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Discussion Starter #1 (Edited)
Hey guys.
This bike has just been gotten going again after having sat unused for 4 years, belongs to a friend of mine.
The tank and the fuel pump were both replaced with used ones as the old ones were full of rust.
The bike goes fine when you roll the throttle on, it gets to redline, it's only happening when the throttle is opened very fast to about 2/3rds of the way to the stop.
I've done a fuel pump test as that was my first thought and it is flowing fine, have also put some injector cleaner through it but the issue is still there.The fuel line doesn't appear to be getting kinked under anything so far as i can see.
What should i check for next?
Also the ecu was replaced as well.
Thanks for any insight.
 

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Captain Obvious ... because obviously it’s obvious
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What do you mean it's flowing fine? Did you do the test for the proper duration and verify the amount? You need to actually feel the fuel line to make sure you cannot feel any kinks.
Have you verified that the STVA is working properly? When were the spark plugs last checked or replaced? Is your SET valve opening properly (if even present)?
 

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The bike goes fine when you roll the throttle on, it gets to redline, it's only happening when the throttle is opened very fast to about 2/3rds of the way to the stop.
+1 to all of Just_Nick's suggestions/comments and also: under what conditions does that happen? Does it happen in gear only or in neutral as well? Do you have reason to believe that if you slowly open the throttle fully, or 2/3 of the way, that it won't bog down? (Please do not try this out if you don't feel comfortable doing it, or cannot guarantee reasonably safe conditions) . Required fuel flow rate depends on load, hence engine speed and throttle opening. If you can get to redline with a partially closed throttle (so accelerating slowly in first gear say), but can't with a mostly or fully open on, then there's probably some restriction in the delivery of the fuel and you should measure the delivered volume as described in the manual and see if what you get is within spec (as Just_Nick suggested).

If the problem is indeed related to throttle opening speed, then that might point to the STVA (again as Just_Nick suggested), but I find that unlikely, as it shouldn't just hang there. At most it should hesitate/stumble momentarily and keep on accelerating.
 

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Discussion Starter #4
Ok when i did the fuel flow test i didn't have that much gas in the tank so only did it for 15 seconds and got 675mls into the container.
The bike got serviced a couple of weeks ago and i'm not sure if the spark plugs were replaced or not, so i will have to find that out.
I rode the bike earlier on today and thats how i know it will get past the 6g rolling it on, at least in the first 4 gears, it would only get to the 6g and refuse to go further when i was using the described larger throttle openings.
I have no idea what the STVA is, or the set valve so i have some searching to do.
I appreciate the help fellas.
 

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Dreaming of buttsecks for years...
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You didn't mention anything about a fault indicator, so looking into the STVA will be a waste of time. 675ml in 15 seconds sounds like a lot. Are you sure you did that right? That's more than three times than "good" expected amount.
 

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Discussion Starter #6
You didn't mention anything about a fault indicator, so looking into the STVA will be a waste of time. 675ml in 15 seconds sounds like a lot. Are you sure you did that right? That's more than three times than "good" expected amount.
Thats definitely what came out, i had the stopwatch and my mate was helping, we even did the 3,2,1 go!
And the FI light isn't coming on so i would assume no codes.
 

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You didn't mention anything about a fault indicator, so looking into the STVA will be a waste of time. 675ml in 15 seconds sounds like a lot. Are you sure you did that right? That's more than three times than "good" expected amount.
Yeah? For the K6/K7 600, I always thought it was 1200ml in 30 seconds, so 675ml in 15 seconds seems right to me.
 

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If the fuel flow amount is more or less right (you need a big restriction to stop accelerating at 6000 rpm), I'd suggest inspecting the injectors next, cleaning them if necessary. That's another area, where a restriction may arise, which isn't detected by a fuel flow (or pressure) test.
 

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The manual says 168ml (5.9 fl oz) or more in 10 seconds. 675ml is almost 23 ounces. Just feels wrong to me. I'd expect a new/perfect pump to be closer to the 10oz range.
 

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Discussion Starter #13
Update.
Took her for a run yesterday after using the injector cleaner and the problem is still there.
I have ordered new spark plugs and will replace them and at the same time check that the butterflies are indeed opening the full way and then i will see how things go and let everyone know.
I appreciate everyones help :)
 

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I think you should investigate your fuel flow further, as TheGeek's concerns seem valid to me. Either you might have measured improperly, which means that a fuel flow restriction remains a prime suspect, or you have unusually high fuel flow, which should be investigated. For instance, might it be, that you're running without a fuel filter?
 

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Discussion Starter #15
I think you should investigate your fuel flow further, as TheGeek's concerns seem valid to me. Either you might have measured improperly, which means that a fuel flow restriction remains a prime suspect, or you have unusually high fuel flow, which should be investigated. For instance, might it be, that you're running without a fuel filter?
I did get the fuel pump second hand, couldn't imagine why anyone would take the fuel filter out of it for, but strange things happen.
We definitely measured the fuel flow correctly, it seems theres a bit of confusion on here over exactly what the correct rate should be!
I will put the new plugs in and try her out again, if there's no change i'll test the pump again and if i get the same results as last time then i'll check to see if it has an internal filter.
 

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I did get the fuel pump second hand, couldn't imagine why anyone would take the fuel filter out of it for, but strange things happen.
We definitely measured the fuel flow correctly, it seems theres a bit of confusion on here over exactly what the correct rate should be!
I will put the new plugs in and try her out again, if there's no change i'll test the pump again and if i get the same results as last time then i'll check to see if it has an internal filter.
There is no confusion, it's explicitly stated in the manual what the volume should be after a specific duration.
 

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Discussion Starter #17
There is no confusion, it's explicitly stated in the manual what the volume should be after a specific duration.
It has a minimum flow amount, it didn't say it should flow x amount in x time.
168mls and more per every10 seconds according to the service manual.
The pump put out 675mls in 15 seconds, which does seem a lot!
 

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Discussion Starter #18
Long over due update.
Replaced the plugs and the fuel pump strainer and that fixed the issue.
Been sitting in the garage for the last few years and started and ridden around the block every few months, and am going to turn her into a track bike.
 
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