I read a thread that said the dealership left the airbox lid off and his 650 went 6 to 7 mph faster. I did this yesterday on my driveway just to see for myself. I got to the same speed in the 400 feet that I had to run, but the take off was much slower.

I didnt have a long enough space to air it out to see what the top speed was but it sure took off slow. If I do modify my airbox lid and let more air in, will I have to change something on my carbs. I am not a mechanic and I am kind of leary of that unknown. I still want a little more speed.

The new belt that I got on there on Thursday hasn't squeeked any. I haven't riden it any distance yet though. I have been perfecting my wheelies in my yard though. My wife is about ready to drop-kick me for the yard damage. My daughter loves to get on the front of my seat and do wheelies with me.

If any of you mechanic gu-roos out there can give me the once over about a good safe air modification that I can do, please fire away. I think I am gonna drill holes and eventually put the UNI-vents in there. I hope I wont have to change my carbs with just this. Will I?

Thanks in advance.

Longarm

 

You won't have to change your carbs, but you will need to rejet. Carbs and I do not get along, so post again about jetting, but I was just letting you know what it was so you didn't think you needed a new carb.

 

Longarm, I would say you are already running lean if you took off slower without the airbox lid on, then you would be runnning even leaner. It should have given you more pep if you were somewhere other that too lean.

 

You definitely have to go with larger main jets or you will lose low end torque.

 

Hey nyroc. I don't have any pics of my air box mod but I will get some and send them to you. I do however need some advice. When I installed my prefilter in my airbox mod, I noticed it floating around during lower rpm's. I removed the stock air filter and ran it. Thats when I noticed that the crank case breather tube ( I assume ) was putting a lot of backpressure into the air box. Can or should I reroot the tube out of the airbox with its own filter??? Any advice would be appreciated.

 

Some old cars used to vent the crankase into the air. If you do, make sure it can flow adequately, and make sure no water can get in. It will eventually get oily and collect dust.

I would not mess with it. That air comes mainly from ring leakage, and should not be very much air. It is harmless to just let the engine re-use it. If it ever is flowing fast, there is something wrong, and needs a ring job or more to fix the compression.

If you ever snorkel, that breather tube is already in a decent place to keep water out. I would leave it.

What I want to do is make a little riser tube in the airbox for the breather, so a little water in the airbox does not go straight into the crankcase.