New bike troubles

Hey guys, so about a week ago I drove up 4 hours to pick up a 78 kz650 and when I brought it home, I was having issues with it. When I started it, gas would pour out of the first carb so I figured it was having issues with the float getting stuck. One thing to add is that it was running fine when I left. Anyways, I decided to pull the carbs and do the pine sol soak. So I did that and when I put the carbs back on, it solved the overflow problem but now it won't run without the choke on. I know you guys are magicians so I was curious what you guys thought.

Thanks,
Jonathan

Onealjp wrote: Hey guys, so about a week ago I drove up 4 hours to pick up a 78 kz650 and when I brought it home, I was having issues with it. When I started it, gas would pour out of the first carb so I figured it was having issues with the float getting stuck. One thing to add is that it was running fine when I left. Anyways, I decided to pull the carbs and do the pine sol soak. So I did that and when I put the carbs back on, it solved the overflow problem but now it won't run without the choke on. I know you guys are magicians so I was curious what you guys thought.

Thanks,
Jonathan

Hello, Jonathan. and WELCOME to KZr!

Soaking, alone, usually isn't sufficient to adequately clean the pilot circuit.

It's important to assure that the pilot jet and the pilot circuit are "as new" clean, and that the pilot fuel mixture is entering the carb throat through the small orifice(s) at the end of the pilot circuit.

Compressed air is very helpful toward blowing the passages clean.

May also use a pressurized canister of carb cleaner spray to squirt through the passages.
Be sure to wear eye protection, because the spray always backfires. ALWAYS.

#6 orifice on side-located pilot air screw design carb.
#3 and #4 orifices on bottom-located pilot mixture screw design carb.






Good Fortune!

This is why I love this forum, before picking up my kz I followed just about everything else on the site and you guys certainly know everything that there is to know about the KZ! I'll pull the carbs back off tomorrow and report back with the results. Thanks!

So I pulled the carbs today and when I took the air screw out of the side, it looked like it was coated in some sort of dried debris. So I cleaned off the screw and shot some compressed air all throughout the pilot circuit. I mounted everything back up and it still wouldn't run without the choke on, even after warming up. I could get it to do different things by adjusting the air screws (obviously) but as soon as I touched the choke or throttle it dropped off.

So since there was that dried debris on the screw that wouldn't come off with just air, I'm assuming that the same problem is going on somewhere in the circuit. Something clogged up there that has to be freed using something more than just compressed air. So I think I'm going to pull them again, do a soak to loosen everything up again and then shoot some compressed air through the pilot circuit. I'm still new so I may not even know what I'm talking about so what do you guys think?

I think you are on the right track. If one part of the carb was dirty or had residue on it there's a very good chance that other areas of the carb are also dirty. Dirty carbs will really make these bikes run poorly (if they even run at all), so cleaning the carbs may solve your problem. Be sure to add an inline fuel filter if the bike doesn't have one, or the carbs may get dirty again very quickly. Ed

It doesn't have an invite fuel filter, so I'll definitely install one. I didn't even think about it, but yeah that definitely might be a problem too. The PO had let it sit since November and when I drained all the old gas out, not all of it drained out. So it might possibly be little bits of gunk in the old gas too. Probably not, but either way the fuel filter will make sure everything is good, so thanks for the idea!

You are correct in your assumption that old gas can gunk up the carbs. It will form a varnish and coat everything it is left in contact with. I went through that drill once, and I'll not go through it again. I now run the bike for 10 - 15 minutes at least once every 10 days during the Winter months to ensure gas doesn't sit too long in the carbs. Obviously I ride more often than that during warmer months, so it's not an issue then. Ed

One of the members here suggested soaking the carbs in diesel fuel for a week and then use compressed air on all passages, so that is what I am doing at the moment, I bought a set of VM26 and the slides were stuck, and after 3 days of soaking they are moving freely, so if you got time, this method sure loosens thing up. .

I tried the pine sol method previously and that seemed to help, I just needed to hit it with some compressed air but maybe I will try the diesel method this time.

You can drain the bowls then refill with seafoam, gumout or similar cleaner and let it soak for a few days.

Well a million things prevented me from fixing the carbs as quickly as I wanted but I was finally able to do it. I pulled the carbs, did the soak, blew everything out with air and installed an inline full filter and then remounted everything. I also seemed to be having an air leak out of the front exhaust headers where they weren't put on correctly so I pulled those off as well and put some copper exhaust gaskets in and replaced a few of the studs that seemed to be stripped. Well the bike now starts right up on the first try and doesn't need the choke on anymore so it must have been a clogged jet, problem solved. However, when I roll on the throttle, the RPMs go up quickly like they should but rather than falling back down when I roll off, they linger there and come down very slowly. Also my idle seems to be a bit low, probably around 900. Not sure if that means anything.

Make sure your throttle cable isn't getting hung up anywhere. Sometimes a cable will get caught and when you turn your handlebars the bike will keep the throttle where you left it.