TOPIC:

Hello there - bike is an 83 KZ750 H4 LTD. The bike has some drive ability issues - it idled fine, but was sputtering and misfiring at low RPMs, as well as mid range RPMs at light to moderate throttle, and it has been like this since I owned the bike, as well as for a couple years with my buddy who was the previous owner. I was going to take a look at my valves first, but I realized the other day while at a red light that the valves were actually really noisy, so I decided that those are fine right now. So I decided to pop the carbs off and clean them out.

Question 1: Does anyone know where to buy new caps that go over the pilot jets? Can you buy new O-Rings for them? Are there any other caps from any other carbs that might work? One of the carbs might have been missing one. I don't know for sure, because when I started tearing down the carbs, it was super late at night, I was tired, and I was just curious to see what jets I actually had in the bike. I did not pay attention to the caps. When I came out the next morning, all the caps had fallen out onto my work bench (they are incredibly loose) and there was only three of them. I thought one fell on the floor and I looked everywhere. My experience with cars is that when a little tiny bolt or nut drops from high up, it can go ANYWHERE. But with that in mind, there really isn't much around my work bench, and I looked all over. Besides, all the caps fell off right onto bench out of the carbs, all three were right next to each other, so I would expect the fourth one to be there as well. Anyway, there is a chance it was in there and I can't find it, but it would make a lot of sense if one of the carbs didn't have a cap on it because all of the misfiring happened at low throttle. Regardless, I need a new cap probably, and if I find the fourth, I need new O-Rings for all of them,

Question 2: How do you get the O-Ring out of the Pilot Screw hole? I want to blow that passage out with brake clean really good but I don't want to mess up that O-Ring. I don't really have a dental pick or anything to get down there, I was wondering it anyone had any tricks.

Question 3: I haven't looked at my Pilot Jets, but my primary jet size is 65 (really hard to read that one) and my secondary jet size is 90. Just want to make sure this sounds right to everyone, every time I try to look up stock jet sizes, I am mostly reading about carbs that did NOT come on LTDs, which I believe everyone else was saying 63 or 70 mains, 125 secondary.

Thanks!

1) I don't know where to get any spare plugs. I haven't looked at the O-rings for those caps but could check it out later because I'm rebuilding a set of those carbs right now.

2) Take a paper clip and bend a J form into the end to fish those parts out. There should be a washer and O-ring in there.

3) The parts fishe has the jet numbers. Look them up at your favorite Kawasaki OEM parts source such as Partzilla.

BTW, most of the various O-rings on the three sets of those Keihin I've rebuilt were all hard as a rock. In particular the O-rings which seal the fuel transfer tubes (you gotta ungang the carbs to get to them) and the O-rings in the floatbowl drain screws. The pilot screw O-rings seem semi pliable. Also, the floatbowl O-rings were smashed flat as a pancake. I always replace those too. I recently bought a bunch of O-rings in the appropriate sizes from oringsusa.com.

Those orange plastic caps with an oring are held in place by a rib that is cast into the float bowl.
Almost all the factory jetting I've seen has been 68/125.


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Adjust the valves.
Steve

Just went through having to replace a couple of those plugs myself. Unfortunately those plugs are unavailable any more except for Ebay which is crazy expensive for what its worth.

I found a really easy solution with this guys idea. Basically you use a Pop rivet with a 3mm o ring,



Like I said I had to do this for 2 of my carbs because the plastic in the plugs had degraded over time and snapped off. I have a bunch of supplies for the DIY kit you can have for free. I have the pop rivets, washers and the O rings in 3mm for it. It is super easy and works perfectly. Just PM me if you want some to make your own and I can give you a better description of how its done.

7-Fiddy LTD wrote: Question 3: I haven't looked at my Pilot Jets, but my primary jet size is 65 (really hard to read that one) and my secondary jet size is 90. Just want to make sure this sounds right to everyone, every time I try to look up stock jet sizes, I am mostly reading about carbs that did NOT come on LTDs, which I believe everyone else was saying 63 or 70 mains, 125 secondary.

Thanks!

Your carbs are jetted for a cruiser style (better midrange), not for top high end power.
Std jetting for KZ750 E & H is 35 - 62 - 125 with N01A needle
Your bike uses N10A with 35-65-90 jets.

N01A is totally different form N10A.

Then there is another Keihin CV34 style, with only 35 and 100 jets. It uses needle N10C.

Can you check your jet needle? It should have the name stamped on to it.

I was checking out the caps tonight and they are just plastic plugs with a rubber sleeve piece over the end. The sleeve piece spins so obviously it's a separate part. I'm afraid to try to remove it for fear of it tearing.

Nessism wrote: I was checking out the caps tonight and they are just plastic plugs with a rubber sleeve piece over the end. The sleeve piece spins so obviously it's a separate part. I'm afraid to try to remove it for fear of it tearing.

That sleeve is just an o-ring that has gotten smooshed over time. And yes it will likely rip. All mine did when I replaced them. The plastic plug has a groove for the o-ring to sit in. The carb rebuild kit I got had a replacement o-ring for them but it turned out to be too big. The solution I got from the carb rebuild manufacturer when I contacted them was to use some kind of grease My solution was to find the right size o-ring. I found the right size online from overseas, but had to buy a minimum order of a small armies worth Once I got the right size o-ring it went in nice and snug with no having to force it in. Its funny how well it works when you have the right part

So as a side note if you need some of the correct sized o-rings Nessism, or any other member reading this, shoot me a PM and I will send you some of the correct sized ones free of charge.

Here is a pic I grabbed from someplace that shows the plug and o-ring well

akolleth wrote:

Nessism wrote: I was checking out the caps tonight and they are just plastic plugs with a rubber sleeve piece over the end. The sleeve piece spins so obviously it's a separate part. I'm afraid to try to remove it for fear of it tearing.

That sleeve is just an o-ring that has gotten smooshed over time. And yes it will likely rip. All mine did when I replaced them. The plastic plug has a groove for the o-ring to sit in. The carb rebuild kit I got had a replacement o-ring for them but it turned out to be too big. The solution I got from the carb rebuild manufacturer when I contacted them was to use some kind of grease My solution was to find the right size o-ring. I found the right size online from overseas, but had to buy a minimum order of a small armies worth Once I got the right size o-ring it went in nice and snug with no having to force it in. Its funny how well it works when you have the right part

So as a side note if you need some of the correct sized o-rings Nessism, or any other member reading this, shoot me a PM and I will send you some of the correct sized ones free of charge.

Here is a pic I grabbed from someplace that shows the plug and o-ring well

Thanks so much for the offer. PM sent!

What size is that o-ring? A metric o-ring kit might have a size that will work --- the fit probably doesn't have to be perfect. summit racing, harbor-freight, eebbaayy, etc. nitrile or viton rubber.

Doing some research on this plug O-ring business...

The OD of the plug (at the O-ring groove) is 3.2mm so an O-ring ID of about 2.5mm or so is about right. The ID of the carb hole is 5.5mm.

I tried a (-006 O-ring) 1.7mm thick x 2.9mm O-ring and couldn't get the plug into the hole.
A 1.5 x 3.0 fits okay. Maybe a smidge loose but doable.

BTW, the plug is held in place by the float bowl. That's why it sticks up as high as it does. If anyone is making their own plugs I'd be sure to match the height of the OEM plugs.

The ones I got that worked perfectly for me were the 1.5mm x 3mm o-rings. YMMV, but those ones were nice and tight without having to force them in on my set of Keihins.