carburator questions

[evanparker]

ok i've been trying to tune the carbs for abotu a year now, i'm really not making much progress. i just wanted to ask a question on the circuits and adjusting them. i have a GS750E 1981 (16v) that someone put BS34's on. it's never been right and i'm trying to avoid buying an old new set of carbs.

I'm just checking my facts, and I have a question.


the first 1/8 of the throttle is controlled by the pilot jet. this little guy:


I am currently running a 50, and it's running and starting fine.

The next circuit 1/8-1/2 is controlled by the height of the needle, it has grooves in it and you can move it up and down. it also has some effect on the other stages. I need to pull my needle up a tiny bit and I *think* it will be right.

The 1/2-3/4 part, what is this controlled by? What can I change to change the mixture at this part?

and 3/4-full, is the main jet. right? I'm running a 120.

the damn bike just keeps overheating oh the highway no matter what i do. plug chops are inconclusive at best. it seems like I have it all right, but it just isn't quite there yet.

[salty_monk]

BS34's on a 750... isn't that a bit "obver carbed"?? I would have thought a 32 was better unless you have major mods.

50 on a pilot jet is pretty big, my 1000 uses 40 as stock with people using pods only needing a 42...

Yes the needle affects the bit you are trying to work with.

Dan

[82Shafty]

Do you have any other symptoms besides overheating?

Usual highway throttle usage is about 1/8th to a 1/4 at cruising speed.

What does your infared thermometer register?

[evanparker]

the temp gauge is reading correctly based on my infrared thermometer, and the engine will run up to and past 320 after an hour straight of riding.

is there anything else that would cause this overheating issue? my air system is air tight, all brand new.

[chef1366]

If the bike is stock with the airbox get a set of 32mm off Ebay and jet it for stock and sell the 34s to someone with an 1100.
That is if it's stock.

[82Shafty]

I never purchased an infared, but I know from reading this site, an ultralight airplane cyl head runs 350-375 normal temps.

http://www.ultralightnews.com/engineinfo/chtwirdia.htm

The ultralight temp guage sensor replaces the spark plug washer ( sounds pretty cool.)

I know that if you are operating oil temp... you do not want to be over 250... usually 170-220 is favorable for oil temp.

I've never been able to get a reading on what a normal range should be on a motorcycle cyl head temp after an hours worth of riding, so I really can't further advise as to what your ideal temp should be.

Maybe one of the warm climate guys could help you out with that one.

Also, check your timing. Timing that is over advanced will cause an engine to run hot.

If you have a bike dyno any where near your house, I would use it to your advantage for tuning. The wide band will let you know if you are fat or skinny.