Engine Swap

No eBay APP ID and/or Cert ID defined in Kunena configurationI am working on restoring an old KZ650, and had a post in electrical because I was wanting to exchange the points and condensors for electronic ignition. After doing a compression test(below 100 in each cylinder, fourth not even reading in the gauge), and being 90% sure the valves aren't the culprit (they were adjusted at a bike shop less than 5k miles ago) I decided to look for a new motor. I found one only an hour away, at 300 bucks. Here is my original post: kzrider.com/forum/11-projects/525441-restoring-old-kz

Just wondering, is there anyway I can tell that this motor will definitely fit in my bike? He has two KZ650 1980 engines, both right around 16k miles with around 175psi per cylinder. Here is the link to one:

I'm going to get it tomorrow if it seems like it will fit. Thanks for any advice on this topic!!

You may have to change the reg/rec, but other than that it bolts right in.

Since you seem to have the choice of two engines, close at hand which have good compression and will be direct bolt ins, in may not interest you at all, but bolting up a 4 cylinder 750cc is also an option. They are pretty much the same engine as the 650, just evolved a bit.

In your shoes, I would grab one of the good compression engines as well, and use your old one as a teardown/rebuild, learning experience. But it nice to know there are other options out there as well, should you decide to get fancy down the road. And as they say, there's no replacement for displacement. While I mostly agree with that, you can likely find a serviceable 750 motor for alot less than it would cost to do a 810cc on a 650.

Sorry if thats' just a little off topic. :laugh:

Cheers

Actually the first thing I looked for was a 4cyl 750, to no avail. I found a couple twin cylinder 750s, which I didn't even realize they made a twin kz..?

And as for your idea on tearing down the old one, that's exactly what I was thinking! I don't have much experience with engines, but would love to learn the ins and outs of them. I was thinking I could install this motor, while tearing down the old and maybe doing some work to it down the road. I'll be going to pick up the engine tomorrow morning.

I tried searching the forum for "650 engine install" and used google, but I can't find much. How much of a job is this? I worked for a bike shop for several months one time when I was teenager, and helped reinstall a motor from a cb750(I think) and remember it being ridiculously hard, even on a bike lift with several jacks. I have two guys to help, that also have a little mechanical experience (we all work at autozone), but I'm wondering what all I will need or what would help to make this easier?

Also, why would the R/R have to be changed? Thanks!

Yup. Lots of 750 twins out there... I am NO guru here, but my understanding was that the 900/1000s pretty much ruled the roost for a long time, and the introduction of a smaller 4 cylinder option first came in the form of the 77 650. Until then, Kawi's 750 offering was the twin... the 750 4's were an evolution of the 650s... (which is why, as 650 owners, you know you have the original and best )

Aaaanyway, if you include the year and model of your bike in your signature, it will help out a little, since I'm not sure what year of KZ you are trying to restore. (Its easy, and Patton will perhaps jump on this, he has a little tutorial for these kinds of things.)

As to the reg/rec, the 1977 650 is a one-off in terms of the charging system. From '78 onwards until sometime in the early '80's the 650 share pretty much all the same components, at which point they went to electronic ignition, instead of the points/contacts you may have in your resto project. So, basically, if you are working on a '77, then your charging system won't be compatible with the setup in an '80 engine. Simple swap, its been done by many, and I am pretty sure you will be able to find a thread on it. (Sorry, a bit too lazy to drag one up right now. :laugh: ) Any of the electronics/650 gurus will probably be happy to point you in the right direction here.

The best advice I've had for removing/reinstalling engines, if you don't want to break your back, and are not removing it in peices from the frame, or splitting the cases, is generally as follows:

- disconnect all wires, tubes, chain etc... from the motor, you want it ready to drop out.
- remove easily dentable stuff: panels, tank, etcc....
- using a soft(ish) surface (keep it simply, your lawn will probably do...), build up some kind of cradle which will support the engine, and another for the frame and all other components.
- tip the bike over onto whatever sort of support you made, make sure it won't land on your foot it something shifts :woohoo: (or perhaps wear steel toes, if you have a pair)
- unbolt the engine. nothing should go anywhere if all is well supported.
- do whatever moivng and shimmying around it takes free the motor from the frame
- lift up your now motorless frame, leaving with the engine on the ground.

-installation is pretty much the reverse....

Worked when i removed/swapped around engines in my 440. Never done it with the 650 yet, but I don't see why it wont work. I guess its a bit of a ghetto way of doing things, but I never did and still don't have all the nice workshop lifts or many friends who can manhandle an engine out of the frame with me Perhaps you are luckier than me, in that regard.

Good luck on the project... And if you aren't already a member, check out kz650.info its another excellent forum, and alot of the 650 guys here are also over there.

Cheers,

Jon

PS - PHOTOS!!!! You can't post enough photos.

When you did the compression test, did you have the throttle wide open and a strong battery>

Yeah throttle was wide open battery was fully charged. Thanks for the info on the swap! Exactly what I was lookin for. I'll get pics of the bike and new motor up tomorrow, as well as this swap process, I'm sure it'll be interesting... Anyways... I was about to borrow a truck to pick this thing up, but that plan fell through. How easily do you think this thing fit in the backseat of nissan altima? :evil:

remove the back seat from the altima,wrap the engine in blankets,one guy grabs one side and backs through the car,set it down,belt it in,your done.

reverse the procedure for removal :woohoo: !

leon

Hey, it's been awhile but I got the motor, brought it home (was surprised how small it really was, fit perfectly in the trunk) and yesterday pulled the old motor and got the new one set in and bolted down. It went in surprisingly easy with a couple friends and two scissor jacks and a piece of 2*4. I'll post pictures tomorrow. I already have my new electronic ignition, so that's my next swap, then onto cleaning and maybe re-jetting the carbs for Pods, not sure yet.

So here are a couple pictures, the swap went really well, now I'm just looking around for good prices on all the parts I need. I'll put up the list here, in case anyone has any leads or extras they would like to sell:

rear and front sprocket + chain
coils and wires
seat
brake shoes rear
pod air filter
dyna jet kit
throttle cable
intake pipes
left side cover (ltd blue)
front fender
kick starter
starter cover
intake pipes(from carb to engine)
Thanks! More pictures will come as I get more done, ignore the messy car port please..