Sounds rough, starts rough, feels rough.

Moderator: Moderators

Post Reply
Michael Kara
Posts: 18
Joined: Mon Dec 16, 2019 12:24 pm
My Bike: ZXR 400 L7

Sounds rough, starts rough, feels rough.

Post by Michael Kara » Tue Dec 17, 2019 5:46 pm

Hello folks.

I recently purchased a L7 without doing much checkup beforehand. Naturaly a few things have appeared over my short period of use.
When cold:
(Oil light does not eluminate when the ignition is on on)
-Starts without choke. On choke it wont start at all.
-Sounds like its running on 3 cylinders
-Used to start off the button. Now it needs a blip of throttle as when I press the button to bring her to life. When I press the button I hear a "click" and nothing else.
-Idle's at 1200 rpm, then drops to 800 and dies unless I keep the bike around 1,2-1,5 rpm.
-Black smoke comes out of the exhaust(made a real mess of my white garage door).


When warm and on the road:
-Idles at about 1,2k rpm.
-Feels lumpy.Sounds like its running on 3 cylinders. After 8-9k rpm it comes alive.
-Feels like having a gap at about 5-7k rpm.


From what I've gathered so far reading here:
-The bike's running rich.
-Possibly weak battery.
-Fouled spark plugs.

Am I in the right direction?

Will take her to a friends garage tomorrow and strip her down. I am low on cash untill the begining of next month so I'm working on a budget at the moment.


Cheers,
Michael

User avatar
banner001
Track day God
Track day God
Posts: 2439
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Sounds rough, starts rough, feels rough.

Post by banner001 » Tue Dec 17, 2019 11:23 pm

Hi, definitely sounds like its running rich (needs no choke to fire up, wont fire with choke)

I would say put the battery on charge, get new plugs and oil.

I know the bike has a strange aftermarket exhaust, i would also look to see what air filter you are using, any modifications to the airbox, and if possible remove the carbs and take notes of the float heights, main jets, take photos of the needles, and see what all of your pilot screws are set to.

As for the "gap at 5-7k rpm" try to apply the choke the next time the bike gets to this area and see if the bike feels better or worse when in this range.

Personally - and its a guess at the moment, i would think they have put in larger jets to accomodate for the larger (possibly off a 600cc bike) exhaust and pipes, and not done anything with the pilot screws/float heights - hence the bike is rich everywhere.

What you really need is a visit to a dyno, but in the meantime just record the carb settings so you can always go back to this current state if anything goes wrong.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

Michael Kara
Posts: 18
Joined: Mon Dec 16, 2019 12:24 pm
My Bike: ZXR 400 L7

Re: Sounds rough, starts rough, feels rough.

Post by Michael Kara » Wed Dec 18, 2019 9:30 am

Thank you Banner.

Going to fire her up soon and head to the garage. Will update as soon as I have news.

In the meantime I'm trying to find the phone of the owner that did the exhaust swap, ask him a few things about what he's done to the bike.

Wouldn't be completely surprised if he never got it to run as it should. In which case we'll have to improvise quite a bit.

Cheers, Michael

Michael Kara
Posts: 18
Joined: Mon Dec 16, 2019 12:24 pm
My Bike: ZXR 400 L7

Re: Sounds rough, starts rough, feels rough.

Post by Michael Kara » Fri Dec 20, 2019 9:44 am

Greetings.


Quick update.

The bike has the stock filter setup but it is in terrible shape and need immediate replacement.

Sparkplugs where completely black. Gotta get some of those as well.

Upon doing some road testing, the bike would clog up when on full throttle at high rpm, something it didn't do before.

Will the bike stop running that rich after I change the air filter?
Kinda worried I might put the new plugs in and have them in the same sorry state in no time.

The bike runs on Shell V power+Redex fuel enhancer and 10w40 Motul 300v.

In the meantime, where should I order a new air filter/sparkplugs from? I can try ebay, but is there a seller you trust/prefer?

Cheers.
Michael.

Michael Kara
Posts: 18
Joined: Mon Dec 16, 2019 12:24 pm
My Bike: ZXR 400 L7

Re: Sounds rough, starts rough, feels rough.

Post by Michael Kara » Fri Dec 20, 2019 8:44 pm

P.S

Would you recommend any specific air filter? (Pipecross, K&N, stock setup).

Since the bike is running rich already, would it make sense to try a more free flowing air filter if the plugs don't fix the issue or tinker with the mixture instead?

Not intrested in making tons of power, I just want it to work right and sound healthy.

