TOPIC:

Well some history on this bike.
81 KZ100K

I got this bike from a buddy of mine. He hardly ever drove it..
In fact from the title in 2001 to the mileage on it now, he only drove it 73 miles!!

I got it and it was leaking from the head gasket in the front.
We cleaned the Main and Pilot jets on the carbs.
Replaced the head gasket and put things back together.
Replaced sparkplugs

Bike starts and runs but is not idling back down after a blip on the throttle.
Took carbs out again.. and looked at the idle mixture screws

carb # # of turns out
1 1.5
2 4.5
3 6.5
4 6.5

We set them all to 1.5 turns out put it back on the bike and put the airbox tubes on them.
Bike started and sounds pretty good. Blip on the throttle and idle comes back down.

Still sounds kinda rough at idle.. So I tried to adjust the mixture screws but did not see much change.
I did notice that a couple of them if i backed the idle mixture screw out a lot the idle went up.
(per the manual it mentioned finding the highest idle with turning the screw in or out).
I did not leave them out that far since if I blipped the throttle it was revving up again.. not going to idle.

I put the idle mixture screws all back to 1.5 turns out.

I am borrowing a "carb stick/synchronizer" and will plug into all of the carbs at once and see if they are out of synch.

Is it normal to have the idle mixture that far from 1.5?

I am thinking of doing the battery to coil modification if after checking spark this weekend if it does not look good.

Any suggestions?

Ok started the bike today .. whew.. it starts good.

Noticed that when it was getting closer to warming up and the idle was back down near 1000rpm it was idling rough. I reached up and touched the far right exhaust pipe and it is cool!! Hrmm goes that means something..Will search on it.. and try to check the spark tomorrow.

I guess its just me talking to my self LOL

Anyways.. still same symptoms rough idle,

Got the bike warmed up and hooked up the manometer and hrmph.. take a look.

[img size=150]
So #2 and #4 are low.

This isn't going to fix the #4 exhaust being cool will it? I pulled all the plugs today and #2 looks the best of all of them, #4 is a bit black.

thanks

Post edited by: mstbone67a, at: 2006/04/30 23:02

Post edited by: mstbone67a, at: 2006/04/30 23:06

For some reason it wouldnt let me edit and put the image in. Here it is , picture of the manometer when at idle.



thanks

I'm not the sharpest crayon in the box, but if you got a cool pipe after the motor is running awhile......you got one cylinder that aint firing.
Carbs I know NOTHING about, but hang in there......one of the resident guru's will chime in quick enuff....
Good luck.

At this point, unless you forgot to mention some very important stuff, you are just mucking around.

First, measure the compression on all cylinders before messing with the carburetors. I suggest that you remove all your plugs and open the throttle. If your compression is outside spec, then you need to investigate why. No amount of carb sync can fix compression issues.

The main reason compression is bad on one or more cylinders on older bikes with unknown maintenance history is the lack of valve clerance. When a bike engine wears, clearance gets less and less. Once you reach a point where there is little or no clearance, the valves begin to stick open. ADJUST CLEARANCES before proceeding.

As far as the carburetors go, you have too little engine vacuum as the vacuum levels on your manometers are too low. Turn the bike off. Move your idle adjustment knob to about in the middle of the adjustment range. Loosen the locknuts on your adjusters. FIRST adjust 1 & 2 so the levels are the same and a bit higher than shown. Then adjust 3&4 to each other. Then use the middle adjuster to adjust 1&2 to 3&4. All the mixture screws should be out at ABOUT the same level. Adjust idle AFTER synchronizing with the adjusters at about 1.5 turns out. Then adjust idle. You have an idle screw out 6.5 turns means you are allowing way too much air in that way and mucking up the synch part of the tuning.

Ok I might have not taken that reading on the manometer correctly..

1. What rpm should i be taking the reading?

Nevermind found this "Start the bike and adjust the idle speed to a fast idle (1500 rpm)"

Which I probably did not have it up to. Sorry.

All of my mixture screws are set to 1.5 turns currently.

Thanks I will recheck compression

I had the same problem on #4. You might double check all float levels and need clip positions whilst you're at it.

Also TRY a fresh new plug in #4.

Will check the float level tonight also.

I have the US version? So no clips is that right?

thanks
Thomas

Hi MSTBONE67a - check your U2U.

Well i got the coil rewire done.
Tried to sync the carbs but the vacuum is not very high on the manometer.

I also noticed that #4 is still cold when idling.

I tried to turn the idle mixture screw and see if it changed and LOL i took the screw out and it still didn't affect it.!!

I swapped coils, and plugs but couldnt swap wires..tooshort to reach.

My plan..
rechecking compression. which was originally fine. Checking with leakdown tester also to see if leaking valve is involved. If nothing found going back to clean that carb out.
Unless someone has any other suggestions.

thanks

Does gas drain from that carb's drain screw continuously? Could there be a blockage keeping fuel from that carb?

- Nate >>