1978 kz650c starting problems

I'm 15 years old and have purchased my first bike. It was a bit of a basket case but I've accomplished a lot of progress so far. I rebuilt the petcock, carbs, installed and gapped new points/condenser, new spark plugs, and new regulator/rectifier. It hadn't been running in 4 years and I am able to kickstart it on starter fluid and get it started but it only runs for less than five seconds before dying. When I attempt to electric start it just whirs but will occasionally slightly engage and turn the engine over, but it usually just whirs. I've read that it could be the starter clutch? How do I replace that? I have found a starter clutch rebuild kit but don't know how to rebuild it. Also, is it possible the actual starter just needs rebuilt because the teeth are worn down? I already know I'll need new right side hand controls because the start button is stuck on so whenever you press the clutch(safety precaution built in for electric start-must hold clutch to electric start) the starter whirs. Any advice is helpful. I'm experienced with working on engines and most things mechanical but I'm new to motorcycles so I'm not 100% familiar with how everything functions.

Get the engine running with kick starter first. Running on starter fluid is really not good for the engine. If it does run on it, you still have major fuel problem.

Welcome aboard. The very best thing you can do now is buy a Kawasaki Service Manual. Pretty much everyone who is successful in maintaining any KZ model eventually buys the manual. If you plan to keep or work on the bike you will need one eventually, so it makes good sense to get one in the beginning rather than messing up something on the bike. I don't think anyone has ever regretted getting one. It is important that you get one that covers your bike's exact model because there are major differences between the various KZ650 models.
The factory service manual provides instructions on the various maintenance procedures and schedules for your bike, procedures for diagnosing problems, proper torque values for the various fasteners (VERY IMPORTANT), and insight into how each system on your bike works even if you are not repairing that system. Studying the manual before you attempt performing service on your bike will impart an understanding of the system you are working on which will increase the odds of success.

The manuals usually are readily available for most models on eBay and other sources; but be sure to get one that has your specific year and model in it as there are differences between the various KZ650 models. I do not recommend Clymers, Haynes, or other aftermarket manuals as I have seen instances where they provide inaccurate advice. You may decide to use those to supplement the factory manual, but in my opinion they are not a suitable substitute. If you have trouble finding one for your model ask us to help. Ed

As I'm sure you have already discovered, a basket case is always full of surprises. While you are waiting for your fsm to arrive, yo can check the fuel level in the carburetors, using the clear tube method. There is a search function on this forum, located under the HOME tab. Type "clear tube method" into the box and click SEARCH. That will pull up a bunch of threads with explanations and drawings. This procedure is also well described in the fsm.
The starter clutch can be a bit of a bear. Since you have a kick starter, I'd recommend taking care of all the routine maintenance first. If you then discover other reasons to tear into the engine, they can all be dealt with at the same time.

Here is something else you should consider...

www.kzrider.com/forum/21-tools/598060-jis-screwdrivers#672883

It only runs for 5 seconds cause that's the amount of starting fluid available
This is a sure sign you are not getting fuel to/or thru the carbs
Make sure fuel is coming out of the petcock, if it is then follow TexasKZ's advice in setting the fuel level in the carb bowls....

I also wouldn't worry about the electric start until getting the bike up and running

wow, kids grow up fast these days. A 650 at 15? roll on, great. I had a 49cc at 16, a lot safer...you seem to have made some decent progress so far, well done.

Starter clutch sounds like screeching, a really nasty sound. I have a video of it on mine but can't upload it, but it is an unmistakable noise. Luckily you have a kick starter, something bereft from the 550's, so maybe put that lower on your to-do list.

Starter fluid spray is a good diagnostic and get you out of trouble fix, but not to be used too often as it washes oil off the bores. it should run all day on that if you needed to prove a point ( and it would probably only last a day)
So I'm thinking forget fuelling -for now and look towards ignition. Get a multimeter and search through some old posts here then see what you find. Good luck!

Tyrell Corp wrote: ...
So I'm thinking forget fuelling -for now and look towards ignition. Get a multimeter and search through some old posts here then see what you find. Good luck!

Well, I for one disagree here. I think carbs and the fuel delivery is still the problem and needs to be addressed first.
15 yrs old or not, it's a learning curve and I think this owner is up to it.

My first bikes were home made 1 1/2hp Briggs and Stratton "mini bikes" on Stingray bicycle frames!!
My first real motorcycle was a mid 60's Suzuki X6 Hustler... which hauled ass!!!

If anyone has any info on how to adjust the carbs it would be appreciated. I did the site search and couldn't find anything for the "clear tube method". I have noticed I do not have a vacuum spot on my #2 carb, and it is gravity fed not vacuum, not sure if that makes a difference. I am really stumped as to why I can't get fuel through the carbs. Petcock is in the on position. It is supplying gas to the gas line and fuel filter. Anyone have any suggestions?

First and most important suggestion - you really need to buy a Kawasaki Service Manual for your bike. They normally are available on eBay; just be sure to get one for your bike's exact year and model as there are major differences. You really will be surprised at how much the manual will help you; they are worth their weight in gold! If you have problems finding one just ask; maybe we can help you find one.

The vacuum port on the upper side of carb #2 should have a tube that runs to the petcock. Vacuum drawn through that tube when the petcock is in the "ON" position acts on a diaphragm which then permits fuel to flow to the carbs. In the "ON" position no fuel will flow if the engine if off or if the vacuum line is not attached. No fuel should ever flow through the vacuum line, it simply controls the petcock. To start the bike after it has been sitting the petcock should be set to the "PRI" position. If your petcock has been changed to a manually operated one the vacuum port on the #2 carb needs to be capped, and the petcock turned to "ON" when starting and running the engine.

There is a good description of the Clear Tube Method in the manual, but in the mean time here is a diagram that should help. Ed

I'll try the clear tube method but in response to the vacuum port on carb 2, I've found other forums mentioning this, it isn't on my carb. Where there should be a vacuum port there is an indent that is solid, no port or even a hole to cover. The petcock is manual and I put it on prime then on to start. This is why I am stumped as to why I can't get fuel through.

I read on another forum that an issue is that it has "cv carbs" with pods instead of an air box. The bike had pods when I purchased it, so I don't know if it originally had an air box or not. I don't know what a "cv carb" even means but the forum said cv carbs and pods don't mix well and the carbs will either need an air box or "jetted". Can someone explain what this means and whether or not it will be an issue?