Sprocket and Chain

Hello everyone, this is my first post. I am the new owner of a 1980 KZ650-F1. I bought it last summer, ebay special, for $1000. It is my first bike so I'm learning just how many things can be wrong at one time. This spring I've put new tires on it, I'm currently rebuilding the carbs and fuel pump, replacing the valve cover gasket, just bought new dyna coils and wires, new plugs, I'm going to use the Kreem 3 step kit to clean out my gas tank, and of course an oil change. All that being said, I've been reading some forums on here about bringing down rpms by changing out the front sprocket. In doing this, do you also need to change the chain or should the one I have on there still work?

Hi 80KAW650,

Welcome to KZR and congratulations on your first bike. However I've got to say that Ma Kaw is pretty smart, particularly with design of the drive ratios that best match their motors to their bikes.

I tried a sixteen tooth counter shaft sprocket on my KZ900 years ago to achieve the lower engine speeds you're talking about. I took it off after just a few days because I lost so much off the line that I judged the set up to be less driveable.

I suggest that you go through most of your plans for restoring your 650 and ride the bike till you really come to know it before you start reengineering it.

OH By the way you should read my article on fuel tanks before you epoxy seal your tank.

kzrider.com/index.php?option=com_content...view&id=22&Itemid=11

Good luck with your new ride.
KZCSI

KzCsi,
Just curious to know. I acid washed my tank which lasted and worked well for a year or maybe even two but seriously that step is really just a fix because after that the rust comes back much easier as the hardened part of the metal rusted up and now the softer metal has been exposed.
I have read this and I have experienced this.
What is your opinion and experience on the matter. These old bikes sure are wonderful but they need much tlc. I got lucky and found a brand new tank for cheap money and I haven't had any problems since.
All kaw tanks after thirty years are prone to this problem and I think acid washing it is much better than kreeming it as I have seen carbs pulled off of bikes that have been kreemed and they don't look pretty.
Good luck on the bike. Looks pretty good from the pic. Just those little gremlins are a real pain. I would go through the electrical wires on the bike making sure that all connections are cleaned and in good shape. My ltd1000 had a worn turn signal wire inside the headlight bucket and shorted out the turn signal light and may have had something to do with the fusebox. Either that or the fusebox connections after the years didn't pass current as well as could have so heated up and melted the main fuse wires. So once again make sure that all connections have been cleaned and connected firmly with no worn out wires like can happen inside the headlight bucket. Bikes can catch on fire or leave you stranded on a nice Sunday ride far from home. No fun. Be preventative and that won't happen and you will continue to enjoy your ride. Ok I have said much already. Peace

Hi SaxJonz,

These fuel tanks are plain old mild steel. I doubt seriously that the surface is any harder than the deeper portions.

I don't subscribe to the theory that once rust starts it cannot be stopped. The truth of the matter is that moisture is hard to completely purge out of the porous rust so that if you clean the tank and leave scaly rust behind you could be leaving moisture behind as well.

I'm not saying that your suggestion that "...after that the rust comes back much easier..." is wrong, I just don't think that the relative hardness of the surface has anything to do with it.

The reason that a tank, once having been cleaned, might be attacked by rust more easily is because the newly cleaned steel has a much more textured surface than the steel did before the rusting and cleaning occurred. The molecules on the raised areas are more exposed to oxygen than the molecules that are simply below a smooth surface.

The reason I still believe in the phosphoric acid treatment is that it leaves that Iron Phosphate coating which is somewhat more resistant to rusting than the bare acid etched steel.

If your rust returned, I've got to wonder if you didn't inadvertently allow the conditions that cause the condensation to happen again.

To avoid future rust either store the bike with an empty or a full tank.

kzcsi

Okay so I've tried cleaning out the rust twice now and I've still got surface rust. The first time I tried 2.5 gal water to .5 pint of acid and left it set 24 hours, tiltlting from side to side every 8 or so hours. The second time I filled the tank with and a 1.5 pints of the muratic acid to where all serfaces were covered and let it sit for about 4 hrs. Do I need more acid less water, more time, what do you suggest?

If you're going to seal it, be sure and get all the rust out or the coating will not adhere. That little bottle of acid that comes in the kit isn't going to do anything. Adding a pint or 2 of acid with 4 gallons of water isn't going to do it either. Add 50/50 muriatic acid and water if the rust is stubborn and fill the tank full, let sit several hours. The acid won't damage any clean metal, so no worry of eating through a good tank. After that, wash out with the Kreem wash or acetone, then add your sealer. If you don't seal after acid wash, the tank will rust again right away, (arguable I guess as others have done it, but my experience anyway). The last problem in following the Kreem instructions comes in the step "entirely coat the tank, let the tank sit, then coat again, lay it in another position, repeat, repeat,repeat, then drain excess". The problem comes when the Kreem turns to sludge before it is drained, by taking too long to do this. My advice is to coat once, let sit, coat again, then drain while the Kreem is still liquid. All that matters is the tank is sealed, you don't need or even want 1/8" coating of Kreem in the tank.

Welcome 80KAW650.

Looks like you found a nice bike there.
Hope you get her running well soon.
They are great bikes.

Check out kz650.info as well for strictly 650 information. Great forum there as well.