Was wondering if anyone was running the K+N filter right off the carb instead of the airbox? If so how much larger did you have to jet it to run right? (pilot jet, mainjet)
THANKS IN ADVANCE!

 

I run the K&N SN2550 filter directly on the carb. I tested the air box set up on a dyno with a K&N filter in the box and lost over 3 HP! I dropped one main jet size [from a 140 to a 137.5] when trying the air box and it ran as good as it could. I would suggest going up one step on the main and possibly raising the needle 1 slot as a starting point, assuming that your jetting was correct in the first place. I have noticed that most DS's that I work on are jetted rich by the riders/owners. The DS likes alot of fuel down low, but puts out much better power on the high end when leaned out. Read your plugs befor you change anything. If your plugs read rich already, don't change anything when you put the filter on the carb. If your plugs read just right, try the afore mentioned change. If your plugs are lean, try 2 jet sizes richer at least. Hope that helps

 

Have ordered the On-Carb K&N for my TM42 Mikuni, hopefully I will have it before next weekend, I'm still dialling in my jetting (a little rich at the moment), I will advise if there seems much improvement over a K&N in the airbox with the lid-off, which I am running at the moment.

 

With the jetting right in both set ups[K&N in the box without the cover or K&N directly on the carb]you should see a 3 HP[dyno proven] gain. Probably the best, cheapest performance gain you can do.

 

Can anyone supply the part # for the K&N filter for in the box.

 

I believe it is BD6500.

 

Knutz, just wondering why you said in your above post that you lost 3 HP in the box. Then down here you say there is a 3 HP gain in the box. Which one is it?

 

I think what he is saying is you gain 3HP by having the filter out of the box... but you also loose a good amount of protection, so it comes down to where you ride deciding whether or not you even want to try running a straight filter.

 

I stated that I lost 3 HP when putting the filter in the box. Then, in the other post, I stated to OzzyDS that he should gain 3 HP when putting the filter directly on the carb.

For the most part, were I ride, protection is not a factor[not much water]. I'm looking into moving the filter back about 5-6 inches off the carb so that it has a better draw of free air from the area just in front of the air box that is no longer used.

 

I have finally got my SN-2550 on, (had to order from the US as K&N down here stated that it was an incorrect part number when I tried to order from them. I will fax through a copy of the barcode next week so they can get their sorry A$$es into the 21st century.

Definately noticed an improvement in throttle response when having a drag. The other benefit is a lovely induction roar, when you accelerate.