marvintheminnow
XS650 Enthusiast
just curious what your plugs look like?
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Went up to a #140 main jet
- Thread starter Crab_Cake
- Start date
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- Tags
- carburetors jetting
Crab_Cake
XS650 Addict
They have been pretty white which was what lead me to believe that I was lean.
I haven't checked them recently though. I will check them today after I get back from school.
The stumbling induced by larger mains is only one of the symptoms you should be watching for and about the most extreme one. You can be too rich before that occurs. You'll need to carefully (and correctly) read your plugs. Also check fuel mileage. If you're too rich you can take a 5 MPG or more hit there.
When you first start jetting, you'll be looking to see if the plugs are all black (too rich) or all white (too lean). Once you get them looking pretty good color-wise, you need to start reading what's called the "smoke" or "mixture" ring. This is a ring of color that should be just at the very bottom of the porcelain .....
If it extends up and covers half or more of the porcelain, then you're set too rich somewhere. With your needles set in the full rich position, I would expect the porcelain on your plugs to be mostly covered. The needle setting has a big influence on the smoke ring because you run in the midrange most of the time.
When you first start jetting, you'll be looking to see if the plugs are all black (too rich) or all white (too lean). Once you get them looking pretty good color-wise, you need to start reading what's called the "smoke" or "mixture" ring. This is a ring of color that should be just at the very bottom of the porcelain .....
If it extends up and covers half or more of the porcelain, then you're set too rich somewhere. With your needles set in the full rich position, I would expect the porcelain on your plugs to be mostly covered. The needle setting has a big influence on the smoke ring because you run in the midrange most of the time.
Crab_Cake
XS650 Addict
On the way back from school today I noticed a little bit of stumbling when I got on the throttle between 60 and 70mph.
I will go back up a notch on the needle. I think my carbs will be perfect with that setup.
I will go back up a notch on the needle. I think my carbs will be perfect with that setup.
On these CV carbs, to properly test main jet size and needle setting you need to use absolute wide open throttle. From about 3 or 3.5K in 2nd or 3rd gear, whack the throttle wide open and run the bike up to near red line. Watch the tach and look for break-up or stumbling in the 4 to 5K range. That would indicate either your needles are set too rich or your mains are too big. Due to the forgiving nature of these CV carbs, these glitches may not show up unless you use the full throttle test. Obviously you won't be riding the bike like that normally but it's necessary to test the jetting that way.
