I'm a new member, but have been reading here for quite some time. Anyway, about five weeks ago I had the thermostat fan switch go out and the bike shut itself off. I replaced it and took it to Dumont this weekend. However, I trailered it all weekend after I took it for a quick run. If I give it gas and sustain the throttle, it begins to cut out and bog. Also, on any hills, it seems to lose all power and attempts to die. Did I scorch the piston and wreck the motor or is it a spark problem? I am going to run a compression check on it this week but I also need to know the proper compression. Can anyone help?

 

Check the vent line from the tank, it might be pinched.

 

Its possible that your fuel tank air replacement hose is pinched. If its pinched, replacement air cannot enter the fuel tank and you will suffer from fuel starvation. Its a pretty common problem on DS's and its easy to diagnose. I would try and crack the gas cap lid and see if that cures your problem. If it does, you can modify your stock gas cap and place a vent in it, or get any one of the many billet gas caps that have a vent built in. If that works, you may just want to completely pinch off that vent hose. The hose is wraped around the tank just onder the tank facia.

Give that a shot and let us know.

 

Haha! Thats two votes for the air tube!

 

Well I guess I should have givin more info like ODP. Try his info & let us know how it goes?

 

Wow what a coincidence! I too was at Dumont this weekend with my new DS and had the same problem. It just sputtered and died just after i'd overtaken my friend on his YFZ 450! You may have seen me getting towed away from comp hill by same YFZ. What a bummer. Anyway I could not get it started until the next morning but it would only run for about 1 minute and would not start again. This sounded to me like enough gas dripped down into the bowl overnight to get it started so I figured it was between the tank and the carb. Tell me more about this vent tube.

 

most atvs now have the went tubve in the gas cap but leave to bombardier to make a totally different design and a crappy one at that. the vent tube is a small semi-clear tube that is connected to the tank under the tank cover. it tis really long and i advise cutting it down. once you remove the tank cover you cannot miss it . this problem is more common than you think. happened to almost all ds owners i know at one point or another. hope that is your problem because it is a easy fix. and very not to expensive either[img]i/expressions/face-icon-small-wink.gif[/img]

 

they make nice caps for the ds that have the vent in them

 

What about the on/off/reserve valve? When I turned it back and forth, it fell like sand in there grinding and wholla I could actually hear gas drip into the carb! I decided to drain the whole tank and a lot of sand was in there. This was only my second tank fill!. It was blowing really hard Friday night and most of Saturday before this problem occured. But how could sand get in the tank? The cap was tight. Through the vent tube maybe? I dont know, Im stumped. Anyways, I assume there is a screen in there, I will take apart tomorrow and take a look. Where is the best place to get a service manual? By the way did I mention how much I love this quad?

 

there is a screen in there. i cleaned mine and it was full of crap. good to do every so often. so many problems stem just from the fuel system and alot of them can be solved by simple maintnance. glad to hear you are on the right track