Hello everyone. I have a 1999 Honda 400ex. It is still on the first bore of a 440 kit. Everything is done right and I try to maintain everything very well and on time. On my last riding trip up to the sand dunes, I noticed that I could not "bump start" my machine by rolling down the dune and dumping the clutch in 3rd or 4th gear, but the starter never had a problem. I thought that it was because I was in the sand. I continued to ride but as the day went on I was noticing that my machine was stalling a lot, even while under a ¾ or full throttle load hauling across the sand, it was just stall out. When I made it back to the parking lot I tried the bump start again on the pavement, even in 5th gear my engine would not turn over. I called it quits before I did any or any more damage to my quad. It does not burn oil nor does it puff smoke. It fires right up when I hit the starter, but it will not stay running and I can not turn it over by dumping the clutch. Does any body have an idea what could be wrong? I would like to have an idea before I begin to tear into my machine. Thanks!

-Jason

 

Iam thinking it might be the carb. When you built the 440 did you rejet. Even if you dont change the exhaust. You still need to up the jet. Does it run hot and did you mod the oil cooler or tank? What compression piston do you have?

 

siezed up .... junk it ...