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Discussion Starter #1
Good afternoon everyone. New to the forum, but old to the Yamaha grizzly. I’ve owned 6 bikes all Yamaha’s and this is my second grizzly. I got this one from a friend about 2 years ago after doing some welding and work on his house we built. It’s a 2006 grizzly 660. It’s all stock other than the rims and tires, light kit and the oversized back rack i built for it. I’m having some issues with this bike as I was getting ready to give it to my son. Last Halloween my wife used the bike to pull a trailer with the kids and friends but apparently the adults decided to ride and she over heated it burning up the rings. Same friend that gave me the bike also has a shop and they rebuilt the top end and replaced the rings on it. The problem now is that it would still cover the spark plug with carbon afternot ran for a short time and would die. Just yesterday I had it running while working in the yard and the bike made a popping noise and died. I went to start it back up and it just turns over real fast but won’t start. Has compression, and a new plug. I put a cap full of fuel in the head and put the spark plug back in and noticed fuel coming from somewhere under the bike. Not sure if it’s the overflow from the carb or if the bike blew a gasket or cracked the block. The carb has never had any work done to it and I was planning to take it off to clean but then found this. Amy ideas where to start would be very helpful. Sorry this post is so long, just have an 11 year old that really wants to ride.
 

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Pull the side covers and look around the cylinder.
If it turns over faster than normal, then you are not making full or any compression.
Additionally, there should be no gas running out of the engine itself if you pour gas in the cylinder. That would indicate a whole in the cylinder or a really badly blown head gasket.
Are you sure you didn't waste a little gas over the cylinder when you put it in the spark plug hole? That would run off the bottom of the engine.
 

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Welcome from Colorado.
The quick fouling plug can be from improper valve adjustment, many have adjusted the valves but while using the wrong style feeler gauge and got the wrong measurement.
In your situation, I would turn off the gas and drain the carb bowl. Then while turning over the engine, spray a little starting fluid into the carb with the air filter is removed.
I'm guessing it will start with a new plug, so get it started and with the side covers off as mentioned above, keep it running a couple dozen seconds on ether and look at the engine, and I would spray soap on the cool engine before starting.
 

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Discussion Starter #4
Just got in from the office and came back out here to look at the bike. Pulled the plug and it has compression. Took a medicine syringe with some fuel in it and put down in the cylinder, fuel comes out from the the bottom, looks like from behind the exhaust manifold. Blown head gasket?
 

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Just got in from the office and came back out here to look at the bike. Pulled the plug and it has compression. Took a medicine syringe with some fuel in it and put down in the cylinder, fuel comes out from the the bottom, looks like from behind the exhaust manifold. Blown head gasket?
Sounds like a cracked head or a severely blown head gasket going only by what you stated.

You can't tell compression by putting your finger over the spark plug hole. It will always move air if the piston is moving up and down in the cylinder. The only way to tell if you are making proper compression is with a compression tester or cylinder leak down tester.
 

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Discussion Starter #6
Thank you sir. Had someone else say that the compression needs to be tested with a meter. My first thought was the head gasket but didn’t think about a cracked head. I hope to have my guy that replaced the rings back up here in the next week or so to look at it and fix it while they are in town working for me. I appreciate all the help, this site is exactly what I needed to find. Lookin forward to sharing and learning on here in the future.
 

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This is just a thought for the leaking gas issue... I'm assuming that 06 660's are the same as 02's or at least very similar. The spark plug has to go pretty deep into the opening before you can start threading it into the top of the head. Well, at the bottom of that opening (just before you start threading into the head) there is a hole to let water and dirt flush out. When you put gas in there, are you sure all the gas went into the cylinder and none flushed out through that hole? That would explain the gas leaking along the engine and dripping underneath.

Right between the two exhaust ports.
 

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This is just a thought for the leaking gas issue... I'm assuming that 06 660's are the same as 02's or at least very similar. The spark plug has to go pretty deep into the opening before you can start threading it into the top of the head. Well, at the bottom of that opening (just before you start threading into the head) there is a hole to let water and dirt flush out. When you put gas in there, are you sure all the gas went into the cylinder and none flushed out through that hole? That would explain the gas leaking along the engine and dripping underneath.

Right between the two exhaust ports.
Learn something new everyday! I believe the only way to guarantee that it doesn't leak, or go down the hole or whatever would be to use a turkey baster. I bet one could be had for $1 and the are really handy when cleaning parts.
 

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Discussion Starter #9
Scorpion, I didn’t know about the port, and I’ve not had the head apart to see if the 06 has that or not. That would make sense. I used a syringe to shoot gas down in the cylinder head, but again that wouldn’t guarantee that it was making it to the ports. I am not an engine guy and hope to have Patrick back up here next week on a project at the office and we will tear it down and have a look. I appreciate the insight, will definitely have to check that out.
 
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