i have heard mixed answers about running the air box lid or not,i ahve a k&n air filter,195 main 2 1/4 turns out and was having a bitch of a time getting to run right with air box lid a dyno jet stage 1 went to the stage three and it seems to work good any hel at all?????

 

In the dyno jet instructions is says if youre just installing an aftermarket air filter use stage 1 jets. It says use stage 3 jets for aftermarket exhaust and air filter, and thats what you have right?

If you use your stock carb, its better to just leave the lid on.

 

I agree with RoughRider01

 

I assume that, since you got a K&N filter, you want to move more air. To do this you will need to take off the air box lid. This will help at the intake. The bigger main jet is called for with the K&N filter because it assumes you have more air flow, which only happens if you remove the lid on the DS650. To get full benefit, you also need to open up the exhaust. Even with the stock carb, if you get more air flowing, you get more power.

 

Disregard what Gashog said.

The Mikuni BSR series carbs have a vaccuum operated slide which only opens under vaccuum. Meaning it requires a kind of suction to get the best response. Keeping the lid on is the best thing to do with the stock carb because of the vaccuum slide, increasing airflow to the stock carb by opening the lid will give you more HP (not really noticeable though) but you will lose throttle response.

If you have a TM42 or 45, Dual 39's or whatever, then the less air restriction the better, because these carbs' slides are opened manually by the throttle.

Jeff

 

If what Tyre Spinner says is true, then you wasted your money on the K&N. And, you also shouldn't have changed your main jet. The truth is that you have proven Tyre Spinner wrong by testing your machine. You said that your machine runs better with the lid off. You will still have enough vacuum to operate the slide, even with the lid off. The stock carb does not have a large enough venturi to reduce the vacuum that much even if you went with a K&N directly attached to the carb.

 

The filter allows the air that's in the box to reach the carb/intake faster and easier. Hence somewhat increasing airflow. But opening the lid and removing the snorkles is just too much I guess.

This topic has been discusses A LOT in the past, and the pros have said to keep the lid on for best throttle response with stock carb.

I'm no pro, heck, I've never even used the stock carb on my DS (I use a TM-45), but this is just what I heard and what makes sense to me.

 

Here,

this past post tells a lot. http://forums.atvconnection.com/mess...did/346585.cfm

 

Thanks for the information Tyre Spinner. I read the discussions you pointed out. My quess about their problems is that the lack of vacuum that these guys are experiencing is due to the crappy endcap in the stock exhaust. It's almost like having a potato stuck in there. this might slow down the air enough to cause the problems they describe. I haven't modified mine yet, but my friend's DS has the K&N with dynojet kit, HMF exhaust and Geckos. It runs like crazy. I rode it up Choke Cherry last weekend, even with the Geckos. I weigh 185. Just barely made it, but I suspect it would be a little faster with better tires.

 

Oh, and I forgot to mention that his air box is open.