TOPIC:

Alright so I recently bought a 1982 Kz 550 LTD from a man about 60 miles from me. he drove the bike to my place with little to no problems. it needed some work, (Speedo broken, rear brakes bad, sprocket and chain needed fix) but overall it still drives and runs.

Recently while i was taking it out for a ride, the idle speed of the motor shot up to 3500 with the idle adjustment backed all the way out, and choke off. after a little more time it shot up to 5000 rpm and wouldn't come down. also, it takes a lot of effort to start the bikes. first it wouldnt turn over, then catch and run for a second or two, then it would run after a minute or two of trying again and again. I'm used to cars, as i'm a newly educated auto mechanic, but i know next to nothing about bikes, let alone old bikes. I'm guessing its an air leak.

I sprayed carb cleaner around some hoses and the carb mounting flanges and found when i sprayed on the flanges, the rpm did drop a bit. but only about 500 rpm. I'm going to replace all the vacuum hoses, and carb flanges. also ill be doing a clean air system delete as it has cold air intakes, and the large air tube is just sitting there doing nothing. its 2018... 82 emissions arent in effect anymore haha. But i was wondering if anyone on here could tell me any common problems these bikes may have with air leaks? maybe a cracked cylinder head i would need to replace or something of that nature.

also on a side note, recently when i was applying throttle on a ride, the throttle would just rotate and not pull the cable by the carbs, but after messing with it a little, it went back to normal. Its not a huge problem right now, but i think it will be in the future. Any suggestions?

Vacuum leak(s). Spraying junk is a poor method to isolate unless the leaks are drastic.

And it sounds like the bike needs maintenance such as lubing cables or replacing them all together. First thing that must be done when buying an old bike is go through all the various maintenance tasks as detailed in the factory service manual and catch everything up.

What would be a good method to isolate leaks? in the auto world i would smoke out the intake, but im doing it all from my own house so i dont have any special equipment. the intake boots look old anyway, and the rubber is hard. I figured there could be small cracks or tears that i wont be able to see without taking everything apart. the culprit seems to be the #3 carb holder, so its hard to get a good look.

If that were my bike the first thing I'd do is remove the carbs and the rubber carb boots that attach to the head. If the boots are hard replace them, same thing for the boots that go between the carbs and airbox.

Next I'd take the carbs apart, all the way. Not just take off the float bowls and spray junk inside. Take the carbs all the way down and soak everything in carb dip. This intimidates some people but trust me, it's way easier than taking the carbs on and off four times because the process was shortcutted. Replace the rubber bits like O-rings but do not buy junky aftermarket "carb kits". Reuse all the original brass parts unless they are damaged beyond reuse.

During reassembly lube the throttle cables before the carbs go back together and make sure the air filter is in good shape. All this is just normal maintenance for 40 year old bikes and should be consider the right of passage.

Did it have a high idle when dropped off? Is the Choke/enriching circuit on? I ask because I stopped for gas on a cold day. After fueling and paying for the gas, I needed the choke to get started. I was meeting a group of bikers only a few blocks away. When I arrived the motor was revving at a high RPM as I sat there out of gear. I must admit this confused me until I realized the choke was still on. Shut the choke off and the idle returned to normal. I had to shake my head at myself for forgetting the choke. Your problem could be as simple as that. Good luck.

The carbs were stripped and rebuilt last year, last owner had a receipt to confirm. The boots are definitely hard, and actually seem to be just as old as the bike itself so those will be replaced for sure. the vacuum lines seem very old too so those will be replaced. I'll lube up the throttle cable while doing all this. if i do need to do a carb rebuild, is there any site or book i could look for that could help me step by step? the service manual i bought was very vague on the rebuild process. i believe they are Teikei TK-22.

z1Driver: no it didnt have one when dropped off, just randomly started. the choke circuit is off when its happening, when the choke is turned on itll rev even higher. but forgetting the choke is something we've all done! im sure ill do it a bunch, im a brand new rider.

If the builder didn't use oem type of parts well after market is not always the best. I found a link for you: gpzweb.s3-website-us-east-1.amazonaws.co...ge/TK26mainPage.html

I don’t know what parts he used unfortunately, but it worked for the previous Owner as long as he’s had it. And my kz550 is a C3, so it has the slide type carbs. Sorry I should have clarifed!

In the link I gave you dig around and they have info on the TK 22.

Update: Replaced carb holders and deleted the clean air system. Idles right where it should, and drives fine! on to my next project with this bike.

side question: if the reed valves arent capped, could it cause a pop in the exhaust as i lay off the throttle? i could only cap one at the moment, and im hoping thats the cause and not an over lean/rich condition

Yes. You can take a short length of hose and connect the two together. Do you still have the hoses you took off? I have even heard of guys gluing a marble or ball bearing in each hose barb. The cleanest solution is to buy or make block off plates. APE sells them.

On the 550's you can press on a 1/2" copper pipe cap. It's not pretty but is cheap and works ok. Be careful pressing it on. the plates can warp then won't seal. Definitely use a support on the back of the plate when pressing the cap on. Leave the reed cage in the valve cover as it has the integral seal.

Sometimes it might take a bit of heat, so if you have two people it helps.