View Full Version : ZX9R Running pretty rough
Hey everyone.
My 2000 ZX9R E1 is running pretty rough at the moment, especially in the just off idle throttle range. It is constantly surging and almost feels as though it's missing as well but as soon as you give it some more throttle it smooths out.
I've changed the plugs, reset the fuel mixtures, pulled the carbs and cleaned all the jets. All looks ok to me. The inside of the carbs were basically spotless, they should be as I had them sonically cleaned at the start of the year. Valve clearances were also done at the start of year and have maybe 4000 miles on them since then. (All were out of spec back then)
I will be doing a carb sync over the weekend but just wondered if anyone had any ideas? I don't really want to pay for a garage to sort it out when I think I've got all the tools needed.
Thanks
I'd start by balancing the carbs and checking the throttle position sensor. Hopefully this will help.
Jambo
Sent without a real keyboard
How would I check the TPS? Haven't got my haynes handy at the moment. I had to unplug it the other day when removing the carbs but didn't think much of it at the time.
You'll need a workshop manual or Haynes as you'll be aiming to adjust it to a given value. I've got a Haynes for the zx6 and kawasaki love to reuse parts but I think it's best done from the correct book :-)
Jambo
Sent without a real keyboard
yorkie_chris
30-10-13, 02:59 PM
arent the old 9Rs carbed?
I'd clean the carbs and balance and fit new plugs, maybe air filter. General fettling :)
Sid Squid
30-10-13, 04:02 PM
The 9R has carbs and a TPS, which, unsurprisingly, is a potentiometer. It's set by measuring the output voltage in exactly the same way as the 6R of the same vintage, however I'm not certain of the setting voltage. I can say that they rarely go out of adjustment, but it it isn't running right it's easily checked.
Unless it's way off I doubt it's the fault though - I've never tried with a 900 but the 600 will run OK even if it's disconnected.
The carbs have been cleaned and all jets were clear. Valves and air filter were done maybe 3 - 4000 miles ago. Plugs were changed after that so have even less miles on them. All I can think of is maybe a carb sync and checking the TPS.
It surges when the throttle is only slightly open at any rpm but most noticeable at low rpms. Almost to point where it's actually impossible to keep a steady speed.
wideguy
30-10-13, 10:55 PM
I'm thinking I'd try a compression test.
Once you give it a little more throttle it's fine and pulls strong. It also hasn't burnt any oil since it's last oil change ~2 - 3000 miles ago and some days seem worse than others.
wideguy
31-10-13, 02:33 PM
How were the idle mixtures set after the carb cleaning? Have you looked at the plugs after a short period idling after warm up?
All screws were set to 2 1/2 turns. I've tried adjusting them to stock 1 1/2, 1 3/4, 1 7/8 and now 2 with little difference.
yorkie_chris
01-11-13, 11:18 AM
Surging is lean on pilots or air leak somewhere... or maybe very severe imbalance
wideguy
01-11-13, 12:51 PM
Because of normal manufacturing variances, the only way to correctly set the idle mixture is by reading the plugs. A quick look will also show you where an intake leak might be, as it would give you a very lean looking plug. Old intake boots get hard, making it sometimes very difficult to get them re-sealed when re-installing carbs.
Like Chris said, out of balance carbs could be the problem too, but it's best to have the idle mixtures all set right before balancing.
With the idle mixture screws at 1 1/2 (stock) is was popping quite a bit on decel. Most people recommend setting them at 2 so I have and all plugs are the same tan brown colour with no deposits or anything to suggest flooding or running too lean.
I'm going to pull all the needles out and check the diaphragms to see if they are ok as well.
Ninthbike
03-11-13, 10:39 AM
With the idle mixture screws at 1 1/2 (stock) is was popping quite a bit on decel. Most people recommend setting them at 2 so I have and all plugs are the same tan brown colour with no deposits or anything to suggest flooding or running too lean.
I'm going to pull all the needles out and check the diaphragms to see if they are ok as well.
This would be my next move. Diaphragms may be split or poorly seated.
Any tips on how to properly seat the diaphragms? I've checked one the other day before it started to rain and found it pretty hard to re-seat. Is red rubber grease, oil or something similar worth smearing around the edges to help it stay in position?
It hadn't shrank. It just didn't want to stay seated if you slightly pushed the needle up the whole diaphragm would pop up.
Matt-EUC
03-11-13, 12:27 PM
My 2000 ZX9R E1 is running pretty rough
Have you tried sandpaper?
wideguy
03-11-13, 01:04 PM
Once you screw the top caps on, the diaphragms are held in place. A little grease to keep them seated until the top caps are on is fine, if you need it.
