejohn2458]

well, i stripped the carbs, put them in the ultra sonic cleaner for about an hour, blew through all the holes, took some torch cleaners to all the tiny little holes and then put it back to gether. I KNOW there clean. As for the valves, when i put the back in, I made sure that they were shimmed correctly. (shim over bucket) and all that good jaz. I know i need to sync the carbs but i dont have a sync tool.

[Big T]

When you say "shimmed correctly" do you mean the clearances are set to spec?

Or, that you got the shims in there?

[littlejohn2458]

it is shimmed correctly. got the clearences set right. I was just wondering if there was a general spec as to what the exhaust temp should be? when i checked the service manual for the pilot jet it just says PRE-SET. not sure if it is running too hot or not. thats all. i am a mechanic and all but i am a marine mechanic not a motorcycle mechanic. things a just a touch different.

[tkent02]

There is no such spec.

[littlejohn2458]

i know that but are the temps that i am getting too high? it seems that 300 degrees seems kinda high off the exhaust pipes? mabe not?

[Turtleface]

i know that but are the temps that i am getting too high? it seems that 300 degrees seems kinda high off the exhaust pipes? mabe not?

Celsius? Or Fahrenheit?

Average combustion temperature (averaged across cars, trucks, motorcycles, etc) is usually in 1000f-1500f degree area, depending on a multitude of factors, such as combustion chamber shape, flow characteristics, finish of combustion chamber, etc..etc.. I'd say 300 degree pipes wouldn't be terribly far off in crazy land. I'd be more worried that your two outside carbs are getting hotter than your two inside carbs, which would indicate that the two outsides are probably doing more work than the two insides. Which would lead me to suggest a carb sync. Try the temp gun again, after that, and report back!

[rapidray]

300 is nothing. We set the dragbikes at 550-600. That's with Lectron carbs & the idle around 2000-2200 rpm though. Completely different animal. Listen to what you were told, adjust rthe mixture screws CORRECTLY, then sync the carbs. Did you measure the float heights while the carbs were going back together? Ray.

[ddaniels]

I would tend to think the two inside pipes would be a bit hotter than the two outside by virtue of them not getting the same amount of air flow around them. The two inside pipes have other hot pipes on each side while the outside ones only have a hot pipe on one side of it. Not sure if that really makes any difference but kinda makes sense to me.

[tkent02]

I would tend to think the two inside pipes would be a bit hotter than the two outside by virtue of them not getting the same amount of air flow around them. The two inside pipes have other hot pipes on each side while the outside ones only have a hot pipe on one side of it. Not sure if that really makes any difference but kinda makes sense to me.

There's no air flow anyway when it's just sitting there cooking the engine in neutral.

[Steve]

Celsius? Or Fahrenheit?

Average combustion temperature (averaged across cars, trucks, motorcycles, etc) is usually in 1000f-1500f degree area, depending on a multitude of factors, such as combustion chamber shape, flow characteristics, finish of combustion chamber, etc..etc..

I only have two references for exhaust temperatures. I used to drive truck cross-country. My boss liked to have gauges in the trucks, I quickly came to appreciate that. Depending on the location of the sensor, we were allowed to run the exhaust temp up to 1300 degrees F if the sensor was before the turbo and about 1050 if the sensor was after the turbo. Granted, this was on a heavy-duty diesel engine (350 Cummins in a Peterbilt ).

I had an exhaust temp gauge in my turbo Corolla. Just cruising down the road, temps were in the 850-1000 range. Under full boost (22 psi ) I would see temps of close to 1800, and that was with the sensor after the turbo.

I would concur with the guess of 1000-1500 on a bike engine, but I do believe that out of all the GSers, maybe only one or two have bothered to measure it. No idea what it should be at idle, but the temps you read would also depend on whether you have the stock double-walled pipes or single-walled headers.

.

[littlejohn2458]

anyone know how to MAKE a carb sync tool? shouldn't be too hard. I would imagine just getting some vacuum gauges then getting the things that screw into the intake right?

[tkent02]

Yep, but if you post a location, someone there will have one for you to use.

[ddaniels]

There's no air flow anyway when it's just sitting there cooking the engine in neutral.

I know what you mean, but by airflow I was really talking about the ambient air temperature around each pipe due to it's relative location to other heat sources. Probably not that much of a factor though. I don't know.