2005 katana 750f throttle response low end and idle issues

[FloridaJoe]

Ok heres the deal, i picked up this 05 750 kar for $100 after it had been layed down and sat for awhile, had to pull the tank and sand slurry the rust out, carbs had to be cleaned and rebuilt, its got new plugs and fresh oil . So right now im into this thing for around a buck 70,
Now that shes running she seems not to idle correctly, theres no low end in first until you near 4k-5k rpms then she comes on like a bear and really pulls in the mid to upper range, keep in mind im a harley guy, love my low end torque, i think suzuki kept the low end on this one at the factory,

any how when i come to a stop after clearing the motor she just shuts off, she wont drop from say 3k - 4k rpms to a 1k rpm idle and hold there. Im thinking synch or tps.. Any you guys familiar with these issues?

On the rebuild I made sure the idle pilot, mid and mains were all clean and perfect as well as no holes in the diaphram and all orifices where clean, i was going to disassemble the carb set because my ultrasound wasnt long enough but i chose to leave them together, thus i left the tps in its original position and did not change the original synch or zero synch the butterflies when i rebuilt them either, just a straight up needle and seat job..

[92xjunker]

If you didn't disassemble the carbs, they aren't clean. Check out carbs 102. It will explain the cleaning procedure.

[Kreylyn]

The A/F screw covers were drilled out, parts removed as part of the clean process, then put back in at 2.5 turns out from lightly seated?

Krey

[FloridaJoe]

If you didn't disassemble the carbs, they aren't clean. Check out carbs 102. It will explain the cleaning procedure.

The carbs were cleaned but not broken down into 4 seperate carbs, thats not needed, theres no butterfly vac leaks, over flow leaks or delivery leaks so that serves no purpose what so ever on this micky carb, all the fuel delivery passages are clean and all the jets were pulled and ultra sounded and verified open, all the orifices were verified open and clean, no tears in the diaphrams,
i think i have the problem narrowed down to the $175 tps wich i snapped an ear off of because some jackass locked it in with an impact wrench (note to guys reading this, you dont have to lock these tps screws in with impact wrenches, if ur worried about backout, use a dab of blue thread lock or nail polish on the thread) as soon as i got the tps off and i bench checked it again & the mf'r started working, arrgghhhh, (probably shouldve just hit it with a hammer a few times before taking it off then rechecked it),,, i was gonna but another $10 tps for it until i found out that the $10 tps was actually an over inflated bend a biker over price from suzuki of $175 for this one , rediculous! So i crazy glued the ear back on cause i got lucky it snapped right on the circle flange, "screw you suzuki!", ive only had it out about for 5 mins but it seams fine now, i figure the tps will probably die somewhere down the road cause its died once already , so im keeping my eye open for a good used one or a cheap new one, hey i might get lucky it could have just been a finicky tps cause the bike sat outside not running for atleast 6-7yrs
thanks

[Xerrith]

Just an FYI I did have to completely disassemble my carbs, and soak them in chem dip for 48 hours on each carb to get the internal pilot circuits cleaned.

1st 24 hour soaking was better, but not great. 2nd 24 hour soaking and they looked factory new, also fixed the issue with the dirty pilot circuit. Best of luck!

[FloridaJoe]

Just an FYI I did have to completely disassemble my carbs, and soak them in chem dip for 48 hours on each carb to get the internal pilot circuits cleaned.

1st 24 hour soaking was better, but not great. 2nd 24 hour soaking and they looked factory new, also fixed the issue with the dirty pilot circuit. Best of luck!

You lost me, i Still dont understand why? You didnt have enough dip or big enough tub to do them bolted together in one shot?
When you say completly breaking down, i take that to mean you seperating the carb rail and butterfly chain, in other words your making one set of four carbs into 4 individual seperate single carbs,, you just dont need to do that to clean any of the air circuit holes, unless you cant fit them in one bath all together, theres no advantage to it, seperating only grants access to the butterfly rail, fuel rail, overflow and something else and all those bores are huge and wouldnt affect operation unless they were jammed full , say like the fuel rail was plugged solid,, the idle, midrange and main circuits have nothing to do with that part of the carb assembly , all the fuel pickups begin in the bowl and delivery ports are in the throat, all are self contained within the inside of ea individual carb and dont even acess that part of the system , the only other air ports are the vac ports for the diaphram slide at 11 and 1 oclock and the idle and midrange at 5 and 7 oclock on the intake side of the carbs and like i said thats not part of the rail assembly it individual to ea carb,,

[92xjunker]

He did it correctly. You need to break down the carbs to clean them. The rack won't fit in the can, unless you get a couple of them and a large pan.

[Kreylyn]

You can disconnect the plug on the TPS to verify it's not messing with the curve. The bike will NOT have an issue running with out it generated by the mapping of the RPM curve. It will default to a base curve, that same curve type used on all Katana that don't use a TPS at all.

Could the TPS be causing a physical issue... meaning that it's actually preventing the carb butterflys from opening /closing physically due to damage, gunk or corrosion preventing it from turning correctly, so on?.. Sure, absolutely. If that's the case, just remove it. You don't need to replace it.

I've had a few of these bikes. I'm not just making this up.

Krey

[Xerrith]

If you don't fully separate them you're running the risk of ruining the fuel line orings on the rail that connect carbs 1, and 4 to 2, and 3. Also the choke plungers are plastic and may be ruined in the dip, are also a big pain to remove with the carbs assembled together. There's also rubber boots inside the carb body's (where the fuel stem valve is, the part that you have The fuel line coming out of) I just didn't want to take the risk of destroying any rubber or plastic bits. I was advised to remove everything except the butterflies themselves and it worked out for me. Also by dissembling them fully you'll find out if any of those orings or rubber pieces need replacing.

I tried soaking them for 24 hours and it still ran like garbage. The second 24 hour soak with them disassembled enabled me to have the bike in a running tuneable state. That was my experience though.

[Olcoyote]

I add Techroline each time I fill thetank on my 2001 750. My tech says the menthonol in the gas can cause the carbs to gum up. Hope this helps