HELP... Kat acting up at stop lights

[kat_tsi03]

hey all I have a 97 Kat 600 and recently it has been acting up at stop lights.. like after you stop and wait (especially at those long lights), then start to roll again the bike wont respond and sputters... giving it gas has no effect and sometimes it wants to or does die. I recently installed a jet kit, full D&D exhaust, and a K & N filter with larger ring. I had the carbs resynch and they told be this condition is becuase the bike gets hot at lights and therefore the air gets denser and the bike richens up. Is this try? if so is there anything i can do about it? because this problem is making the bike almost unrideable if you have to set for any amount of time... any ideas would be great!

thanks

[Court93kat]

I hope someone replies to your question because my bike does the exact same thing. I believe one of the adjustments are off with the jet kit, but I am not sure which one.

Anyone?!?!?!??

[The CyberPoet]

There are two possible issues:

(A) The vacuum diaphram in the petcock isn't getting enough vacuum at idle when hot (such as a hole in the vacuum line or low vacuum levels), OR

(B) Carb settings. If it wasn't doing this before all the mods, here's the scoop:

Pilot screws need to be richer, main jets may need to be increased by a size. A smooth idle should be smooth whether the bike is hot or cool.

Q: For the jetkit, did you go stage 1, 2, or 3? With a pre-98 and the list of mods you have stated, it should require more fueling than the stock set-up on a stage 1 jet-kit will give you (because the exhaust has less back-pressure and the intake is drafting in more air as well, the fueling part of the equation needs to be richened up).

As for my opinion on the shop that did it -- lazy, incompetent, too rushed to do good work (a form of incompetence) or under-equipped (your pick). With an exhaust gas analyzer and a dyno (or even just with an exhaust gas analyzer) they should have been able to set the fueling at idle correctly without any issues.

Get the bike hot (5 miles of riding hot), and set the idle thumbwheel to 1200 RPM on your bike. If that doesn't keep the idle happy, let it cool down, pull the tank, yank the carbs, find the pilot screws, and turn them out another half turn each. Retest. If that still doesn't make it happy, go another half-turn. If that still doesn't do the trick, open them up and replace the main jet with one a size larger, turn the pilot screws back down one full turn and retest.

By the time this test-tweak-test loop is over, you're going to be an expert at removing the tank and changing the carb settings.

Good Luck!
=-= The CyberPoet

[kat_tsi03]

Ok here is what the setting are currently....

Its setup as a stage one per the dynojet instructions however they told me to go 10 points higher if i had the after market exhaust and the K&N with larger ring so... needles set at groove 3 from top, main jet is a 120 and the screws are set to 2.5 turns out. I also removed those lines comming from the top of the carbs and drapping over the air box per the instructions..

I really dont have a problem with it idleing at a stop light but when i give it gas is when the problem starts... like its loading up and wont respond. I was thinking that it is already too rich but maybe thats not the case. As for the pet cock idea thats something i didnt think of... Maybe ill try turning the petcock to prime and riding around and see if the issue goes away. Is so is there any reason why i just cant leave it on prime all the time? wont the floats stop it from over fulling the bowls?

I agree with your shop theory... they are a bunch of morons and all they did was synch my carbs. I did it my self prior but i think that my tool may be off because i could not get them to synch and when i finally got them close they said they were still way off. so not sure who to beleave there....

thanks for all the help

troy

[kat_tsi03]

more info

ok took the bike out to an empty parking lot today to get a better feel for the problem.. even with the petcock turned to prime the issues exists. I also noticed that no matter what (how long i let it set) there is a tiny dead spot at about 2000 to 2500 rpm where the bike will sputter and not make any power. My thinking is that this is the same dead spot that is amplified if the bike sets for an extened period of time. Also it was fairly cooler today and the issue didnt seem to be any better so the whole overheating thing seems to be hot air. Now another question if i was to make the changes to the screws at the bottom of the carbs like you mentioned eariler wont this mess up my carb synchonization? O and i check the idle after the bike was warm, it idleing right at 1200 so i am not going to mess with that any

thanks for all the help!

troy

[md86]

Have you checked your plugs lately ? When mine was doing something similar , it was because I was running too rich at idle , so sitting for a few minutes would load the plugs and about foul them . I adjusted the pilots (little screws on the bottom you mentioned ?) and it got better . Check your plugs and tell us if they're black like I suspect ....

