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Snow mobile help needed

Discussion in 'Off Topic Threads' started by shootgood, Jun 3, 2013.

  1. shootgood

    shootgood Member

    Joined:
    Jan 29, 1998
    Messages:
    260
    First off thank you everyone for their advise I tried what everyone sugested but am still at a loss and could not find my old thread. As a review I have a Yamaha srx 700 snow mobile (2001). The snow mobile started fine during the summer and I last started it in Jan (due to the prior owner I bought it from in Feb. 2012 telling me to start the sled every month or so to keep the carbs from loading up). I am the 1st to admit I know nothing about snow mobiles, my wife was really wanting one and we thought we found a nice one with 6000 hours. The sled started fine, then in Jan I want to start the snow mobile and the pull chord would not pull (very, very stiff)-I had a mechanic friend come over and try and help and after several attempts the chord seemed to relase or what not and pulled and started fine ( I thought nothing of it thinking it might have had compression release or something and it was released by messing with things in a panic). Well in the mean time our house sold so we were able to get a house with land so we can use the mobile-went to start the snow mobile to put it on the trailer and the rope would not pull, would not turn over-nothing. Got the sled moved into mechanic friends garage and pulled the plugs and checked and plugs looked good and with the plugs out the chord will pull fine-put the plugs back in and can hardly pull the chord. Any help you could provide would be appreciated. I am totally at a loss and don't know where to begin-thanks in advance--Shoot good
     
  2. letts

    letts TS Member

    Joined:
    Oct 31, 2006
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    308
    Make sure that you shut the fuel off when you park the machine, this is very important if you trailer it. Fuel may be bypassing the floats in the carbs and filling the motor which locks it up until it is drained or pushed out which may happen when the plugs are removed. That's my best guess from your description of the problem.

    Letts
     
  3. kevin a.

    kevin a. Member

    Joined:
    Apr 17, 2011
    Messages:
    586
    dont know yamahas but my arctic cat and polaris have a drain plug on the motors

    might need new needle and seats for carbs
     
  4. shootgood

    shootgood Member

    Joined:
    Jan 29, 1998
    Messages:
    260
    But it pulls fine with plugs out, once they are back in it barely pulls- plugs are not soaked-just really weird. This the the 1st snow mobile I have had and it might be something really minor-it is weird b/c it had been starting fine and it would run and idle great by itself and no issues but now the pull chord is like 4 times as hard to pull as before. Just at a loss--thanks again--Shoot good
     
  5. Stl Flyn

    Stl Flyn Well-Known Member

    Joined:
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    Take the belt off and see if it is easier then. Could be the belt is catching in the clutch which would make it rotate the track when pulling. Or, the belt may be just slipping on the clutch, but not fully engaging, by wedging in the clutch. The clutch is centrifugal. The faster it spins, the closer the two plates get to each other causing the belt to engage, or wedge in the clutch. If the return springs get weak, the plates could be getting close enough to pinch the belt before higher RPM's are met. 6000 miles would be about when clutch work would be needed as normal maintenance. Is the belt new?
     
  6. shootgood

    shootgood Member

    Joined:
    Jan 29, 1998
    Messages:
    260
    the belt is new-i can pull the rope now with the plugs out and look down on the left side and see that the belt does not move/turn when rope is pulled-I think the belt my only go in motion when the sled is moving or am I off base? Thanks again to everyone-- Shoot good
     
  7. HSLDS

    HSLDS Well-Known Member

    Joined:
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    OK,

    Here is a really way out there thought.

    If you had leak down, and fuel flowed in the cylinders, and if the pistons were positioned just right (or wrong) it is possible that the fuel leaked down into the sump (the area of the crankcase where the oil would sit in a four stroke engine.

    You now have a situation where you are getting a compression stroke on both the up and down movement of the pistons.

    Might be worth seeing if there is an access plug that lets you drain the sump of the crankcase...
     