I've been thinking about the bike prior to the ultrsonic carb cleaning.. were the carbs gunked up badly? Was the bike run with the carbs gunked up badly?
My first thought when I read your original post was of a Pratt & Whitney R-2800 radial I worked on years ago. The flight engineer had got behind on his mixture control settings, ran the engine lean long enough to partially melt the exhaust valves. The resulting symptom, written up by the pilot, was, "Engine lopes at idle." The engine otherwise ran very well, and would actually still make take off power at full throttle.
Hence, my thought of doing a compression test.
I'm stumped for any other ideas.
When I first bought it, it ran sort of ok but then started to run rough. Shortly after, not sure how many miles, I got it booked in for a full service.
The Air filter was really bad so had that changed.
Almost all valve clearances were out of spec.
All the mixture screws were set differently, but mostly set too rich.
Carbs had some gunk in them from being stood for 5 - 6 months before I bought it but were cleaned.
All was sorted in the service and the carbs still looked spotless when I removed the float bowls the other week. I've never had any overheating problems and it's never failed to start or idle. It just idles rough and doesn't like being run at just off idle throttle.
I'm about to go a check all the diaphragms, TPS and do a carb sync today whilst the sun is out and I'll let you know what I find. If this doesn't sort it I think I'll have to do a compression test.
wideguy
03-11-13, 01:49 PM
Well, from what you say, it probably doesn't have any problems not solvable by carb sync and TPS setting.
yorkie_chris
03-11-13, 05:08 PM
The TPS does next to bugger all on these sort carby engines, not enough to make it surge
Checked all the carb diaphragms and they are all fine.
Hooked up my Morgan Cabrtune and carbs were way out of sync. Both sets took almost a full turn on the adjuster screws to sync them up.
Now after the sync is was idling really smooth at 2000rpm. When I lowered it down to 1100rpm it still sounded smooth but now it pulses between 1100 - 1300. It's not random, it pulses every 0.5 - 1 second consistently. I still had the carbtune hooked up and even on there it showed all 4 gauges pulsing up and down in unison.
Any ideas on what could cause this?
Think I might disconnect the TPS and start the bike, see if it still pulses. Other than that I'm lost.
Also one of the previous owners installed a gear indicator but this hasn't properly worked since I bought the bike. When I start the bike it counts down from 9 to 1 then sits at 1 and doesn't change even when I cycle through the gears. I've followed the wiring and it appears to go to a sensor that is connected near the rear sprocket. Not sure how that will be able to tell what gear I'm in though. Just wondering if this could be somehow causing this problem if it was installed incorrectly shorting out somewhere etc.
wideguy
03-11-13, 09:31 PM
What's wrong with an 1100 rpm idle? I'd run it like that, hoping it would heal with use.
1100 rpm is what it's meant to be. After syncing the carbs the idle went up to 2000 rpm, so I adjusted it back to 1100 rpm and now it surges. But when I adjust the idle back to 2000 rpm it doesn't surge.
I'll see if it continues tomorrow after a proper ride but just wondering what I should look for next if it continues to surge at idle.
I'm thinking that the out of sync carbs were masking the surging. Now that they are in sync the surging is more pronounced which may be the underlying reason for the terrible low speed / throttle running.
wideguy
04-11-13, 12:10 PM
I happened to think of another instance of surging at idle that I ran into years ago. It turned out to be worn throttle linkage which was allowing the throttle plate to flutter. Could be worth looking for something like that.
yorkie_chris
04-11-13, 12:11 PM
Aye that's not unusual but doesn't generally give real problems unless the gob in the shaft is letting air leak in. I fixed quite a few solex carbs on trikes by machining carb body out and fitting a bushing.
Like most others above, my thoughts would be that the idle setting is too lean (or air leak, same effect). If you have an air leak and adjust the idle mixture to compensate than it screws up the pick-up off idle (to rich and the carb itself is set too low at the balanced idle setting).
Now you've balanced the carbs do they respond to idle mixture adjustment?
In my experience there can often be up to 1/4 turn variation in setting between carbs to get the right mixture (if they were identical you wouldn't really need an adjuster). Try each one in turn to verify that they all actually affect the running, you ought to be able to richen and lean off each one enough to make that cylinder effectively stop firing at idle in both directions.
If you have a multimeter with a thermocouple you could do a simple temperature check on each of the header pipes at idle, as close to the head as possible, often a good indicator that they're running more or less the same. I've used a small hardwood stick to hold the T-couple against the pipe before now, it will char after a while but acts as quite a good insulator to get a decently reliable reading.
