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Tayzx6E

Troublesome ninja - laundry list of replaced items.. whats left?

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Hey friends, as i posted in the new riders intro sub, im having trouble with my 93 kawi zx6e, and being a young adult with very low fundage, i can use all the help i can get.

so in short, shes having a bog/stutter issue at 7.5k rpms in 3rd, and @ 6k in 4th and above.

heres a list of things gone through/checked/replaced,

 

fuel lines replaced

tank filters cleaned

new carbs

stage 1 kit

float needles replaced and set to factory height

carbs completely cleaned and setup

new in-line fuel filter

new fuel pump

new battery

new stator

new regulator/rectifier

new spark plugs

carbs checked for vaccum

 

As far as im aware, the bike idles and the engine runs as normal, no abnormal sounds.

im at a total loss. i really want to see her full potential and can use all the help i can get. Thanks and much appreciated.

 

Tay

 

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Just asking... does this bike have the stock oem exhaust on it? Have the valve clearances been checked? Compression checked?

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24 minutes ago, ZRX4ME said:

Just asking... does this bike have the stock oem exhaust on it? Have the valve clearances been checked? Compression checked?

when i acquired the bike, it came with a 4 into 1 slip on muzzy, stock on this bike i believe are dual 1 inchers. have not done a valve clearance check, a buddy of mine said he would do that, but we havent found the time to yet. we did a compression check and that is indeed good. could the exhaust have too much or not enough flow?

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Regardless of carb work, if the exhaust back pressure is too low you can have lean spots in the rpm range. I’ve seen them in multiples, such as 1500, 3000, and 6000 rpm.my own particular case was my ‘85 GPz 900r Ninja with a 4-onto-1 Yoshimura Zyclone system. Cured using a K&N/Dynojet kit.

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Would it help to try to remove the baffle? Or is that a no go? I purchased a stage 1 Dyno kit, and it helped some, so should I shim the needles higher to the last clip location? It seems to be problematic in the clip range on the graph. I apologise for all the questions.

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Tayze— unless you see an obvious issue diagnosis is always Engine Mechanical 1st, then ignition system status, finally Fuel system. Throwing parts and procedures at a problem accomplishes nothing. Run a compression test before you do anything else so you know what you’re dealing with. If the results are poor then a leakdown test is in order.  Remember- there is no law stating you can have only one problem at a time. Since engine mechanical and ignition determines carburetor it best to get those squared away before futzing with the carbs. You have to know what’s good so you can determine what’s bad. Diagnosis is the key.

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I appreciate the input. When I bought my bike it definitely needed some love, Most everything that me and my Dad have done / bought was because there was obvious problems with them. Stator was bad and had just twisted wires going into the harness. The Voltage regulator tested bad. 2 of the carbs had broken bolts where the airbox plate bolted to the carbs. Missing all the plastic. We have breathed new life into her. My Dad  is pretty good mechanically, he works at an auto shop (not as a tech) and can do most things but he don't know what he don't know. So I'm hoping that the members here can lay a trail of breadcrumbs for us to follow so she runs GREAT. Thanks again in advance.

Tay 

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any mechanics on the board any longer? they may be of assistance....

 

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Neo, I'm going to oversee Taylor running a compression test in my garage, possibly tomorrow.

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In addition may want to try and find a forum for the 90's z kawis.

For just about any motorcycle you can usually find a forum that has folks that know their way around the motorcycle front to back and can give you advice/tips/common things to check for, which can save you a ton of time and $$$.

Also make sure to pick up a service manual, which I'm sure terry has already suggested

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On 10/23/2017 at 5:14 PM, ZRX4ME said:

....... Throwing parts and procedures at a problem accomplishes nothing.......

 

Hey hey hey - that's what keeps those parts sellers in business!

 

LOL

 

Just this past week we repaired a customer's machine, and he ended up paying "the stupid tax".

 

Personally, I think he got off cheap, $400.00. 

 

He brought in his machine with a no-start no run condition.

 

The technician hooked the machine up to the computer and followed the manufacturer's diagnostic process to the letter. 

 

Ultimately we found the customer had poorly wired in a set of LED lights and the resulting incompetence resulted in water entering his fuse box, destroying multiple jcase fuses and possibly long term damage to the fuse box itself. 

 

When I called the customer, he told me that he was an expert HVAC technician and that we should've checked the fuse box 1st thing - 

 

To which I replied "Yes, you probably should have".

 

I see too many good motorcycles destroyed with good intent. 

 

Always have, always will.......

 

 

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One of the best lines I heard from a customer while at work was..."There was nothing wrong with my car when it was towed in here."

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Update-

Did some top end work on her(shims, etc) and in the process also found that the coils were rusted, so I replaced those, and still no dice. While I was at terry's, we found out I had decent, but obviously not like-new compression. I'm still at a loss. Any more advice would be welcome..

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Many, many items on that bike that could be an issue. But the next step in the diagnostic path is Engine Ignition. 2 items you can try: attach a voltmeter to the battery and check charging system voltage st the rpm range where the problem appears.   You can also run voltage drop tests between the battery and coils, battery and alternator output, and battery and engine ground. 2) use an inductive ignition timing light to see if spark remains constant at all 4 plugs during the stutter. Lots more to test, but these items will get you started. It’s best to make absolutely certain that Engine Mechanical  and Engine Electrical/Ignition systems are 100% before going through Engine Fuel diagnosis. Keep in mind that there is no law stating that you can have only one problem at a time.

 

 

 

 

 

 

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On 1/5/2018 at 10:59 PM, Tayzx6E said:

Update-

Did some top end work on her(shims, etc) and in the process also found that the coils were rusted, so I replaced those, and still no dice. While I was at terry's, we found out I had decent, but obviously not like-new compression. I'm still at a loss. Any more advice would be welcome..

 

Dont have any advice at the moment but will say good on you for your persistence!  

If anything, your learning how to work on the old girl, and thats something you cant always put a price on.  

Have you got ahold of a maint/service manual for the bike yet? Those will usually have a "no start" tree for you to check off as you troubleshoot.

Have you joined a Kawi ZX forum and asked for any help?

I hope you get her going and look forward to checking the bike out on a ride this year!  B)

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If this is a no start, how did this bike go from a bog/stutter( your 1st post) to a no-start in 2.5 months? What changed?

"Rusted coils"   Never heard that one before.

 At this point what exactly is the issue--a bog/stutter or a no-start?

 A forum, ZX or otherwise isnt going to fix your bike. As stated above, you need a shop manual and maybe some guidance.

 

 Here are your 1st steps IN ORDER:

1) Engine Mechanical. We already know your compression is acceptable. Providing your cams are in time-if they were removed during valve shim change as you said was done-if it ran before it should run now. Valve clearances  should be in spec.

2) Engine Electrical-battery capacity in spec. Ignition coils should be able to provide a spark capable of jumping a 6mm gap to ground while cranking. Recheck spark plugs to make sure they are clean, dry, and properly gapped.  Torque them to spec-Ive seen a few older bikes with stripped spark plug threads from over-tightening, and also seen plugs left loose and blow out of the cylinder head. If it runs you need to check charging system operation.

    Need to know the exact symptom--no start or bog/stutter?  Do the 1st steps then STOP and let us know your results. If there is a problem with Engine Mechanical or Engine Electrical we'll address those 1st. THEN if those are good we'll move on fuel system etc.

   If you have good compression, good and properly timed spark, good valve timing, air,  good fuel with proper delivery, and an exhaust system not plugged IT HAS TO RUN.

   HOW it runs opens up other avenues of diagnosis.

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Haaa!!!  I hadnt read the original post in long time so I probably just assumed a no start when I saw the compression update.

See there,..I help out with problems before you even have them!  Thats how awesome I am!  :headbang: :rolling:

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Aaron, sync wont help with either a no-start or a mid-to-high rpm stutter.

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I dont see where he says he synced them though. Looks like hes had the carbs off and all apart so just making sure.

Isnt one of the advantages of synced carbs quicker smoother revs?  I have always heard a throttle plate(s) not being equal with the others will cause the fuel/air mixture in that particular runner(s) to not be in a even "pulsed" flow for all the intake valves to be making smooth perfect music with each other.

So possibly, varying rpm's could mean going from good power, to not so good power?

And for da record I'm not trying to debate it, I'm always up for a good learnin or to correct the bad spirits that dwell in my head:crazy:

 

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Aaron, youre not really synchronizing the carburetors(or throttle bodies if injected). What you are doing is equalizing the engine vacuum on the engine-side of the throttle plates. The goal is equalizing power output among all cylinders. Think of trying to make a 4-cylinder engine behave as one cylinder. Many items go into the making of engine vacuum: Compression variance between cylinders, valve clearance(and valve timing, as a loose valve opens later and closes earlier, a tight valve opens earlier and closes later), spark plug gap, idle and slow speed fuel mixture, and throttle opening angle(clearance) at idle speed. The piston on its downward stroke creates vacuum in the  cylinder head's intake port which is maintained by the throttle plate. At closed throttle(idle speed) the engine vacuum is high. The more the throttle plate is open the more vacuum is relieved, and the vacuum is low. At wide-open throttle vacuum approaches 0" Hg. At idle speed it is normally 17-19" Hg. During decel with closed throttle it is 21-23 or more " Hg. Synch has its greatest effect at idle and part-throttle operation, less, if at all at midrange, and none at WOT(wide open throttle). Think of a 4-cyl as 4 separate engines sharing a common crankshaft. If one engine is weaker than the other 3 the output will not be equal among the engines(cylinders), and crankshaft  will not rotate at a uniform rate. This will show up as a vibration, lower output, higher fuel consumption, etc. One cylinder might require a different fuel ratio than what is provided to the other cylinders, that one cylinder might run hotter or cooler than the others. Think of a 4-man rowboat in a competition, 2 participants rowing with equal and full effort, and 2 rowing with 1/3 to 1/2 the effort of the 1st 2. Not a smooth power output, and not the full power of 4 rowing with full equal effort. Same deal with a multi-cylinder engine.

It IS possible in some cases to equalize the vacuum readings to compensate for a compression, ignition, or fuel system fault.  But doing so masks a problem, doesnt correct it. If throttles are synched with other system faults and the result is a wider-than-normal throttle opening angle, the Throttle Position Sensor voltage to the ecu will be incorrect, the lower engine vacuum will cause the mass airflow sensor voltage to be incorrect, possible ignition timings will be incorrect, etc. The ECU is a computer, and GIGO(Garbage In, Garbage Out) applies here. Fuel injection duration signals will be incorrect,  and in carburetors operation of the main metering system and idle and transition circuits will be incorrect. The 3 main points  here is 1) EVERYTHING has to be correct before sync, 2) Sync will not cause a no-start or midrange stutter, and most importantly...3) WE DO NOT KNOW WHAT HIS EXACT SYMPTOMS ARE 2 AND A HALF MONTHS AFTER HIS INITIAL POST.  It's useless to speculate what could be the problem(s). And as I posted earlier in this thread, throwing parts and procedures in the hope of a full repair is a time-consuming and expensive exercise in futility and is not a substitute for a thorough diagnosis.

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So if I keep my throttle in the wide open position I shouldn't have to worry about a throttle body sync (equalization)? :) Dammit, I wasted my money on that sync tool! :)

 

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