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

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Todd, can you even go full throttle long enough on your bikes to notice a difference?

Besides...if you didnt spend $$ on a tool, you'd find another place to spend it. Same as ME!!!  lol

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On 1/8/2018 at 11:26 PM, ZRX4ME said:

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.

 

 

I AINT READIN ALL THAT SHIT!!!         :asshat:

 

lol!  just kiddin  :lol:

Thanks for writing all that Terry.  I did learn a couple things in there.  This part you wrote  " 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"

....is what made trying a carb sync come into my head if its not been done yet.   I do have a lil better understanding of the cause/effect of un-synced carbs now.  :headbang:

 

 

Taylor,  now that the temps are gonna be a little warmer for a few days maybe try to get through these next steps Terry wrote for you.  If you don't have a volt/ohm meter or a timing light, borrow or go buy, their both cheap and you'll use them again. 

I'll quote and repost it here since we got a little off track. 

 

On 1/6/2018 at 12:54 AM, ZRX4ME said:

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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You are all going to laugh at this, but, after extensive testing, (and riding) the issue was fuel ( and exhaust) related. Turns out, when I purchased my bike, I wasn't aware that it had an aftermarket 4 into 1 full system exhaust, and it was causing a major mid-range flat spot, which was the original problem from the start. (besides looking like I rescued the bike from a junk yard). being a carbed bike, I had a former mc mechanic friend of a friend tweak it every which way, and it still didn't take kindly. So, I went and purchase the oem 4 into 2 exhaust. And, bingo! No more flat spot through the power band.

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OUTSTANDING!!!

Mods, as popular as they are, are not always complete, or done well. Many times a highly modded car would come into the shop with a driveability issue. Unless we saw something obvious, we advised the customer to remove the mods(usually exhaust, intake mods and the like) and we'd diagnose it from there.

 One of my Mazda mentors in my Jurassic-era youth had a great line which still applies today--"Always look FIRST where the human was LAST".

And, depending on how many things have been changed, you can easily get caught up in a game of chasing your tail in terms of what affects what else.

You initially stated you had new carbs and Stage 1 kits installed. So, you wouldnt think it could be carb-related. But in a way, it was. By installing the oem exhaust you have restored the backpressure necessary to allow your carbs to provide enough fuel for proper engine operation.

A 4-into-1 performance exhaust reduces backpressure.  This backpressure keeps the fuel from leaving the cylinder during valve overlap, effectively leaning out the mixture.  Then, at certain rpm ranges you can have flat spots during acceleration as you did. As did I when I installed a Yoshimura 4-into-1 Zyclone system on my '85 900r Ninja, replacing a trashed set of Kerkers.   2 flat spots at at 3500 and 7000 rpm was the result, corrected by the installation of a K&N/Dynojet Jetting Kit. Bike ran great after that. But I found a like-new oem 900r Ninja full system cheap, and installed it for the quiet, left the jetting kit in, and the bike ran even better. Sold to former member BE to get my ZRX.

   Glad you have it fixed, and more importantly, that YOU fixed it yourself.  GOOD JOB!!

 

 

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Research is key... I may have spoke too soon, but.. I have learned. While the oem exhaust has helped immensely, it still wasn't where it should have performance-wise, even as a 25 year old bike. It's old, but it's not that old. 

So I combed through the parts fisch, looking for things that were missing completely, or not all there on this bike. First file I opened was the airbox. Right away I could tell I was missing 4 hoses and fittings that ran from the carburator to the ram air tubes. Ordered the fellas with the quickness, and installed them as such. Went for a test an hour ago, And may I say, HOLY S***, this is THE best performance I have ever experienced with this machine, since I have aquired it. Ill omit the mph it went, but let's just say I went faster than I should have, lol.

 

I want to put a giant THANK YOU to Terry (ZRX4ME), for pushing me to comb over to everything, and to be meticulous and show me things that I would have never even had thought of checking. He has helped become a better mechanic, and will help me in all my future endeavors. I am forever grateful. Edit: not sure what to do with the bike now, never got this far. I guess I ride it? ?

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 Terry is great to know:)

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I gave her a couple healthy modifications if anyone in particular cares. ? Zx9r tail swap, and wheel anodized prior to tire mount, with matching chain.

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