1980 KZ650 - The Long Road Home

I will start by saying I have only drove a motorcycle once in my life before yesterday and have never before worked on one. With all of that being true, yesterday I plunked down $500 for a '80 KZ650. The motorcycle ran but seemed to have a nasty smoking problem. The seller tried to convince me it was gas and the carbs were running to rich. No matter, I wanted a bike I could tear down and really get to know. Also, when they went to drop it off yesterday, sometime along the way, the starter button quit working. No biggie, it has a kick starter that would do. The best part was though, the motorcycle seemed to be addicted to carb cleaner. The previous owner would have to spray some into each of the pod filters to get it to run. Only if the engine had recently be turned off would it cooperate and start up. After they dropped it off, I proceeded to start it up and stall it out and kill for around an hour and a half. In the meantime, my oil was being burnt at an alarming rate and I practically ran it dry. Today I ate my Wheaties and drank some Hercules juice and struggled for over two hours to get the engine out of the frame. One sunburned and sore back later, my engine now resides on pavement outside my apartment.





Now comes that part I have never done, tearing apart a motorcycle engine. The biggest engine I have ever tore down and rebuilt was a 15hp Briggs and Stratton. There is quite the difference. Now, I have been reading that if you put the 750 jug on the 650 it will all bolt right together. I am thinking about it since this engine either has some piston problems, valve problems, or both. So, just pretend, I get the 750 jugs and intake cam as well. I have read, for the cam you need to swap the gears out. Is that it? I then read that for the larger bore, the head will need bored. Is that all that needs to be modified? I use my same crank and rods? Or do you think I am better off just keeping what I have and rebuilding it? I am fairly certain I will need to rejet my carbs. When I had them apart yesterday I think my main read something around 89.5 Now all the stuff I have read say it should be in the 100's with pod filters. Any help on my crazy journey ahead would be great. Like I said, this is all new territory for me, but I hope I am up for the challenge.

Thanks For Your Time,
Andrew

Things to have on hand or do when you have a project
1. If your working outside, wear a T-shirt at least.
Sunblock on your arms, neck and ears.
2. Buy a repair manual, more band aids, metric tools (if you haven't already) and study the manual a few nights befor tearing down the motor.
3. Have an area, room or space to work on your project in peace. Radio ok for background noise or peace of mind. Not too loud though. Yes, it makes a difference.
4. Have plenty of carb cleaner and degreaser on hand and a barrel to clean parts in.
5. Time. Lots of it!!!
6. A sense of humor when things go not the way you plan.
7. MONEY!
I'm sure there is more, just can't think of it.
Welcome and keep us informed of your project. It looks like a good one. Ask us any question you may have.

my .02

if you really must have a 750, then buy a running condition 750 engine off ebay or try members here and install it.

The work to get the 650 engine back together is going to be difficult and loaded with learning experiences (mistakes) I ruined my first head and jugs, it took me 4 head gaskets between ruined heads and forgotten cam chain parts... shit will happen.

Now add on finding and buying 750 pieces, clearancing the cases (the 750 sleeves are thicker than the 650 and the cases need to be clearanced,easy to do, or so I read)

Carb tuning with your new beast

Selecting a head/valves/cams/cam chain style

I am not saying it can't be done, but I would recommend get the 650 running and ride it, enjoy it for a season (it took me 3 years just to get to that point) THEN start building the engine.

I would be surprised if in a year you don't have a spare 650 or 750 engine to go through and build as a go-fast engine... heck if you want to pay $60 and shipping I will send you an extra (with the top end in many pieces) however I bet shipping will be killer.


Take your time, buy a manual and work in steps, other wise it will all seem to daunting.

Get a Kawasaki Factory service manual for your specific year/model before you start opening it up. Ebay has them all the time. It will more than pay for itself by preventing costly mistakes. Also, don't even think about doing a rebuild without appropriate torque wrenches or you'll be buying timeserts AND torque wrenches before you're done. Good luck. Ed

Thanks everyone for the comments and suggestions. I think I will be going with hardr0ck68 on this one and fix the 650 first before I do anything else. After I had the engine out I removed the valve cover and checked the clearance. Only one valve one in spec, one other was .0015" much less than the .007" and all the others I could not even get the feeler gauge between. So from there I planned to take the head off and see what I had going on. I ended up with the head still attached and the jug coming off the lower block. OK, not what I wanted but it would let me look at the cylinders and rings. The rings looked brand new and there was no at the top of them that I could feel. That does not mean that they are sealing good, but it's nice that it may be just fine. The pistons where all silver minus one are the far edge either 1 or 4. It was golden like honey on the edges and had black carbon buildup in the center. Now, when I looked up into the head, most of the valves where good. A couple of them did have some buildup. However, the one corresponding to the nasty piston, was quite filthy with a mix of black and brown. My spark plugs all seemed to have black on them from oil, one though was white (not sure what that is.) I have all of the top-end parts loaded into my car and will be taking them home with me this weekend. My next course of action is to get a gasket kit, shims (mine where 245, I'm trying 235, 230, 225), carb kits, new jets. I hope after I clean up and lap the valves, get my clearance right, and rejet/rebuild the carbs it will run good and fix its appetite for oil. If not, I can always just buy and running one and part mine out, sell it whole, or keep working on it. Thanks again to everyone and defiantly where sunblock in 95* weather.

white plugs usually indicate a lean condition. Which with the small main ket and pods I'm not surprised.

^^ Thanks, that is good to know. I have gotten the upper half to my dad's house and ordered some shims, gaskets, and jets ( www.z1enterprises.com/detail.aspx?ID=53 hope those are the right ones) Once it all comes in I will be cheking out my valve clearance and figuring out which I will need. Then will come the fun part of trying to put it all back together right. One quick question regarding the starter button, I opened up the plastic case in which it is housed and tried to just jump across the pins. If my button was the problem and my wire was good, would it have turned over the starter? What I may do is just try and find that whole assembly and replace it. So, if anyone has one laying around let me know. Thanks again to everyone, hopefully I can atleast get this bike running before snow hits and then get the rest of it looking good.
Andrew

I would first check the starter itself, by putting 12v to the starter lug from the battery. Use a cable to jump from the battery to the starter (make sure you also jump the ground it the motor is out of the bike, you can just ground it to the starter body).