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Going back to Tuning the SWR carbs

Discussion in 'The Lounge' started by yamaridersd, Dec 10, 2017.

  1. yamaridersd

    yamaridersd XS400 Member

    I’ve given up on the swap to fuel injection... way to much money and work!!!! So I’ve decided to stick with these SWR... “Sun World Racing” carburetors. So far I’ve had no luck getting them to idle but, top end..... I can only describe as “MORE THAN FUN!!!!!!!”
    On (cold) startup, (with full choke) starts on first kick,and idles @ 1,000-1,100 rpm. Once warmed up (10-20 miles / 230-260°F) stays at 3-4,000 rpm. From what I know..... sounds to be rich on choke and lean at temp!!! (Both carbs are synced!! Both cylinders seem to be burning at the same temps and compression....

    Does anyone have any tips on this tune!?!?!?
  2. drewpy

    drewpy Excess twin Top Contributor

    I'm fuel injecting mine ATM, what was your issue?
  3. yamaridersd

    yamaridersd XS400 Member

    The fuel injection was just too much $$ I finally got the Sun World Racing carbs working perfectly! Turned this bike into a beast!! Super responsive throttle! I actually kept up with a 2007 Honda goldwing up till about 120mph! (With a bigger cam and 2 into 1 exhaust) All I had to do was replace the jets for kehin style jets and replace the jet block seals and hours of Testing, tuning and e-mailing the manufacturer to get specs and settings! I never realized the amount of lag on throttle response of the original bs carbs! If you get the SWR carbs from mikes xs... I can help!
    spectra likes this.
  4. xschris

    xschris a lifestyle not a trend Top Contributor

    120mph on a sohc xs400? What gears did you use for that. You must have been way past red line.
  5. yamaridersd

    yamaridersd XS400 Member

    Just a smaller rear gear. And a slightly larger rear tire. The 120 was redline about 9300.

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