1979 Kawasaki KZ 650 SR Top end rebuild first run and break in.

Last summer I bought this bike and a parts bike (no title) for $600. I didn't know but the hopefully soon-to-be runner had low compression, big bummer as now I had to tear apart this motor. I bought new rings, head gaskets, plugs. measured the valve shim clearances (all nearly at 0 when I initially measured them.) First I replaced the coils, points/condenser, and I dug into the carbs and cleaned them out like 4 or 5 times and leveled the floats with a clear tube. After that I tried kicking 'er over and got nothing, I had good spark and fuel, so I measured compression and had maybe 90psi on each cylinder, aside from one with 130 psi (never got a measure with the bike warm unfortunately since it didn't run except on starting fluid. I replaced the rings and honed the cylinders, did a refresh on all of the gaskets to fix some oil leaks and now it runs. Not too well though.
For my carburetors, I have a set of 4 VM24SS carbs (I think) it's the one with the air screw slightly recessed on the air intake side, I put the screw in lightly and backed it out 1 1/4 turns. I also synced the slides with a piece of wire and the bike runs... fine. It's not outstanding, it idles a little funny and has a little throttle lag, but I haven't bothered vacuum syncing the carbs because I don't have the gauges yet and the vacuum would change once the rings are broken yet. I'm also waiting for new pod filters to come in as it's what was on the bike when I bought it. I'm hoping they already re-jetted it for pods.

I haven't taken it on the road yet, and I've avoided monkeying with it too much or letting it idle because I'm not sure what the proper break in procedure would be. Any tips to get it running before I go on the road, what kind of break in do I need to follow? I'm also running just traditional motorcycle oil, 10w-40, not full synthetic, because that's what I've been recommended.

Thank you all!

Also, anyone know if there's any gas tanks I could find online that would fit and not look too stupid? Mine is all rusted out and dented, I can fix it, but it will take time.

Lake Speed JR. can tell you how to break in your rings.



kevin cameron's idea on break-in


break-in oil importance

When you had the carbs apart, did you by any chance write down what jets and needles are in there now? That could prove to be really useful information moving forward.

Easy to start a debate on this topic like what oil to use.
In my head the cam and crank bearings dont break in since they floats on oil and not touching any metal.
The main important thing is to have prepared the engine for startup by using some assembly lube on the bearings not much or use  oil.
I use ordinary motorcycle mineral oil no sythetic .
The things that breaks in is the rings and bores and that happens real fast.So before startup try to make sure everything is in order so you have a good possibility to ride the bike straight away and dont have to have it idle.
First start the engine and rev it up and down to 3000rpm several times until the cylinders feel a little hot to touch.
Then let it cool .Then start it again and rev it the same way until it gets hot to the touch on cylinders.
Then let it cool and check the torque on cyl stud nuts.
Then go for a 10 minute ride and let it cool down a little and check for oil leaks. Then ride it when little traffick and give it moderate load and try to not keep steady throttle. after that rev it up to 4000rpm and accelerate a little hard the first 50 miles.After that increase the load riding uphill and rev it higher and accelerate harder to make sure the rings get good pressure into the bores. After that accelerate hard and higher in revs for short periods.In my opinion the engine is then  finished seating rings and finished braked in after 200 miles. If you are to gentle or let it idle for long time you risk glazing the bores and it may start to burn oil.
That is how i do it, but there is many other opinions .
 

Unfortunately, I didn't take any records of what the stock jets were. I'll probably just take everything apart again when I'm done with work and write all the measurements down. No sense in delaying the inevitable.

Thank you for the advice. I wish the Kawasaki manual would just have a general break in procedure for this type of maintenance. It would really help dispel a lot of debate. Truth is, even Kawasaki probably doesn't know. I've heard so many different break-in procedures from so many different people it's unreal.
Your method is what I frequently hear a lot of people talking about online. It's like your training the engine about how it's going to be run. Thankfully it really it's not a huge deal, since the piston rings are extremely easy to replace anyway.
 

Kawasaki, like other OEM's, specified a very slow break-in procedure.  Keep revs down to 4000rpm for 500 miles, then 6000rpm until 1000 miles.  My personal belief, is that this recommendation, in part, relates to the manufacturer wanting the new rider to get well acquainted with the bike before gassing it hard, and getting themselves in trouble from all the power!  

Babying the bike like this runs contrary to what many say is best to seat the rings; combustion pressure is needed, so that means a good bit of throttle early in the engines life.

My experience in auto assembly plants, has the vehicles being driven HARD right from the first start.  Maybe they are doing this on purpose to seat the rings?  Ha ha.  I doubt that's the reason.  

Many automotive OEM's don't even put a break-in procedure in the owners manual.  And the first oil change is often recommended at 10,000 miles!  Why?  Because it doesn't matter!  

When braking-in an engine, or just rings, all you have to do is drive.  Don't rip the engine up to redline immediately, just drive it normally and everything will be fine.

Generally engines are like teenagers, treat them gently and they will drink to excess and perform poorly - show them "who the boss is" to get the best from them 

This is another one of the topics that tends to create many different opinions on what is best, much like pod filters, or which oil etc. I do not agree with all that is written within this link, but it may prove to be of interest to some. Will add that for the most part he is talking about liquid cooled engines more than air cooled engines. But anyway if you have not seen or read this it may provide more info, or may just confuse us more.
www.mototuneusa.com/break_in_secrets.htm