Absolutely will not idle/ hard start

[f00lishroy071]

Ok let me start out by saying that KR has so much great info and is very helpful. Alot of smart people on here. Anyways, this is my first post, and let me assure you I have searched my *** off for my problem in this forum. Ive read Carbs 101 and probably close to a hundred threads for at least a half an hour a day for the past 3 weeks. Ok so here it is...

98 Katana 600 will not idle (simply dies without choke) and is sometimes hard to start. Also, when i can get it to stay with the choke on (around 5000 rpms), it is kind of erratic and bounces around a little.

Here's a list of things I have tried already

*Pilot screws at 1.5, 2.5, 3.5 turns out- none change the idle
*replaced pilot O rings
*Cleaned the jets, trust me they are all clean and none are clogged
*replaced the intake boot O rings
*replaced vaccum caps on the carbs (the ones you remove to hook up carb sync tool)
*Visually synched the carbs so the first hole is 1/2 visible
*Petcock is fine
*checked for vaccum leaks with WD-40, no luck

This problem is driving me mad....I just want it to run . I'm 18, so im no expert obviously, but my dad is pretty good with this. We are both stumped. Thanks everyone!

[RossW]

adjust your valves and do a real vacuum synch on the carbs. Visual synch is just a starting point and won't work for crap if your valves are out of adjustment.

[Kreylyn]

It's a good idea to check the valve clearances and then fully sync the carbs as mentioned above. You said you read carbs 101 and cleaned the jets... did you do a body dip with the jets installed, or fully remove all jets for the cleaning... are you talking the pilot jets, main jets, or both. Have you checked the float levels, cleaned and blown out the float ports, made sure the float needles and passages they fit in are in good working order and clean?

Do you have the stock airbox, with a stock airfilter in place while trying to get it to idle? Are you using the tank for fuel supply, or a secondary source? Are all the vacuum tubes plugged in or blocked off?

Is everything stock, or any aftermarket parts?... filters (air and/or fuel)? Jet kit? Exhaust?

Lots of questions I know, and everyone could be causing the issue.

Krey

[Rowdy]

any backstory?
did it sit for a while, was it winterised? if any of the previous drain tank and fill with fresh gas. how are the plugs?
fuel filters? if you have fuel filters are they clean?
i just went through the same problems.
was a combo of bad plugs, mickey moused jet kit, bad gas, clogged fuel filters, and open/incorrectly routed vacuum lines..

[f00lishroy071]

You think the valves could cause an idle issue? I was thinking about checking them since i thought i heard a little rattling from the head. When they were cleaned we took the jets apart, all the jets. The carbs are as clean as possible in every nook and cranny.
I built a sync tool, but we couldn't get it to idle correctly so we just visually synched them.
Airbox is stock, yes it was in place when trying to idle, and i have tried with the tank on and with gear oil can as an auxiliary tank.

Everything is stock, but just to be sure how do i know if the jets are stock or from a kit?

We changed the plugs when i got it, as well as oil. It sat for like 4 months and was kind of neglected on the maintenance, gas wasn't stabilized or anything.

Vacuum tubes? What do you mean by that? I bought 3 new rubber caps for what im assuming you are talking about.

If it is still a vacuum leak problem, where could the problem be (besides where i mentioned earlier)

Thanks

[Kreylyn]

Have they been cleaned more than once?

Many here (myself included) can tell you, sometimes once just isn't quite enough.

Krey

[f00lishroy071]

Yes, they have been cleaned more than once

[Rowdy]

You think the valves could cause an idle issue? I was thinking about checking them since i thought i heard a little rattling from the head. When they were cleaned we took the jets apart, all the jets. The carbs are as clean as possible in every nook and cranny.
I built a sync tool, but we couldn't get it to idle correctly so we just visually synched them.
Airbox is stock, yes it was in place when trying to idle, and i have tried with the tank on and with gear oil can as an auxiliary tank.

Everything is stock, but just to be sure how do i know if the jets are stock or from a kit?

We changed the plugs when i got it, as well as oil. It sat for like 4 months and was kind of neglected on the maintenance, gas wasn't stabilized or anything.

Vacuum tubes? What do you mean by that? I bought 3 new rubber caps for what im assuming you are talking about.

If it is still a vacuum leak problem, where could the problem be (besides where i mentioned earlier)

Thanks

drain the tank. gas is probably half water.

[Court93kat]

Also don't forget there is a vacuum port on the far right side of the carb rack. On the side of carb #4. There is SUPPOSED to be a hose from there going to the back port of the petcock to allow fuel to flow once the engine is running. If that port has nothing hooked up to it, there is your vacuum leak. Other than that, everyone else's advice is dead on. Good luck finding it. Nothing more irritating than a bike that just won't run right.

[f00lishroy071]

haha of course we drained the gas! And yes that vacuum line IS there and goes to the tank.

[ATOMonkey]

Put your hand half over the airbox inlet when you try to start it. Report back with any results.

[f00lishroy071]

I will try, but does it have to be over it when im starting it or when it is started, cause i can't pull the clutch in, press the button, and hold my hand over the airbox at the same time. Also, it is alot harder to start when it is warm (right after its been run)

[ATOMonkey]

Put a zip tie on the clutch.

Harder to start when warm is another good indicator that it's running ultra lean and/or there's a massive vacuum leak somewhere.

[f00lishroy071]

Ok so i put my hand over half the airbox intake (without choke) and when it started it sat around 1k rpms for a few seconds and then dies, but when i do that and then twist the throttle up to about 4k rpms it sits there until i take my hand off (without choke). So what does this mean? That its getting too much air? Thanks

[katitoy]

I had the same problem before. Idle rough and have to pull my choke every cold start otherwise it will not start.

This FIXED it. Seafoam. I placed Seafoam in my gas tank (1 is to 1 meaning 1 ounce per gallon). Kat has 5.3 gal so I placed 5 ounces of Seafoam. Ok ok, I placed 6 ounces to make mixture stronger.

Half way thru, my idle became smoother and so far...I don't use my choke on cold start. My 2 cents.