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Discussion Starter #1
Hey guys, im new to these small four stroke engines but not engines in general. I got this quad from a friend of mine. Long story short, it ran fine before it was stored. The quad has been sitting for almost 6 maybe more years. We tore the carb off and went through it did not replace anything but just did a full cleanup. The fuel was junk and the bowl was quite varnished. Anyhow, fast forward and i have it all back together, runs like a dream when driving it hauls butt, but when it idles there is some rpm fluctuations maybe up and down a couple hundred rpm. The real issue is the back firing through the intake. Every maybe 8 seconds it pops pretty hard and i believe thats what split the carb/intake boot. Ive repaired that temporarily to get the quad going and its air tight.

Whats ypur thoughts on the bacm firing through intake? I have check the cam chain and timing, tension is good and the timing marks align correctly, the one tiny jet in the fuel bowl was completely clogged and the screw below it seems buggered a bit aswell. What does that tiny jet do in the circuit. I was tempted to buy on of those cheap ebay carbs to see bit i have been warned they can cause more problems than i already have!

Any thoughts, im going to grab a rebuild kit. What else could it be aside from the carb?

Thanks guys

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It must be the carb. You have covered everything else.
I would do a carb rebuild and do a carb cleaning using a dip solution. Dipping the carb cleans much better than spray cleaners. I use Solder Seal Gunks "Hydroseal II".....a fantastic cleaner.
 

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Discussion Starter #3
Thanks man, ya i never soaked it bit ive wondered what i should use. When the shindy kit rolls in ill tear it down and soal er

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I had great luck with a zoom zoom carb off eBay....just bolt on and go,didn't even have to adjust it at all. It's was for a 2000 Kodiak 400
 

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Discussion Starter #5
I soaked the mikuni overnight. My rebuild kit comes tomorrow so im committed now lol. Im feeling pretty good after i pulled a jet out that i didnt even know was in there. She was gummed and barely flowed

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I soaked the mikuni overnight. My rebuild kit comes tomorrow so im committed now lol. Im feeling pretty good after i pulled a jet out that i didnt even know was in there. She was gummed and barely flowed

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How did this turn out?!

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Discussion Starter #7
Hey, it went great. I blew all the orifices out in the morning. Put in the new jet kit and all that. She fired right up and runs really well. I found when its cold there is still a bit of surging at idle but it goes away after a few minutes.
 

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Beauty! Mine surges as well, which I always thought was normal when it was cold. Good work regardless!

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