Jetting.. Getting it as close to perfect

[Capone]

Mods in sig. Temp here was around 70 deg. elevation is 500 ft. I'm running a CEL 017-017 needle, 50 Pilot, 160 Main, airscrew 1 1/2 turns out. I did a WOT plug check in 3rd with the 160 main. Checked the plug, the very end of the "bridge" by the center electrode was light grey, and got browner as you got to the base. I changed to a 170, wouldn't even hit powerband. 165 barely hits powerband but bogs. Obviously it's pretty close to being perfect, but I'm thinking I may change to a CGL 017-016 needle for the WOT use. Any thoughts?

 

Edited April 1, 2007 by Capone

[dajogejr]

You need to run out at least 5th gear WOT, if not 6th. There is more load on the engine in the higher gears.

Your mains are too big, cubs don't even run that large of a main.

When you're WOT, your needle in not a factor, only the main.

Leave the CEL, dial the main in by hitting the upper gears, then adjust the clip if needed.

Your pilot might be a bit big, but not too bad. Might end up with a 45 or 48...

 

Forget about what the end of the plug looks like...here is the correct way to check your mains.

 

 

http://www.dfn.com/benkaren/plugchop.html

[Capone]

You need to run out at least 5th gear WOT, if not 6th. There is more load on the engine in the higher gears.

Your mains are too big, cubs don't even run that large of a main.

When you're WOT, your needle in not a factor, only the main.

Leave the CEL, dial the main in by hitting the upper gears, then adjust the clip if needed.

Your pilot might be a bit big, but not too bad. Might end up with a 45 or 48...

 

Forget about what the end of the plug looks like...here is the correct way to check your mains.

http://www.dfn.com/benkaren/plugchop.html

 

 

If they were lean in 3rd WOT, doesn't that mean 6th with more load would be even leaner? The bike runs insane with a 160, and shitty with a 165, I would think that's gotta be close. I'm pretty sure needle taper is a factor at WOT... considering if going up a main is too rich, going down a needle clip is too much, I would think it's the only solution?

 

[dajogejr]

Look very closely at the chart you posted.

The bottom says 1/8 to 1/4 throttle, the left side says 1/2 to 3/4 throttle.

 

If the needle had anything to do with WOT....wouldn't it be on the chart?

 

If it runs good at 160...and runs poorly at 165, that will only get worse in higher gears. Lower gears pull richer jetting a bit easier. Higher gears don't.

 

I don't think you're too lean, I think you're too rich. Cut a plug after a 3rd gear WOT run and see how it looks. (Remember, do NOT warm the bike up on the plug, it will give a false reading)...use a new plug just for a 1-3 WOT run.

[Capone]

Ok more questions with this quad. After playing with jetting, I changed airscrew to 1/2 turn out and it felt too rich. Wouldn't make power past 1/8 throttle. The temp here has risen to 75-80 deg. I keep playing with the airscrew and it feels like the best power is around 2 turns out. That seems like a litte much to me? Is it in need of a different adjustment? I was drag racing today it also felt like it had a midrange(whatever you want to call midrange on a drag port) had a slight miss, almost like a lean popping miss. Any ideas? Keep in mind my first post I didn't even have 2 hours on the motor. I've put about 4 on it so far. It's not running bad, I just want it reliable and as close to perfect as possible.

Edited April 30, 2007 by Capone

[bigboybanshee]

That midrange "miss" was probably a sputter. I agree with Dave, it sounds like it's too rich. Especially if you're going up in jetting and the problem gets worse...think about it. :shrug: