I'm working on a 2001 Bombardier Ds650 for someone and i can't figure out it's problem. Here's what i know. It will pull start, and starts pretty good. and once it's warmed up it will start with the starter but not perfectly. I cleaned the carb out and cleaned every part. Gas is new and clean. Exhaust is not clogged in anyway. Ignition timing is correct. Spark is dark blue and jumps over an inch. Choke works but seems to start better with out it. When it's warming up it runs a bit lean (pops every once in awhile/choke is off) Has enough oil and is clean. air filter is clean, nothing plugging up the intake hoses. Battery is good and turns the engine over pretty good. Spark plugs are clean, i even tired different ones. If you try to choke it, it gets flooded. We don't have a compression tester that'll fit it but just putting my finger over a spark plug hole it has a good amount of it. (i know that's a dumb way to check but that's all i had) compression release is working correctly. I put it at TDC and put compressed air in the cylinder and it kept pressure until the piston moved down. When it is running it doesn't smoke at all. I wouldn't think it would be related but it needs a new temp light, and the tach doesn't work but gets power/ground so that's something in the tach itself, i tried unhooking it and it didn't make any difference. So my guess is either get a carb kit or more likely something with when the piston/rings/valves? get warm they seal better? so does anyone have any ideas? any help is appreciated and thanks

 

I would definitly check your valves and make sure the clearences are good, thats what it sounds like to me!

 

pilot jet might be a place to check

 

thanks for the replies i'll look into both. does anyone know what the compression should be? I rigged a compression tester fitting but couldn't use the correct hose so the gauge didn't keep the pressure so i had to watch the needle and it was only at 45psi but i'm not sure if the compression release would have something to do with that or not. thanks again for the help.

 

I would definitly check your valves and pilot jet like sandman said. Do a search on here and you will find what your correct compression should be, but make sure you use a good tester. sounds like the one you were using might not give you a accurate reading! Let me know what you find out!

 

do a search on here and you will find how to do a compression test.

 

Since you said that any choke at all floods it, my money is on valve adjustment on the intake side. It sounds like it is bleeding off a bit of compression while cold and is also letting too much wet fuel trickle in when cold.

I don't think you will learn too much with a compression test as long as you have a decompression lever on the cam. That is going to show 120 lbs I believe no matter what your compression is at.

I bet you have no clearance on the intake valves.

If it was a pilot jet being too small (which is the other most common culprit for hard starting when cold) it will start and warm up much easier with the choke on.

 

Actually, you might have two issues. After you solve the valve adjustment thing, try starting the bike cold with no choke at all. If it fires right up and runs great, your pilot jet is too large and will flood. When the carburation is dialed in optimally it will force you to use the choke to start cold.

Just a possibility.

 

thanks so much for the help. I'll try to check the valves out today yet. I'll let you know what i find.

 

I checked the valve clearance and the exhaust has .005 and the intake doesn't have any. Now where is the best (cheapest) place to get the shims to get some clearance for the intakes? and are they all universal or does each make of atv have their own version of them