yamaha 4 stroke choke/backfiring
 

Hey guys. I am new to the golf cart world. I recently picked up an older 4 stroke yamaha golf cart. it sat for 5 years. so it backfires and the choke cable was broke. we put a cable from a bicycle on it for a temporary fix. Saturday when it was warm outside I finally got to get it going. But I had to pull on the cable slightly every once and awhile to keep it going. The motor would run but it wouldn't go. So after I bumped the cable and it got warm it ran for hours. but it is also backfiring. I took the carb out and cleaned it up and that didn't help. I also changed the oil and added a little sea foam to the gas and added fresh gas. otherwise it runs fine. so my question is where do I start to correct these issues. yesterday it was colder outside and it didn't want to go so I just quit. when I get home today im going to try to find the numbers on it to see exactly what kind it is. any help will be much much appreciated.

Re: yamaha 4 stroke choke/backfiring
 

For backfire, make sure the air intake box is PERFECTLY sealed... I even added a large tie wrap on mine!

For the rest, did you change the spark plug?

Re: yamaha 4 stroke choke/backfiring
 

yeah I changed the spark plug as well.forgot to mention that. I was wondering if maybe a new carb is in order.

Re: yamaha 4 stroke choke/backfiring
 

Carbs rarely go bad if the box lid is warped and not perfectly sealed it will cause issues iv had to tape warped air box lids before to get them to run right

Re: yamaha 4 stroke choke/backfiring
 

Spicyunicorn and sformal are giving you good info. Sure sounds like it is running lean, or intermittently running lean, hence the need to pull the choke to rectify it.

It is likely an air leak. In addition to checking the air filter, check the carb mounting studs for tightness and potentially the gaskets could be leaking forward of the carb where it mounts to the head.

The more seafoam that runs through it the better the carb should get. It does a pretty good job of cleaning out existing varnish too.

Re: yamaha 4 stroke choke/backfiring
 

I kinda thought the airbox wasn't on properly. I took 3 zipstrips and put those on but that may not be enough. I really appreciate the advice. I will try these options and let you all know.

Re: yamaha 4 stroke choke/backfiring
 

So i got home from work to try to find identifying numbers on this cart but no luck. I looked under the glove box, umdwr rear bumper. I also took a look at the air box again. It isnt sealed the best so im going to work on that tomorrow. This poor thing doesnt have a top either so i giess we are going to build one. And last for now is it appears in the rear end there is a part where you fill the rear end and that appears to be leaking. But i guess i cant complain for a hundred dollar cart that needs some tlc.

Re: yamaha 4 stroke choke/backfiring
 

A couple pictures and we could identify it

Re: yamaha 4 stroke choke/backfiring
 

Get us a pic of your cart. :thumbup: Sounds like this cart just needs going through with a really good tune up. And air box will need to be completely sealed. Bungy cords work great if the tabs are completely broken: run one over the center and hook underneath. Just be mindful of the clutch. Probably should pull fuel pump, tear it apart, and clean also. Check and replace fuel lines if needed. Be sure to get the exact same size!! Check the line going to the back of the engine also. The cart will never run right if it is leaking. It's what helps operate the fuel pump with vacuum. Most backfires on 4 stroke Yamaha's is due to the throttle on the carb not closing all the way when you let off the pedal. You probably need to adjust the valves on this cart also.

But get us some pic's of your cart and we'll let you know what you have. :thumbup:

And welcome to the forum.

Re: yamaha 4 stroke choke/backfiring
 

Heres one from front