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My 92 Katana 600 dies on idle with the choke off, no matter how warm the engine. I've found that leaving it on 1/2 - 3/4 choke gives it a good balance. I know that choke can cause fouling and carbon deposits if you use it too much, but my thought is dirty carbs run lean and choke can richen it up to a normal mixture. Is this flawed logic?

  • clean the carbs, make sure the jets are clean then adjust the mixture and idle speed to within correct limits. Oh and make sure the air filter is clean... – Solar Mike Nov 7 '17 at 6:43
  • A clogged air filter would be more likely to help in this situation as it would richen the mixture @SolarMike, but all good advice in general. – GdD Nov 7 '17 at 8:45
  • @GdD So, back to treat the symptom or the cause... – Solar Mike Nov 7 '17 at 8:59
  • Totally @SolarMike, carb cleaner is your friend, maybe a can of seafoam as well. – GdD Nov 7 '17 at 9:00
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You can roughly compensate with the choke for a shortage of fuel, but you can't properly control your choke to compensate the exact right amount while driving, so your bike will run terrible if you try to.

Furthermore, if your choke is one in the literal form, so that it restricts the inlet flow, it will also (heavily) limit your power as already mentioned by others. An engaged choke that is properly tuned, enriches the mixture the right amount only AT IDLE. It will become way too rich if you use the same setting while driving. The fuel metering and ignition advance will be off.

So i'd strongly advise you to pull open your carb and clean it. Often, the float chamber is full of rust powder and dirt. Check the fuel lines and filters for blockings/restrictions and dirt and make sure fuel from the tank can freely reach your carbs. While you're busy, i'd also recommend checking your sparkplugs and exhaust for sooth deposits.

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No, a choke cannot compensate for dirty carbs because you'll never get full power out of your motorcycle if you run on it. Here's a picture of a carb: Carburetor

When you pull the choke it closes the choke butterfly valve or a choke plate, reducing the airflow and richening the mixture. That means no matter how much the throttle valve opens you will not get full airflow, so you won't get full revs. It's not a good idea, I'd only do it to get to a place I could get things fixed.

If your engine is dying on idle you need to resolve the problem. It's probably pretty simple, it could be dirty carbs, it could be a clogged fuel filter, your best bet is a can of carb cleaner and a bit of time. Be sure to use it in a well ventilated area!

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  • on some bikes the "choke" is actually an enrichment circuit with a second fuel tube controlled by a valve, which is actuated by the choke lever/plunger/solenoid-- in these cases this wouldn't hold exactly true – Ceshion Nov 7 '17 at 17:25
  • For sure @Ceshion, I'm assuming manual choke as its implied by the OP – GdD Nov 7 '17 at 18:36

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