  8. Stl Flyn

    Stl Flyn Well-Known Member

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    OK, you established that when the plugs are out, you can pull the cord with little resistance, correct? Is this consistent? Has it ever been hard to pull with no compression in the cylinders, or with the plugs out? Also, is there a brake lock on this sled?

    Reason I asked about the belt being new, is that when the belt is new, it is shorter, and is not worn thinner yet. Which will make it grab the clutch further out on the compression plates of the clutch. Even though the clutch may still spin, without moving the belt, it still could be creating resistance on the clutch, which would also create resistance, to the crankshaft, which is what the pull cord is turning. It may be doing it intermittently, this is why I ask if it is pulling consistently easy, when the plugs are removed.

    If you take the belt completely off, then pull with the plugs in, and you feel resistance, then you know for sure it is not the belt, or clutch for that matter. Then go backwards with process of elimination from there, to the pull cord.

    You have to remember also that with the plugs removed there will be no compression in the compression stroke. Which means less resistance to the pull. With a three cylinder, two stroke motor, one cylinder will always be in the compression stroke, with the pull of the cord, creating more resistance then with the plugs removed.

    Update: I was thinking of the reed valves, exhaust port valves, of todays more fuel efficient 2 strokes. While they are valves, I was not sure how they where activated. I did say it was a far out possibility. LOL. Thanks for the correction.
     
  9. oldschool

    oldschool TS Member

    Joined:
    Oct 17, 2011
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    Stl Flyn is right the belt maybe dragging on the bottom of the primary (front clutch). You can take the belt off to check this situation but do not start the engine and rev it enough to engage it, this can be dangerous. You can also get enough slack by pushing in on the inner face of the rear clutch while turning it clockwise while pulling the belt into the faces of the rear clutch as you let off the inner face. Now if the engine is started and revved high enough to engage the front clutch it will not slam together but grab the belt. Yes is would be alot easier with three hands.
     
  10. mg1polo

    mg1polo TS Supporters TS Supporters

    Joined:
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    1,301
    Location:
    Grand Rapids, MI.
    Seriously Mr. Flyn! I'm not trying to bust your bubble, but a 2001 Yamaha 700 SRX is a Three cylinder two stroke engine. There is not a two stroke engine anywhere in the world that has a camshaft or valves.
    Mr. ShootGood, I sent you a PM.
     
  11. burtona

    burtona Member

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    Jan 28, 2011
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    Except some Detroit diesels!
     
  12. BobKatz

    BobKatz Member

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    Nov 19, 2009
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    I have a sx700. You have a hod rod! Take the belt off to eliminate any drive train issue. Pull plugs and engine should turn over freely. Assuming engine turns over freely drain old fuel and add fresh fuel. Add about 1/4 thimble of fuel in each cylinder before reinstalling plugs. Be sure key is on and on/off switch on handlebar is on and choke is on. Try and start it. Assuming you have spark it will at least try to start. I don't know what "pulls hard" is relative to but a 700 is a big engine to pull start. Try the above and if it doesn't work and if you want to PM me I can walk you thru other checks. It is a 2 stroke, reed valve engine, triple pipe sled. If it's anyones first sled be carefull its easily a 115-120 MPH sled!
     
  13. HSLDS

    HSLDS Well-Known Member

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    You get the service manual from here for a fiver...
     
  14. shootgood

    shootgood Member

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    Jan 29, 1998
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    Thanks everyone for the help. For those who said they pm'd me I used to visit this site a lot and to be honest I don't know how to check them. My email address is granders@dcemail.com Thanks for the tips I will mess with it this weekend. I know it is a fast sled but my wife just had to have it lol.
     
  15. Thom Simpson

    Thom Simpson Member

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    Jan 29, 1998
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    Are you at different altitudes? My king cat pulls hard at home 4000ft, but nice and easy at 8000. Has to do with jetting. Do you have spark? Can you start it even if hard pulling?

    I have an 05 900 king cat 800 mi, and a 2000 or 2002 powder special 700 1700mi. Make you deal on both...i meed a new Pgun. LOL