Running on 3 cylinders | 96 FZR 1000

[TomcatMJ]

"hang on 3k and doesn't move"..means that you can't rev higher than 3k or does this mean it hangs when your'e revving back to idle? If first, just check if your EXUP-shaft and EXU-Servo work properly...if the shaft doen't move the servo signals its standing to the tci, if the servo is unconnected or defective the tci also stops revving up higher (but usually at 4k, not 3k) for securing the motor...if there is no EXUP anymore just check if the Servo is still connected (just without the cables to the shaft) or if there is an EXUP Terminator/Dummy installed..without Servo or a replacement for the servo the TCI doesn't rev up either...
If the problem is hangig at 3k during revving down then the mixture-adjustment should be checked as a too rich mixture sometimes let the revs stay somewhere before after a while revving back to idle...

[noodlemonkey]

Sadly. I'm in Cape Town South Africa.

I did some reading about float heights and never really took it seriously until I understood what a large role it plays in the overall performance. So I've reset everything correctly this time.

Top tip. When adjusting your float heights. Tilt the carbs so that the floats don't compress the needle spring. Otherwise you could be up to 4mm out on your settings.

I'll keep cracking away at it. But would really like to figure out why no.3 is dead.

[Jordan_Ciaramitaro]

Haha, just a mere 8300 miles. Probably need to bring along the tank bag for that road trip.

Float height will play a huge role. How does the inside of your tank look? If your fuel is getting cloudy from rust it can clog the pilot jets among other voodoo. This typically happens on cylinders 1&2 due to the lean angle on the kickstand.

The pilot jets on these carbs are super easy to clog.

[noodlemonkey]

Haha, just a mere 8300 miles. Probably need to bring along the tank bag for that road trip.

Float height will play a huge role. How does the inside of your tank look? If your fuel is getting cloudy from rust it can clog the pilot jets among other voodoo. This typically happens on cylinders 1&2 due to the lean angle on the kickstand.

The pilot jets on these carbs are super easy to clog.

Definitely - Probably some road side snacks will be required as well

So currently all testings have been done using a fuel bottom which is clear and clean - haven't had the bike run well enough to actually take it for a ride,

Just wanting to confirm a few things just to be extra sure as I cannot find direct information online.

First and foremost - What are your thoughts on my emulsion tubes? I know they look a bit worn - but compared to my previous set - they look amazing.


And then onwards - Have i got the jets in the correct places? - reason i ask is because I cannot quite remember which way they went in when I took them out - oops....


and lastly - these babies are clean... all look exactly like this one - Anyone see anything out of place?


one last thing to note - this is taken of carb for cylinder no.4

[noodlemonkey]

Also - as read here http://www.factorypro.com/tech_tuning_p ... gines.html

Because my emulsion tubes are slightly worn - can i lean the mixture with the float heights?

How can I check if my needles aren't sealing - I've already put my carbs on the bench - tilted up to best mimic the angle on the bike with my fuel bottle connected way above it and left it for a few hours with card board underneath it - and no leaks - BUT - i can almost "see" that carb no.3 is dumping fuel when the bike is running - suspecting that's why its not running on cylinder no.3

just pulling at straws here...

[Stig]

That toob looks well worn from that image. Have you checked the seals under the Toobs and the small choke seals in the top of the carb bodies where the tops seat. Also check the air and pilot circuits are clean

I had a low throttle problem too after checking and swapping out coils and all possible external possibilities we again stripped out the carbs. We then used an air line with 150psi to blow through all the jets and recesses well used carb cleaner. (Emulsion Toobs had been done a few weeks previous)
Blowing the carbs thro' cleared the issue

[Jordan_Ciaramitaro]

I can only see the first picture for some reason, however, it seems this engine is so sensitive to its fuel mixture from a drivability stand point. High revving WOT it seems you could almost let 4 fuel lines drain into the intake and it would be happy.

Considering you have a full exhaust, I assume your EXUP valve is missing? Mine is, which sparks other thoughts since we have similar issues.

How crucial is the EXUP valve?

In my head I feel that the lack of restriction allows excess airflow at low rpm which makes a CV carb dump more fuel. The excess overlap of the cam allows some of the air to flow through the head before closing the exhaust valves, a condition that may be counteracted by excess back pressure created by the EXUP valve.

As a result you have excess fuel and less air in the combustion chamber. This creates and overly rich condition which sorts itself out as the engine's revs and load increase and it overcomes the cam overlap and the air to fuel ratio becomes stoich.

I have my bike running dang near perfectly from take off, but it stalls in the midrange unless the engine is very warm, not sit in traffic warm, but riding it like ghost rider for a good 20 minutes warm. Even then it is lean in mid-range and wot.

How I got it to run so well off idle was by lowering the floats to 10mm from 4mm ( remember R1 carbs)

I have a converter/EXUP valve assembly and can from an R1 I may try to fit on this bike. I don't mind loosing top end power as long as it runs right from idle to redline. It goes way faster than I can really ever take it on the roads around here anyways.

For the record, the emulsion tubes on these carbs look to be in great shape, but as mentioned previously, it's not always visible to the naked eye.

