Hey all,
I'm working on my brothers sled. It's a stock 97 mxz 670. Two years ago he had work done on it at a shop and they replaced the fuel pump swaped out the track and really messed up the carbs. They had the mains at 350 on the pto side and 340 on the mag side. His sled ran like crap last year the little that he rode it. Mainly lost a lot on acceloration and top speed. Last year at the end of winter we tried to start it and from one pull to the next the motor locked up. You can still pull the recoil but it's incredibly difficult, like it's vapor locked. Here is what I've done and discovered so far. When I remove the spark plugs the recoil pulls just fine...very smooth. I took apart and cleaned the exhaust valves. They were dirty but not locked up or anything. I discovered about a quart of gas and oil in the pipe, oil in the exhaust valves and the crank case was full to the top with gas and oil. I pulled the plugs and tiped the sled on its side...pulled the recoil and emptied out most of the fluid from the crank but it still is vapor locked (hard to pull the recoil) when I put the plugs back in. Aslo the carbs are off and the pipe is off too. Does anyone have a clue why it would be locked up like this when I put the plugs in?
Full Version: mxz 670 vapor lock?
the motor is locked up because it is flooded with fuel.
the carbs need cleaning, ensuring that the needle, seat and floats are not sticking.
the carbs need cleaning, ensuring that the needle, seat and floats are not sticking.
QUOTE(Throne777 @ Nov 11 2007, 02:08 AM) 
Hey all,
I'm working on my brothers sled. It's a stock 97 mxz 670. Two years ago he had work done on it at a shop and they replaced the fuel pump swaped out the track and really messed up the carbs. They had the mains at 350 on the pto side and 340 on the mag side. His sled ran like crap last year the little that he rode it. Mainly lost a lot on acceloration and top speed. Last year at the end of winter we tried to start it and from one pull to the next the motor locked up. You can still pull the recoil but it's incredibly difficult, like it's vapor locked. Here is what I've done and discovered so far. When I remove the spark plugs the recoil pulls just fine...very smooth. I took apart and cleaned the exhaust valves. They were dirty but not locked up or anything. I discovered about a quart of gas and oil in the pipe, oil in the exhaust valves and the crank case was full to the top with gas and oil. I pulled the plugs and tiped the sled on its side...pulled the recoil and emptied out most of the fluid from the crank but it still is vapor locked (hard to pull the recoil) when I put the plugs back in. Aslo the carbs are off and the pipe is off too. Does anyone have a clue why it would be locked up like this when I put the plugs in?
I'm working on my brothers sled. It's a stock 97 mxz 670. Two years ago he had work done on it at a shop and they replaced the fuel pump swaped out the track and really messed up the carbs. They had the mains at 350 on the pto side and 340 on the mag side. His sled ran like crap last year the little that he rode it. Mainly lost a lot on acceloration and top speed. Last year at the end of winter we tried to start it and from one pull to the next the motor locked up. You can still pull the recoil but it's incredibly difficult, like it's vapor locked. Here is what I've done and discovered so far. When I remove the spark plugs the recoil pulls just fine...very smooth. I took apart and cleaned the exhaust valves. They were dirty but not locked up or anything. I discovered about a quart of gas and oil in the pipe, oil in the exhaust valves and the crank case was full to the top with gas and oil. I pulled the plugs and tiped the sled on its side...pulled the recoil and emptied out most of the fluid from the crank but it still is vapor locked (hard to pull the recoil) when I put the plugs back in. Aslo the carbs are off and the pipe is off too. Does anyone have a clue why it would be locked up like this when I put the plugs in?
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