Re-Visiting the Runs like sh*t 81 GPz550

Just an easy to try suggestion;

Remove the coil HT wires from the plug caps on suspect cylinders. Cut about a 1/4 inch off the ends. Screw the plug caps back on and try again.

this Spring I bought a few feet of 7mm copper core unshielded plug wire and replaced 20 year old hard and crusty ones. Made a big difference to starting and running.

Sat Sept 14 update:

I rode the bike today for a while. Shot some video, took some readings.

Here is an imgr link to the riding video. imgur.com/a/gMDKHl3 . It really runs rough then cleans out at around 5k RPM and will pull while surging.

Compression test after a few miles of rough running: 1. 150 2. 130 3. 135 4. 140

IR temp on head pipes after few miles of rough riding: 1. 400 degrees. 2 194 3. 196 4. 408

pic of the plugs after a few miles of rough riding.

 

I'm building a different set of carbs this afternoon. Will update ...



 

2 & 3 share the same coil.

The 2/3 spark plugs looks like runnig very rich on fuel.
A weak spark (low voltage coil = un-burnt fue)l can effect the same.
Grab your multimeter and check the voltage on coil 2/3.
Better do a relay coil mod, it gives you full voltage to the coils.

 
 
 
 

I'm taking new coils to the bike today, along with the new carbs.

Where did you source this?

<<this Spring I bought a few feet of 7mm copper core unshielded plug wire and replaced 20 year old hard and crusty ones>>

<<As asked above, how are you sure the middle two are the ones not firing at idle? >>

IR temp gauge on header pipes. Two center pipes are 150 degrees lower in temp, aprox.

Re Same Coil

My mechanic friend keeps swapping the coils on the bike and suggesting that since there is no improvement that this shows the coils are not the issue.

What do you think of this?

Chopper1963 wrote

Where did you source this?

<<this Spring I bought a few feet of 7mm copper core unshielded plug wire and replaced 20 year old hard and crusty ones>>


Chopper

i got the ignition wire from Aircraft Spruce but your lical bike shop probably carries it .

temperature readings indicate no fire or poor fire on 2 &3. Sooty plugs could be to rich - carbs - or weak spark. Its easier to check coils or just nip a 1/4 inch off the plug wire and make a new fresh connection with the plug cap than to rebuild carbs. Cant count the number of times I've had to do thst over the years. 

start with the easy stuff.

PS. As to mechanic - no comment





 





 

chopper1963 wrote:

Re Same Coil

My mechanic friend keeps swapping the coils on the bike and suggesting that since there is no improvement that this shows the coils are not the issue.

What do you think of this?

I would check for myself. It is easy enough.

When you say swapping coils do You mean just the two or do you have spares? Wire itself is rarely the problem if ever, it's solid core but knocking off about 10mm at the end won't hurt. You have to remember the pair of High tension leads on each coil going to plugs work in tandem with each other. If one wire can't find Ground the other one won't work either. Check your sparkplug caps, ALL of the OEM Kawasaki ones were resistor style. Should be 5-10K ohms, depending on type. One of these fail, no spark on other.  

I used an IR temp gauge on the head pipes.