70F carb questions
  • Blue Hawaii
    Posts: 10
    Joined: Wed Jul 29, 2009 4:59 pm

    70F carb questions

    by Blue Hawaii » Sat Aug 15, 2009 12:24 am

    I was able to rejet my 230F to a 132 main I bought at a Suzuki store, and use the stock 42 pilot with the needle clip in the 4th position, removed snorkle, new filter, removed the pipe baffle and she runs like a charm from sea level to about 9500'. From 9500' to 11,500'(Mauna Loa NOAA Observation Observatory here on Hawaii) she wants to sputter with high revs. Low revs has plenty of power. Most of the other dual purpose guys that I ride with were having the same problem, so I figured that my mods where golden and that is just how it is.

    Since I had such great success with the 230F, I thought that I'd rejet the 100F that has always given me problems and got to the point that my son didn't want to ride it. High revs, stalls, hard starts. I thought that I could use the 102 main from the 230F, but it was too tall (long). Again back to Suzuki to see what they had in their parts bin. They had the shorter 102 main and the correct 38 pilot. I couldn't change the needle clip because it only has the one groove. I cleaned the carb with the proper cleaner and installed everything back how the Honda service manual said. Now it runs like a champ as well!

    I want to do the same for the 70F but can't find what sizes to change to. So at the very least, I took the carb apart and cleaned everything real well, put it all back together, turned the air screw out the 2-1/2 turns and adjusted the idle. Starts on first kick, idles real fine, but when you crack the throttle, she hesitates, sputters slightly then pulls. Usually happens after you shift, which is herky jerky. I've tried to adjust the clutch, but it either slips or grabs.

    Any suggestions or comments would be appreciated.
    2006 CRF450X
    2005 CRF230F
    2006 CRF100F
    2005 CRF70F
    2005 YZF600R
    2008 EX250R
  • User avatar
    Kiwi
    Posts: 363
    Joined: Thu Sep 25, 2008 12:22 pm

    by Kiwi » Thu May 23, 2013 3:54 pm

    If your CRF70F has a big hesitation on throttle tip-in (but later clears up and runs better) then it is a sign of being lean. Try adjusting the air bleed first (turn it counter-clockwise to richen up the mixture). If that doesn't work then you might need to adjust the needle height and/or run a larger (richer) jet.

    But I'm guessing it has to do with the air bleed screw.
    2007 CRF450X with modified airbox, Uni filter w/no backfire screen, NCVS needle on 4th, 172 main, CRFs fuel screw at 2, Boyesen QS3, stock smog, 450R cam, FMF Megabomb header, Pro Circuit T-4 muffler, Pro Taper Evo bars, AS suspension

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