jetting

[clutchcover]

I have seen simailar topics posted, but I haven't seen the question really answered. In stock condition what will modifying the airbox do to jetting? Someone said to run at least a 155, but the stock jetting is 160 not? I would like to run my bike a tad rich, but not too much. Jetting everytime the weather changes here gets tiresome. I would like to run without the airbox lid, but don't want an overly lean condition. I am also running torque pipe. It is a 97 kdx200. How much effect does the removal actually have on performance? Thanks in advance.

 

[gooby]

i run a 155 m w lid gone fmf torque....:) as far as the lid goes can u say asthma,stuffed up ,can't breath.both my bikes have no lid.160 is an overly rich cond stock that's why u can go smaller even with the mods .running rich isn't a good thing for the engine either u know.carbon,spooge etc...

 

[clutchcover]

Gotcha, I like to run slightly rich because the weather varies greatly at unexpected moments. I did not want to pull the lid or drill it and have a severely lean condition. Thanks a bunch.

 

[jeffw]

Drilling/cutting/removing the lid makes the otherwise stock bike run rich, not lean. The unrestricted air flow will create greater velocity through the carb and pull proportionately more fuel from the jets than before.

This should be especially noticeable at your altitude in Idaho. Give it a try, take off the cover, tape the CDI to something or let it dangle against the air filter, and take a short ride. I'll bet your midrange will stumble/blubber all over itself.

 

[clutchcover]

I will try this, but wouldn't the increased airflow also compensate for increased fuel? This is a good point and I will try what you said.

 

[70 marlin]

Quote: Jeff Fredette. from a phone conversation. take that lide and fling it! and never look back.

 

[Mac]

Originally posted by jeffw
Drilling/cutting/removing the lid makes the otherwise stock bike run rich, not lean.

Nice theory but incorrect.
Removing the airbox lid will lean your jetting.

 

[jeffw]

Just my experience, Mac. Like I said, give it a try.

 

[clutchcover]

Tried it out. It didn't blubber at all. The box was too noisy though. I ended up drilling 4 half inch holes. It made a big improvement. It still runs a tad rich though. Checked plug at wot and still was a slight chocolate brown. Haven't fouled a plug yet, so I might leave it for a little bit. Will eventually work on the jetting when I get some time. Thanks to all for the advise.

 

[andrew]

If you've still got standard jetting (#160) you are too rich. Just try going down one size at a time ie #158 first to see how it goes, then perhaps #155. Don't think you'd need to go much leaner than that.

the point is, small incremental adjustments=no risk, and it's cheap.

Cheers,