KOTM Feb 2009 Mat0302

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Mechanics 101 Can't get it to run right? Find a trick to add HP?
From the first oil change to completely rebuilding the engine,
this is the place to talk about the heart of the beast!

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Old 03-19-2012, 03:08 PM   #1
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Join Date: Jan 2010
Posts: 65

Default katana drives me crazy!!

ive got a problem that drives me crazy and i cant find a solution for it!
it starts ok with a cold or warm engine. a litlle lazzy when warm,it seems to stay 2-3 second to rise to idle! not always! it works better when the engine is cold. with engine warm, somethimes when i blip the throttle,it go under idle and return ,rarely the engine stall. when stiil not warm enough idle is solid. Warm idle is a little bouncy, maybe 50-100 rev. i use carbtune to sync the carbs.
i thought the mixture was rich!.ive modified the floats from 14mm to 15,5mm, pilot screw from 1 turn to 3 1/2 turns and still the same thing!
it was doing the same thing,sometimes it was going under idle and return,rarely the engine was stalling
pilot screw isnt helping at all ,closed or open it all happens the same.
ill write down the latest modifications,the problem is still there
ive cleaned the carburators but they've never been left 24hrs in a cleaning solution, they've only been sprayed with cleaning spray and compressed air.
ive changed the orings from the carburators ,the rubber tap from the pilot jet,from the emulsion tubes,from the floats, pilot screw, from the syncronizing port.
what i've check and replace until now:
-all o-ring from carbs
-i tried floats from 14mm to 15,5mm thinking it's rich at idle (now i bet it's a little air leak)
-i tried pilot screw from 1 1/2 turns to 3 1/2 turns (those was changing idle a little bit, but the issue was still there)
-emulsion tubes factory pro nickel plated
-factory pro TI JET KIT
-sealed airbox boots with RTV
-new o-ring between carbs and cylinder head
-new stock air filter champion
-new spark plugs
-cut an inch of plug wires and put back spark plug boots
-stock headers a little modified by me (4 in 1 and welds grind out) with a carbon muffler MIVV from a gsxr srad
-valve clearance check
-compression on four cylinders is 212 psi (manual says between 142-213 psi)
-12V (maybe more) at ingnition coils
-good battery(one year old stock yuasa)
-good charging 14,6 V
-choke lever and cable and everything check
-valve cover hose, drain airbox hose, vaccum hose to petcock....
-rebuild petcock

what is wrong with it? last thing that i will do is soak the carbs for 12 hours! please give me ideas!

Last edited by sarpe; 03-19-2012 at 04:36 PM..
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Old 03-19-2012, 04:26 PM   #2
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the 2 biggest thing that pop out to me is the float height should be 13mm I believe and the pilot screw which I think you mean air fuel ratio screws you would want to set this to 2.5 turns out to start with.
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Old 03-19-2012, 04:30 PM   #3
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it's a pre 98 600....factory pro say 14mm and 2,5 turns pilot screw....now it's 14mm and 2,5 turns...runs realy good...no hesitation, nothing... but those issues drive me crazy.
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Old 03-19-2012, 04:31 PM   #4
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Pre or post?
When all else fails get a bigger hammer
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Old 03-19-2012, 04:38 PM   #5
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Originally Posted by sarpe View Post
it's a pre 98 600

A dealer of rebuilt Katana carbs.
Partly Chris's Motorcycles
A rebuilt set of carburetors will cost more than $5 dollars
DREAM Katana

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Old 04-03-2012, 03:02 AM   #6
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yesterday i use a gunson colortune to adjust idle mixture and i find that first cylinder was not working!! until now i was runing on 3 cylinder somethimes i think! motorcycle was starting very well cold, warm but that ragged idle was there because occasionally(or all the time) was runing on 3!
Spark plug was wet on that first cylinder and i had spark on all cylinders!!! what is going on here?!
i measured coils and here is wat i get:
primary-3,1 ohms first coil
-3,2 ohms second
manuals say 2-4 ohms
secondary-plug cap to plug cap-38.100 ohms first coil
-37.400 ohms second
one manual say between 30.000-40.000 ohms
second manual say between 12.000-18.000 ohms
took out 2 plug cap to measure them and both measured 11.100 ohms! i didn't find in manual how much resistance must have! i think should have 5000 ohms?
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Old 04-17-2012, 04:04 AM   #7
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yesterday i tried with another 2 coils and nothing changed! now i will try with another ignitor box!
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Old 04-17-2012, 04:13 AM   #8
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the ignitor box is not the problem if you have spark on 3 cylinders. that would take out at least 2 cylinders.

there is a click when the plug cable is correctly pushed on the spark plug. sometimes it requires a whole lot of weight on it. other than that..ive got to say the classic...soak the carbs
2015 BMW S1000R

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Old 04-17-2012, 08:49 AM   #9
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i have gas, spark, everything but i think spark is weak or spark timing is not good...
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Old 06-09-2012, 03:30 PM   #10
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update: put a 35 pilot jet and that solved the problem! it may need also to raise needle one noch because it's lazy at 6000 rpm. i'm happy now!
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