1980 KZ650F Cleanup and tune

I pulled the trigger on the KZ650 I had posted about in the New Members forum.

Got the bike (and parts bike) home yesterday. I was able to get it to turn over with starting fluid. I only sprayed a little on the pod filters to see if it'd do anything, and it started briefly.

I tore into the carbs today. Need to replace the gaskets at the very least, the jets are all cleaned now and the schmoo cleaned off all the carbs. Some of the o-rings inside the carbs need replaced. Accelerator pump diaphram needs replaced. Chokes all need rebuilt, the bushings are disinegrated. I will probably make some at work out of aluminim. The boots that go from carbs to intake manifold need replaced, I didn't like the look of the JB weld repairs that had been made. The boots that go from the carb to pod filters need replaced. I was thinking I'd go back to factory airbox, but I wonder if I can make some kind of custom airbox.

The throttle cables work, but there is plastic missing in some spots so they will get replaced.

There's been some wiring hack jobs done, and I hate messy wiring so that'll get fixed (wire nuts for house wiring... probably not the best idea for a bike).

Need a new rear tire. Front and rear brakes definitely work, but I will inspect pads (was told they are pretty new) and check out the pistons, flush brake lines if they all look good. Parts bike has the dual front caliper setup, I may eventually switch that over if it's not a major undertaking.

There are other little things here and there that need fixed...
The ignition works, but feels pretty darn worn out.
The seat bracket that holds keeps the seat from opening too far is missing (I added a piece of wire in the meantime).
Side covers are missing.
Toolbox is missing, but I may make a larger one that goes from the battery box to the rear of the frame above the rear fender.

I've noticed that all the carb kits I have seen do not mention KZ650F. Would I be okay ordering one that's for a late 70's KZ650B or D? They sure look the same, but I don't want to make any assumptions.

I also saw something about oil needing to be JASO certified, so now I don't want to put the Castrol High Mileage 10W40 I just got today in the bike. What do these bikes like to have for oil?

First Picture, before I bought it.

Sitting in the garage now, getting worked over.

Parts bike sitting outside.

Looks like a couple of neat projects there. Let us know how it goes. We're here if you need advice.

I think the big question I have at the moment is about carb rebuild kits. Most of them say they are for KZ650 B/C/D but none of them say F. I'd like to get some in the next couple of days since I'll have a 4 day weekend but it'll be a bummer if they don't work. Will probably buy a cheaper kit just to check and see if all the holes line up

Don't waste your money on the carb kits usually the bowl gasket can be reused , just clean the jets that are in the carbs. The jets in those aftermarket kits are not Mikuni and you really don't know the jet sizes.

Looking forward to your project.
Are you keeping her relatively stock, or something custom?
If you need a tail piece, or other parts, ask, as I'm sure someone will have what your looking for.

rstnick wrote: Looking forward to your project.
Are you keeping her relatively stock, or something custom?
If you need a tail piece, or other parts, ask, as I'm sure someone will have what your looking for.

I'd like to go stock as much as possible.

I was out fiddling around and after some reading, the '80 I have is an LTD (single front caliper). The parts bike is a '79, has dual discs on it (missing the left side caliper, which I do have on the 80). It's got what looks to be the stock handlebars. I tried to fit them on the 80, but the single caliper brake line is too short. I'd like to move the dual caliper setup to the 80 and use the taller handlebars, so that's the next thing I will be working on (if it's possible) while I wait for parts to arrive

Should have the carb rebuild kits and some other stuff this weekend

baldy110 wrote: Don't waste your money on the carb kits usually the bowl gasket can be reused , just clean the jets that are in the carbs. The jets in those aftermarket kits are not Mikuni and you really don't know the jet sizes.

The gaskets are trash, cracked, not reuseable. I'll stick with the existing jets but I do need the gaskets for sure. Thanks for the tip about jets, much appreciated!

Got the carbs rebuilt. Need to replace the fuel rails, they all leak (the middle tee and the two straight ones). The middle one is a greyish material and has the rubber overmolded on the ends which include o-ring type humps and they are all worn out.

Might be able to try some teflon tape on there to fix it temporarily until I can machine some new ones with o-ring grooves.

The choke bushings are all in pretty bad shape too. Plastic doesn't last very long, so I am going to machine some new ones out of brass. I ordered plenty of material to make extras if anyone is interested.

The fuel petcock seems to not be working very well either (rebuild kit not here yet).

Looks like I am waiting for stuff to show up... plenty to clean up in the meantime

Some people should not be allowed to touch jb weld, haha! The fuel petcock had jb weld all around the valve body where the diaphragm goes.... But I don't think they used enough hardener because it came off without too much trouble.

I got the valve cleaned up and ready for the rebuild kit. Lapped the tank-to-valve sealing surface with a diamond plate to make for a bit better seal.

Going to pull carbs back off and try to teflo n tape the fuel rails to stop that leak. I found some o rings that are about the right size so I may try cutting out the molded on orings and replacing with real orings.

Try some shrink tube on the fuel T rails. Works for me perfect.

Teflon tape works great for those Tees and lasts a long time. People don't realize JB weld epoxy breaks down in contact with gasolo that's why it came apart so easily.