Hello, I installed a SXS airbox cover part # 59206003600 on my 2004 200 EXC and it now bog's from idle to when transision to the main jet or flat out. It also bog's down when I go to throddle out of a corner. I am current running a 175 main jet with a NOSE neddle with the clip in the middle (3rd) position. The bike ran fine with this set-up and the orginal airbox cover w/no vents. My spark plug NGK BR8EG looks tanish-white. Do I need to run richer jetting??

have you touched the carbs recently ? .... changed the airbox for individual filters? ..... upped the idle jets etc etc? ... if so put it back to standard ... and see if better ... if you want to modify , .. do it one thing at a time , and isolate the problem that way ... take your time

if you need you bike jetted for 7000, take it to a shop and have it jetted.
If you dont understand your carburetor and make the wrong adjustment you can lean out and blow up the engine.
when you jet a bike for 7000, you need to change everything, main jet, idle jet, idle mixture, idle, and needle position.

First place I'd check is the carbs - make sure the choke isn't engaged!
Choke on = easy start + easy idle + easy revs + bog under load.

Too much air (hole in the airbox, hose off the airbox) can do this too.

I think you went the wrong direction when you changed the main jet. Put the 115 jet back in, then work up from there. When you get it right, the spark plug inner insulator should be a light tan color. Black is too much fuel, and white with blisters is too lean. Good luck!

Sounds like you PILOT jets are gummed up. try to run it with the choke on and see if it runs better. what happens is, when the pilot jets are clogged they dont let enough fuel through to allow it to idle. also, when you roll the throttle on then the venturi lets more air through and the jets aren't allowing enough fuel to accomodate the increase in air flow causing the bog down.

Hi and welcome to FixYa,

Initially, check the burn color of the spark plug tips to determine if it is lean or mix. If lean, then a possibility for the bogging down would be an air leak. The air leak could be from the warped / out of position coupling tubes from the air box, airbox cover, torn air filter or even installing aftermarket free breather air filters similar to K & Ns (with having done a re-jetting/tuning).

Additionally, you could drain the carb bowls individually to determine the quantity and quality of fuel from each.

Good luck and thank you for asking FixYa.

Hi and welcome to FixYa,

Offhand, it appears that you have an air leak (not a vacuum leak). This could be caused by:

• loose, detached rubber coupling from the airbox to the air intake;
• torn, defective, loose air filter/cleaner;
• improperly sealed cover of the airbox;
• air filter was replaced with an aftermarket such as K&N and no rejetting, air/fuel mix adjustment and exhaust tuning done.

There are instances when the electrical has an issue and it affects the electronics, specifically the CDI at higher RPMs.

Would appreciate an update based on the above. Good luck and thank you for using FixYa.

The main jet need cleaning.(you should clean them all though)

Main Jet: Main jet comes into play at three-quarters open to full throttle conditions. CRITICAL to high-speed engine operation. Not only does it meter the gas into the engine, it can aid in cooling the engine as well.

Please rate this Fixya

the countershaft seal can be pried out easily,just dont do much damage to seal surfaces(on the motor).

as to your jetting problem,put the clip on the main needle back to "stock".

and buy several "main"jets,larger,and,smaller.
"jet-tests"MUST be done after a high-speed test(check sparkplug color,should be "tan")

poping,most all the time (on bikes)is caused by an air-leak somewhere along the exhaust system,

ALSO,when you change:
cams,
airbox,
exhaust's
--it's a GIVEN to re-jet the carb!!