Low Compression/Not Starting

Hey all, recently acquired my first KZ1300 (1980 B2 Touring) which is not starting. Hoping to get some guidance on what I might want to take a look at. Based on what the seller told me, the bike was running a bit over a year ago when he last used it. Carbs were dry and gummed up and there is a bit of rust in the tank (no chunks/fuel discoloration). There is an inline fuel filter. Oil was a bit low/dirty which I changed out. The engine does turn over without any funny sounds but doesn't start.

I have verified the following:
- Spark on all 6 plugs
- Carb is clean
- Battery is good

After I cleaned the carbs, I checked compression with my finger on 1 which had almost no pressure and 2 which had some. I have a pressure tester coming in tomorrow to verify this. Based on some of the threads here, I pulled the valve cover to check clearances and found the following:

Exhaust/Front
GAP:  1.8  0.21  1.21  1.1  0.1  1.134
SHIM: 255  245   245   245  255  245
SHIM: 240  245   245   245  240  245
GAP:  0.1  0.86  0.33  0.48 0.46 0.20
Intake/Rear

These are not exact since the feelers I was using were inch based and had weird metric numbers. I have a new one also coming in tomorrow that is in 0.01mm increments to confirm this as well. The variations in the gaps didn't really sit well with me since I'm not really sure what is normal for these.


Any thoughts on what I might want to take a look at next?

When I bought my motorcycle, the seller also told me that before stopping the motorcycle, it was working perfectly...
 To go fast and rule out several things from the start.
 Remove the spark plugs and use a syringe to inject a couple of cubic centimeters of gasoline into each cylinder, reinstall the spark plugs, and try to start it. If the motorcycle starts, you're already well on your way.
 Do that and let us know how it goes, along with a photo of your motorcycle. Translated with DeepL.com (free version)

Laserjet25 wrote:

Hey all, recently acquired my first KZ1300 (1980 B2 Touring) which is not starting. Hoping to get some guidance on what I might want to take a look at. Based on what the seller told me, the bike was running a bit over a year ago when he last used it. Carbs were dry and gummed up and there is a bit of rust in the tank (no chunks/fuel discoloration). There is an inline fuel filter. Oil was a bit low/dirty which I changed out. The engine does turn over without any funny sounds but doesn't start.

I have verified the following:
- Spark on all 6 plugs
- Carb is clean
- Battery is good

After I cleaned the carbs, I checked compression with my finger on 1 which had almost no pressure and 2 which had some. I have a pressure tester coming in tomorrow to verify this. Based on some of the threads here, I pulled the valve cover to check clearances and found the following:

Exhaust/Front
GAP:  1.8  0.21  1.21  1.1  0.1  1.134
SHIM: 255  245   245   245  255  245
SHIM: 240  245   245   245  240  245
GAP:  0.1  0.86  0.33  0.48 0.46 0.20
Intake/Rear

These are not exact since the feelers I was using were inch based and had weird metric numbers. I have a new one also coming in tomorrow that is in 0.01mm increments to confirm this as well. The variations in the gaps didn't really sit well with me since I'm not really sure what is normal for these.


Any thoughts on what I might want to take a look at next?

First, Welcome to the site.

Now that you are  a member, you have access to all the Service Manuals and Parts diagrams. you can find them on the Index page and they are downloadable to you for free. You need to Login before looking for them since "Visitors" don't have access to those pages.

I'd advise you to spend some time looking through the FAQ section and familiarize yourself with the problematic issues and resolves associated with these KZ's . There's a wealth of information there.

Pay particular attention to the issue with the camshaft drive chain system and the tensioner. Before you do anything, you need to inspect the tensioner and update it either modify it and install a stop screw on the back end of the tensioner. Also, inspect the tensioning roller and tensioning nylon sprocket. Failure to do so and you take the risk of jumping the cam timing and bending a valve. I can't emphasize this enough .

Looking at your shim clearances- Either you have a few typos in there or you need to do some significant shim adjustments. The intakes should be .004"- .006" or in metric .010mm - .015mm,  the exhaust should be .006" - .010" or in metric .015mm - .025mm. You've reported several clearances over 1 mm (.040") and I wouldn't even attempt to start this engine for fear of spitting a shim .

The choke system on these carbs works fine on a cold running engine. For start up on a dry engine that hasn't been started in a long time, the choke system isn't enough. I have a WD40 spray bottle that has seals in it that can handle petroleum products, and I fill it with gasoline for starting dry engines. You can spray fuel at the intakes of the carbs and once the engine fires, you can keep squirting the carb intakes until the engine carries on by itself.

I'll leave it at that for now. Let us know how you are making out.

KB

Really appreciate all the enthusiasm everyone has here to keep these beautiful bikes alive! I took a quick look through of the FAQ and will definitely have to spend some more time in there before taking the bike out.

@kawboy I remeasured a few times with new feelers and came up with slightly different numbers but still had a few with over a 1mm gap. Since I haven't opened the side yet, I'm using the starter to approximate the cams and used the average from a few cycles. The new (hopefully) more accurate values are listed below. The cam chain has less than half an inch of play (feels tight) and the nylon sprocket looks to be in acceptable condition. The bike has around 22.5k miles on it, which I forgot to mention in my original post.

I tried to do a leak down test but wasn't able to get any cylinders under pressure, and all either leaked out exhaust or intake. Adjusting the cam position did not seem to make any difference here. Finger test indicates all cylinders have very low/no compression. About 1-2 oz of oil was injected through the spark plug holes before doing these tests. My initial thoughts were that something was likely a bit sticky with the valves but after seeing how far off some of these shim gaps are, I'm not really sure what is going on. The markings on some of the shims were different, so I'm assuming they were checked/changed at least once before. I'm going to triple check either tonight or tomorrow that I got all of those gaps measured correctly. Any thoughts on how these could get so far out of spec or if any of this indicates leaky vales?


Exhaust/Front
GAP:  1.55 0.25  1.1  1.1  0.16  1.115
SHIM: 255  245   245   245  255  245
SHIM: 240  245   245   245  240  245
GAP:  0.15  0.86  0.33  0.48 0.46 0.21
Intake/Rear

Better check the camshaft timing before going any further. I suspect that the cam timing jumped a tooth and bent a few valves and either the previous owner reset the timing and couldn't get the bike to run and then flogged it and you got stuck with a non-runner or he left it as found, and the cam timing will be off.

The only time you might find significant shim gaps would be on valves that are bent. When the head of the valve gets bent, the valve will not fully close so the valve stem doesn't come all the way up, which leaves a clearance reading like what you are seeing.

Camshaft drive chains shouldn't have any noticeable "play".

Sorry, but that's my best guess here.

KB