ZX9r running prob with main ram air scoops removed

[cammy9r]

All my test rides were round town and on the motoway at about 70-80mph and the bike accelerates well through the gears. So i thought it was all good. Re-torqued the bolts and then had the confidence to take the bike to hyper speeds, but yesterday i did notice something wrong with the power output of the bike while out for a run. The problem is the bike was struggling to get over 89mph while in 6th gear. The other day it did well over this when moving up through the gears. I have a feeling it is something to do with the pipe that goes into the carbs from the front of the air scoop. I had the pipe at the front of the bike and it ran very poorly especially when opening up the throttle, there was just no power. Max speed 60mph and that was a struggle.

So i put the pipe at the intake hole on the right side as this is where the carb intake is; with the reasoning that it it now in a similar place as the original set up, just further back. After doing this the bike seemed to be running great accelerating hard when i opened the throttle. But doing 50-60mph in top and rolling on the throttle the bike lays back if it is running out of fuel, top speed was 114mph after dropping 2 gears and working them back up
On another thought, if the tank was vapour locking would it cause the same running problem when opening up the throttle. So i took the bike out on the road with the fuel cap open to check if it was still the same....it was. So i assume the tank is not vapour locking.

The carbs have not been altered ( i did re balance them ) since the bike was put of the road and it ran very well before.
Have any of you guys experienced major power loss with the removal of the ram air on your bikes and with a shorty can? I was thinking of tapping the ram air stuff back on and going back out for a test run to see if it makes a difference. If there is no difference then i will suspect a problem with the carbs, would this be right?
:(
Any help on the matter?

[Foxy]

I have a mate with the same problem with a thunder cat.
I'm suspecting it is the same problem you are having.
My best guess is the ram air system.
Its a hard one to fix, but you will find that rather than it running out of fuel, you are probably running too lean.
You'll need to fab up something to prevent too much airflow into the air intake.
With the kat the frame was modified and coke bottle tops placed in the air intakes to prevent too much air from getting in, its still splutters a little and a rejet wouldn't go astray.

you probly have paint in your spark plugs.[:o)]
but on a more serious note,there was a topic about removing ram air tubes a while ago,I think Exben said that he'd experienced no probs by doing this but someone else did have probs.i'll see if i can find that topic for ya.in the mean time you should see if you can find a Suzuki:D

[EXBEN]

Nah forget the Suzi thats bad advice.:D
I have no probs running without the ram air ( Same motor too)
Have you checked/ Replaced the filter, checked the pump, & the mini filter in the tank. Sounds like you may be running outa fuel flow in top gear, whereas if you run up through the gears it gives the pump a chance to replenish the float bowls enough.

[Foxy]

Hey Ben, would it be the same case for the YZF? The thing runs fine when the fairings are on, but when there off it splutters and struggle at 100k's

[EXBEN]

Sounds like it needs bigger main jets,has it been rejetted.
Has it got a free flowing exhaust & air filter,if so It will more than likely need a rejet. I had to change my needles & go up 4 sizes in mains ,but I've also got a diferent airbox.

[cammy9r]

Thanks for the replies guys, will keep posted any improvements on my bike probs

[cammy9r]

http://www.streetfighters.com.au/forum/upload/13495411945141.jpg

Done this to the bike yesterday and took it out for a blast and it went like a rocket, even in top gear no hesitation.

I think i will try to make up a scoop that sits directly facing the air flow as opposed to the sitting at an angle like it is just now.
Perhaps it is turbulance disrupting air flow or maybe the angle of the frame is causing some kind of venturi effect and sooking the air out of the standard airbox. Will feck around with it some more and see. I never expected it to perform as well as when it was faired up with the proper ducting, lets face it Kwak put it there for a reason. But i still want some good performance

[EXBEN]

Or you could just try rejetting.

