1000 J carb rebuild tutorial

otakar wrote:

Those are standard BS34s on that bike and use the same parts as other BS34s but ALL the jetting is different from the civilian bikes. That is still my favorite carb.

When you say the jetting is different than on the civilian models, how so? I'm going to clean and/or replace float valves then, on the bench, see if it holds gas. As far as jetting goes I'm leaving it as is unless there is some way I can increase MPGs with jetting (without harming the engine). Eventually I'm taking it cross country but it averages 37 on the highway.

Several ways to possibly increase the gas mileage:

1.Run maximum tire pressure.

2.Check the drive chain for tight spots, make sure it's lubricated properly and adjusted. Inspect the sprockets for "Hooking"(bent teeth).

3.Do a plug check(it envolves chopping the throttle,hitting the kill switch, and coasting to a stop,a side road where you can get up to about 50-60 mph will do. Bring along a ratchet,& new plugs to do this).

4."Reading" a sparkplug is easy, check the center electrode for color; BLACK is too rich,WHITE,too lean, and a LIGHT TAN, just about right

5.Check the air filter(s) for clogging as dirty filters affect milage.

6.Change the fuel filter(if you have one) for a new one.

If those are Police carbs, they should have adjustable needles. You can drop the needle by one or two notches and increase your fuel efficiency. The police bikes had "fat" needles and the mid range can be leaned out a bit for touring.

Reading the insulator for jetting is misleading. Read the base ring instead.

Unless the weather holds out in the northeast, the plug chop will have to be done in the spring. Oktar, by dropping the needle, I assume you mean to lean it out. On a recent highway trip to PA. I noted the best mileage in the 3000 to 4000 RPM range while 5-6000 RPM highway cruising got me the worst. (a sprocket size change is on order when needed). At present the fueling is just right as far as I can tell. No bluing on the pipes and rpm holds steady. I appreciate all the help. I'm ordering the float valves and gaskets from Z1 and possibly new o-rings for the fuel fittings between the carbs. Mark

otakar wrote:

If those are Police carbs, they should have adjustable needles.

Interesting comment this fact I did not know. Funny how "non-civilian" bikes elude EPA CARB emissions with respect to "fixed" needles ?...

When I did my last sprocket and chain change I converted to a Tsubaki 540 "O" ring chain and a 18/40 sprocket ratio. This gives me about 75MPH at 4000RPM. Also I noticed the chain life is unbelievable. Where I used to adjust my chain every 200-300Mi with my 630 stock setup, I have not had to touch my chain adjusters for over 1000Mi. Jeff at Z1E set me up with everything I required, and it did not cost any more than the stock setup. Actually I think it may have been cheaper. I am getting 40MPG city/highway combined and my engine is highly modified. You can learn about this conversion on this thread. It is in the last few pages. I am also running a set of BS34 modified carbs. However mine are set up to be much "Fatter" in the mid range. I have custom needles in mine. To answer your question, yes, by dropping the needle one notch on the clip, it will lean out the midrange mixture.

kzrider.com/index.php?option=com_kunena&...w&catid=11&id=169462

Polar_Bus wrote:

otakar wrote:

If those are Police carbs, they should have adjustable needles.

Interesting comment this fact I did not know. Funny how "non-civilian" bikes elude EPA CARB emissions with respect to "fixed" needles ?...

The biggest change on the police carbs are the "jet needles" and "needle jets". This is what made them a bit faster and quicker than civilian bikes. The wider front end on the bikes made them more stable and smaller front wheel made them a bit more maneuverable. Out of the box, the police bikes could hold their own with a GPz1100.

I'm not cleaning the carbs for a couple of weeks but I couldn't take it any more so I sneaked a peek at the needles. These are the original carbs on the 2002 Police but they are not adjustable. There is but one place for a c-clip and there are no spacers. There is a number on the needle following the square symbol. It is 5GN45. Any thoughts? Also, starting in 2002, the KZPs came with a 530 chain, when it wears out I'll steepen the ratio.

hello,

I have a 1992 KZ1000P and I am also looking into checking out my carbs because I was getting gas leaking into the airbox and then on the ground under the bike.
I found I had a bad vacuum petcock and rebuilt it with a kit from Z1. Then after a few weeks I saw the same thing, gas leaking in the airbox.
I confirmed that the petcock was not leaking, so now I am thinking I have a float issue.

In the Chiltons or Clymer manual, the one with the KZP on the cover, it has a section in the back with a police supplement.
In the carb section it lists the different jets etc. that the Police model has.

These bikes have the BS34 carbs. I don't know about the adjustable needle on my year. I'll check when I get he carbs off.

This past spring I rebuilt a set of carbs for a 1983 750 Honda Magna. I didn't separate the bodies and used carb cleaner on the bodies and only pulled the parts that come out easily like the jets and floats.
I had no issues with the rubber on the enrichener ( choke).

When I take mine apart I won't separate them unless something needs top be fixed.

The manual has the clear tube method for determining float settings. I will try that and see what happens.


Too bad there is no pre-made carb rebuild kits like they have for the earlier models up to 1979 or 80.
then you just buy the 4 kits and replace parts.

Bill

The civil bikes had a 5FLZ or a 5FL needle needle. What that means is this; They are dual taper and triple taper 50mm needles and here are the tapers

5FLZ triple taper 2.25*-3.50*-6.00*
5FL Dual taper 2.25*-3.50*
5GN Dual taper 2.50*-4.00*

As you notice the Police needles are quite a bit more aggressive. For touring they will consume quite a bit more gas. I can look to see if I have some of the 5Fl needles and would be willing to trade you if you wish. You are also running a Y-6 needle jet compared to the civilian Y-1 jet that is also quite a bit larger. I might have some of those to trade also if you wish. Just PM me if you want.

If changing those jets will help MPG in the 5000 RPM range will improve gas mileage I would like to do it providing a dangerous lean condition won't exist. I plan to take this bike cross country in the summer. PM sent. Mark