1976 KZ400 Gift

Thanks for the input Ed. The battery is not fully charged and most likely bad. I got it with the bike and it wouldn't fully charge. It did, however, turn the motor fairly quickly. Was going to get a new one...guess might as well get it now.

Might also have an issue with the pet cock. I pulled the tank off, which had very little fuel in it, with the switch in the off position but the gas still kinda dripped out. Seemed like when I tipped it, the sediment bowl may have filled and flowed a bit more. I fully cleaned the pet cock, put on a new screen, a new bowl gasket and new gasket that goes between it and the tank. Anything else I should try?

Got the petcock issue fixed today and set the float height. Charged the brand new battery and hooked it up...no good. Looks like there's definitely issue with the spark. When I pulled the plug and grounded it against the block, you can see a strong spark right when I kick the starter then nothing as the motor spins. I did install new points/condenser and set the gap. What could be causing this?

Ignition contact points are dirty. Or the insulators are not installed correctly. Loose connection, bad plug wire/ cap.

It's alive! I got another set of spark plugs and re-gapped the points and the thing fired right up. Revs fine but doesn't want to idle below 1,500 rpm. Going to check the timing and get a buddy to help me balance the carbs. Hopefully that takes care of the motor then it's on to brake pads and new tires then ride!

Glad to hear it's running! If it won't idle well at low rpm be sure to test the carb holders for leaks. If they leak the bike will idle very poorly, and the lower you set the idle, the rougher the engine will run. Carb holders will eventually develop tiny cracks in the mating surfaces between the holders and the cylinder head that can cause them to leak at idle. These cracks cannot be seen with the carb holders in place. I suggest you try the following. Get the engine warmed up and temporarily set the idle as low as possible without killing the engine (lower than 900 rpm if possible). The lower the better because with the idle very low the slides are nearly shut and the vacuum inside the carb holders is at its highest. Then spray carb cleaner around the carb holders, especially where they mate with the cylinder head and where the carbs attach to them. Carb cleaner works best for this test as it doesn't leave an oily mess with WD40 or evaporate so quickly that it is not drawn into the leaks as can happen with propane or starting fluid (ether). If the engine dies or reacts to the carb cleaner, you need to replace the carb holders. Carb holder leak related problems are noticeable at idle but generally don't have much impact when riding or at higher rpm because the throttle is open and the slides are up at least somewhat. If you find you need to replace the carb holders soak the screws with Kroil for a couple days before attempting to remove them, and use JIS standard, NOT Phillips, screwdriver bits, and this will greatly improve the odds that you will not break or strip a carb holder fastener as so many have done. Let me know if you you need info on JIS bits, I have a good link for making your own at no cost. Ed

Thanks Ed. Good thing to check...I was hoping I was done taking the carbs on and off but I've done it some many times now that it doesn't take very long.

I took the bike over to a buddy's house to help me sync the carbs. We fired the bike up and he said I don't have leaks at the carb holders but at a part of the idle circuit. I circled the part in question on the pic. He said I have a vacuum leak there and suggested maybe putting in an o-ring. He said this is similar to some part on VW carbs that has issues and has to be machined with a groove to hold an o-ring to fix. The whole time adjusting the idle screw couldn't get the bike to hold idle and it ran very rich.
I took the bike home and read up on these carbs trying to find a mention of this wore out circuit. I couldn't find any. I took the carbs back off this morning, checked all the jets, switched the needles to the original ones which were a tiny bit shorter and adjusted the sync screw since I noticed the butterflies were quite a bit off. I set the idle screw to 1.5 turns out and fired the bike. It ran much better and turning in the idle screws another .5 turns got it to hold pretty clean idle at 1,100 rpm. The bike also revved just fine. Letting the bike idle for about 10 min also seemed to make a diff...guessing it hasn't ran in many years.
Has anyone ran into issue with the carb part I circled in the pic? The bike seems to run fine now so I'm not sure what really needs to be done. Thanks.

Had a real surprise when I went to change the oil. The bike did start to puke oil out of the breather after idling a while so I knew it must have been overfilled. I put a 5 liter pan underneath and started draining it...it overflowed! Probably by about a liter. How could someone do this?! Putting the correct amount of oil in it helped it run even better.