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Discussion Starter · #1 ·
Hey all,


I just picked up a 1981 KZ550C2 LTD off someone who couldn't get it running and I'm having a bit of trouble myself.

The starter is new and good.
I've put in new fuel and installed an inline filter.
I'm getting fuel to the carb float bowls.
It has pod filters but I`ve removed them for troubleshooting and as far as I know the carb jets are stock.

I'm getting spark at all the plugs but it looks weak to me. I measured the resistance at the ignitor coils and I'm getting 2.0 ohms. The manual says I should be at 3.2 to 4.8 ohms
I've got the coil with the black wire going to cyl #1/#4 and the coil with the green wire going to #2/#3.
I've also tried swapping the plug wires which swaps the ignitor coil.

I've pulled off the valve cover and when I'm at TDC on #1 (far left cylinder) I've counted the pins from the EX line on the exhaust cam to the Z5 line on the intake can and I'm getting 43 pins which tells me the timing is correct.

I did noticed cylinders 1 and 3 are missing the choke flaps.

I set the petcock to prime for about 15 seconds, then to the ON position.
I tried starting with the choke closed with no throttle input and it would turn over but wouldn't fire.

After cranking it quite some time I managed to get it to run for about 10 seconds but then it died and I couldn't get it started again.
I've tried starting it with manipulating the throttle but would only get a bit of popping and no firing.

Are the ignitors low resistance? Would the weak spark and the choke flaps missing cause it to not want to fire?

I've read these bikes are temperamental with regards to choke and temperature when starting.

I'm kind of running out of ideas here and starting to get a but frustrated.

I was thinking of ordering a carb rebuild kit and new coils.
I'm an aircraft mechanic so I know a bit about engines but not much, and I'm not familiar with these old bikes.
Any help is greatly appreciated!

-N
 

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There are some other 550 owners here who will likely provide their input, but it sounds like you should start with some good aftermarket coils and fix the choke. Also, you should be aware that running without the pods or without an airbox can cause issues like hard starting and poor carb performance.
 

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Discussion Starter · #3 ·
There are some other 550 owners here who will likely provide their input, but it sounds like you should start with some good aftermarket coils and fix the choke. Also, you should be aware that running without the pods or without an airbox can cause issues like hard starting and poor carb performance.
yeah im just trying to get it to run. once it is actually firing i will put the pods back on.
 

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It may not run without any air filter. The lack of stock air box is by itself a problem. AT least throw a rag on the carb intakes. All these attempts people do to get 'more power'. They don't get any, just more noise and headaches.
 

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1981 has not run in a while. I will guess that the carbs will need to be disassembled, cleaned and adjusted. New gas will not help if the jets are not clean. With choke flaps it means that you have slide valve carbs not CV carbs. My 80 and 82 kz 550's would run fine with missing choke flaps, but they are a weak link in the system.
 

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1983 GPz 750, green
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The Keihin carbs have choke flaps and are CV carbs. My 1985 GPz550 uses the Mikuni carbs BS with no choke flaps and its a CV carb. Pod filters are just no good on these CV carbs, wasted effort and money, generally a bad idea.
 

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Based on Partzilla parts diagrams for the bike in question, it does not have CV carbs. So maybe, with the proper jetting it can be made to run right with pods. Having said that, if it were my bike, I would be looking for a stock airbox.

I totally missed the fact that the carbs had not been cleaned. Thanks to jpd for catching that. This should be the first item of business if the bike has been sitting for years.

Here is the link to the carb for this bike.

 

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1983 GPz 750, green
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The service manual says the carbs are TK K22P-2C, no other information in the manual regarding jets. It is not a CV carb.
 

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I had both an 80 and an 82 KZ550 standard. They had slide valve carbs with a choke plate that had an aluminum bypass flapper in them. That flapper would break off. My current 82 GPZ model has CV carbs. Not sure at what year the LTD went to CV's The slide valve have rectangular top covers the CV are round. Yes when that aluminum bypass broke off it went through the engine. I found several missing in the 100,000 miles I put on the two bikes. One time it did cause damage. I heard it hold open the intake and backfire in the carb, next bounce around the piston, then hold open the exhaust and after burn in the pipe then finely rattle down the pipe. The engine made expensive sounding noises. I didn't have the location or the money to repair it and found a replacement engine from a wreck so I just replaced the engine.

Once you get the engine running I would recommend starting the bike and let it warm up all the way till it can run without choke before driving off. I think I broke the flappers off by turning the choke off while in motion. That was 40 years ago before knew better. If there was a caution in the owners manual I missed it.
 

