Hey guys. This forum rocks  , I've been able to do all work on my bike myself from your excellent write-ups, except for changing the tires. I recently upgraded to a Wileyco for a GSXR600 with a flange midpipe, a lunchbox and a carb jet kit from srinath (40/150/1 #4 washer).

The bike's powerband has really changed after the rejet. That lame flat spot from 4-6 has gone away, but its been replaced with a little less top end power (too rich now?) and a really REALLY bad surging and stuttering at any RPMs for the first few miles after warm up, only in 1st and 2nd gear. When I say surging and stuttering, I mean like a light switch, power on and off. Could this be the 40's? Needle too high with one washer?  I had a similar problem when I just had the midpipe and can, but it wasn't close to as violent.

Other then these small problems, the bike runs much nicer throughout the powerband, I just think I can get it a little bit better and acting up less at lower RPMs.

I read up on this for as much as my little brain can handle. There are so many differing opinions, I'm not sure where to start. I was thinking about getting a range of jets, maybe 145 and 147.5 mains and a 37.5 mid. I figure I'm running rich somewhere, my plugs are pretty dark too. I'm running at sea level, Washington DC, and its hot and humid here. Any suggestions ? Can anyone mail me a few sets of jets to work with and some advice? I'll gladly PayPal you some funds, or write ya a check!

Thanks in advance. I'll probably be posting again soon when my Sonic springs and PJ-1 fork oil gets in.  I'm trying the .90s and a 50/50 mix of 10w and 15w.

Zack

Surging when cold is a dead giveaway sign its lean.
You hold steady throttle and it arbitrarily increases rpm and goes back down by itself. That is a surge and its called a lean surge and its cured by setting the float just 1-2 mm higher (BTW where are they set now) ... if its at the gasket or just below, up it 1-2 mm. if its already 1-2 mm above the gasket level, raise the needle and maybe open mix screws 1/2 turn.
Again check for air leaks and that nothing is clogged of course.
Cool.
Srinath.

Wow, you really think it could STILL be lean?

My floats are at stock height, I haven't changed them. The funny thing is, once its warmed up and I've had it at higher RPMs for a few miles, the problem more or less goes away. I have the mixture screw out 3 turns from all the way in... seemed like a good start.  If you really think its still lean, I can try and take the carbs apart again this weekend and check the float height. I'd really be amazed if it was still lean though, seems like a crazy amount of fuel going in already! 

Set the floats to the top of gasket. If they already there set them 1-2 mm higher. if they are above that, raise needle with an extra shim.
You have trouble when cold and goes away when hot its just a shade lean. BTW no vacuum leaks and all stuff is clean and not clogged right Check air filter also. Whe hot, everythign expands and seals up better. So a vacuum leak may vanish when hot too.
Cool.
Srinath.

Yeah, so this problem is still persisting,  I think its happening just in 1st-2nd gear, when there is load on the bike, like starting form a dead stop on a hill or when I first try to get moving after the bike has been parked. The problem doesn't seem to be as bad when I'm rolling already and try to take off. And when I say "surging" its more like stuttering. The power goes on and off, like a switch, and really bucks the bike hard. It isn't any sort of increase in power, it is a total loss of it, followed by a sharp return of power, then loss again, all within a second. Trying to power though it by twisting up the throttle doesn't help, it just causes more violent stuttering of the engine. Also, the lights turn on and off as this happens... WTF

Please tell me its still the carbs and not the clutch or something worse...   Battery connection?

I'm going to take the carbs apart again this weekend and take a look for leaks and o-rings. Is there anything else I should keep an eye out for that would lead to any of these problems? 

Thanks, I would really really hate to take this to the dealers...

Quote from: Zack on June 08, 2007, 06:32:09 AM

Battery connection?

Could be. Seriously. I had that happen once, felt very much as you're describing. Take 15 seconds to check...

Quote from: Wrecent_Wryder on June 08, 2007, 06:36:37 AM

Quote from: Zack on June 08, 2007, 06:32:09 AM

Battery connection?

Could be. Seriously. I had that happen once, felt very much as you're describing. Take 15 seconds to check...

You know, come to think of it... my battery terminal is sorta botched. I'll check that out before I head home from work. Man I REALLY hope that's all it is. Thanks WW.

This may or may not help. I had a part throttle misfire, load or no load, cold or not, and it shimming the needles up took care of it.

Quote from: pherako on June 08, 2007, 10:28:48 AM
This may or may not help. I had a part throttle misfire, load or no load, cold or not, and it shimming the needles up took care of it.

Thanks man, any advice helps. I have a few things that may be the culprit, so we'll see.

While you're in there, take a look at the auxiliary ground wire, the little one running to the negative terminal, make sure it's not failing. That could be cutting out one cylinder.

Ah found the culprit! Turns out it WAS a loose electrical connection! Jetting is pretty good, not a problem there. 

Quote from: Zack on June 11, 2007, 05:38:18 AM
Ah found the culprit! Turns out it WAS a loose electrical connection! Jetting is pretty good, not a problem there. 

Exactly which one, just out of curiosity?

Quote from: Wrecent_Wryder on June 11, 2007, 06:28:51 AM

Quote from: BoBo on June 11, 2007, 05:38:18 AM
Ah found the culprit! Turns out it WAS a loose electrical connection! Jetting is pretty good, not a problem there. 

Exactly which one, just out of curiosity?

First off, good call on the battery connection! It was the positive terminal under the rubber cap on the battery that wasn't keeping contact. I noticed this when I sat further back on my seat it would sputter... when I moved up toward the tank it would stop.  Looks like the PO squashed the terminal so it wasn't lining up at all, and then the screw holding the wire terminal down was stripping out the battery terminal threads... basically it took some pipe wrenches and lots of squeezing to get it back in shape.  Since that was fixed, it has been great. I beat the living $hit out of my bike yesterday on some back roads... man o man.

Quote from: Zack on June 11, 2007, 10:24:45 AM

It was the positive terminal under the rubber cap on the battery that wasn't keeping contact. I noticed this when I sat further back on my seat it would sputter... when I moved up toward the tank it would stop.  Looks like the PO squashed the terminal so it wasn't lining up at all, and then the screw holding the wire terminal down was stripping out the battery terminal threads... basically it took some pipe wrenches and lots of squeezing to get it back in shape.  Since that was fixed, it has been great. I beat the living $hit out of my bike yesterday on some back roads... man o man.

Glad to hear it worked out- that's probably the best possible thing it could have been...  and yeah, when they're running right, you know it.

How do you set the float height?

James