Quantcast
Jump to content

Need help

EasyE

By EasyE
in Yamaha ATV Forum

 Share

Recommended Posts

EasyE Newbie

EasyE

Posted
Posted

I have just recently gotten a yamaha big bear 350 atv and I think the carburetor is a little off on its setting,bc it cuts out at full throttle and it makes a weird pluff kinda sound 3-4 seconds after I hit the kill switch to shut the atv off. I don't know why it's doing that so any help will be greatly appreciated.

Mech Grand Master

Mech

Posted
Posted

The "whoomph" noise is the carb backfiring and trying to set fire to your air-filter. Check there's a flame proof mesh between the carb and air-filter.

The reason the carb backfires like that is because the mixture is too lean. I'd suggest trying adjusting the idle mixture and speed to cure that, but the high speed symptom sounds like the whole carb is running lean. You could check the carb is getting plenty of fuel right to it's fuel bowl by undoing the drain screw on the bottom of the carb and making sure fuel keeps running out even after the bowl has drained. Then check the carb breathers are clean and not crimped off or anything. Then, if it's getting plenty of fuel to the bowl but not revving right out, probably best to take the carb off and strip it entirely, clean and adjust it, and that should cure the problems.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
 Share
Go to topic listing

  • Popular Now

  • Similar Forum Topics

    • hengstserepair
      2000 Yamaha Breeze 125 slips in Forwards, runs fine in reverse
      By hengstserepair
      Howdy ya'll. I am working ona 2000 Yamaha Breeze 125. It was in rought shape when I received it and I am working through issues as they pop up. The quad had been sitting for years. I was able to get her running again, but I need your help with the following issue:
      I don't trust the transmission yet and I don't want to make problems any worse. So, I haven't pushed things hard at all. Low rpms, less than 5mph in reverse.

      Nuetral: Runs as expected
      Reverse: She seems to be driving fine at slow speeds. Going into reverse at idle is fine, coming out of reverse back into neutral won't work (the shifter is just stuck). As soon as I turn off the quad, I am able to shift around without any issue.
      Forward: It slips. It seems to only transfer power to the wheels on a smooth surface and going slightly downhill. When shifting into forward at idle, there is a clacking sounds during the transition. Shifting back to nuetral works just fine.

      Other Notable Symptoms: There was old oil in the vbelt and when I was tuning the carb, it starting blowing out of the CVT cooling vent at the front of the quad. Made quite a mess. There is positive crankcase pressure due to piston blowby, that I have not decided whether or not I am going to fix (customer budget dependant).  Since the oil was old, much darker than the new oil that is in the crankcase, I am thinking it seeped past a bad seal while it was sitting for years. The oil that was in it when I first got it had gas in it.

      Thoughts: I am thinking maybe there is an issue with the clutch. I worry about the old oil intermingling with the dry centrifugal clutch. I was thinking my next step would be to take the cover off of the clutch and inspect it.

      Let me know what you all think. Any advice and ideas is greatly appreciated. This is only the 3rd quad I have worked on and I have a lot to learn.

      Lorne
    • Rockbottom
      2008 Yamaha Big Bear 400 will not start
      By Rockbottom
      2008 400 big bear was running now will not start
      have power to relay, in neutral, press start have power to starter but nothing happens starter does not turn
      i have good ground at battery to frame and added ground from wire harness to frame beside batter/ frame ground
      blue white wire to cdi has power with key on
      I believe the neutral lock out is working since is was before i shut it down
      if i put  it in gear and hit the start button with key on the relay does not click or send power the starter
      The 3 wires at the relay have power with key on
      What should i test next?
      thanks ahead
    • Mister907
      2000 Yamaha big bear 400 won’t start
      By Mister907
      Hi guys, I have a 2004 big bear 400. Last winter while plowing the driveway, I heard a loud pop from the left side of the engine. It continued to run as I looked for leaky fluid, but then died shortly after backing it up and won’t start now. The oil light comes on when I try to start it, no noise or anything else. 
      No blown fuses that I can find.
    • jeffinotown
      2007 Yamaha Big Bear IRS Short
      By jeffinotown
      Hey guys and gals. I've been working on my friends 2007 big bear IRS. Unfortunately after 3 different people got their hands on it and only made things worse every time.  After months of finding just crazy problems everywhere. I'm finally at the point we're its almost 100% !!! But I'm getting a short somewhere between the 4xW switch I believe. I managed to by searching the internet like a  fiend, got my hands on an official Yamaha wire harness for the year and make. But I don't have the numbered component list and to be honest. After hours of going through and making everything so it's  easy to reference. If anyone has a picture of the referenced components. I would be forever in your debt. I've spent hours marking up the blown up diagram so it will be easy, for any possible future repairs. Please and thank you. Here's a picture of what i have so far.  Unsealed it in plastic so oil and crap won't spill or get smudged. This damn things worth it's weight in gold.              Thanks Jeff                2007 Yamaha big bear 400 IRS.       YFM40FBW
    • crankin
      Starter circuit cut out relay 1997 Yamaha Big Bear 350 4x4
      By crankin
      I have a 1997 Yamaha Big Bear 350 4x4. It used to start right up. Then all of a sudden it wouldn't crank. I have a schematic for it so I started tracing the problem. I had no power at the starter solenoid. According to the schematic the power comes from the neutral switch and through the starter circuit cut out relay. I cannot locate the cut out relay on this machine.. If I apply power to the relay it will crank with the start button.
      The neutral switch is hard to get to with all the brackets on this thing. I did find out from all my research that if I apply the rear brake lever it will start.
      Does anybody know if the cut out relay exists and where it might be found?

COMMUNITY SECTIONS

ATV FORUMS

QUADCRAZY MEMBERSHIP

Be a part of best online community of ATV riders and join thousands of people who love ATVs! Share your ATV photos, videos, ATV rides, get help with your ATV and more. Not a member?

SIGN UP TODAY

ADVERTISE WITH US

FOLLOW US ON

  • Automotive Webmaster
×
×
  • Create New...