[cammy9r]

Suppose your right there Ben, but the bike ran well before hand and the carbs were never touched so the problem has to lay with some other modification that i did. The biggest of which was the semi removal of the ram air system. So my aim was to get this sorted out first then dabble with the carbs; to which my knowledge is limited and would have to do lots of research. I was given this link by someone and it helped a good bit.

http://sportrider.com/tech/146_9910_ram/

I might have known that the very bike I decided to tear apart would be the world leader in ram air design.

Anyway, after reading that and some others I started modding the air scoops to get the best performance (that I could feel). Now the scoops face directly into the air flow and I gave them a tapered front to increase the intake area. It is now just a little lower in area than the scoops under the headlights. I also fitted both equaliser pipes and placed them into the modded scoops at the same angle. Took the bike out to my local test strip and gave it a blast through the gears. It accelerated like I remember it did and I liked it .
so now for the roll on test in 6th gear from 50. Pick up was slowish as expected. At 70 it started to pull, at 80 it pulled harder all the way through the ton up to a ton forty at which point it was getting difficult to hold on and FEEL in control. I backed off the throttle a little than opened it up again; there was a slight splutter/cough from the bike then it soared of down the track. I am pretty happy with performance now so will run it as it is and see how the bike goes.
It is never going to be as good as a 9 with fairings/ram air at higher speeds (perhaps with some pro tuning it could be) but that’s something I can live with. Might even drop a tooth from the front or add at rear if there’s room between chain and hugger. This should give me a little more oomph low down so I can play better with the bikes new speed band.

A bike on a dyno doing 150mph is not affected by ram air or high pressure winds, the air box I assume will have a negative charge (vacuum, that being lower than atmospheric pressure).
If I was to put my bike on a dyno I have no doubts that it would give a good enough power/torque reading. BUT out on the open road with no proper air scoops and badly positioned equalisers the bike as struggling because of the effect of the fast air flow around me. You see there was a good chance that the air box was not getting a positive charge but the float bowls were causing the bike to over fuel and run out of power.
Here is what I think was wrong. The intake pipes were at a bad angle at low speed the engine was soaking in the air with no probs but at higher speeds the air flow around the bike was creating a vacuum like situation (meaning only a pressure difference) in the air box. While revving hard through the gears the engine has quite a high induction, I believe it was high enough to over come the effect caused by the air flow hence the bike accelerated like a rocket. However at low speed and top gear the engine has lower induction and cannot pull in the air it needs as it weaker than this venturi effect, the result being over fuelling and dramatic power loss.
Again this is what I believe was happening based on observation and a bloody good think/research.
Good thing is the bike seems to be cured although the top end rush is no longer there; that being 140 + mph. However these speeds are not really a factor on a road bike.

Thanks for all the input you have given me guys it's good to get help once in a while.

[cammy9r]

http://www.streetfighters.com.au/forum/upload/69337566446152.jpg

http://www.streetfighters.com.au/forum/upload/69337566442288.jpg

This is the final set up for the scoops although i will have to try and make them a good bit neater later on. Someone said it reminded them of the ram air scoops on the triumph speed four. Going to take it out for a longer ride today see how it goes.

hey Cammy nice bike, being following its progress for ages now...i had exactly the same problem with my 2000 zx9 that i fightered. Simply could not work it out.

But had the realisation that the ram air is causing the problem...so instead of trimming down the existing ducts like yours, i removed them altogether...however this now caused the same thing but at higher constant speeds.

So my set up now -and its been working well- is that ive put a piece of cardboard behind the frame holes (but not blocking the air box)...ill take some photos tomorrow in daylight. However eventually im gonna make some dirt-bike style rad side covers that will cover over the frame holes (limiting the airflow).

From my limited understanding is that it was creating a sort of imbalance in the vacuumm for the scoops and the equaliser pipes, which causes the loss of power.

