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Discussion Starter #1
Hello all. I have a beautiful 1989 Yamaha TW200 with just 1260 original miles on it.
The only way to get it started is to spray one of the sprays... carb cleaner, starting fluid..... e.t.c. into the intake. Then it will fire up. I'll have to maybe do it a couple times before she keeps going but once she warms up it's great. And when warm I can shut it off and hit the starter and away I go. Here's what's all been done..
Carb rebuilt several times.
New floats, jets, accelerator
 

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Cold compression test might tell us something.
 

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Please answer regarding the carb idle mixture screw.
It is under a cap usually and could be overlooked by someone not used to working on these carbs.
Also, where are you located? If you are near NYC, I can run through the carb for you. I'm just sitting here working on my own stuff anyway.
 

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Discussion Starter #7
Please answer regarding the carb idle mixture screw.
It is under a cap usually and could be overlooked by someone not used to working on these carbs.
Also, where are you located? If you are near NYC, I can run through the carb for you. I'm just sitting here working on my own stuff anyway.
Yes this screw has been either replaced or adjusted or both
 

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Discussion Starter #8
Please answer regarding the carb idle mixture screw.
It is under a cap usually and could be overlooked by someone not used to working on these carbs.
Also, where are you located? If you are near NYC, I can run through the carb for you. I'm just sitting here working on my own stuff anyway.
Located in central Kentucky
Stop on by... don't forget your mask.
 

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...double post...
 
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Are you using thr choke/enricher?

Are you sparying the starter fluid into the air box?

Sounds like a problem in the choke or idle circuit.

Without an in person inspection of the carb, we may not be able to assist you.

Perhaps as a last resort, consider replacing the carb, either OEM, or one of the less expensive replacement CV carbs.

jn
 

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...double post.
 

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Discussion Starter #13
Are you using thr choke/enricher?

Are you sparying the starter fluid into the air box?

Sounds like a problem in the choke or idle circuit.

Without an in person inspection of the carb, we may not be able to assist you.

Perhaps as a last resort, consider replacing the carb, either OEM, or one of the less expensive replacement CV carbs.

jn
The choke doesn't seem to work.
I've gone thru it, and two friends who know more than me and are good mechanics haven't figured it out
 

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Discussion Starter #14
It seems like for whatever reason the engine isn't pulling the fuel into the combustion chamber.
I have a manual for this bike and two of us made sure the carb was put together correctly and everything is in place. We checked the passageways and found no obstructions. My friend knows a mechanic at a local motorcycle shop and plans to pick his brain Monday. And yes, I've sprayed into the intake duct located just under the seat. Just ahead of the battery.
 

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Did you make sure all of the passages were clear after cleaning the carb bodies? I have seen many cards clogged so bad with mineral deposits and varnish that only boiling them out would get them actually cleared of debris. An ultrasonic cleaner would also work to get it truly clean. Especially if the carb has been sitting for years.
 

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Discussion Starter #16
I have access to an ultrasonic cleaner. I'll try that. The thing is, we haven't found any passages plugged. But... when all else fails.... it doesn't cost me anything to run it through the cleaner. I'll try that next week when I get the bike back. Thanks
 

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How many turns out from lightly seated is the mixture screw?

I've gone 3.5 turns or more on a stock early carb.

Also, while it is apart... Measure the Jets against the factory idle jet. Some jet numbering systems (especially Chinese junk) vary greatly.
I've had the best luck with stock jets that have been ultrasonically cleaned.

The only aftermarket carb stuff I trust would come from Procycle.
And I have no affiliation with them.

Sent from my SM-G975U using Tapatalk
 

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Discussion Starter #18
Jets are from Yamaha. I don't know how many turns because I'm not working on it myself right now.
It's at a friend's place and he's the one working on it. He's in his 40s or maybe 50 by now and had worked on literally hundreds of motorcycles and mini bikes since he could hold a screwdriver and he said he's never met a problem like this that he couldn't solve. He's stumped. I'll send him this link and maybe he can chime in
 

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He and I are of the same vintage.
It is not common to go out that many turns.
I remember thinking "that is a lot of turns!"
Ask him to start at 2.5 turns and work from there. And if there is a choice when going from lean to rich and picking a spot in between.... Stay to the rich side of things.

Hope I've helped.
I wish you good luck.

Sent from my SM-G975U using Tapatalk
 

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If compression is good as you stated, besides cleaning out the tank, petcock and fuel line, I would just buy a new $35 fleBay carb and be done with it. My 2 cents.
 
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