info on good starting point on jetting

[jaredssc17]

i just bought a 82 650xs the air box is gone and has the cheap uni foam filters on it that im changing to k and n style pods. altho the mufflers are gone and its just the head pipes the bike was not ran with just head pipes, it came with mikes xs britt mufflers. i plan on just making step up pipes with no mufflers stepping up to 2 inch tail pipes. i know i have the less pop. carbs to use. i live in north eastern ohio. elavation is about 1100 to 1300 feet. i have not pulled the carbs off yet. it did come with a bag full of jets. i did see a main in there of 142.5. i was going to maybe use that as a good starting point for a main. i havent looked for the others yet.

 

[bloodthirstysystem]

start with the stock jets, use the forum search.. there are many threads on this topic

 

[gentlemanjim]

137.5 mains 47.5 pilots, XSjohns needles

 

[jaredssc17]

well good news my carbs are fully rebuilt. looks like everything but the butterflys have been changed. i found in one of the boxs a crap load of new jets and other new carb parts. the main is a 137.5. the pilots i couldnt read. it looks to be 45.5 or 47.5's the needle has numbers and letters of 5Ix11 on them. they have 5 clip slots so i would say the 5I is five slots and a tapper of 11? they do look likea diff. tapper then stock to me.

 

[Sundie]

what are the numbers on you needle jet and air jet.

 

[jaredssc17]

i didnt get all in on the carbs i just toke them off and looked over them. i hope to get them all apart friday after work.

 

[XSLeo]

A good place to start is with the stock jets and work from there.

 

[jaredssc17]

i know a thing or two about jetting. im going to far from stock with the jetting. stock isnt going to help at all for me.

 

[Sundie]

i know a thing or two about jetting. im going to far from stock with the jetting. stock isnt going to help at all for me.

Then why ask? "where to start?" stock.

Let us know how the fun goes.

 

[XSLeo]

Quite often, even with the K&N filters and open pipes stock is a good place to start.
You may get those 147's to run, the 137.5 or 140 will be much better.
I have pretty much what you will have and run a 130 main and a 45 pilot with the BS38's off a 76.
I have some BS34's from an 82 I wil soon try. I will start with the stock jets and work from there.

 

[Lunatic]

i know a thing or two about jetting. im going to far from stock with the jetting. stock isnt going to help at all for me.

My '80 with pods and straight pipes wouldn't run until I put the jetting back to stock. It's the best place to start for sure.