hondaracer2oo4
New member
I am working on a 2003 Viper 700 for a buddy. It has 5500 miles on it. He burned down the center cylinder last winter and it has been sitting since. I always do the pre season tune up for him on this machine. Every year on these yamaha vipers the pilot jets are always clogged with crud that I have to pick at and blow out with the compressor. Last year was no different, I pulled the carbs and found clogged pilot jets. I cleaned them and the other jets and reinstalled. Upon start up it didnt want to start, it was flooded for some reason. When it did start it backfired so badly on start up that it split the W pipe for the exhaust. I welded up the split and the machine seemed to run fine. Well he brought it up north to go on his annual ride. He said that he loaded it on the trailer with no issues and it seemed to run fine. When he got up north and went for the first ride, he knew immediately it was not running right. He said that they pulled the air box off and opened up the drains to the carbs, he says that the center carb had no fuel come out. He said that they then took the carbs off, played around with them a little, checked the pilot jet and other jets, everything looked good. Put it back togeather and it ran perfect. They then went out and road about 50 miles with no issues and perfect running. He states that he came out of a corner onto a straight away with WOT for about 15 seconds, he suddenly noticed that the machine was slowing down and he saw that the gauges were dead. He coasted to a stop and tried to start but the motor was stuck. He pulled plugs and found center plug has aluminum on it. They towed it back and it has been sitting ever since.
Now I am tearing into it to find out the damage and find the reason for the burn down. So far I have found that when I pulled the carbs, the left and center had ZERO fuel in them and the right one had a small dribble in the bottom of the bowl. I found that the pilot jet on the center cylinder was clogged with varnish(I could see light through the plug but it must have been a very thin film over the hole) I blew the jet out and found no other clogged jets in the carbs, Needle and seats worked appropriately.
Next I removed the fuel pump and disassembled, I found that one of the small diaphragms inside has a crack across it. So the fuel pump will need to be replaced, that was all I found wrong in the fuel pump.
So this is as far as I have gotten with tearing into it. I was hopefully looking for some advice on what else I should be on the look out for. I know that a clogged pilot could cause the burn down but I am baffled about the lack of any fuel in the carbs. I suppose it could have evaporated over the year it has been sitting.
Now I am tearing into it to find out the damage and find the reason for the burn down. So far I have found that when I pulled the carbs, the left and center had ZERO fuel in them and the right one had a small dribble in the bottom of the bowl. I found that the pilot jet on the center cylinder was clogged with varnish(I could see light through the plug but it must have been a very thin film over the hole) I blew the jet out and found no other clogged jets in the carbs, Needle and seats worked appropriately.
Next I removed the fuel pump and disassembled, I found that one of the small diaphragms inside has a crack across it. So the fuel pump will need to be replaced, that was all I found wrong in the fuel pump.
So this is as far as I have gotten with tearing into it. I was hopefully looking for some advice on what else I should be on the look out for. I know that a clogged pilot could cause the burn down but I am baffled about the lack of any fuel in the carbs. I suppose it could have evaporated over the year it has been sitting.
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