I recently put in a UNI filter and since then I have been noticing a very clear hesitation in power around 6000 - 9000 rpm. It probably does it above that but I usually shift before then, and when I tested above 9K I didnt notice it as much. One thing is wierd though, it is most pronounced in first through third gear, i dont know why, maybe because im always in the higher rpms on that?

The hesitation is almost exactly like when you run out of gas in ON position before changing to RES. The only difference is, when i let off the gas/shift to get below ~6k rpm it goes away (instead of staying and possibly dieing), and it isnt quite as bad either, its quite noticable, but i can still accelerate, unlike when I run out of gas.

Today when it did it, i switched the petcock to PRI thinking the bowls were emptying. At first I thought it went away, but then it either came back or it was less pronounced. The only thing I have changed relative to the engine was the air filter. I put some carb cleaner in this tank when i first noticed the problem and am waiting for it to run through and do its thing.


Let me know if you have any idea on what this problem could be caused by. My guess so far is that the jet for the top end is just a tiny bit cloged, or is just plain to small, because it works fine below 6k and right around 6k.

Thanks in advance!!

Lean needle... You are probably at ~1/2 throttle at that range.. I'll lift the needle. Now in higher gears you are closer to 3/4 throttle for that rpm... so you are using the main jet... and its all fine there. Unless the issue is there in higher gears as well... in which case its lean on the mains.
Cool.
Srinath.

yea, its there in all the gears, just most noticeable in the first 3. So its not something bad? Just the mixture changed because i put the new filter right? In the one thread, where the guy (sorry, forgot your name) made the jetting matrix, i saw that stock exhaust and uni filter was 40 pilots and i think it was like 122.5 mains? Not sure on the number, but that would fix it right?

You were right on on the throttle positions where it happens so that must be it. Just glad to hear that its not something very bad!

One other thing, does changing from the stock air filter change the sound of the bike? Because it got a bit louder, almost like it sounded when my header was loose, but i already checked them, so thats not it.

125 mains...
UNi and paper sound a little different... but I dont remember if you can hear it when riding... if you had your ear at the intake you probably could hear more wind noise.
Cool.
Srinath.

I think i may have found the problem. The diaphram in my left carb has about a 1inch rip in it. The bike still runs fine, but i think that is either whats causing the hesitation or causing something thats causing the hesitation. Let me know what you think. Im not so hot on carbs so i dont know what the diaphram controls, but i ordered 2 of them (not cheep, $16 each) just incase the other one is broked!

Quote from: seshadri_srinath on October 30, 2003, 08:50:13 AM
Lean needle... You are probably at ~1/2 throttle at that range.. I'll lift the needle. Now in higher gears you are closer to 3/4 throttle for that rpm... so you are using the main jet... and its all fine there. Unless the issue is there in higher gears as well... in which case its lean on the mains.
Cool.
Srinath.

I'm having the same problem mentioned in the first post after rejetting. Is Srinath suggesting shimming the needle?

06 GS
Lunchbox
20 pilot
62.5 Mid
142 Main

Severe power loss whenever I'm over ~55mph without being wide open on the throttle. Seems to run smoothly below this speed

Mate on a newer bike like yours try a 65 mid main. Sounds like your lean in the middle.

I use a 20, 65, 145 setup and it runs sweet!


I didn't need to do anything to my needles.

I'm still stock on the exhaust though

I'd be surprised if the exhaust really makes that much difference at half throttle.

Your mid range jet activates at half throttle and that is where you mention your bike seams to hesitate.


Just leave your main jet at 142 considerring its in the upper rpm band that the increased flow of a sports exhaust will raise its head.

This sounds like the same problem I am having with my 97' GS.

seshadri_srinath, would you be willing to take a look at my GS?  I live in Charlotte and a friend of mine told me you might be able to help.  Anything would be beneficial.

Thanks!
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