Cuts out under load
Close
    
    
Results 1 to 8 of 8
  1. #1
    Junior Member austinripp's Avatar
    Join Date
    Feb 2016
    Posts
    4

    Cuts out under load

    I've about exhausted what I can to figure this out.

    Background - 1989 tw200ca, 10k miles; in Clear Lake, TX (essentially sea level)
    has been used regularly until ~2yrs ago when it decided to misbehave - I would like to be back on the bike a bit more.

    Symptoms -
    Starts easily and idles fine. after driving about 200 yards it will cut out as if it has lost power. Driving at night, I noticed that the lights don't dim or flicker at all during these cutouts.
    If I pull in the clutch, it will continue running fine but stutter if the clutch lever isn't pulled. When the clutch is pulled, I can rev it hard and it will ramp up RPMs quickly. It just cannot handle any load during these episodes.
    After about a mile, it will run just fine (probably forever). If I stop at a light for a long time, it might do the stutter again, but not as drastically.

    I'm about to ditch the bike and get a Honda, but I actually think the TW is perfect...

    What has been tried (from reading other threads) -
    adjustment of stock carb, air mix screw, jetting, seafoam - no joy
    replacement of stock carb with Chinese clone (found in other forums) - no change
    replacement of NG plug - no change, recently plug is blackish (running rich)
    replacement of plug cable/coil - no change
    replacement of gas tank/clean petcock - no change
    replacement of CDI (found vendor on other forum) - no change
    removal of superfluous cabling (LED body lights, voltmeter, external batt charger cable) - no change
    removed fuel filter - no change

    I'm open to ideas or suggestions -

  2. #2
    GOF
    GOF is offline
    Senior Member GOF's Avatar
    Join Date
    Dec 2018
    Location
    Buffalo, NY
    Posts
    340
    Have you tested the battery? Checked connections? Inspected/tested the pickup coil and stator?
    1988 Suzuki Savage
    1987 Yamaha TW200

  3. #3
    Senior Member TWBigBlake's Avatar
    Join Date
    Apr 2019
    Location
    Tacoma, WA
    Posts
    189
    Does it sputter when it cuts out? Or does the engine just cleanly stop running? You running stock tank cap or vented? Replaced fuel lines?

    Check for leaks around carb/spray some seafoam at it while idling, see if idle increases.

    You could be experiencing air starvation, idle jet is set well enough that starting, idling and initial motion isn't an issue, but as soon as main jet transitions, you start dumping fuel and there isn't enough air to burn all the fuel. What size main jet? Elevation?
    Last edited by TWBigBlake; 09-04-2019 at 04:20 PM.

  4. Remove Advertisements
    TW200Forum.com
    Advertisements
     

  5. #4
    Junior Member austinripp's Avatar
    Join Date
    Feb 2016
    Posts
    4
    Batt has good voltage. I disconnect it if I'm not going to ride for a couple of months. Good voltage when running - batt hasn't had to be charged off the bike ever.
    I replaced the pickup coil, but not sure how to test the stator. I veered away from an electrical gremlin when I saw steady lights during the sputters.

    Thanks--

  6. #5
    Junior Member austinripp's Avatar
    Join Date
    Feb 2016
    Posts
    4
    Quote Originally Posted by TWBigBlake View Post
    Does it sputter when it cuts out? Or does the engine just cleanly stop running? You running stock tank cap or vented? Replaced fuel lines?

    Check for leaks around carb/spray some seafoam at it while idling, see if idle increases.

    You could be experiencing air starvation, idle jet is set well enough that starting, idling and initial motion isn't an issue, but as soon as main jet transitions, you start dumping fuel and there isn't enough air to burn all the fuel. What size main jet? Elevation?
    It just sputters and doesn't die completely. My reaction is to pull the clutch lever - it will then just run smoothly while I coast... I can freely rev the engine while coasting.

    I have the stock tank cap. I did replace fuel lines when I put the cheap carb on.

    I'm not sure the main jet size. Elevation is about 30ft above sea level. I took the stock carb off about a year ago. The newer carb made no difference.

    Air starvation makes sense. I'll try the carb spray and see what happens.

  7. #6
    Senior Member RaZed1's Avatar
    Join Date
    Oct 2015
    Posts
    281
    I'm betting the carb intake has a vacuum leak. What you describe sounds like a lean condition (revs easily unloaded, but does not handle any load) With the engine idling, wave an unlit torch around the carb/intake. (or spray carb cleaner). If the RPM's increase, you found the issue.

    It's pretty common for these seals/boots to dry out, crack, leak on bikes that are 30+ years old.
    Last edited by RaZed1; 09-05-2019 at 12:34 PM.

  8. #7
    Senior Member Errtu's Avatar
    Join Date
    Jul 2017
    Location
    Buena Vista, CO
    Posts
    132
    I replaced both boots from the carb and upon inspecting them they both had cracks and rot that was causing issues.

    I had a similar problem with a Chinese carb I installed. Idles fine but would die under load. Setting the fuel mixture

    fixed my issue.
    Last edited by Errtu; 09-05-2019 at 02:26 PM.
    2001 Yamaha TW200
    2015 Nissan Xterra PRO-4X

  9. #8
    Junior Member austinripp's Avatar
    Join Date
    Feb 2016
    Posts
    4
    Quote Originally Posted by RaZed1 View Post
    I'm betting the carb intake has a vacuum leak. What you describe sounds like a lean condition (revs easily unloaded, but does not handle any load) With the engine idling, wave an unlit torch around the carb/intake. (or spray carb cleaner). If the RPM's increase, you found the issue.

    It's pretty common for these seals/boots to dry out, crack, leak on bikes that are 30+ years old.
    No change when spraying carb cleaner around the carb/engine boot.
    Should note that after chugging for 200-500 yds, it will run just fine.

Sponosred Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •