84 200es runs but won't stay running

[Bryce200Es]

Hello everyone! first post on here. I have a 84 200es that I am currently getting going. The problem I'm having right now is when I start it up I can keep it running while pushing on the throttle but as soon as I let off it dies. Also it will backfire once in a while. any ideas what the problem is?

[kingkongslie]

There is a screw on the side of the carb that you can use to adjust your throttle. If you turn it to the right it will do the same thing as pushing the throttle. You will want to turn it just in enough to keep the bike running smoothly at idle. If it revs up too much at idle just back the screw off counterclockwise.

Backfiring could be a number of things but I would start with your timing and valve adjustment.

[DohcBikes]

Don't mess with the timing yet.

Start with a new NGK spark plug.

Is your fuel new?

[Bryce200Es]

I got a new spark plug for it already but the fuel is old. I used mechanic in a bottle and the stuff says not to drain the old fuel. Should i drain it anyway?

[DohcBikes]

Yes. And leave the snake oil on the shelf next time. One should always be skeptical of a product that tells you it's ok to use old fuel!!

[Bryce200Es]

The stuff fixed our zero turn right up so I figured it would do the job again

[fieldy]

Backfires when?

[mendoAu]

Could be a CDI ready to die.

[wonderboy]

+1 on what DohcBikes says. Drain the old fuel. No amount of additive can make old nasty fuel usable. My personal opinion is that all those aftermarket fuel additives are a waste of money and can't possibly do all they claim to do.

http://b3cfuel.com/products/mechanic-in-a-bottle <-- These guys make me laugh!

Save your money and use it to buy fresh gas.

If you had old fuel in there, most likely you will need to clean the carb. The idle circuits are small and easily clogged. The service manual is a mandatory download if you are new to this (even for the veterans).

Go here and navigate to your machine and download, print, and read the manual. This book will get you going in the right direction on any job you may have to do.
http://www.kb0nly.info/ATC/index.php?dir=

[RubberSalt]

Old gas = can't burn well - replace with new gas. You'll need to drain the carb and the tank. There should be a little screw on the bottom of the carburator. Turn this to drain it. Leave the tank on and it'll drain out. You can disconnect the fuel line and it'll drain faster.

Improper carb adjustment (fuel screw and air screw)= wont idle.

Timing isn't a problem or it wouldn't run
Valve adjustment could cause it to pop and back fire, but it would be very very very hard to start if it was out of whack enough. Wait for a later date on this one.
CDI isn't a problem or it wouldn't run