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Thread: Stumped with 1992 TW200 starting issues

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    Senior Member kennethshaw's Avatar
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    Stumped with 1992 TW200 starting issues

    I recently picked up a 1992 tw200 with 192 miles. I've cleaned the carbs twice and still can't get it to start and stay running. Here are some of the issues. When I was able to start it, it would only start with 4 1/2 turns out on the air mixture screw. Oddly enough, it would not start with the choke pulled. I have a 40 slow jet and 116 main with 4 shims. It has a new battery and turns over easily. I've resurrected a number of these tw200's but this one has me scratching my head. Any recommendations from you master mechanics would be greatly appreciated.

    Thanks!
    Ken
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    Senior Member Sthrnromr's Avatar
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    Stumped with 1992 TW200 starting issues

    Stupid questions but I have to ask. Are you sure the cleaned carb is getting clean fuel where it’s required? Tank, lines, jets etc, all getting good clean fuel? 92 with 192 miles has spent a lot of time sitting. Also, getting proper spark? New plug? Verified spark when turning over?
    Last edited by Sthrnromr; 05-12-2019 at 07:51 PM.
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    Super Moderator littletommy's Avatar
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    Not sure, but that doesn't sound like the right jets and shims that would come with it originally.
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    Senior Member GaryL's Avatar
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    When you say you cleaned the carb you don't say how you cleaned it. If you rebuilt the carb did you remove the float needle valve cup from the body and check the tiny screen under it? You should actually replace the float needle valve assembly any way and check the height of the float to make sure it is set to the correct height. Fuel/gas must be flowing through the entire delivery system from the tank, through the petcock and into the carb. Check the entire system to be sure there are no clogs. When re installing the carb the pilot SCREW should be set at between 2-2.5 turns out from the full in position and it is absolutely imperative there is an air tight seal on both sides of the carb or you are barking at the moon. Jets and shims! Apparently someone has been in this carb to make some changes. Did that someone put the carb back together correctly??? Are you following his lead and doing the same? Did someone use some BS after market kit. I would go directly back to real OEM stock jets, needle and original form with no shims just to get you back to a working carb. After it is know to be working correctly then you can do what ever additional tuning you like and do it one thing at a time so you know what you just did works or not.
    I will assume here, A 1992 with 192 miles sure has sat a lot. The tank likely has crud growing inside and the petcock screens are likely clogged. Any old gas that was in the tank has turned to varnish and you will likely find a rust build up inside. Any stale fuel that entered the carb from the tank probably had all sorts of particles in it that would easily clog the internal passageways and cause the issues you are having. Such a carb requires a complete disassembly and a deep cleaning in an ultrasonic machine or a deep soak in a 1 gallon can of Berrymans carb soak for a few days plus a thin wire pushed through all the passageways. During the reassembly you must follow the diagram and assemble it to factory specs with all parts in the right place as designed and do not depend on the way the one before you had it. If you see rust inside the tank it must be cleaned and there are lots of threads "HOW TO" here. I use Metal Rescue available at the big box stores and soak the inside for a few days with it at full strength. A new petcock is a good idea and order new screws with the gasket washers as well. An in line fuel filter is a major plus also.

    GaryL
    Last edited by GaryL; 05-13-2019 at 04:19 AM.
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    Senior Member elime's Avatar
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    I think GaryL is on to something when he says someone else has been in there.

    I once bought a carb kit that had a #116 high speed jet and a lot of shims along with many of other parts. When I installed all the pieces it ran like very poorly and I ended up putting the original used parts back in.

    Here are pictures of some of the pieces from that kit:
    Pic #4: Original needle on top. Multi grooved one came in kit.
    Does your carb have any of the non original parts in it?
    P5190022.JPG PICT2571.JPG P5190027.JPGPICT2564.JPG
    P5190023.JPG
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    Super Moderator Purple's Avatar
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    One jet kit is not the same as the other, despite the sizes on the packet – plus, you don’t know if those shims (or anything else) has been done to compensate for the introduction of aftermarket parts

    I agree with the others – take the carb back to stock with OEM parts, clean it like your life depended on it, and re-assemble it properly (which may be different than its present state) – then take it from there

