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Discussion Starter · #1 ·
I bought a 2003 Honda 300ex the Monday after Thanksgiving. I did a test ride and looked the engine over for any sign of oil/gas leaks. It ran very strong and I didn't find any leaks. The guy that I got it from lived less than a quarter mile from me, so I paid him and took off on my first ride. A couple of days later It started to run rough at full throttle. A few days after that it started to pour oil. I took the gas tank off and gave it the white vinegar treatment to remove rust and any build up. I washed out with water and sodium bicarbonate. Next I filled the tank with ethanol free gas. I shook the tank around and immediately dumped it out. I also cleaned up the petcock and made sure that gas would pass through it. I put the tank back on and fully expected it to run better. It ran after I got back together, but if anything it ran and smoked even worse. It also wouldn't idle. I accidentally let it go dead while trying to shift it into reverse and it wouldn't crank back up. This morning I went throught the whole process to hopefully get it going. It cranked after I shot a little starting fluid to it, but it ran rough and smoked like a loaded freight train. The minute that I let go of the throttle it died again and wouldn't start again. I can't even to begin to look for the oil leak when it won't stay running so right now all I have is a 300+ paperweight. I'm not a mechanic by any means so I was hoping someone here could offer an idea what is going on with it. I've had the thing for a month and only got to ride it 5 hours or so. I'm so disgusted with it that I can't even stand to look at right now. Any advice would be greatly appreciated.





 

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Where did it start pouring oil out ? Check the oil level and smell it. If it smells like gas, dump the oil
and fill with proper amount. Did you check to see if the petcock shuts off ? It could be a leaking
petcock and stuck carb float valve have filled the crankcase with gas.

Mad
 

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Discussion Starter · #3 ·
I actually think I may have found the oil leak today. Apparently whoever installed the 330 kit used rtv silicone instead of the proper gaskets when he put it back together. It seems pretty obvious that's the reason it didn't leak for a couple of days, and then got progressively worse over a few days. The carburetor still has me puzzled though. I'm thinking about buying an aftermarket carburetor off and just drop a new one in while I have it taken apart. Has anyone had any experience with those?
 

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I have a Chinese carb on my Big Bear. It works good. Keep in mind that they aren't always jetted properly.
If you can use the jets out of the stock carb, maybe do that. I bought mine from a seller on eBay
that had lots of positive reviews. There are different quality units.
 

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Discussion Starter · #5 ·
I actually think I may have found the oil leak today. Apparently whoever installed the 330 kit used rtv silicone instead of the proper gaskets when he put it back together. It seems pretty obvious that's the reason it didn't leak for a couple of day, and then carburetor off and just drop a new one in while I have it taken apart. Has anyone had any experience with those?
I have a Chinese carb on my Big Bear. It works good. Keep in mind that they aren't always jetted properly.
If you can use the jets out of the stock carb, maybe do that. I bought mine from a seller on eBay
that had lots of positive reviews. There are different quality units.
Thanks for the reply. I was looking at one on Amazon for $45 that has a 4 1/2 star rating. I'll have a guy I know check it out to see if it comes with the right jets. I owned and maintained 2 stroke dirt bikes when I was a teenager through my early teens. As long it was something in the top end I could pretty much fix it. That was 30 years ago though and this thing has parts on it that I can't readily identify without a repair manual. This is my first Quad and I bought it because I've always wanted one but I wish I had a little more knowledge about them before I jumped in. Thanks for your help.
 
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