[Jason Shoulet]

I am posting this to close out the thread and hopefully help someone else with these issues.  Before breaking the carb apart I decided to change the spark plug which resolved the issue of the kart dying after a few laps.  After changing the spark plug the apparent rich condition was also eliminated once the engine was brought up to temp (110 degrees).  As a side note, I also added an additional breather tube to my gas tank cap using a 1/4 inch copper barb which eliminated a bogging issue I was having when I had more than a half tank of gas and I would come off the gas and try to get back on it.

To summarize, here’s the issues I had and the things that fixed them:

1. Bogging in top of 5th and all of 6th gear. Rebuilt Mikuni fuel pump which solved this issue (one of the two small internal diaphragms was bent).
2. Excessive white smokey exhaust, heavy bubbling in the radiator and overheating. Replaced head gasket which resolved all these issues.
3. Kart dying after 2 solid laps.  Changed spark plug which resolved this issue.
4. Bogging when coming off the gas and then getting back onto it when the gas tank was half or more full. Added breather tube on gas cap which resolved this issue.

[Jason Shoulet]

Thanks for the concern/advice Dave.

Here’s an update on the troubleshooting progress:

1. Replaced the head gasket which fixed my temperature problem and my bubbling radiator fluid problem.
2. The kart is still running rich which was slightly improved via an adjustment to the air screw (had to go 3 turns out which is another indication it’s running rich and the jetting is off)
3. After running the kart for 5 or 6 laps up and down the street it dies.

I’m going to pull the carb apart to adjust the needle clip up one notch and see what jets are being used.

[Jason Shoulet]

After some additional troubleshooting I believe I have a blown head gasket that is allowing coolant into the cylinder.  The exhaust is now white, it’s overheating, I can see bubbles in the radiator and after a quick cold start the plug is soaked.  A slow coolant leak would also explain why it can make (2) passes before fouling the plug and shutting down.  Changing the gasket tonight.

[Jason Shoulet]

Thanks for such a quick response.  The lines are set up the same as they were when I purchased the kart (never touched anything before the issues started) and it ran it without issue for months.  I can also see the fuel return line feeding fuel back to the gas tank (I can see it in the line coming from the carb and I can see it draining in the tank itself).

What’s really stumping me is the ability to make (2) long 1st through 6th gear passes without issue before it dies.

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