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Discussion Starter · #1 ·
I am in the process of getting an 89 zx7 H1 back on the road and I have gotten myself a carb sync tool from motion pro but I think my carbs are so far out of whack that everything I am trying isn't helping. I can do all the adjusting on carbs 1 and 2 but I can't get them balanced and after a little bit the motor will just hang up at 4 grand and not come back down.

I have taken these carbs apart at least twice and cleaned them so I know they are clean and ready to go. I think in my cleaning and putting back together I have my carb sync screws so far off that I can't even get an even place to start. So that is what I am looking for and didn't know if anyone here had a good place to start with those screws so I can perhaps get them close and see what I can do then.

If not I will probably just pick a number of turns out that doesn't look too bad, make all the carbs even and see what happens. Any and all help would be greatly appreciated. Thanks.
 

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ok stop right there. There is a quick and dirty way to get the bike to start by doing a mechanical sync. If you look in the throats of the carbs you will see at the bottom near the butterflies a series of holes. What you want to do is get as many of the holes exposed as you can. There should be about 5 per carb. Now on the 5th hole you will only be able to expose about half of it. That should get you close enough to start. Now make sure your floats are all set to 14-15mm and the pilots should start at 2 turns out. The bike should start. Idle like crap but start. Now connect your tool. On a side not, make sure you do not have any intake leaks at the head. You may need to take the boots off and either replace the O-rings, or use some rtv sealer and let it set up. Then calibrate the tool and go to town.
If IIRC, the no.3 carb doesn't adjust with the turn of the sync screw. Might be no.2. That is your main carb.
 

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BTW I have the same bike with H2 carbs so it may react differently, but it's still the same idea.
 

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Discussion Starter · #4 ·
Thank you so much for the info. I have all the pilot screws set to where the manual said and I can get it to idle pretty decent but as soon as I start playing with it, it hangs up and makes me mad. I will definitely try everything you said here and see what I can learn.

I don't think I have any leaks around the boots because I did spray some starting fluid around them to make sure and it seems to be ok.

Thanks again for the info.
 

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Discussion Starter · #5 ·
Ok finally got my BMW project on the road so now I can focus my efforts back to the zx7. I took the carb boots off and rtv'd all of them just to make sure none of them were sucking air. I then replaced the vacuum port plugs because it was still sucking some air.

Now it idles much better and I haven't hooked up the sync tool yet because when it gets warmer it will idle back down after I give it some gas but usually likes to take it's time getting back down there and getting it to rev past like 4500 is almost impossible. Could that really all just be from sync issues or am I missing something else?

I'd like to get these carbs close so I can start working on the rest to have it ready for the spring, she's been down and out for far too long now.
 

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Ok finally got my BMW project on the road so now I can focus my efforts back to the zx7. I took the carb boots off and rtv'd all of them just to make sure none of them were sucking air. I then replaced the vacuum port plugs because it was still sucking some air.

Now it idles much better and I haven't hooked up the sync tool yet because when it gets warmer it will idle back down after I give it some gas but usually likes to take it's time getting back down there and getting it to rev past like 4500 is almost impossible. Could that really all just be from sync issues or am I missing something else?

I'd like to get these carbs close so I can start working on the rest to have it ready for the spring, she's been down and out for far too long now.
You still have a vacuum leak somewhere.
 

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Discussion Starter · #7 ·
OK, I can get behind that thought that I still have a vacuum leak somewhere. Are there obvious places I should be looking because I know the carb boots and the vacuum ports are now solid. I also replaced all the rubber O-rings on the gas lines that connect the carbs.
 

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OK PA. It's cold there. Try turning your pilots out to 3 turns. It will be a little rich but wont give any major issues till you try to hot start it. It will keep the idle from hanging too. After you get the sync done at 3 turns, close each pilot 1/4-1/2 turn, and recheck the sync. Should still be pretty close. Right now I'm at 2.5 turns and it's just about perfect for 60* weather.
 

