87 carb problems!!!!
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  1. #1
    Member chevy_lifted_4x4's Avatar
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    I've got an 87 with some carb problems that I cannot figure out. I used to ride the bike all the time with no problems until about 2 years ago. It sat in my barn during that 2 years. A couple months ago I pulled it out to get it road worthly again. Couldn't get it to run, so I bought a Keyster carb kit off ebay (May have been my problem from the beginning) I got the kit installed and fired up and rode for a couple miles and ran great. The next time I went to ride it, it ran horrible. I couldnt get it to idle without the choke on, but I could get it to rev up only if you played with the throttle for a couple seconds. I figured the carb was gummed again. Took it apart again and cleaned several times. No luck. Parts I replaced recently hoping would cure the problem-

    1.Both boots on both sides of carb-due to shrinking and small cracks

    2. diaphragm kit on side of carb

    3. gasket on plastic cover over slide

    4. 2 different spark plugs

    5. o-ring between carb boot and head.





    I read some other posts on here about people having problems with the ebay keyster carb kits? I tried my old main jet and needle and it runs slightly better but no where close to where it should. It will kind of run with the choke about half way out. Adjusted pilot screw 2 1/2 turns out. Checked valves and are both good. Carb is %100 clean. I thought about ordering OEM jets and giving that a try but I hate to just guess. Already spent around $200 on guessing. Any suggestions? Thanks a lot

  2. #2
    Member chevy_lifted_4x4's Avatar
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    Update---- I put in my old main jet and needle and it runs a LOT better but still cant get it to idle and rev at lower rpm's. It will stay idling and run better with about 1/2 choke out.

  3. #3
    Senior Member retmotor's Avatar
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    Sounds like not enough fuel at idle. I believe the pilot jet and screw have the most to do with lower rpms and idle.

    If it ran good and now it doesn't, I'd really suspect some kind of fuel obstruction. Debris has a way of working loose in equpment that's been sitting.
    The value of the internet is that when you're wrong someone will immediately correct you, and when you're right, someone will immediately correct you". Lizrdbrth

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  5. #4
    Senior Member jbfla's Avatar
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    Quote Originally Posted by chevy_lifted_4x4 View Post
    ... It will stay idling and run better with about 1/2 choke out...
    If you need the choke to keep it running after the engine is warmed up, there's not enough fuel coming through pilot circuit , or there is a vacuum leak.



    Jb
    2018 Triumph Street Twin..............2016 CB500F
    2014 XT250 ..................................2008 H-D Softail Deluxe
    2008 SV 650..................................2007 DR 650..

  6. #5
    Senior Member evan's Avatar
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    As you probably already know your first mistake was buying a carb kit. I've cleaned out plenty of gummed up carbs that have been sitting for years and never need a carb kit (maybe a float bowl gasket). The carb isn't worn out, just plugged. Carefully take it apart. Does the idle mixture screw have a little washer and o ring on it? Very easy to lose them if you don't carefully remove them and will not idle right without it. I like to spray carb cleaner thru each circuit and see exactly where its supposed to come out (WEAR EYE PROTECTION cuz carb spray in your eye really really hurts!) Next use your rubber tipped compreessed air nozzle and blow air thru it. Then try to go the reverse thru the circuit. It can be tough to get that tiny flake out so back and forth with carb spray and air. You really have to take your time. * also when you do get it running right. Drain the carb on a regular basis and I turn the petcock off and run the the engine till it quits. Then I drain carb. Don't want it gumming up again. I also use seafoam like a lot of other members here do.
    Mike Carter. Woodland, California (NorCal). '89 Tw200 (Black Widow Edition). Blood red Jimbo shield, Cycleracks, Nuvi 500 GPS, Kolpin fuel pack jr., D shield bark busters, 55t rear sprocket, Golden boy front tire, Ricochet shield.

