Carb Jet Help

[Rudiger]

I purchased a sigma6 jet kit from ebay. They sent 112 and 117 main jets. After looking through the jet database they seem larger than what others are using. So I set the carbs up with the 112 and 1 washer on the stock needle. I replaced both diaphragms with the jbmindustries replacements because the real issue was I had a torn diaphragm.

Bike
2011 Airbox removed. KN r-0990 Filter
Yosmura slip on.
elevation ~400ft

So my question is should i really start with the 117 and work my way down? That seems excessive after looking through the database. I still have the carbs on the table so switching now would be the easiest time. What do you folks think? This is my first run at really trying to tune this bike.

Thanks

[vmax]

Originally Posted by Rudiger

I purchased a sigma6 jet kit from ebay. They sent 112 and 117 main jets. After looking through the jet database they seem larger than what others are using. So I set the carbs up with the 112 and 1 washer on the stock needle. I replaced both diaphragms with the jbmindustries replacements because the real issue was I had a torn diaphragm.

Bike
2011 Airbox removed. KN r-0990 Filter
Yosmura slip on.
elevation ~400ft

So my question is should i really start with the 117 and work my way down? That seems excessive after looking through the database. I still have the carbs on the table so switching now would be the easiest time. What do you folks think? This is my first run at really trying to tune this bike.

Thanks

Remove airbox mostly people using 110 or 112. I think 112 was the biggest setup. So doing 112 then down.

[Rudiger]

See thats what I was thinking. 117 seemed too excessive. I put the 112 in and will be putting everything back together tomorrow. So hopefully everything works out great because otherwise I'll have to order a smaller jet size.

[jkv45]

Keep in-mind that there can be a difference in flow from a OEM (carb manufacturer) jet marked "110" to an aftermarket jet marked "110".

They may look the same, but there can be small internal difference that will change the flow characteristics.

Generally though, a 117 main would most likely be overly rich.

[Ghostt]

OEM and aftermarket net sizes are NOT the same!!!!!

since you've already started down this road, go with the 112, then once you get it running, and dialed in, then maybe try one shim, at a time. Each time being sure to test it and tweak to personal taste.

Did you tune the idle mixture screws?

Carburetor tuning is a slow and step by step process, make small and as few changes at a time, so when something doesn't work, you know exactly what was the cause, instead of being totally lost, and having another post titled " JET KIT WENT WRONG" etc........

[Rudiger]

Originally Posted by Ghostt

Did you tune the idle mixture screws?

I removed the caps but have not touched the mixture screws. My intent was to get it put back together with new jets and run it before I changed anything else. Right now I'm stuck in the middle of a valve adjustment waiting on new shims. Bike has 13500mi and never had valve clearances checked and as a result needs 3 or 4 shims.

Thanks for your input.