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Discussion Starter · #9 ·
is there anywhere else i should be specifically looking for vacuum leaks that i might be missing? i thought i got all the major components but i'm more familiar with the original H series two stroke bikes so i could definitely be missing something small and never even know it.
 

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Check the vacuum nipples on the intake boots. Mine leak a little, and I have to run a little rich to compensate. I'm just lazy to fix it right.
 

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several good ways to look for vac leaks. One is to use a can of starter fluid and using the straw included spray small amount around anywhere you suspect a vac leak (manifold to head, manifold to carb boots, throttle shafts in the carbs, diaphram hats, etc.) If your idle jumps up you'll know youve found a leak.

I personally prefer an unlit propane torch (direct the unlit gas to where you suspect a leak). Its not as pinpoint but its less messy and less likely to start a fire. You can even put a rubber hose over the nozzle and more accurately direct the propane if you are struggling getting in between stuff.
 

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Discussion Starter · #12 ·
I found my initial leaks using the starting fluid method. And after I siliconed up the boots I shot it again and couldn't find anything, but that doesn't mean that there isn't some other stupid leak somewhere I just casually overlooked.

Christi, you rock and thanks for all your help. I really do appreciate having someone with some real knowledge of my bike helping me out.
 

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Well it helps to have the same bike hehe. All I have to do is go outside.
 

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Discussion Starter · #14 ·
Ok so I checked the carbs and none of them are sucking air at all. There's a small victory. However I am only running on cylinders 3 and 4. My 1 and 2 headers are so cold I can touch them. Now I'm getting pissed. Also my spark all across the board is shit. Especially on 1 and 2. I know that the coils are 1 and 4 and 2 and 3 so I don't understand why I would have shit on 1 and 3. Also if its not coil related and you are thinking it's carb related which I haven't completely ruled out, on carb 4 it pushes air out of it while its running. You can feel it push air out with your hand.

As always any and all helps is always appreciated.
 

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Id start by checking (unbolting, cleaning and re-attaching) your grounds. Also check your battery under load (voltage during cranking). After that you are going to need to check your voltage output from your alternator. I dont have my manual handy, but I would bet CK will chime in here and offer some insight on that.

Other possibile causes are bad plug wires/end caps, corrosion in the main power connections, or a short in the ignition circuit. Start at the Battery and Alternator and work forward toward the plugs.
 

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Pull the airbox and spray some starter fluid down the suspect carbs. Just dust em, don't drown them. If they liven up then its a carb issue. If there is no change it still could be carbs but most likely electrical. I just have to change the cdi on mine cause it would drop two cylinders when it warmed up.
 

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Discussion Starter · #17 ·
Definitely will do. Should have thought of the starter fluid trick I used it before.

But changing out the cdi, tell me more.
 

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I cant remember if you said you did anything with the spark plugs, wires, coils. I dont have the same model as you do. Start tinkering around with them. Check the spark plugs on 1&2 and swap em over to 3&4. If you get the same result, swap the plug wires. If you still have the same result, i have coils off of a 95 zx7. Idk if coils are interchangeable across the board on the 7s. If after that you still get the same result its possible to be the cdi.

Sent from my DROID4 using Motorcycle.com Free App
 

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92ninjas the coils interchange all the way from 89-03 so it's all good. I have a few spares if you need them. Yeah my CDI/Ignitor decided to get hot and drop two cylinders. So I swapped it out. Only choice I had was for a 92 zx600c. Works great just have to watch my RPM's as the 600 has a 14k limit and the 7's have a 12k limit.
 

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Discussion Starter · #20 ·
I swapped plugs and wires on pretty much all the cylinders same shitty, weak spark all the way around. My battery is pretty much brand new, I think I bought it back in July or so. I definitely would be interested in some known to work wonderfully coil packs so shoot me a price and we'll go from there. Thanks guys and ladies.
 
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