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Thread: 625 front sprocket size

  1. #1
    Join Date
    Apr 2012
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    227

    Default 625 front sprocket size

    So I have an 04 625 SMC and I have a 15t front sprocket (42t rear). Seems like first gear is almost unuseable. Will going up to a 16t make much difference for me? I dont want to kill the low end, but want a more useable first gear. Wadda ya think?

  2. #2
    Join Date
    Sep 2008
    Location
    Not far from Horse Shoe, NC
    Posts
    115

    Default

    The from-factory sprockets in the USA's 2004 625SMC are 16-tooth front and 38-tooth rear (not absolutely positive about the rear, but pretty sure-- I can count when I get home this afternoon), so your current gearing is really pretty low (numerically high) comparatively. If you just switched to the 16-tooth front, you'd probably pick up a good bit more useability in first-- it's been recommended here numerous times to use the KTM OEM front sprocket rather than aftermarket to reduce the possibility of countershaft seal leaks.

    If you typically need more flat-out speed (highways and such), you may also want to drop a tooth or 3 in the rear. But for around town and the fun stuff, just going with 16-42 should be the good ticket.

    Bryan
    -=-=-=-=-=-=-=-=-=-=-=-=-=-
    '04 KTM 625 SMC
    '99 Ducati 900 SSie
    -=-=-=-=-=-=-=-=-=-=-=-=-=-

  3. #3
    Join Date
    Apr 2009
    Location
    Western NC
    Posts
    944

    Default

    I agree 16/42 is about the best combination I've tried ,and yeah 1st/2nd gear's are like a dump truck especially going from 3rd to 2nd fast with no slipper.
    2011 KatoomaBerg FS 570/2011 FS 570 (SOLD) 2010 FE 570 SUMO'ed/2004 KTM 625 SMC(SOLD)
    Suspension by: FastBikeIndustries.com
    HARLEY-DAVIDSON = "The most effective way to convert gasoline into noise without the pesky effects of horsepower"

  4. #4
    Join Date
    Apr 2012
    Posts
    227

    Default

    Cool thanks guys. I find its really low when streetriding. Leaving parking lots and such that has pedestrians and car movement. Real herky jerky in first, and second lugs. I will try a 16 and see how it does. Got to be better than it is!

    The guy that had it before me gave me some dirt wheels and tires for it too, so apparently he had it geared for dirt. But it does make for REAL easy up first gear wheelies!

  5. #5
    Join Date
    Aug 2008
    Location
    Grandville, Mi.
    Posts
    169

    Default

    Jerking and lugging on the beeg 625 is from being in too high a gear; Big singles struggle against themselves at about 1/8 to 1/4 throttle. Alarka is very wise with 625's, but keep in mind the right gearing in NC is not always what is best in the midwest, with what roads we have vs being in paradise. I have been running 16/40 gearing for a couple years, and will top out at about 114. But for the expressway, if you must run it, (sigh)... I am gonna try a 38 on back, as the bike feels put upon to hold a sustained 70mph for more than a mile, unless you are hotdogging it. Keep in mind, tho, that many of our 625's have been tweaked; Mine has a crower cam and a 5 angle valve job, and a thinner .035 headgasket, with Leo Vince slip-ons, and makes 60.5 rwhp @ 7,600 rpm, so a true stocker will act a bit different, depending on state of tune, and esp jetting. One last thing, re jerking... Has your bike been desmogged, is the air filter cover been removed, do you have a jd jet kit installed yet? Sorry for the bit of complication, but I mean well.

  6. #6
    Join Date
    Apr 2008
    Posts
    472

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    Gear it up you'll like it better I would go 17 myself as 17/40 is stock 05-06. I'm running stock but going to 17/42 with my new chain ran 16/40 but was a little low for my taste.

  7. #7
    Join Date
    Apr 2012
    Posts
    227

    Default

    Well what i mean by jerking is from being too low geared. Its just too much power in too low of a gear. Feels like it wants to jump out from under me with that gear in first. The when I go to second to smooth it out, its too high of a gear for the low speed im going.

    And for me, it will never be on a road that has a higher speed limit than 50 mph. Just how it is where I live. So I have no need to go 115 mph. Which is why I chose this bike.

    Only mods on mine right now is the the top of the airbox has been cut out, and the slide derestricted.It had a Pro Circuit T4 on it when I got it, but it was much too loud for me living in a condo. He gave me the stocker when I bought the bike, so I threw that on (not gutted). Running a 172 main and a 50 pilot with the needle on the 6th (from the top) position and no JD kit. Jetting feels and looks pretty good. I just ordered the parts to remove the SAS today. Found i had a pretty good leak on the left head pipe to tail connection, so I ordered a new graphite seal for that too.

  8. #8
    Join Date
    Feb 2007
    Location
    Denver, CO
    Posts
    890

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    Definitely go up to that 16, I'm running 16/42 and can't imagine it with a 15 tooth front...with a good yank I can get her up in 3rd while seated, can't imagine with a 15 tooth...
    "The Marines I have seen around the world have the cleanest bodies, the filthiest minds, the highest morale, and the lowest morals of any group of animals I have ever seen. Thank God for the United States Marine Corps!" - Eleanor Roosevelt

  9. #9
    Join Date
    Aug 2008
    Location
    Grandville, Mi.
    Posts
    169

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    I will know next fri how well the 16/38 combo works, when I bought the bike, it had a 17 on the front, and the bike was in a marginal state of tune (bottled up stocker cans) and it seemed geared too tall, now that i've picked up 7 hp, and the carburetion is right on, with way better throttle response, it is feasable that if you were not on tight roads, a good running 625 could pull that tall gear, making first gear more practical, vs. quick shift into 2nd after moving only 20 to 30 feet.

    Whatever your riding style and local roads dictate, I always say.

  10. #10
    Join Date
    Apr 2012
    Posts
    227

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    I ordered a 16t, but I have a 42t rear. And yeah, with that 15 front it is scary in first!! Doesnt help that im only about 155lbs. Second wasnt much less scary!

  11. #11
    Join Date
    Apr 2012
    Location
    Mill Creek, Wa
    Posts
    104

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    i'm interested in the 16t front feedback. i have a 17/42 combo now and i rarely use it on the freeway, so i think dropping a toof in the front would be a good call. and maybe i'll pick up a 15/45 for my dirty set up.

  12. #12
    Join Date
    Apr 2012
    Posts
    227

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    Grant I will just send you my 15t back with the other stuff and you can give it a try before buying new.

  13. #13
    Join Date
    May 2011
    Location
    Lake Jackson, Texas
    Posts
    1,250

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    Not sure if my 2001 640 gearing is the same, but I run 15/38 and its pretty dang peppy. I can bring her up in 4th standing up and tops out at exactly 100.
    Wes
    '06 525 exc
    My YouTube channel - http://www.youtube.com/mxriderwd

    Avoid Munn Racing, Chip is a crook

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