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97 MM 600 Engine Opinions

Escmanaze

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Dec 8, 2007
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Hi Guys,
Below are some pics and video of my MM 600. There is a lot of moisture on the exhaust end, and I wasn't sure if it was sounding right either. I am certainly not a mechanic, so if there is something wrong, that just means I'll end up taking it to the shop, but I wanted your opinion first - based on what you see and hear, is a trip to the shop called for here?


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B
Jan 26, 2013
79
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8
is that the first time you have run it all summer? I'm not an expert on the 600 twins but its not uncommon to get condensation in the exhaust when the humidity goes up or in the spring/fall when you get below the dew point at night.

Also not uncommon for those exhaust donut and header gaskets to leak as they get old. Do you have a compression tester? pull compression and see if the 2 cylinders are close. anything around 130 or higher is good.
 

Escmanaze

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Dec 8, 2007
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well I put them away in about march, and I think I started them up right around May, but then yes, I got busy and they didn't get started all summer. I tried in August, but it actually wouldn't start at all, so then at the end of september I bought some starter fluid and that got it started.

I don't have a compression tester, otherwise I would love to test the compression to see if it's all good.

Maybe I should take it to a shop to see if the compression is good or if there are leaks as you mention? Problem is, there isn't a Yamaha dealer around here that I'm particularly in love with.
 

retiredpop

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The engine sounds about right to me. It could be that your old gas is not igniting very well so that is why it sounds off to you. That is probably why you had to resort to starting fluid in order to fire it up. It could be that the engine got flooded when trying to start it and that is why you have so much oil and wetness on the y-pipe. If it got flooded there will be extra fuel and oil laying in the crankcase that eventually will get burnt when it is running.

If you pull the exhaust springs you can easily pull apart the joint to check the gasket ( commonly referred to as the donut) . It is part number 2 on the following parts diagram.http://www.ronniesmailorder.com/oemparts/a/yam/5003ba42f8700212fc83f674/exhaust-for-mm600

What I would do is drain or siphon the old gas from the tank and refill with fresh. Lift the back end of the sled so the track is free to spin. Start it up and let it idle for a bit to warm the engine and then rev it to engage the clutches. Spin the track to 50mph or 80kmph in short bursts. You will probably get a ton of blue smoke but that is just cleaning out the crankcase of old fuel and oil.

After that if you still think something is wrong then either take it to someone who can work on it. Any shop with a compression tester could do the test. They are also fairly inexpensive to purchase and then you have your own for the future.
 

Escmanaze

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Dec 8, 2007
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thanks

thanks tons for the responses guys. I'll probably just give it a whirl and hope for the best. I'll report back after I'm able to try it some more.
 

sno*jet

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Dec 13, 2007
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that right spring in your video looks loose. Id replace it. but pull off the pipe and clean that manifold first and check the pipe seal (donut)
normal to get a little residue in that area but that is excessive.
 

Givemeaboost

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Nov 26, 2007
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Great Falls, MT
You can borrow a tester at Autozone or Oreillys. Just have to leave a deposit till you return it. If you test it yourself make sure to hold the throttle open when you turn it over.




Ken........
 
B
Jan 26, 2013
79
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thanks tons for the responses guys. I'll probably just give it a whirl and hope for the best. I'll report back after I'm able to try it some more.

Fresh gas for sure. You had a hard time starting it because the gas evaporated from the bowls and left the oil behind. You would pull and pull forever trying to get gas back to the carbs especially if the tank is low.

If you put summer gas in it now don't be surprised if when you ride it the first tank it runs funny. It's called Reid vapor pressure and it refers to how gasoline vaporizes (volatile) at certain temperatures. You could put summer gas in an open container at cold temperatures for weeks and it would sit there. Put winter gas out on a hot summer day and you can practically watch it evaporate into the air. That's why come June when you go to start your sled to put it away for the summer it won't start, the bowls are dry. A little pre mix down the spark plug holes is better than ether because it won't scuff the cylinder walls.
 
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