[cammy9r]

http://www.streetfighters.com.au/forum/upload/7394068544312.jpg


I know this is really late but is has cleared all the probs i was having with the ram air issue. The float bowl equalising pipe has been re routed to the top clean filtered side of the air box by using some 90* alu tube and some straight bits. I poked it through the air filter and now the bowls will always be equal to the air box. It has ran with no faults or hesitation for nearly 1 year now. The mod is from a zx7rr race forum and has been tested with great results for them. Maybe it will help others with a similar problem.

[Hillsy]

Yeah - two thumbs up for that mod Cammy. It worked on my 9 as well. I've also done the crankcase breather mod to the Kleen intakes. Take all the Kleen shit off until you have 2 pipes sticking out of the rocker cover, join with a "T" piece (I used a 19MM black plastic irrigation "T" piece from my local hardware) and connect to the crankcase breather. Keeps the crankcase in a constant vacuum which helps it spin up easier and gives more power up top.

[cutcat]

Cammy, just a quick question with regard to the balancing pipe you ran through the air filter. Instead of going through the air filter element can you simply run the hose up the side of the air box to the lid and join in there??

[cammy9r]

NOoooo

Only joking :D, i see no reason why you can't do that. as long as it is on the filtered air side it should be no problem.
Make sure you have clearance between the tank and the air box though.
Let us all know how you get on.

[cutcat]

Geeez, don't scare me like that!
I asked this question just now on my other topic.....what is all the gear on the rocker cover for and how does it work?????

[cammy9r]

i gave a quick answer on your other topic cutcat

So we are talking KLX110 are we not[?]seems to me that ya dont listen to wot any of us say & asume that ya bike is actually a ZEEx9 or somewot & so that ya bike is not working at all[?]
Trick test ride though[^]

[cammy9r]

quote:Originally posted by mad mundy

So we are talking KLX110 are we not[?]seems to me that ya dont listen to wot any of us say & asume that ya bike is actually a ZEEx9 or somewot & so that ya bike is not working at all[?]
Trick test ride though[^]


really no idea what your talking about but the test run did get me some strange looks from some other bikers.

[Loz]

Wow nice one this appears to solve my first problem right away. Any further details Cammy?

By the way, STUNNING bike, I just looked through your build gallery. Phaaaaark.

[Loz]

Just did a cack-handed version of this mod on the Minja2 and am happy to report it basically did what it says on the box. Bike now runs without surging on the freeway although it's clearly in need of a re-jet and tune. Thanks Cammy!

For future reference, in case anybody else wants to 'fighter a ZX9 or other ram air-equipped Ninja, there's more information at these sites:
http://www.factorypro.com/Prod_Pages/prodk51.html
http://homepage.ntlworld.com/webzxr/zxr750r/Features/ventbowl.html
http://homepage.ntlworld.com/webzxr/zxr750r/Features/ken/ram_air_carbs.html

I might also put up a few pics one of these days showing exactly how I went about it step by step.

[cutcat]

Hey Loz, good to hear you're up and running. Look forward to some pics.
As for my ZX7R, with a K&N air filter and a Yoshi muffler, with the above mods made...a Dynajet kit was just the thing to solve my jetting probs. She'e maybe a whisker rich still but way fast.

[bond12221]

hey guys, i just stumbled upon this forum and its exactly the problem im having, going through the gears its good untill i start to cruise at 100 then it start to cut in and out, ive got a zx6r with the air intakes removed (it is a streetfighter) my mechanic saysits running to lean and to put a piece of foam over the air filter to restrict air flow, any other suggestion from anyone??

[Hillsy]

quote:Originally posted by bond12221

hey guys, i just stumbled upon this forum and its exactly the problem im having, going through the gears its good untill i start to cruise at 100 then it start to cut in and out, ive got a zx6r with the air intakes removed (it is a streetfighter) my mechanic saysits running to lean and to put a piece of foam over the air filter to restrict air flow, any other suggestion from anyone??


Do the mod that links your balance pipe into the airbox and see how it runs (you'll most likely find it is still lean).
If it's still not running right, re-jetting is the answer. Restricting the air flow will work - but it will also restrict your power.

