So last night i got a 1998 300ex in really good cosmetic condition and it starts and runs. The problem is that after riding for like 20 mins, ill go to shift into second and it starts to bog really hard. Then I go back to first and it keeps bogging. Any ideas?

 

Strange, so in the first 20 min you can bang through all the gears and rpm range with no issues? Any mods or aftermarket parts, all origional?

 

Well its all stock and to tell you the truth i never kicked it past third so im not sure what happens. Theres a lot of snow here so ive been riding on the road a bit and havent cranked it out yet

 

When you got it was she sitting for awhile? Is it running on the gas that was in the tank when you got it?
My experience with bogging is its carb issue. I would clean the air filter and the carb. If its running ok might just be able to use sea foam.
Take the ex for a rip, and pay attention to when it bogs 2nd, 3rd gear? 1/4-1/2-3/4 throttle?

 

Okay not to sound stupid but how would i clean the air filter?

 

Open the air box, remove the clamp from the filter, pull the filter. Take the foam and wash it. I use a cleaner from the auto parts store but have used gas in the past. Let dry. Then spray it down with foam filter oil and install.

 

Okay thank you very much ill do that later today