    As it stands, you have no base reference point for any of it …..
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    Senior Member imlost's Avatar
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    Look for everything outside of the carb, first, and eliminate those possibilities. Like has been previously mentioned, make sure it's not starved for fuel. Remove the petcock and inspect the filter on the pickup. Also, a bad CDI will cause it to run crappy - This was the case with the '87 I'm working on. With a bad CDI, it can still fire and run, but with my experience, it wouldn't take any throttle. It would die when you put the fuel to it, and it didn't want to idle.
    Last edited by imlost; 05-13-2019 at 11:56 AM.
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    Senior Member kennethshaw's Avatar
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    Thanks to all who have replied. I’ll provide more background on what I’ve done. So the carb came in stock but the idle (air mixture) screw was turned out 4.5 turns. The brass jets had all corroded to the point that they were pitted so I replaced the idle (air mixture) screw, emulsion tube that holds the main jet, main jet, and pilot jet. All were OEM Yamaha parts. I ultrasonically cleaned the carb (with Simple Green mix) and also sprayed carb cleaner through any passages. I put it back together and it started up okay but again but needed the idle (air mixture) screw at 4.5 turns with no choke before it would start. When I would try to lay on the throttle, it would bog instantly. In the past, I usually added shims to account for this. So I added two shims and it would start and throttle improved marginally but would still bog. I added another two and now I have trouble starting and keeping it running. It will start and run for 1 second and then die. This only works 1-2 times before it won’t start at all. I know that it isn’t the petcock because I have a temporary fuel set up (motion pro) hanging bottle with a direct tube to the carb. So I know it’s not a fuel flow issue. What I will do tonight is take all the shims out and see if it will stay running. My understanding is that the shimmed needle shouldn’t have an effect on idle but I’ll remove just in case.

    For the CDI, how do I test to know if it is bad?
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    Senior Member imlost's Avatar
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    Quote Originally Posted by kennethshaw View Post

    For the CDI, how do I test to know if it is bad?
    I stuck the CDI in the freezer for an hour or so, and then quickly reinstalled it. The bike would run good for a couple minutes until it warmed up. Though this is definitely not a "tell all" of what all could be wrong, it was enough of an indicator for me to believe the CDI was the culprit. My hunch paid off.
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    Senior Member GaryL's Avatar
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    Go here. https://www.partzilla.com/catalog/ya...00m/carburetor
    Part number 17 and part number 32 could be culprits and you don't mention having replaced them. Number 17 has a tiny fine mesh screen above it which is always clogged when ever there is other corrosion inside the carb. The rubber diaphragm on part 32 is also subject to be cracked and the plunger behind it could certainly be stuck. Using the actual part names given by Yamaha in the schematic helps us to know what parts you have replaced.
    Another often faulty part on these older bikes is the rubber boot between the air box and carb that tends to harden and shrink. This will not allow for an air tight seal on the intake side and any air leak on either side is NFG! If you have not personally inspected the air box itself then do so. Mice love to build nests up in the air intake right behind the battery and their nest material will clog the air flow. 4.5 turns out on the Pilot screw #4 is absolutely no good and you might check you plug for fouling as it is running far too rich. # 11 is your pilot jet size 40 and number 14 is your main jet size 114. If all else fails then I will suggest buying part # 1 or sending the carb to someone here who is willing to mess with it. If you have a second TW that is running good then swap carbs and see if this corrects the issue which will immediately tell you if it is or is not carb related. CDIs do fail but that is the very last place I would look before you are certain it is not in the carb.
    Part #6 here for the carb joint , https://www.partzilla.com/catalog/ya...-tw200m/intake. BTW, Any carb from 1987-2000 is what you are dealing with and we call them the Old Style carbs, they changed in 2001 and the new ones will work however you have to buy the joint boots on both sides and change the cable routing. IMO, new style carbs are not much better than old style ones but I leave that up to you. The 1987 models are very common to have faulty CDIs but from 1988 up the CDI issue is much less common.

    GaryL
    Last edited by GaryL; 05-13-2019 at 02:10 PM.
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    Since light travels faster than sound, some people appear bright until you hear them speak.
    If I agreed with you, we'd both be wrong.

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    Kubota BX2370 Subcompact tractor with snow blower
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