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Hey guys... OK long story short, I've been having a stumbling problem since I got the bike a week ago. It's a 1996 zx6e... so I planned on replacing the spark plugs tonight and cleaning the carbs. I follow a write up someone sent me on cleaning the carbs and everything seemed to go ok as far as getting the carbs off... i didnt do a crazy extensive cleaning but i did a decent one. Anyhow, i get everything back together and do the spark plugs and go to start the bike... It starts right up but it's idling at around 4000 rpm and super rough and loud like a dirt bike...

So i think back to a few things that I did that were questionable...

1.) When I went to tighten the rings that hold the carbs on, at one point i thought i was tightening the ring, but i was really tightening another screw RIGHT next to it that is on the carb... It's a small screw with a spring around it. Problem is I don't know how far i turned it and what it is! Here are the best pics of it i could get... the screw driver points to where it is:





2.) I didn't gap the plugs because I didn't have a gap tool where I was at... I know, lazy but every time I've ever checked gap they're always right on so I took the lazy way out... Sure, that could cause a rough running problem, but that wouldn't account for the high idle right?

3.) Are these 2 holes on top and one hose coming out of the airbox supposed to be empty? I didn't notice them until i was reassembling everything and I didn't seem to have any leftover hoses to plug into them....




Please help me out guys, anything will do. As it stands right now, the bike starts right up but just shoots right up to like 4000 rpm at idle and sounds like shit... The idle adjustment screw isn't doing it and the choke doesn't appear to be either... I'm about 90% sure the screw i messed with is what's causing it but I don't know what it is or how I can fix it!
 

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It sounds like your carb sync screw. If that is the case, try turning it the opposite direction as you originally turned with the bike running and continually adjust your idle. Until the bike smooth's out. I would also suggest buying a set of carb sync guages or have a dealer do a carb sync to be sure the butterfly's are operating properly. Also since you've done a carb clean I may advise if you didn't already that you take out the pilot plug and do an idle drop to make your bike run optimally on the bottom-end.
 

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Hi,
I had a look at my carbs this weekend too and can confirm that you have changed the setting of the carb sync screw.
Basically I think it controls the revs/ mix for each individual carb, so that each cylinder is as close to the others as possible. When they are not in sync that is when it runs really rough, since one cylinder is not running as well as or even better than the others. The mismatch causes the rough running. It is quite tricky to get them really EXACT too I have been told, but usually you can get it close enough.
As long as you only moved ONE of those screws you may not have put the settings too far out on the carbs. You could screw it back out as dustinsn says ( since you would have been tightening it in until you realised, right?) Of course you are unlikely to get it back to exactly the setting it was at before using this method. I think that you will have to do a carb balance which requires vacuum gauges if you want it running real smooth.

As a first start though, you could use one of the neighbouring screws as a very rough guide (count how many turns in it is, then unscrew it back out) The one that you mistakenly re-set could be set to this rough ' x turns out' setting to get the bike back up and running so that you can get it checked properly with a garage or if you have gauges yourself you could do the sync..

This link below shows how to do a carb sync if you have gauges yourself.


http://www.themcdonalds.net/richard/bike/zx6r/maint/balancecarbs.shtml

Good Luck..
Ali
 

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Kind of right, but mostly wrong Ali. What a carb sync does is adjusts the butterfly in each carb to the same amount of vacuum on the engine side of the carb. at idle. So by using the vacuum guages, which you mentioned and I do reccommend you use. You set the vacuum of each carb to make them even. There are 3 sync screw's the two outside screw control each pair of carbs while the screw in the middle sync's the 2 set's of carb's together.

You mentioned to turn one in and then back out and try to match the others. I would NOT do that. Each screw is going to be set differently for the reason i described above with the screws sync'ing different sets of carbs. Yeah so if you have questions let me know.
 

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Originally posted by dustinsn3485
Kind of right, but mostly wrong Ali. What a carb sync does is adjusts the butterfly in each carb to the same amount of vacuum on the engine side of the carb. at idle. So by using the vacuum guages, which you mentioned and I do reccommend you use. You set the vacuum of each carb to make them even. There are 3 sync screw's the two outside screw control each pair of carbs while the screw in the middle sync's the 2 set's of carb's together.

You mentioned to turn one in and then back out and try to match the others. I would NOT do that. Each screw is going to be set differently for the reason i described above with the screws sync'ing different sets of carbs. Yeah so if you have questions let me know.
I agree. I tried to sync the carbs by ear before but didn't really work well. When I synched them with the tool, I saw that I was pretty close, and I was only off on syncing the pairs. So I would suggest investing in a carb sync tool or have a friend lend it to you.
 

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Ooooooops !!!

sorry, spinktodo, I really 'screwed' up there big time!

Yep, you are right dustinsn, it is the vacuum you are setting for each carb, using vacuum gauges I guess it should have been obvious.. feel like an idiot now....

I just suggested setting to a neighbouring screw setting if it was Really WAY off the mark and the engine was not running at all, to get it running well enough to get you on the road to a garage, but it sounds from what dusrinsn says that a proper carb balance is essential using the gauges no matter what..

Dustinsn, you also mentioned an idle drop to set it for the low end revs. What do you mean by this? I thought that you just had to set the pilot screws to a set value (2 turns out in my case ) and they stayed at that setting. I know that you would want to reset the pilot screws if you moved to a different location with higher or lower altitude, but I was not aware that it was possible to do this.

Is there some way that you can set them at optimal for the low end as well? I had to reset mine cos it was running rich (at 3 turns out)and it is much better now than it was, but I am not sure it is quite 100% right.

Sorry again to everyone for confusing the issue. I will shut up in future (the one thing I did get right was the link to someone elses page on how to do it properly!)
A
 

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Discussion Starter #7
Ok so yea now im even more lost and pissed off:

So I bought the sync tool, tore it all apart again, hooked it up and sync'd it like I've been reading... everything went well, a little too well i guess... I messed with the settings quite a few times to get it as close as i could, but eventually it was pretty decent i think. Ofcourse because the cylinders are surging the vacum jumps a little bit as expected but i got them all pretty level as you'll see in the picture below.

Long story short, i get it all done and back together and take it for a ride. Seems ok at first but it begins the surging thing again only at constant throttle. But now its worse than before because it boggs really bad if im crusing and then flick the throttle to accelerate... I mean dont get me wrong, the bike appears to be running WELL and it doesnt feel like a big mechanical issue... I'm about 99.9% sure its just something lame with the jetting or whatever but I need help!!! I've only got another good month of riding before winter, and once thats over is when I'll tear it all apart and get everything perfect.

So I'm thinking about a few things...

First of there were a number of vacuum issues and whatnot that i fixed that could be causing a new problem now that its not set up for it.

Also, I just thought about this: I did all this tuning with the bike on the side stand (the center stand isnt installed) Would that cause a problem once the bike is level?

Could it just be a jetting issue? The guy said it was jetted for that pipe, but who knows what he THINKS were the right jets...

All I know is that this is driving me crazy because I work on cars ALL day at work, then I come home and mess with this thing all night with no avail. And the worst part is that times ticking away to winter and the bikes messed up more because i tried to fix something that could have waited! HELP PLEASE

 

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If you think jetting is an issue, I would suggest go with Ivan's jet kit. No hassles. Works out of the box.
Also are you sure you have all those little o-rings between the cover that holds the slides and the carb body?

That is a main cause for leaks. Make sure you have them all.
 

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Discussion Starter #9
What's ivans jet kit and where can i get one? I don't know how these jet kits work with the number ratings either... im all fuel injected educated :(
 
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