Cheers,
Michael

Andy400
Posts: 4
Joined: Sun Jan 05, 2020 10:01 am
My Bike: Zxr400 l9

Re: Sounds rough, starts rough, feels rough.

Post by Andy400 » Sun Jan 05, 2020 1:13 pm

Hi did you have any lunch? I have l9 someone change to titanium beet exhaust. Runs badly up to about 4k but pulls through and accelerates well have been told it might be unfixable but no one seems to know

Andy400
Posts: 4
Joined: Sun Jan 05, 2020 10:01 am
My Bike: Zxr400 l9

Re: Sounds rough, starts rough, feels rough.

Post by Andy400 » Sun Jan 05, 2020 1:13 pm

Sorry meant luck not lunch. Bad typing

User avatar
banner001
Track day God
Track day God
Posts: 2439
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Sounds rough, starts rough, feels rough.

Post by banner001 » Sun Jan 05, 2020 2:22 pm

If its rich on idle there are only 2 real things you can do.

Option 1 - screw all of your pilot adjuster screws 1/2 turn clockwise, this will limit the flow of fuel on startup/idle, if it makes no difference then give it another 1/4 turn and keep doing this until the bike fires up from cold with the choke and then idles better when warm.

Option 2 - raise the height of the fuel floats by 1-2 mm, this has the effect of allowing less fuel to be present in the fuel bowl so less can be pulled through by the engine. This will lean out all of the bike though, not just idle.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

Andy400
Posts: 4
Joined: Sun Jan 05, 2020 10:01 am
My Bike: Zxr400 l9

Re: Sounds rough, starts rough, feels rough.

Post by Andy400 » Sun Jan 05, 2020 2:55 pm

Cheers I'm no mechanic I have to keep taking to garage it's going for dyno check next week but I'm considering trying to get an original exhaust as they told me this titanium beet is prob what's causing problem and I dont know any better

User avatar
banner001
Track day God
Track day God
Posts: 2439
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Sounds rough, starts rough, feels rough.

Post by banner001 » Sun Jan 05, 2020 8:36 pm

Smart move, a dyno is going to cost you £60 or so, make sure that they do proper roll ons, so 1/8 throttle, 1/4 throttle, 1/2 throttle and then full throttle, that way it can be diagnosed properly.

This is because when you wind the throttle you allow the engine to develop vacuum at different rates and with a different final amount (kinda), its not a fuel injected bike, or on flatslides, the fuelling is controlled by engine vacuum which is somewhat related to throttle position.

Post the results on here and we can see if what the garage is saying seems to add up.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

Andy400
Posts: 4
Joined: Sun Jan 05, 2020 10:01 am
My Bike: Zxr400 l9

Re: Sounds rough, starts rough, feels rough.

Post by Andy400 » Mon Jan 06, 2020 8:26 am

Cheers I will do I've not long had the bike and I think the guy has mugged me off because I'm not mechanical and he knew due to my height I liked the bike

Michael Kara
Posts: 18
Joined: Mon Dec 16, 2019 12:24 pm
My Bike: ZXR 400 L7

Re: Sounds rough, starts rough, feels rough.

Post by Michael Kara » Sun Jan 12, 2020 8:39 pm

Hello again guys.

Quick update.

Have only changed oil and plugs so far. Been working overtime day in day out(hotels have that during holiday season).

I want to get a new air filter but I'm unsure on which one to order. I don't want to mess with the carbs before getting the new air filter in.
I'm thinking it might solve my bike running rich without having to mess with the carbs.

In the meantime, the bike still sounds uncoordinated at idle.
If I don't fire up the bike every couple of days she's a real b@tch to start(takes about 5-10 minutes).
Last time she wouldn't fire without choke. Fired only on full choke and throttle blip, then revved super high to 4k and then cut out.
Started her again, without choke maintained 1,6k revs myself untill she got warmed up. If I touched the choke at all the bike would cut out again.
White smoke would come out the back during start up, but it dissapears once the bike is warm.
Temperatures where around 2-4 degrees.

Once warm she runs better.
Bike runs on Shell V power and Redex fuel cleaner.

Cheers.

User avatar
banner001
Track day God
Track day God
Posts: 2439
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Sounds rough, starts rough, feels rough.

Post by banner001 » Sun Jan 12, 2020 10:20 pm

To be honest I doubt an air filter is going to make a vast amount of difference, stock kawasaki foam is fine, or you can go with a k&n.

I don't really trust any of these "free flowing air filters" claims as I've never seen one tested with a bikes amount of engine vacuum... I might have to make an experimental setup one day
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003

Post Reply