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Apex chaincase gear reduction

Discussion in 'Apex General Talk' started by Snowman11, Mar 22, 2018.

  1. Snowman11

    Snowman11 Pro

    Messages:
    147
    Location:
    Upstate ny
    Country:
    USA
    Snowmobile:
    06 Apex GT
    I've seen this topic vaguely covered in past threads ,, but to no real awnser , is dropping a tooth or two in upper chaincase gear a good idea with a motor witch already turns almost 11,000 rpm ?? I realize it wouldn't effect the clutch side much , but I would like to try it.... I have an mxz I dropped a tooth size on and gained some low end snap... I realize this is a 4 stroke and already has that , but I'm willing to sacrifice some top speed to gain. A little more bottom end ... A gear is only like $30 , and let's u use more of the tourque the motor is already making with out adding engine more to decrease engine longevity.... Any thoughts on any of this ???
     
  2.  
  3. Fabio

    Fabio VIP Member VIP Member

    Messages:
    688
    Location:
    Woodbridge, ON
    I dropped a tooth on the upper gear the year after I bought my new 07 apex gt, sold the sled a few years ago with over 24 000km and it ran like the first day I bought it. Only issue I had was the low idle syndrome when coming to a stop but obviously not related to the gear change.

    You will be fine..
     
  4. Snowman11

    Snowman11 Pro

    Messages:
    147
    Location:
    Upstate ny
    Country:
    USA
    Snowmobile:
    06 Apex GT
    Did it help your bottom end enough to notice ? And Yes I've read the long huge thread on your idle issuie , was it ever resolved or did u come to a fix before selling it ?
     
  5. Fabio

    Fabio VIP Member VIP Member

    Messages:
    688
    Location:
    Woodbridge, ON
    It does add a bit more bottom end, if you ride mostly tight trails than I would do it just don’t expect a huge difference.

    No, never really came up with a fix but the Co adjustments made it a lot better, almost completely fixed the issue for me.

    Besides normal wear and tear items sled was pretty solid, all I added was the wrp seat and yamaheaters cause it can get real cold in northern Ontario/Quebec.
     
  6. Snowman11

    Snowman11 Pro

    Messages:
    147
    Location:
    Upstate ny
    Country:
    USA
    Snowmobile:
    06 Apex GT
    Yw
    Yeah I've seen alot of others have had trouble and same issuie fixed by co adjustments.. gear swap made a huge difference in my 2 smoker but thats a whole nother animal .. I'd rather have. The sled be snappy than do 130 , I dont have the room or desire for that .. did u have to drop chain size as well ? How many size teeth did u go down ?
     
  7. Fabio

    Fabio VIP Member VIP Member

    Messages:
    688
    Location:
    Woodbridge, ON
    Only went down one tooth, I’m pretty sure if you go down two teeth you would have to change the chain also.
     
  8. justin gallant

    justin gallant Pro

    Messages:
    196
    Location:
    moncton
    Country:
    Canada
    Snowmobile:
    2006 apex GT
    LOCATION:
    moncton new-brunswick
    I had the same problem on my 06 GT " idle" stall upon stop. Co adjustement fixed it for me. Ran perfect all season!
     
  9. Snowman11

    Snowman11 Pro

    Messages:
    147
    Location:
    Upstate ny
    Country:
    USA
    Snowmobile:
    06 Apex GT
    That's so odd that so many had this problem and had to adjust the CO... And why it would need adjusting down the road .. maybe the factory adjusts for an outside temp and certain areas exceed this .. just being fuel injected should be enough..
     
  10. tedgoesfast

    tedgoesfast Expert

    Messages:
    390
    Location:
    fredericton nb
    Remember when gearing down you give the sled less rolling resistance if you have studded good and match clutching it will accelerate guicker and still have decent top end 24\38 works out to ,116 mph at 1to 1 23 \38 works out to 112 mph at 1to 1 at besdt Yamaha clutching might have ,2 percent overdrive unless you machine front clutch to close more
     
  11. justin gallant

    justin gallant Pro

    Messages:
    196
    Location:
    moncton
    Country:
    Canada
    Snowmobile:
    2006 apex GT
    LOCATION:
    moncton new-brunswick
    I might have the answer for having to adjust the CO... Just my 2 cents.
    Working on diesel engines with electronic injectors, after a while the injectors get wore out and the engine does not run right. By doing an injector calibration I'm able to fix this problem. It actualy trims the injectors by adjusting the fuel flow like it was new again.
    Like I said this is just my 2 cents
     
  12. thor452

    thor452 Because I can Lifetime VIP Member VIP Member

    Messages:
    2,715
    Location:
    Shawano,WI 54166
    Country:
    USA
    Snowmobile:
    2012 Apex XTX 2017 Sidewinder LTX-LE
    I get what you are saying here But I don't think they would wear that quickly. yes 15-20K miles is allot for a sled but not for a four stroke engine. I think it is mostly a valve adjustment issue being masked by adjusting fuel. There has been no definitive results to prove what exactly is the problem but more than a few have fixed it by doing a valve adjustment.
     
  13. Snowman11

    Snowman11 Pro

    Messages:
    147
    Location:
    Upstate ny
    Country:
    USA
    Snowmobile:
    06 Apex GT
    So are u saying that unless Ive got picks for more grip and a clutch kit .. dropping a tooth isn't that effective ?
     
  14. Snowman11

    Snowman11 Pro

    Messages:
    147
    Location:
    Upstate ny
    Country:
    USA
    Snowmobile:
    06 Apex GT
    I would tend to agree with this if the sled had like 50,000 miles on it , but I don't think they "wear down" that quick , but then again I'm no engineer , just a dumb jet mechanic , I think it maybe a combo of valve adjustment and a injector issuie .. maybe slighty dirty injectors .. or a fuel pump that is ever so slightly tired and isn't making 100% pressure , but not enough to cause any other noticeable issuies
     
    justin gallant likes this.
  15. Fleecer

    Fleecer Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    287
    Country:
    USA
    Snowmobile:
    Yamaha Apex MTX
    I'l chime in and share my opinion after having owned a dozen apexes with a variety of gear ratios.

    For trail riding the best gear ratio is 23/38.....period. Short tracks come with 24/38 and by going to 23/38 will make sled faster everywhere...low, mid and yes faster topend.

    LTXs, and XTX come geared 23/38 already. I would not go lower unless putting longer/bigger lug track. Gearing lower for trail riding will be a losing proposition imo....

    Big lug/long tracks the best ratio is 23/40 or 22/38. I've run these gears in several MTXs and with a 162 x 2.5 track would pull 118 mph speedoon hard pan. Could also maintain 100mph in 3ft of snow heading up the river and get decent mpg. Again...just my opinion....
     
    justin gallant likes this.
  16. justin gallant

    justin gallant Pro

    Messages:
    196
    Location:
    moncton
    Country:
    Canada
    Snowmobile:
    2006 apex GT
    LOCATION:
    moncton new-brunswick
    So if I have a 121 GT changed over to a 136" chances are my top gear is still the stock 24 tooth? That would explain why I find it's a little slower on top speed than a regular ltx. I bought a 22 from eBay but by what you are saying best to get a 23 for trail. ??
     

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