[bond12221]

hanks hillsy

ive actually had the bike rejetted only 2 weeks ago but the mechanic must not hae tested it at high speeds, cant afford to get it re jetted again so might just cover the air filter with foam, untill then can anyone tell me if im doing the bike any damage by running the bike lean, at cruising speeds and when i twist the throttle (the ptorblem only happens when im cruising, when i twist the throttle all the way it goes like a rocket)

[Loz]

Arr shit you shouldn't have had it jetted, the problem is with the balance of pressure between the airbox and the carb float bowls. It's exactly what was happening with my ZX9 before I did the mod described above. Once you've done the airbox mod, it's time to look at re-jetting.

My pics of the airbox hack - this is on a 1994-1997 B model ZX9R:

The two bendy tubes coming from the carbs up and out through the frame holes to the front of the bike are the float bowl pressurisation tubes. Not sure if they're the same on a ZX6, I know the ZX7s are slightly different. There'll be something though.
http://lh4.google.com/lozzobear/Rtt16wvh-aI/AAAAAAAABTU/SVsNwbXNLTc/s800/IMG_1364.jpg

Using a $2 copper t-junction from bunnings, I've cut and joined the two float bowl pressurisaton tubes. I've then stuck another straight bit of cut-off tube so it points up through where the airbox will be. I left it long so I could cut it down when I knew how much it should poke out:
http://lh3.google.com/lozzobear/Rtt17gvh-bI/AAAAAAAABTc/nZjIrUrczUA/s800/IMG_1466.jpg

Re-fit the airbox and locate roughly where you'll need to drill it, then go for it. I tried to make the hole a bee's dick smaller than the tube diameter, to keep the airbox sealed. I failed. You might succeed. Please note scratch trail where ham-fisted drill user has lost control and wandered off down the airbox:
http://lh6.google.com/lozzobear/Rtt1-Qvh-eI/AAAAAAAABT0/lf7k48ge57M/s800/IMG_1469.jpg

Drill the filter next - it's very flexy so you can make a fairly small hole. You definately want this bit to be airtight. Fit the airbox with the tube up through it, then fit the filter and poke the tube through. Cut off the excess length so the cover will fit back on, and voila, there you go. The bike should now run without any surging at high speeds - although the jetting will need some adjustment to match the new airbox behaviour.
http://lh6.google.com/lozzobear/Rtt19Qvh-dI/AAAAAAAABTs/x7qEM5My1VQ/s800/IMG_1468.jpg

[bond12221]

faaaark that looks way too complicated for me (im mechanically challened) thanks for the info though

would blocking off one of the air intakes work or like i said before putting a piece of foam over the airfilter??

also am i doing damage to the bike as it is with the problem at the moment?? cheers

[Loz]

Dunno if you're doing any damage at the moment. But this is a piece of piss to do, "mechanically challenged" is my middle name. Get yourself a workshop manual for your bike (easy to find on the web) and dive in buddy, don't be afraid! This isn't a delicate bit of engine work, it's tubes and plastic.

[bond12221]

hey again guys, well i thik ive sorted the problem with the zx6r. it was running way lean like i mentioned before so i put a piece of foam over the air filter and it made it better but not a 100% so i put a second piece over the top and now the problems seems to be mostly sorted. i can do 110 without too much lag and it has also seemed to smooth out the power down low. as far as i can tell i havent lost any ponies so thats good news (was gonna inc pics of the procedure but i put the airbox cover back on after realising to take a pic)

thnks to everyone (especially loz) for the generous info. cheers

[cammy9r]

quote:Originally posted by Loz

Wow nice one this appears to solve my first problem right away. Any further details Cammy?

By the way, STUNNING bike, I just looked through your build gallery. Phaaaaark.


Sorry for not replying, haven't been on the site for a while. Seems like you have got it in hand though. Some good links too. I am happy that this thread has helped.

