Back together... now runs hot, stalls

[Mick77]

   Is this just the life of a GSF400?  I got it all back together and running.  I took it out for another ride (with 1/2 tank of gas just in case) and it ran fine.  Still a little off on the power, but runs smoothly.  First gear really lugs, until about 5-6k and then rips.  All other gears to 6th seem ok as far as throttle response goes, just a little less power than normal.  I only rode it maybe 4 or 5 miles, about half at 55-60mph, the other half stop and go.  Several times when I stopped, it would bog down when the throttle was closed and I had pulled in the clutch to stop.  This was after downshifting from about 4th all the way to 2nd sometimes 1st.  The fan also came on, which it usually doesnt do, unless I've been on the freeway, or it's really hot (it's been in the triples here in TX) but it was about 80 degrees when I rode today.  In the interest of saving myself some $$ while tearing apart and draining and wasting fluids, I used anti-freeze for automobiles, since I had some handy.  It said it was good for aluminum radiators, so I felt safe enough just having something in there when I tested my handiwork. Could it be that "motorcycle" antifreeze would solve the hot problem?  Which direction should I go with the carbs?  I'm working on getting a compression guage so I can see if this mechanic is right about #1 only having 90psi.  I really dont want to do an entire valve job.  By the way, all my plugs are slightly carbony-black, but not wet or white.  Is that pretty close to right?   

[gsxr400 racer]

    First gear really lugs, until about 5-6k and then rips.  All other gears to 6th seem ok as far as throttle response goes, just a little less power than normal. 
Sounds like you have carb issues, all 4 pipes getting equally hot??

I only rode it maybe 4 or 5 miles, about half at 55-60mph, the other half stop and go.  Several times when I stopped, it would bog down when the throttle was closed and I had pulled in the clutch to stop.  This was after downshifting from about 4th all the way to 2nd sometimes 1st. 
This is enough to foul plugs out if your carbs are not running right...
 The fan also came on, which it usually doesnt do, unless I've been on the freeway, or it's really hot (it's been in the triples here in TX) but it was about 80 degrees when I rode today.  In the interest of saving myself some $$ while tearing apart and draining and wasting fluids, I used anti-freeze for automobiles, since I had some handy.  It said it was good for aluminum radiators, so I felt safe enough just having something in there when I tested my handiwork.
Check to see if you had a air bubble and it is still filled up. Works great as long as you mixed it 50/50 with distilled water if not already a 50/50 mix...
 Could it be that "motorcycle" antifreeze would solve the hot problem? 
NO

 Which direction should I go with the carbs?
May have to clean them and get oring kits as well as make sure fuel tap screen is clean, tank has no rust and the rubber plugs that cover the pilots fit in the hole snug...  

I'm working on getting a compression gauge so I can see if this mechanic is right about #1 only having 90psi.  I really don't want to do an entire valve job.
Still maybe a possibility and also maybe rings... Does it smoke???

  By the way, all my plugs are slightly carbony-black, but not wet or white.  Is that pretty close to right?   
Sounds like your running rich do to if all is stock; leaky orings, float needle, mixture setting, float level or even weak spark.

Cheers
Jay

[Mick77]

Pipes are all sorta close, as far as I can tell with my hand close... which is no good indicator.  I have no way to get exact temp on the pipes ATM.

After riding it, I pulled all the plugs (rode it twice, pulled/checked plugs both times) and they look the same.  I'll see if I can post a picture of how they look.  It's hard to describe a color or degree of browny-blackness.

I filled the radiator, then filled the overflow after the first ride.  I was being lazy, not wanting to pull the tank off again.  Looks like I will after all :)

Carb has all new o-rings, and I have cleaned #1... didn't have time to do the rest, but if one was clogged..... yeah, I know, I shoulda done them all and probably will in the next few days.  2,3,4 cylinders were all running normal when the problem started.  Better safe than sorry though, and to get all the wrenching done at one time.

No smoke at all of any kind.  Well, maybe just a LITTLE smoke if you rev the snot out of it, but thats all.

[pmackie]

By the way, all my plugs are slightly carbony-black, but not wet or white.  Is that pretty close to right?   

On new plugs, you would want to see a nice, light, brown colour appearing. Black, slightly sooty sounds like it's rich somewhere in the range.

Jay's(GSXR400) notes are right on. Pick them off one at a time. O-rings and float level first, then likely air screws/pilots and then see how things go.

[PitterB4]

Yeah, if it were me, I'd get the manual and take the carbs back to stock settings all around (except maybe a half turn more out on the screws) and see where you were.

[Mick77]

I was looking in my manual for stock settings, and unless I'm just not seeing them, it doesn't say.  It does say things like "Pilot jet----PRE SET 1 1/4 turns out" and then says not to mess with it.  YEah, right.  So does this mean that when it's all the way in, it's really 1 1/4 turns out, or that I have to back it out some?  And on the mix screws, it doesn't say anything.  I just need to know where to start from on those so that I can fiddle with the mixture tonight... but don't want to do it if my pilots are all wrong, ya know?  Since I have no way to test the compression right now I'm just going to play around with the rest of the stuff, do what I can, and see what happens.  If its all for nothing, and my compression is bad, at least I learned something and it wont take as many questions and time when I get it right. 

All this time I've forgotten to mention that it has a Supertrapp slip on and a K&N filter.  dont know how that factors in...

[PitterB4]

Check out the jetting thread that stickied in this forum. 

The 1 1/4 turns out is the mixture screws.  With those mods, I'd start at 2 or 2.5 out as a baseline.  Make sure the floats are set right (start with the stock setting).  Does it have a jet kit?  If so, check out that jetting thread and see where most peole have their clip set on the needle or start with it in the middle.  Make sure your main jet is within a size or two from stock. 

I just meant get everything set so a) you know where it is and can make adjustments from there and b) you can rule out wildly screwed up stuff (mix screw all the way in, float level way off...) as the cause of your problems. 

[Mick77]

Well, come to find out, it HAD an aftermarket jet kit in it, but the guy that had it before me put the factory ones back in because He couldnt make it run right with the aftermarket ones.  He changed back when he took the K&N pod filters off because they wouldnt fit either.  Might be selling those..  It seems to run "OK" on 2 turns out on the inside 2 cyl, and 1.5 on the outside 2.  For now.  That was as far as I got on my adjustments, It's still a work in progress, but it runs smooth, except for a small hiccup between 4-6k on the tach.

[andrewsw]

I have a hiccup in that same range. almost a stumble when coming off cruise throttle just a hair. goes away if you whack it.

I'm surprised you need more gas in the middle two carbs... usually, it's the other way around, isn't it?

So otherwise it's stock, eh?

jetting these bikes is, well, an art, I guess, because science doesn't seem to do it...

I'm not sure what to think of the pod filters... one factory tech told me they were crap because of turbulence issues, but who knows.

[PitterB4]

4-6k is a common flat spot on the B4.  Try raising the needles (move clips or add shims).  I think that's what most people have had the most luck with.