[dsn_klr650] airbox mod, now engine is louder...why?

[Alan L Henderson]

At 11:36 PM 5/14/2000 +1200, you wrote:

>Well I removed the airbox from my KLR 250 and drilled some extra holes >near the intake periscope. The air intake area is now about x3. I >cleaned the box and replaced it. Now when the engine is seriously >pulling, revs high or low the engine is noticably louder, more of a >hollow and loud sounding engine noise. Why is this? Something to do >with the petrol/air ratio? Would it be lower with air finding its way >into the carb easier now? I know I'm a bit alone on this as this mod is >on a 250...but in principle you 650 guys should have a few answers. >Would altering the carb for a slightly richer mixture reset matters and >provide some more power....perhaps? >Cheers, >Chris. >

What you are hearing is the intake "drake" or "honk" that we refer to sometimes. One of the purposes of the air box is to suppress the honk so the manufacturers can pass the noise standards. On a dirt bike it is also there to keep the intake high on the bike so when you ride into water deeper than you thought that water won't get into the engine. Generally if you improve flow by opening the air box you should adjust the mixture to take advantage of the increased flow and to not damage the engine from running to lean. More air + the same amount of fuel = a lean running engine. Alan Henderson A13 Iowa