[Taipan]

Hi All

My bike is having major problems and I can't seem to cure it? Mine has the tubes sticking through the frame and the float bowl breather tubes vented into the airbox as seen above.

The bike starts, idles and revs fine, but if you ride down the motorway at approx 70mph for a few miles then when you exit and ride round town she runs really lumpy, like on or even 2 cylinders?

I have to find some room to thrash it a few times and then its as if its sucked the fuel through and then its fine. If I just ride round town all day she's as good as gold, but motorway use kills it?

I can't see how my set up is any different to other peoples, except maybe my scoops? Perhaps the wind is not entering the scoops but passing it and creating a vacuum and this is causing the fuel starvation? But if that was the case wouldn't it equalise if say I was sat at a red light, which it doesn't?

Thought? Ideas? Opinions? Anything gratefully recieved as this is driving me mad!

Many thanks

[Taipan]

Cammy, looking through your pictures of your build, are your scoops custom made or are they the full standard ram air scoops cut down?
Many thanks

[joe.d]

I guess you know my bike I have a SRAD 750 with a K2 1000 Motor, it used to hit a wall at 10.000 rpm 6th was fairly useless, So I used a cold air system from a Ricer car, and kept the intakes as close to the original lengh on my streetfigher, and it solved to problem, some people say Hmmmm, air intakes dont make no differance, I say BS. I guess suzuki put them on the gixers for a reason.

anyhow here they are.
http://members.shaw.ca/britjoe/august28.jpg

[2ndclasscitizen]

quote:Originally posted by Loz

Arr shit you shouldn't have had it jetted, the problem is with the balance of pressure between the airbox and the carb float bowls. It's exactly what was happening with my ZX9 before I did the mod described above. Once you've done the airbox mod, it's time to look at re-jetting.

My pics of the airbox hack - this is on a 1994-1997 B model ZX9R:

The two bendy tubes coming from the carbs up and out through the frame holes to the front of the bike are the float bowl pressurisation tubes. Not sure if they're the same on a ZX6, I know the ZX7s are slightly different. There'll be something though.
http://lh4.google.com/lozzobear/Rtt16wvh-aI/AAAAAAAABTU/SVsNwbXNLTc/s800/IMG_1364.jpg

Using a $2 copper t-junction from bunnings, I've cut and joined the two float bowl pressurisaton tubes. I've then stuck another straight bit of cut-off tube so it points up through where the airbox will be. I left it long so I could cut it down when I knew how much it should poke out:


Re-fit the airbox and locate roughly where you'll need to drill it, then go for it. I tried to make the hole a bee's dick smaller than the tube diameter, to keep the airbox sealed. I failed. You might succeed. Please note scratch trail where ham-fisted drill user has lost control and wandered off down the airbox:


Drill the filter next - it's very flexy so you can make a fairly small hole. You definately want this bit to be airtight. Fit the airbox with the tube up through it, then fit the filter and poke the tube through. Cut off the excess length so the cover will fit back on, and voila, there you go. The bike should now run without any surging at high speeds - although the jetting will need some adjustment to match the new airbox behaviour.

As an add-on to this, it works with G-series 6R's. On the 6R, there's a small black hard plastic tube coming from the floats with a tube of it (instead of the 2 tubes coming straight from the floats.) I drilled through the side below the filter, and now have the tube poked up through the filter. I think it would probably be better to drill through the airbox lid and direct it through there, but not sure of the clearance.

[Taipan]

I did this mod on my ZX9 C1 and it resolved all issues. The only problem I was left with was carb icing, but I suspect thats not a problem many Aussies incur!;):D

[Lucas]

quote:Originally posted by Taipan

I did this mod on my ZX9 C1 and it resolved all issues. The only problem I was left with was carb icing, but I suspect thats not a problem many Aussies incur!;):D


2ndclass may get that problem in Canberra. It does get a little chilly here/