Well I am trying to get some help on my 1990 dr350S. So I figured out the vacuum port, which was my original question. So now I need to know why I can rev the bike up and have a nice constant scream, but when I try and take off, it goes for 3 seconds and starts to putt putt and die? Could it be that I ALSO plugged a vent port???

This bike was running (with original vacuum) before I took off the carb to clean. Was running a bit lean so I attempted to richen it by moving the needle clip down.

I have airbox mod and progrip exhaust
Main jet: 140
Pilot jet: 37.5
Needle clip on the 3rd down
air/fuel screw: 2.5 or so

according to wikipidia, the town elevation is 129ft


I have cleaned the carb, taken out all the needles and jets (except for the big white slide receiver. I blew carb cleaner into all the ports and used compressed air in all the holes that let air through. Float is perfectly set, triple checked it. The needle is in great condition


In the pictures it shows the ports I plugged.


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You can't just arbitrarily plug vents and think everything is going to work just fine. Carburetors need to breath. They need to feel atmospheric pressure for the vacuum slide to work properly and to vent the bowl where the float is. If you think about the float, what's it doing ? It's floating on top of the fuel in the bowl. Well, if its on top of the fuel, then what's above the fuel... air. Where did that air come from ? That air needs to be able to change volume as the fuel level rises and falls. Same for the vacuum slide. It's air that pushes it up when the bike is under heavy load and allows more fuel in to feed that load.

Now, when you're just sitting still twisting the throttle, the bike isn't asking for much fuel, even at high RPM's. But when it's under a load, that's when those slides move up more consistantly and provide that extra fuel needed. You need to fine where and how those vents are supposed to be hooked up and put it back that way.

 

Thanks for your reply. I will have to try it out with that one unplugged, since I found out which was the vacuum. Before I did not know which it was so I plugged each one that let air through

 

Ok, its running but only in the 1/4 range. I can cruise around fine but once I try and open it up, it starts to want to cut out.


So not getting enough fuel. This is which jet/needle??

 

Moving the needle clip down a notch will as you say enrichen the fuel supply as it lifts out of the main jet. You may now be getting too much fuel. Try putting the clip back to the correct notch and see if this makes a difference.