[DonTZ125]

How crucial is the EXUP valve?

In my head I feel that the lack of restriction allows excess airflow at low rpm which makes a CV carb dump more fuel. The excess overlap of the cam allows some of the air to flow through the head before closing the exhaust valves, a condition that may be counteracted by excess back pressure created by the EXUP valve.

As a result you have excess fuel and less air in the combustion chamber. This creates and overly rich condition which sorts itself out as the engine's revs and load increase and it overcomes the cam overlap and the air to fuel ratio becomes stoich.

From my readings and such, it's the other way around. By choking down the exhaust flow path, the velocity increases to the point that reversion is drastically reduced. The intake charge isn't contaminated by recirculating exhaust gasses, which allows superior combustion and less unburned fuel.

[Jordan_Ciaramitaro]

Probably more accurate, my theory is just that and I have no data or information to support it.

Thanks for explaining! Let's see if the OP confirms he does not have an EXUP valve as well.

[Jordan_Ciaramitaro]

Got home from work and could not stop thinking about this so i tried to fit the R1 EXUP converter assembly I had and it is just too large. It's from a 2015 model which has a much smaller engine physically than old dinosaur.

So I cut the EXUP valve off and welded it on the end as an experiment, just in case it didn't work out I could restore the d&d system.

All I can say is wow, what a difference. It's so smooth and quiet now until you get into it then it becomes a monster. I used the R1 can which is essentially just an asthetic pipe as all of the muffler assembly is housed in the converter. At wot it's actually significantly louder than the d&d, but at idle and low speed it's quieter than my Suzuki gz250. I love it, it's like a sleeper!

The off idle acceleration is much better now, not perfect likely due to the R1 carbs needle profile. The mid range is epic.

Also did a bunch of research and learned that Dontz125 is spot on with his EXUP operation explanation.

Here is a quick photos, remember this is just proof of concept, I can make it all pretty later.

Additionally I found my throttle cables are contributing significantly to my hanging throttle.

I hope this information helps the OP, not trying to hijack the thread.

[noodlemonkey]

Thanks Jordan_Ciaramitaro - Your help and input is greatly appreciated - My bike isn't running an EXUP valve and is running an aftermarket Camshaft - but not sure on the specs - previous owner was supposed to get me the information but never did - might be worth another phone call,

Okay - Just on a quick update - Been away on business and finally managed to get back to the bike yesterday afternoon,

I placed the carbs back on the bike yesterday after taking them off once again to check and see what was happening - also to double triple check everything - I removed the full emulsion tube section including the plastic housing. If you look from the bottom where it sticks out of the bowl and up towards to top of the emulsion tube - they look pretty spot on in terms of round-ness, which I'm happy with.

Onwards - I primed the system with fuel and carb no.3 the problematic cylinder started overflowing as the pump didn't stop priming - upon closer inspection it was just dumping fuel from everywhere, needless to say - I took the bowl off whilst still on the bike and just randomly decreased the height of the float - to close earlier.

Got the bike running and by checking with a water spray bottle on the exhaust pipes - I could see that cylinder no.3 was still dead - I continued to richen up the adjustment screw and by about 4turns cylinder no.3 was alive and producing heat the same as the others.

So now what i;ve done is mimic the float height and adjustment settings to all the other carbs - Will try that out later and see what happens,

Stay tuned - Making progress here...

[noodlemonkey]

I need some insight here - If my valve clearances are out in terms of just slightly - how would it effect the bike? hard starting? over fueling? spluttering? because I know mine are out slightly - just need to know what I'm dealing with.

[noodlemonkey]

another quick question - If its running rich with only 1.5 turns out on the adjustment screw - how can I lean it up some more? lift the slide needles? lift the float more? or is this a direct showing that my emulsion tubes are worn?

Thanks in advance.

[Jordan_Ciaramitaro]

Excellent!

Really it depends on specifically where it is rich at. If it is across the board, I would adjust float height first. If it is grossly rich at wot, may need a smaller main.

Assuming it's with the off idle low rpm acceleration. In my experience with these carbs, it's a fine balance between lowering the floats( increasing the gap between float and carb body) and needle height. Lowering the needle will slightly affect the off idle mixture and so will the float height. Do the float height 1mm at a time, I know it sux but once it's done it's done.

Something I have been considering is the needle diaphragm spring. Maybe a spacer or stiffer replacement spring. The slides on this bike open way sooner than on the Ducati.

It would be really neat to have an adjustable spring tensioner on the outside of the cup......hmmm

[noodlemonkey]

okay - so update time,

I got the bike out and it started up easier than ever before without the choke - meaning its still running rich - after letting it run for a bit, I tried twisting the throttle and it immediately does nothing - although if i slowly open the throttle it starts to climb, but then shoots up to 3K rpm and sits there and doesn't come down for at least 10seconds - meaning - once again - running extremely rich - So I've lowered the slide needle to the highest clip point and will try again.

Also - my float heights are set to 16mm with the valve springs compressed - so technically add roughly 4mm for the spring and it sits at 20mm - trying to lean it out as much as possible - nothing seems to work - Grrrrr

Here are what my plugs look like - very dark and sooty,