78 340 Invader carb questions

[78invader2]

Hi guys, new here. I bought a 78 invader 340 and was wondering what the stock main jet size is for it. The guy I bought it from raced it and said not to run it in colder weather since he changed the jets. I wanna return it back to stock for drivability. Also what position was the needle set at? The needles are at the top position now. Thanks for the help!!

[mswyka]

175

[78invader2]

Thanks! What do the numbers mean for jets? Is it the higher the number the more fuel or something like that?

[gixxer6]

I think the needle clip should be in the middle slot. 

The larger the number the bigger (richer) the jet. 

If the jetting has been changed, it would be wise to check all of the jet sizes, not just the mains. 

[rminier]

  The numbering for the jets corresponds to the amount of fuel flow...a 175 main jet will flow more than a 165, for example. The previous owner may have used a slightly smaller than stock main jet when running at 25 or 30 degrees F. to maximize performance at those temps, but that could make the motor run too lean when it's 0 degrees, so it was good he mentioned it. Just make sure it has the stock 175 Main jets in it, and ride and enjoy.
  It's doubtful that the previous owner changed the needle, but you should probably take a look. The stock needle was a 6DH4, which should be stamped in the side of the needle, and the stock clip position is the 2nd groove down from the top.
  Whoops, gixxer just posted ahead of me....my '79 Invader manual shows the 2nd groove, but not much diff between 2nd or 3rd.

[78invader2]

Sounds good! I believe he said he ran a 150 and a 160 Main jet in it. And the needle is set on the very top position. I will be checking the pilot jets too. I also found out it has a 440 LTD 4/6 clutch on it, so I need to change that back to the 340 clutch as well.