[kat_tsi03]

Plugs...

O yes they are really black which told me i was running rich.. however if i change them wont i just mess up another set of plugs? I know i have to mess with those screws but does anyone know of a good way to adjust them without taking off the carbs.. and if i adjust them will i have to resynch the carbs?

[The CyberPoet]

Re: Plugs...

O yes they are really black which told me i was running rich.. however if i change them wont i just mess up another set of plugs? I know i have to mess with those screws but does anyone know of a good way to adjust them without taking off the carbs.. and if i adjust them will i have to resynch the carbs?

If the carbs are sync'd, adjusting them all the same number of turns won't change the sync adjustment. Some people have done it using either a 90 degree screwdriver (an expensive tool, available from motionpro.com via partsunlimited via any dealership), or with a flexible shafted screwdriver (any auto parts store). Me, I just take the carbs out, adjust them and put it back together...

As for the plugs, if they are dirty, replace them. Period. Yes, you will most likely run through several (half a dozen?) sets of plugs trying to get the carbs tweaked right for your set-up, but that's the price you pay unless you use an exhaust analyzer. You may be able to clean them with carb cleaner and a toothbrush, or if you get lucky, you might be able to track down a spark plug cleaner (a tiny form of sand-blaster that uses plastic beads and is built just for spark plugs) -- JC Whitney used to carry a 12 volt version in the 80's, but all I see now are the air compressor-driven ones...

Cheers
=-= The CyberPeot

[md86]

Turn your pilot screws in a 1/4-1/2 turn and see if it helps . You might be able to salvage the plugs . Scrape 'em off real good and pop em back in there . When it feels like your adjustments have made a good difference , put the new plugs in and see what THEY look like after a little bit .

[kat_tsi03]

cool thanks for all the help guys. i think im going to take the carbs off this weekend and turn in the screws 1/2 turn and see how she acts. You were right the 90 degree screw driver is going for $109.00 Screw that ill just take off the carbs. lol

troy

[techtown]

The first thing I think of is the jetting? Have you tried putting back your old jets? Remember that the Katana motor has very small exhaust & intake ports in the head so usally jetting isn't needed. If the bike runs good with stock jets you probly will not get more power by going up in jet size.

[xbubbax]

The first thing I think of is the jetting? Have you tried putting back your old jets? Remember that the Katana motor has very small exhaust & intake ports in the head so usally jetting isn't needed. If the bike runs good with stock jets you probly will not get more power by going up in jet size.

,but when opening the jet size your allowing more flow of gas into the carbs, that doesnt effect intake displacement. if you went up a jetsize it allows for more gas to go in, and with a aftermarket can, that will allow more exhaust out speeding up the process and making a bigger bang for your gas. jets do help with HP but without the other proper upgrades its not that good of an upgrade. if u upped the intake size, your enging would be the equivalant to a GS1000 intake with stock small exhaust ports and that would cause a big BOOM and prob blow a hole in the exhaust header. BOOM im guessing this is in theory

[The CyberPoet]

,but when opening the jet size your allowing more flow of gas into the carbs, that doesnt effect intake displacement. if you went up a jetsize it allows for more gas to go in, and with a aftermarket can, that will allow more exhaust out speeding up the process and making a bigger bang for your gas. jets do help with HP but without the other proper upgrades its not that good of an upgrade. if u upped the intake size, your enging would be the equivalant to a GS1000 intake with stock small exhaust ports and that would cause a big BOOM and prob blow a hole in the exhaust header. BOOM im guessing this is in theory

I had to read this several times to see what you were saying...
Although the Kats do have small intake and exhaust ports compared to a one liter engine, they do still custom cut the needles and alter the jetting some to ensure complaince with certain requirements, as the bikes comes from the factory (sound level & exhaust gas complainces required by DOT/EPA/etc). This is why stage 1 jetkits exist for the Katana's -- to remove the artificial power reductions at certain RPM levels induced by the stock needles & jets. And a stage 1 kit will bring benefits with the stock exhaust and air intakes (i.e. - without any other "concurrent' mods).

Cheers
=-= The CyberPoet