CR80 Fuel Issue (Newbie Help Please)

This topic has 6 replies, 3 voices, and was last updated 10 years, 9 months ago by Jason Shoulet.

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- October 23, 2015 at 10:48 am #55783
  
  Timothy Strawkas
  Participant
  
  I can not tell in the pictures, but it almost sounds like you have the feed pump feeding the pump around line, and the pick up pump sucking the feed line. Or both pumps are feeding the carb and none are pulling the fuel out of the carb.
  
  Oh I just seen the other comment you had. This kart is not A street toy, They don’t run great there because there not designed for it. Keep it off the street.
  - October 23, 2015 at 10:56 am #55784
    
    Jason Shoulet
    Participant
    
    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.
- October 26, 2015 at 3:52 pm #55873
  
  Jason Shoulet
  Participant
  
  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.
- October 26, 2015 at 4:45 pm #55878
  
  Dave Holstein
  Participant
  
  I would like to put my two cents into this, I race 80s at my local 3/4 mile track, and I would like to advise you to NOT drive this on the street, you are on a very low/no grip condition and all you need to do is eat a cars bumper once and you’ll be driving a wheelchair forever if your lucky!
  
  hate to sound like a real pain but I would recomend you get out on a track and push it till it breaks loose and then you will see just how helpless you are when you loose traction, if your in the area of central/northern California the Sanzaru karting championship runs at Sonoma raceway and has an 80 masters class (32 and up).
- October 30, 2015 at 10:45 am #56083
  Jason Shoulet
  Participant
  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.
- November 2, 2015 at 3:32 pm #56195
  Jason Shoulet
  Participant
  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.
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