Kawasaki Ninja ZX Forum banner

1 - 20 of 30 Posts

·
Registered
Joined
·
42 Posts
Discussion Starter #1
Hi all,
Long time reader, first time poster. Loving the zx7 section. I'm usually able to find what I need on here with a quick search but unfortunately, not today.

Here's the story:
Bought a 97 zx7r at the end of last summer with 26,000 km, full muzzy exhaust and a supposed jet kit. The bike didn't run and the PO didn't know why as it was his first bike and he only rode it 4 times in the two years he owned it. I've done lots of work on bikes and had a friend that knew carbs. So, I threw the guy a low ball offer and he took it. Brought it home, tore it down and got my friend to sort out the carbs. I'm not sure what he did, but he got it running. Not great by any means, but good enough to ride for the last couple months of fall. And then there was winter..
Brought it out of winter storage a couple weeks back and it took about 20 min to get it started. When it finally started it ran like crap for about 25 min and then seemed smooth out. On the ride home I noticed the revs were taking forever to come down to idle and it just wouldn't hold steady (bouncing idle). I figured I needed to have the carbs cleaned so started to look in to it. As I started to get quotes I started to realize that I've been paying people to do a job that I'm totally capable of doing. If I can build a turbo'd car engine, I sure as hell should be able to clean and rebuild my own damn carbs! So, I cleaned them, put them back together without changing any settings or adjustments and it runs great... but only with the fuel off!?!?!?! If I run it with the fuel on it keeps bogging and dying out. WTF??? With the fuel off it revs like never before, quick throttle response, faster dripping revs, like a dream compared to before the cleaning.

Here's how everything was set before and after the cleaning:

-Tube from top vac lines (2 into 1) to air box- Eliminated smog crap
-#2 diaphragm boot has a tiny hole (only seen by holding it up to the light stretched out)
-Needles have the clip 3rd spot from the bottom and no shim under needle #3 ...??
-Main jets are 172, 182 ,182 ,172 ....???
-Pilot jets are 35
-Float height is @ 11mm
-Adj screw is @ 2 turns out

I have a spare set of stock carbs on the way for parts (diaphragm and needle shim) and reference as well as a 6 Sigma jet kit (stage 1-3) and a motion pro carb sync tool.

From what I've been reading the float heights don't sound right. Further more, those main jet sizes seem really weird.. In all the posts I've read, I've never heard of 172's and 182's. If stock is 170 & 180 and the most popular jet kits seem to be 172's and 162's... My setup makes no logical sense what so ever!

Any help or suggestions might save more of my hair from being torn out. Thanks in advance:smile

K.C.
 

·
Premium Member
Joined
·
11,231 Posts
Incorrect float heights (set way too high causing it to flood the engine) or stuck float valves. If it runs great with the fuel off then I doubt its your carb settings (other than floats that is).
 

·
Premium Member
Joined
·
5,064 Posts
thinking the petcock might have been rebuilt wrong... just guessing tho
 

·
Premium Member
Joined
·
11,231 Posts
thinking the petcock might have been rebuilt wrong... just guessing tho
I don't know how it would be possible to put that together backwards, but maybe.

You might wanna take note of that 11mm float height though. 11mm is way way too high.
 

·
Registered
Joined
·
42 Posts
Discussion Starter #5 (Edited)
I don't know how it would be possible to put that together backwards, but maybe.

You might wanna take note of that 11mm float height though. 11mm is way way too high.
With the jets I have where do you think I should be on the float height?? 14mm, 15mm?? And is 2 turns out ok on that adjuster screw?? I'm kinda lost at this point.
 

·
Premium Member
Joined
·
2,387 Posts
With the jets I have where do you think I should be on the float height?? 14mm, 15mm?? And is 2 turns out ok on that adjuster screw?? I'm kinda lost at this point.
I am running a factory jet kit with the 172-182 mains and floats should be around 15mm. 11 is way too high.
 

·
Premium Member
Joined
·
11,231 Posts

·
Banned
Joined
·
3,608 Posts
Yes start by lowering your float height to at least 14mm! When I fixed EVIL7TWINS bike it was set to like 12mm. I lowered it and it runs grrrrrrreeaat!
 

·
Registered
Joined
·
42 Posts
Discussion Starter #9
Ok, out to the garage now to set them to 14. I'll report back shortly with the results.
 

