Just rejetted- Need some tuning advice

[Hi-T]

Ok- I ride an '01.  I just rejetted- Went one size up on the pilot, one size up on the mid main, and three sizes up on the Main.  I put on a vance and hines, and replaced the drop in with a k&n drop in.  Also picked up on Bobs advancer.  

The bike definately has more giddie up- but when I get up to 9-10k rpms it starts to cough and shutter a little.  I assume The main jet is too big and starts to flood when the throttle is open completely- Which means drop the jets down one size or put on some pod filters.

Correct me if I'm wrong... seriously please do.

[mjm]

Ok- I ride an '01.  I just rejetted- Went one size up on the pilot, one size up on the mid main, and three sizes up on the Main.  I put on a vance and hines, and replaced the drop in with a k&n drop in.  Also picked up on Bobs advancer.  

The bike definately has more giddie up- but when I get up to 9-10k rpms it starts to cough and shutter a little.  I assume The main jet is too big and starts to flood when the throttle is open completely- Which means drop the jets down one size or put on some pod filters.

Correct me if I'm wrong... seriously please do.

Definately go with the pod filters - and up several more sizes on the main jet.  On my 2001 w/pods and slip-on I ended up at 150 main jets.  I left the mid-main alone and raised the needles with the washer trick - with the increase in the mid-main you may want to try a 147.5 or even a 145 main rather than the 150.  Do a search on Jetting Matrix - you will find reports from several people who have re-jetted the 2001+ bikes.

[Hi-T]

Yeah - I did my homework and figured I start conservative.  But before I dig back into the carbs I'd like to know for sure why it hesitates at 9-10k rpm.

MJM- did you keep your petcock?  I ran a staright line and a fuel filter this time.  I capped off the vaccum lines and was having a terrible time with gas leaking back from the carbs into the air box.  I uncapped one of the vaccum tubes and the problem went away... any input?

I would have shimmed the needles but the washers don't exist in Utah...  I went everywhere, needles in hand, and could only find a fiber washer that would fit the needle and the slide- so I opted for the larger mid main jet.

Anyways- thanks for the input.

[Gisser]

I agree with your diagnosis:  Too rich on top.  From what I've read elsewhere those K&N replacement filters do not breathe noticably better than the stock paper element.  The difference is barely measurable although the K&N has a restrictor option that may you otherwise.  On the other hand, the difference in filtration--or lack thereof wrt the K&N--is significant.  

It should also be noted that aftermarket pipes come with very conservative advice concerning jetting changes.  Seems like most every aftermarket pipe shootout I've seen in the mags forego increasing the main jet at all.

[Gisser]

"convince" you otherwise.

[mjm]

I ran a staright line and a fuel filter this time.  I capped off the vaccum lines and was having a terrible time with gas leaking back from the carbs into the air box.  I uncapped one of the vaccum tubes and the problem went away... any input?

I would have shimmed the needles but the washers don't exist in Utah...  I went everywhere, needles in hand, and could only find a fiber washer that would fit the needle and the slide- so I opted for the larger mid main jet.

Stock petcock works fine for me - unless you had a problem with starvation, why did you by-pass?  Getting gas leaking back into the airbox sounds like a float level problem - re-check how you have the lines attached and make sure they are all in the right place - leaving a vacum line open will royally screw up the carburation on that carb.  The washers are easily available from most harware stores cannot remember the number reference off hand #3 or #4?  My local Tru-Value store has them in steel, aluminium, brass, stainless etc - The reason to put them in is to richen the one quater through three quarter throttle range - If that area is OK with the larger mid-main no reason to go for the washers.

You reference roughness at an RPM range - jetting is more related to throttle position than RPM.  If it runs crappy at 9000 with full throttle, mid throttle and light throttle then you have an ignition problem.  If it only runs crappy at full throttle, you have to ask what the position of the needle is when that happen - have you just snapped the throttle open?  Then the slide may not be fully open yet and it may be needle hieght that is the problem, not th main jet at all.  Have you been opening it slowly etc - you get the idea.

- try getting into top gear at fairly low revs (3500 or so) and opening the throttle - preferably going up hill so there is a real load on the engine and holding it open to as fast as your license will bear then pull in the clutch and hit the kill switch at the same time - coast to a stop, pull the plug and check the plug tip insulator for color.  The key here is to hold the throttle open long enough that the slide us fully up so you are running just on the main. If it is black or dark brown you are too rich. If light tan trending to grey/white you are probably OK on the main.  If its white  too lean.

[JohNLA]

Hi-T, Did you have to buy 4 pilots ? If so, would you like to sell 2 to me ? The two dealers I have hasseled can't seem to find them. I should look up the order numbers and take that with me.

[Hi-T]

John- My suzuki dealership didn't have them- I actually got them from the Yamaha dealership-  I'll check back with them and see if they have any more.

As far as the roughness... I think it has more to do with throttle position.  It will shutter at any RPM when I have the throttle fully open.  If I take it back- even a hair- it livens back up and takes off.  

So- if that has to do with the slide/needle posistion- where does that take me?  What's the best way to test?