90 kat lacks power? tried a lot of things... maybe carb issues??

[hpjc10]

hey guys im new to the site, just got a 1990 kat for pretty cheap. the bike runs and rides, got it up to 90, but it seems as though it has none of the power it should have, less hp than my kz440. it does not seem to be willing to take off unless you rev it to 6000-6500 rpms and even then, it takes off at a crawl and its difficult not to have it stall. after its warm, and i stop moving, the idle will hang at about 3k rpm, no matter where the idle screw is, until i slightly catch the clutch, then it will drop stay there, then go up again after a few seconds.

i cleaned the carbs manually, and added some seafoam to the gas, also while the carbs were off i visually synced them by lowering all the throttle valves completley then tightening the screws slightly so there was tension on the springs then used the idle adjusting knob to get it to idle.

reconditioned air filter with k&n cleaner stuff

did a valve adjustment, two of the exhaust valves were a little too tight, but none of this has helped.

does anyone have any ideas? any help would be appreciated!

just dont want to pay $98 to have a shop tell me whats wrong..

[05RedKat600]

Full carb soak and vacuum sync the carbs. You HAVE to vacuum sync the carbs, you can't just visually sync them. You can try doing that first and see if it fixes your idle, but you'll probably have to soak the carbs.

[muddyman184]

do you have the factory airbox or the K&n pods? if you have the pods thay could cause an issue. Check your throttle cable make sure it is moveing freely and not sticking.

[05RedKat600]

do you have the factory airbox or the K&n pods? if you have the pods thay could cause an issue. Check your throttle cable make sure it is moveing freely and not sticking.

Boom, I missed that! That's probably most of the problem right there. K&N's and Kats don't get along.

[Wild-Bill]

The problem is that you're running too lean. You've got the classic symptoms.

The most common cause is that your pilot circuits are dirty (still).

Second most common is that you're getting too much air flow. It sounds like you may be using either pods or a K&N filter in the stock airbox. Either one is a problem. The CV carbs on the Kat need the restriction and air volume from the stock filter/airbox combo. Without that, they don't develop the vacuum they need to move the slides properly and they'll run lean unless you spend huge amounts of time tweaking the jetting (which, at best will be close, not right). You also may have some air leaks from a bad/disconnected/missing vacuum line, bad o-rings between the carb boots and the head, open drain hose on the bottom of the airbox or loose airbox-carb boots.

Third most common cause is mis-adjusted Air/Fuel screws. The factory setting is supposed to be 1.75 turns out but with the ethanol mix fuel we get these days your bike will run better at 2.25-2.5 turns. Worth setting right while you've got the carbs off to soak.

[hpjc10]

no pods, stock airbox with K&n fliter. pilot screws are factory sealed. i blew out all of the jets and the pilot circuit and there wasn't any crud.

the K&n air filter could be a problem? this is the one i have, used with the stock air box.- http://www.d2moto.com/p-6462-kn-air-...FacQNAod_EleJQ

i will try to cover the hole up a bit with some cardboard to restrict the airflow some and see if that adds hp.

[05RedKat600]

no pods, stock airbox with K&n fliter. pilot screws are factory sealed. i blew out all of the jets and the pilot circuit and there wasn't any crud.

the K&n air filter could be a problem? this is the one i have, used with the stock air box.- http://www.d2moto.com/p-6462-kn-air-...FacQNAod_EleJQ

i will try to cover the hole up a bit with some cardboard to restrict the airflow some and see if that adds hp.

If the air screws are factory sealed, then you haven't cleaned the pilot circuit. That air screw blocks some of the passage so it can't be fully cleaned until they are out. Remove the plugs, remove the screws, and see what shape they are then. Then when you put them back in set them at 2.5 turns out.

Yes, K&N's and Kats don't get along. Go back to a stock air cleaner and I bet the majority of your issues go away.

[hpjc10]

Ok I will give this a try tomorrow and share the results! thanks for the quick responses!

[Lykkan]

Also, contemplate on checking for vacuum leaks (after the air box, not before) Adjusting the idle screw with no effect is one of those symptoms. Possibly the carbs are not into the rubber intakes all the way?

[hpjc10]

so heres what happened. i reassembled the bike with the cleaned K&N air filter etc, and put cardboard in front of the hole, with a smaller diameter hole in the cardboard than is there for the air filter. this caused my bike to run really rich (a lot of white smoke), so i removed the cardboard, and it runs amazing now, with all of the power it should have. theres still some variation in the idle, i believe the carbs need to be vacuum synced, but thats not difficult, and they are only slightly out of sync. my next big problems with the bike are that the guy who had it last apparently was not a very good mechanic. missing a bolt on the rear brake caliper, causing it to **** out my brake fluid every time the brake is pressed. also, under the right side timing advancer cover, the gasket was half gone, causing me to leak all my oil out. AND to top it all off, the low beam filament is blown. lucky i had a nice guy for my inspection. new gasket and bulb on the way, permatex in the meantime, prob going to take parts off of my old kawi for the rear brake and hope for the best. thanks guys for pointing me in the right direction

[KatanaGSX92]

...also, under the right side timing advancer cover, the gasket was half gone, causing me to leak all my oil out.

If you are losing ALL of your oil from the "timing advancer cover" then you have a much bigger problem. Typically, there will only be about a tablespoon full of oil under that cover, if any at all. I have to assume that you were exagerating in that statement otherwise you have your work cut out for you!