·
Premium Member
Joined
·
3,530 Posts
I don't know how it would be possible to put that together backwards, but maybe.
I was wondering the same thing. It may be that the only reason it would run with the fuel petcock off was because the petcock was doing the job of the floats and restricting fuel flow.

You might wanna take note of that 11mm float height though. 11mm is way way too high.
Yes start by lowering your float height to at least 14mm!!

+1

Been saying it for a long time. 14mm seems to be the sweet spot for these bikes. They love it.
 

·
Registered
Joined
·
42 Posts
Discussion Starter #11
Pet cock is fine. Pulled the line, tested on, off, and res and it all works properly.

Ok, set the floats to 14mm, started the bike with the fuel off and it was running fine. Turned the fuel on and same thing.. died within about 30 seconds.

Current settings
-2 turns out
-floats @ 14mm
-#35 pilots
-172,182,182,172

1) Should I try 15MM float height??
2) Maybe the adjuster screw???

Thanks again guys. I feel like I'm finally kinda on the right track. Keep those reply's coming!!
 

·
Registered
Joined
·
42 Posts
Discussion Starter #12 (Edited)
Trying 15mm.. Update to come.

Update:
The 15mm float adjustment did not help. It actually didn't seem to change anything. Bike still died within 25 0r 30 seconds of turning the fuel on. WTF?!?!?!?
I don't think 15.5mm will change anything anything and I haven't read about anyone set at 16mm...

Anyone??
 

·
Premium Member
Joined
·
11,231 Posts
Maybe the floats are stuck open and its just pouring fuel in, have you considered that?

That is the only other thing it could be.
 

·
Registered
Joined
·
42 Posts
Discussion Starter #14
I thought of that but all the floats seem to move freely when apart plus they were just cleaned.
 

·
Premium Member
Joined
·
11,231 Posts
Just because the floats move freely doesn't mean there isnt crap in the valve seat preventing them from closing. And just because they were cleaned, doesn't mean they are clean.

That is the only possible thing that could cause this. I bet if you take the airbox off so you can look into the carbs, put the bike in first with the clutch out and thumb the starter (with the fuel on so the pump runs) you will see it pushing fuel into the motor up past the needle in at least one carb.
 

·
Registered
Joined
·
42 Posts
Discussion Starter #16
Just because the floats move freely doesn't mean there isnt crap in the valve seat preventing them from closing. And just because they were cleaned, doesn't mean they are clean.

That is the only possible thing that could cause this. I bet if you take the airbox off so you can look into the carbs, put the bike in first with the clutch out and thumb the starter (with the fuel on so the pump runs) you will see it pushing fuel into the motor up past the needle in at least one carb.
Right you are! #2 seems to be the problem. Couldn't see it until i lifted the diaphragm thingy. Quite the puddle of fuel on top of the butterfly. 1 3 and 4 are dry as a bone.

I'm going to take #2 apart and give it good cleaning now. I'll report back after testing.
 

·
Registered
Joined
·
42 Posts
Discussion Starter #17
Ok, Cleaned out the float thingy again and no more fuel leaking into #2... But it will still only run with the fuel off.. :banghead:banghead:bangheadWTF??%$#^&*&$!!!!

What else could it be??

I'm still at 2 turns out on the adjuster.. Ideas??
 

·
Premium Member
Joined
·
11,231 Posts
Check it again and make sure. There is no other possible reason that it should only run with the fuel off other than that its flooding the carbs. The setting for the "adjuster" or the pilot screw shouldn't have anything to do with it. If the bike runs fine with the fuel off, then the carb settings are not the problem.
 

·
Banned
Joined
·
3,608 Posts
Try this. Pull the vacuum line off the bike with the fuel on. and plug the line. If it still stalls out then you're still looking at carb issues. Have you replaced the O-rings around the float needle and seats? Mine were bad and was flooding out a little but not too horrible. It could be the diaphragm in the petcock is what is the problem and pulling fuel past it into the engine. So take the vac line off, plug it so you dont get an air leak. and report back. BTW 14mm should be fine as I found 7s like that setting.
 

·
Premium Member
Joined
·
11,231 Posts
There is no vac line on the petcock on a P-model either the fuel is on and flowing, or off and not. There is no conceivable way that the fuel being on should be a problem unless hes got like a 60 PSI fuel pump in that thing.
 
1 - 20 of 30 Posts
Top