  7. #6
    Senior Member jbfla's Avatar
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    Quote Originally Posted by importmech View Post
    ...I like to spray carb cleaner thru each circuit and see exactly where its supposed to come out (WEAR EYE PROTECTION cuz carb spray in your eye really really hurts!) Next use your rubber tipped compreessed air nozzle and blow air thru it. Then try to go the reverse thru the circuit. It can be tough to get that tiny flake out so back and forth with carb spray and air. You really have to take your time. * ...
    importmech,



    Excellent description of the procedure!!!







    Jb
    2018 Triumph Street Twin..............2016 CB500F
    2014 XT250 ..................................2008 H-D Softail Deluxe
    2008 SV 650..................................2007 DR 650..

  8. #7
    Member chevy_lifted_4x4's Avatar
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    Quote Originally Posted by importmech View Post
    As you probably already know your first mistake was buying a carb kit. I've cleaned out plenty of gummed up carbs that have been sitting for years and never need a carb kit (maybe a float bowl gasket). The carb isn't worn out, just plugged. Carefully take it apart. Does the idle mixture screw have a little washer and o ring on it? Very easy to lose them if you don't carefully remove them and will not idle right without it. I like to spray carb cleaner thru each circuit and see exactly where its supposed to come out (WEAR EYE PROTECTION cuz carb spray in your eye really really hurts!) Next use your rubber tipped compreessed air nozzle and blow air thru it. Then try to go the reverse thru the circuit. It can be tough to get that tiny flake out so back and forth with carb spray and air. You really have to take your time. * also when you do get it running right. Drain the carb on a regular basis and I turn the petcock off and run the the engine till it quits. Then I drain carb. Don't want it gumming up again. I also use seafoam like a lot of other members here do.




    I'll give it another try. Since I did have it running very well after the rebuild, I keep leaning toward something still clogged in the carb. I've sprayed carb cleaner through every port. My kit came with a #38 pilot jet. I tried my old #40 jet after cleaning it well, and it didn't make a difference. I'll give it one more good cleaning in both directions and post what I come up with. Thanks a lot.

  9. #8
    Senior Member evan's Avatar
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    Carbs can be a bitch to get cleaned out. I just cleaned out my TTR225 carb and while it runs alot better and starts easier, I still think I missed something inside and will have to do it again....
    Mike Carter. Woodland, California (NorCal). '89 Tw200 (Black Widow Edition). Blood red Jimbo shield, Cycleracks, Nuvi 500 GPS, Kolpin fuel pack jr., D shield bark busters, 55t rear sprocket, Golden boy front tire, Ricochet shield.

  10. #9
    Member chevy_lifted_4x4's Avatar
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    Well, I took the carb apart for the 700th time. I used 2 cans of carb cleaner and blasted every port in each direction with my air nozzle. Everything seems to flow fine from what I can tell. I put the new main jet in again and it ran like crap. Switched back to the old one and it ran better again but still wont run unless the choke is 1/2 on. Messed with the pilot screw in and out but doesnt make much difference. Any other suggestions? This thing is driving me nuts.



    Edit-

    I was just looking at the carb diagram and it looks like there may be a lower gasket that goes to the main jet? Its #12 in the following diagram



    http://www.ronayers.com/Fiche/TypeID/26/Type/CARBURETOR_(NON-CALIFORNIA_MODEL)/MakeID/4/Make/Yamaha/YearID/28/Year/1987/ModelID/9234/Model/TW_200/GroupID/443465/Group/CARBURETOR_(NON-CALIFORNIA_MODEL)

  11. #10
    Senior Member evan's Avatar
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    If you can't find an intake vacuum leak its just got to be the carb fuel or air circuit plugged. You said it was parked in a barn. any rodent chewing damage? Does the main jet have a tube behind it with little holes in it. Its been awhile since I've cleaned mine so don't remember. I'll have to look at carb pic in my service manual. * looking a pic now. shows an oring on main nozzle and pilot screw. Those both still good?
    Mike Carter. Woodland, California (NorCal). '89 Tw200 (Black Widow Edition). Blood red Jimbo shield, Cycleracks, Nuvi 500 GPS, Kolpin fuel pack jr., D shield bark busters, 55t rear sprocket, Golden boy front tire, Ricochet shield.

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