Won't get fuel into combustion chamber - fixing up older '90
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  1. #1
    Member praeses's Avatar
    Join Date
    Jul 2011
    I've been trying to get an older '90 TW200 (non-CA) model running for awhile. I did have it running poorly for a bit, buy I can't get it to start at all. It'll sputter with a bit of gas in the cylinder however. What I am hoping is there is something I missed. I bought the bike in non-running condition but here is what I have replaced with brand new (since it was previously bad or iffy) and have since tested and appears okay:

    CDI (spark is consistent now, old one was intermittent

    Spark Plug

    Valve Clearance Adjustment

    Intake Boots (old ones leaked, shrunk too much/too hard

    Float bowl seal (looked dry)

    Petcock (wouldn't shut off)

    Float valve (needle, seat, seal, filter, etc)

    Fuel filter (wasn't one)

    Needle (corrosion at resting point)

    Main jet & nozzle (emulsifier tube thing) (corroded larger)

    Pilot jet & needle & seals (corroded)

    Coasting Enrichner and hose

    So far its getting to be a decent repair bill, and I seem to have taken a step backwards as it used to eventually sputter on its own. I have done a full cleaning 3 times(2nd and 3rd times I didn't find any new crud), had the carb out another 3 to inspect. Bike turns over fine and sparks fine, gas no longer leaks, but no gas is getting into the combustion chamber. Float level has been checked multiple times (7.5mm below body when bike is upright). Intake filter/etc is cleaned/oiled, no apparent leaks on either intake boot or between boot and head.

    There's got to be something I'm missing, any hints redundant or otherwise would be much appreciated. In the meantime I'm going to be keeping my eye out for another carburetor.
    2008 TW200 Yamaha luggage rack w/small el-cheapo JC Whitney trunk and large tool tube, Jimbo Shield, re-wired headlight, Blaster Shock waiting to be installed.

    1989 TW200 Work in Progress

    1994 ZX6E (rebuilt transmission, then rebuilt replacement motor, then rebuilt transmission in replacement motor, fun fun) large JC Whitney trunk fixed to the back of a computer chair re-welded to make a nifty luggage rack

  2. #2
    Senior Member FortPayne's Avatar
    Join Date
    Nov 2011
    Boy do I know the feeling! You clean that carb 50 times, try and start it and boom- still feels like a carb issue. If your sure, and I mean sure, that spark is good and consistant then I would start at the tank and work my way down. I know you've probably been through it a dozen times but just for your peace of mind that its not some simple little gremlin....

    Fresh fuel, take cap off tank for testing the fuel system, disconnect fuel line from carb and test flow. This makes sure petcock, fuel filter, and line are clear. Reconnect fuel line if all is good. Next check your air intake. Make sure you have a clean box and filter. Mine was horrible.

    You've done the carb. Did you do the Air Screw adjustment? If you dont know, its the screw in the bottom of the carb closest to the engine intake manifold. It is sometimes still plugged, but the screw is under the plug. Screw it in and the unscrew it ~3 turns.

    If none of that helps with what you've already done to the carb I would find a friend with a tw and switch carbs for testing.

    P.S.- compression good?
    Tenaciously Deviant Unwittingly Brilliant

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