KZ1000 No.2 cylinder just won't work.

G'day guys,

not sure about the forum protocols here, but for those that are interested, this problem I'm about to list has been documented in :
www.kzrider.com/forum/2-engine/546740-so...gs?limit=20&start=20

BUT....I thought I'd post here under a new heading so it's more descriptive of my problem.

To begin :

The No.2 cylinder on my 1982 KZ1000 LTD doesn't seem to be working. Here's what is going on :
When the engine is running, there is heaps of power, but you can feel that it's not running at full potential. This eventually leads to ta vibration running through the motor and =- upon inspection - No.2 spark plug can be found to be VERY black and sooty. The other 3 plugs are all in decent shape.

I have spark at the plug. However, when the plug lead is removed whilst running, it has no effect on the engine, whereas No's 1, 3 and 4 cause the motor to shake when removed. Whilst the spark looks strong, I have not officially checked it's strength.

This evening I went through all my checks again.
Compression.....1 - 105 psi, No.2 - 115 psi, No.3 - 105 psi, No.4 - 115 psi

I changed the leads.....switched No.1 to No.2 - no change - so i guess it's not the lead, because No.1 works really well.

I changed the coils around - no change.....No's 1 and 4 still fire strong using the coil from2 and 3.

I have switched the tube from the fuel petcock from No.2 to No.1. No change.

I have pulled the carbies off and - whilst I am certainly not an expert, there doesn't seemt o be any blocked passages. i have not got an y kits to put through, but inspection of the needle shows minimal wear and no holes in the diaphram. A small amount of "crap" was cleaned from the carb.

I sprayed some carby cleaner directly into No.2 cylinder from inside the air filter area - revs DECREASED.....seems like too much fuel. I have also checked the float levels and there doesn't seem t6o be an overfilling of the bowl....although as stated I'm no professional.

I took the valve cover off the other day and checked the clearances - all within specs (0.05 - 0.15).

Does anyone have any ideas ? Does this sound like a carby problem and should i just take them to be rebuilt ? I have been told it could be the spark strength, but surely by switching the coils and leads this would show up.

After any ideas at all.....bike runs great, and if I didn't know any better I'd think she was just running like a 30 year old bike should, but there is definitely a problem - one whole cylinder is not working.

Peter

Have you checked the Fuel Level in your float bowls with the Clear Tube Test? If the fuel level is to high, it will run rich.
When you did your compression test, did you hold the throttle wide open? As those #'s are low.
When you cleaned your carbs, do you blow them out, all passages, with compressed air?
The spark plug wires are easy and cheap to replace. Most automotive, or small engine stores will have the wire by the foot. 4 feet of new wire, less than $4. You can check the Plug wire end, Plug Caps with a OHM meter.
Check the # stamped on the jets against the listed #'s in the service manual in my signature. Be aware that jets can be drilled out, so its a good idea to compare #2 with another carb, just to be sure it doesn't have a jet that's been drilled.

Does installing a brand new spark plug in #2 cylinder provide combustion in the #2 cylinder until the new plug fouls?

Good Fortune!

G'day guys,

Patton - when I put a new plug in No.2 the bike does run "better", but at idle when you pull the plug lead off it still doesn't seem to make much difference. It does run smoother though before eventually fouling.
The only time it made a difference was a couple of weeks back when i quickly showed it to my mechanic, and he took the revs up to something like 3000 rpm, then removed the plug boot....the engine changed a little.

Motor Head - I did the sight tube test - looks OK.
Compression test was done with throttle fully open.
I did blow out carb holes with compressed air....maybe need to do it again, but wouldn't a blockage mean a lean mixture - not too much ?
Sparl plug wires aren't that easy or cheap here in Australia - hence the reason I switched them around. Surely if the lead was dead it wouldn't fire on another cylinder - which it did.
I haven't checked the jet setting.....maybe I'll pull them off again and check. Why would jets be drilled out ?

Some will drill the jets instead of buying new ones that are bigger. Or in some cases simply they are not available.
Blockage in the Fuel circuit would make it leaner. Blockage in the Air circuit will make it Richer.
I forgot, or wasn't aware you are down under. I remember how different it was, from living there for 9 years. Still parts are available if you need them, either locally or on-line.
If you had the throttle open during that compression test. Then either your gauge is not reading the full value, or the compression is low. Looks even enough, but low. Do you have a Leak Down Tester? If so i would see what percentage of 100psi the cylinders hold. If they show high leakage, your ready for a rebuild. If they show it is not leaking, then you may have a camshaft timing issue to sort out.

Not sure if this will help any, but IIRC the carbs on that bike have a plug on the bottom of the pilot jet. Fuel is pulled via a small passageway between the main jet port and the pilot jet port. If the plug is missing or not fitting tight, it can and will create issues with being too rich on that carb, since the pilot jet will be getting fuel from both locations.

Yes a plug and o-ring at the pilot jet. Also a plug at the front of the float bowl, with a gasket where the float bowl bolts on. Plugs off the float bowl from the carb venturi.

As suggested in the other thread, has engine performance been tested with a brand new spark plug in #2 cylinder, and running with the petcock in PRIme position, and with a cap/plug on the vacuum nipple that usually supplies vacuum to the petcock?

Such test is intended to eliminate the possibility of a leaking diaphragm in the petcock which might allow fuel to flow through the vacuum hose and be drawn into the combustion chamber along with the regular mixture being furnished by the carb.

Good Fortune!

What are the measured valve clearances on #2 cylinder?

Good Fortune!

With a good fully charged battery, what voltage is being actually received at the ignition coil primary terminal?
Full battery voltage should be present at the coil.

How does such voltage being actually received at the coil compare to the voltage as measured between the battery posts? Ideally, both should be the same.

Good Fortune!

Would double-check the fuel level in #2 carb float bowl, using the clear-tube test.
And assure the fuel level isn't too high.

If necessary, fuel level may be adjusted by manipulating the tang on the float mechanism.

Generally, the tang position should not be manipulated in an effort to resolve fuel discharge from an overflow nipple.

Good Fortune!

Hey Patton,

thanks very much for the tips.....I'll do some checks tomorrow and get back to you. Just reading up on how to use a Voltmeter (which I'll buy tomorrow) to test the wires to the coil.

Peter