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Discussion Starter · #10 ·
A bit of an update, I've managed to get the bike running, but the initial start is very difficult. Have to crank it for several minutes, then manipulate the throttle slightly to get it to start.
I let the bike run for close to an hour. I tried driving it down the alley and it has no power and will bog down and die if I go past 1/4 open throttle. It will also bog down and die when in I'm stationary in neutral and I try to rev the throttle.

As a recap and as far as maintenance I've done the following:

-Carbs disassembled, cleaned in a sonic cleaner, rebuilt with a brand new rebuild kit with stock needles and jets.
The carb has been set up according to the factory settings in the maintenance manual.
-ordered and installed all 4 new choke flaps.
-ordered and installed a factory airbox.
-Removed the valve cover and counted the pins for the timing chain which are correct.
-Removed the timing advancer to make sure its not seized and moves freely
-Brand new spark plugs
-Brand new battery
-New fuel and inline filter
-I checked the valve clearance and they all seem to be within tolerance.

Two of the airbox boots seem to be a bit short but still partially cover the carb. while idling I sprayed carb cleaner around the boots before and after the carb and there was no change in RPM so I don't think there is an air leak there. However I've got all 4 new air boots arriving early next week.
Like i said the coil resistance is 2.0 Ohms. I'm not sure if that would cause a loss of power.
I tried adjusting all 4 fuel/air mixture screws by about half a turn both rich and lean and didn't seem to resolve the issue.
The bike has a 4 into 1 exhaust from the previous owner, not sure if that would contribute to a loss of power?

I'm really running out of ideas here and don't really know what to try next.
Thanks,

-N
 

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If it were me, I would do a compression check. It may not be the problem but its good to know the overall health of the engine regardless. If the compression is too low, no amount of carb or ignition fiddling will get it to run right so its good to check it out.

The low ohms on the coils is worrisome. How does the spark look?
 

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Discussion Starter · #12 ·
If it were me, I would do a compression check. It may not be the problem but its good to know the overall health of the engine regardless. If the compression is too low, no amount of carb or ignition fiddling will get it to run right so its good to check it out.

The low ohms on the coils is worrisome. How does the spark look?
I disconnected the fuel, removed each spark plug one by and and turned the engine over with my thumb covering the hole. I feel compression but I know thats not the most accurate test. I may look into getting a compression tester.

I checked what the spark looks like on my 2015 DR650 and in comparison the KZ spark looks very weak. I'm going to test the resistances on the coils again and may order a couple new ones.
 

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1983 GPz 750, green
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There is a fellow that has a very informative web site with all kinds of info regarding the 550 engine/carbs. Go here and start reading: Kawasaki Gpz550 Camshaft Info
When I was rebuilding my 550 I found that the service manual was incorrect/unclear on a number of vital issues. In particular the cam timing, cam markings. At first the bike would not run, or only a minute at a time but very poorly, re-adjusting the cam timing solved the problem. Also he has much info on the carbs. index Lou D's Motorcycle Stuff. Hope that helps you out. Let us know what you find.
43240
 

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Discussion Starter · #14 ·
I came across that website while researching. I checked the cam timing according to the picture you linked.
 

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Discussion Starter · #16 ·

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It comes with an adapter so you are good to go. If you don't have a Princess Auto close to you, you can probably find a similar one at any Canadian Tire store. Before using it, read up on using one for multi cylinder motorcycles. There are steps people often miss, like holding the throttle wide open.
 

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Discussion Starter · #18 ·
It comes with an adapter so you are good to go. If you don't have a Princess Auto close to you, you can probably find a similar one at any Canadian Tire store. Before using it, read up on using one for multi cylinder motorcycles. There are steps people often miss, like holding the throttle wide open.
I really hope wipe open isn't part of the test because I cant give it throttle without it bogging and dieing haha
I'll definitely do some research first.
Thanks!
 

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Ok sorry. A compression test is not done with the engine running. Basically, remove all spark plugs first and then check one cylinder at a time. Holding the throttle wide open makes sure it can get enough air to get an accurate compression reading but the engine cannot be running. There is more to it than that. Read up on it and ask questions if in doubt.
 

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Discussion Starter · #20 ·
Ok sorry. A compression test is not done with the engine running. Basically, remove all spark plugs first and then check one cylinder at a time. Holding the throttle wide open makes sure it can get enough air to get an accurate compression reading but the engine cannot be running. There is more to it than that. Read up on it and ask questions if in doubt.
Right that makes sense. Gotta remove the spark plug. No spark = no combustion. I knew that. :p It's been a long day hah.
I'll definitely read up on it before I do it.
 
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