Just a thought.
yorkie_chris
04-11-13, 03:33 PM
You ever tried an IR thermometer for same thing?
I would if I had one! :D
Home stuff I just use a Fluke DMM with a K-type th-cpl input, for "professional" jobs we use gas temps for combustion stuff, and K-types or PRT's for metal temps.
I'm not sure quite how accurate the thermal imagers are, very good for broad brush surveys of stuff to identify hotspots (switchgear etc) or heat losses in buildings etc, possibly limited usefulness for auto bits and pieces where you need accurate measurements and you usually know where to look anyway. They might be better than I think.
yorkie_chris
04-11-13, 03:59 PM
Guess I'll give it a try. You reckon tickover EGT is accurate enough to set mixtures? Would you expect differences for the inner two pots on a four?
My mate gets like ring-type thermocouples around the spark plug on his microlight, suppose you could have some quite interesting monitoring.
Not really accurate enough on the pipe outside skin I'd suggest. Gas temp might give a significantly better reading.
Most useful aspect from a DIY point of view is just to see if all 4 are running more or less the same, troubleshooting.
Trouble is there could be a variety of reasons for temps to be measurably different, cyl comp ratio, comp pressures reached (leakage), variations in ignition timing, different cooling flow round exh ports etc.
I guess easy way to assess it is to put a th-cpl on one pipe and tweak the mixture rich and lean and see how sensitive it is, you might find it's more useful than I'd expect.
It was a little harder to start this morning. Needed even more choke to idle and didn't like to idle at 1100rpm so had to increase it. Only got 2 minutes down the road and had turn back as I nearly came off twice on roundabouts due to ice.
Will have to get a good look at it at the weekend and try all the things suggested here.
have you thought about investing in a colourtune. i know people are going to say 'crap' 'dont waste your money' etc.etc but i have used one in the past with good results.
another cppl things to consider is the PCV and CPS.
from what you are saying it sounds to me like air is being drawn in from somewhere but i'm stupid so dont listen to me.
oohhh and i use to have a Cortina yeaaaars ago that run like a bag off poo at tickover, turned out to be sticky valves.
I'm pretty certain I don't have an air leak. I've had the carbs off twice and checked all rubber parts which were all fine and it still ran the same afterwards.
The rough tickover and just off idle throttle has been there since before it had a full service, which included doing the valves so I wouldn't have thought it would be sticking valves unless it's something easy to miss. (can't see a garage not trying to get more money out of me for sticking valves)
I'll have to triple check for an air leak and maybe spray some easy start, or what ever it is called, around the carbs to see if the idle changes.
Another thing I forgot to mention is that when warming the bike up on the side stand. If I turn the handle bars from full left lock to center the idle drops. It doesn't matter if it's on the side stand or upright.
Could this be a symptom of a worn throttle linkage as mentioned earlier? or something else.
Biker Biggles
04-11-13, 07:57 PM
Another thing I forgot to mention is that when warming the bike up on the side stand. If I turn the handle bars from full left lock to center the idle drops. It doesn't matter if it's on the side stand or upright.
Could this be a symptom of a worn throttle linkage as mentioned earlier? or something else.
Throttle cable too tight will cause revs to go up and down when moving the bars.There should be a bit of slack in it to allow for movement.
Another thing I forgot to mention is that when warming the bike up on the side stand. If I turn the handle bars from full left lock to center the idle drops. It doesn't matter if it's on the side stand or upright.
Could this be a symptom of a worn throttle linkage as mentioned earlier? or something else.
does it also do it when the bike is warm and the choke is off?
Sid Squid
04-11-13, 08:50 PM
ZX9 throttle cables are fiddly to route correctly, and can cause changing idle speed. I doubt this is the cause of the main problem you're having though. As said above they're probably a dab too tight if the idle speed changes with bar movement.
does it also do it when the bike is warm and the choke is off?
I'm not sure. I'll check next time I'm on it, however I think it might just be when the choke is on.
wideguy
04-11-13, 10:51 PM
Have you actually checked for intakes leaks yet? I've learned to do it first if I have newly installed carbs and idle problems.
I have checked all rubber parts and hoses and all seem fine but I haven't actually tried spraying anything around the carb intakes to see if it effect idle speed.
The throttle response has dramatically improved since the carb sync but the idle has gotten worse so I'm think that I may not have connected something properly as it was dark and I only had a street light to work with when re-assembling everything.
wideguy
06-11-13, 01:52 PM
Even old intake boots soften up when heated, and they do warm up when you run the engine. They often need the clamps re-torqued after running. Repositioning the clamps can often stop a leak (find it first!).
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