'81 550 takes lots of cranking to start, backfires

I bought this 81 550-C2 off a guy that liked to wrench. Most of the bike is in great condition, and it runs nicely once it starts, but the problem is it takes many many cranks to get it to run. It usually just cranks on and on and eventually catches, then dies after one or two turns. Repeat this for a minute or two, it'll run for 3 seconds then die. After another minute of that, it finally runs.

Carb #2, and to a lesser extent #3, is drippy out of the overflow tube. I took the carbs apart yesterday and cleaned them well. I also adjusted the floats to be parallel to the bowl lip. I started it yesterday after the carb cleaning and it still dripped out of #2.

To top it off, after starting it spat flames out of one tailpipe. The bike makes popping/small backfire noises when idling, especially when cold. It usually smells like gas, but I'm not sure if that's because of the drippy carb or because it's running rich.

Any ideas what's going on with my 550? I want it to purr, not grunt!

BTW. The carbs aren't synced. I am trying to get my hands on a set of gauges to sync it up. Is there a guide anywhere on how to sync the carbs?

Will it start with starting fluid?

I don't know where you saw a spec to adjust the floats to be parallel to the bowl lip, but if it was my bike I would start by adjusting the fuel level. Find the correct fuel level spec in the Kawasaki Service Manual and use the clear tube method to adjust the fuel level.

Regarding syncing the carbs, that process is described in detail in the Kawasaki Service Manual.

If you do not have the manual you really should get one. Trying to work on these bikes without one is a big mistake. Ed

baldy110 wrote: Will it start with starting fluid?

I haven't tried.

650ed wrote: If you do not have the manual you really should get one. Trying to work on these bikes without one is a big mistake. Ed

The previous owner gave me a printed out service manual, but it's missing the Transmission and Fuel & Exhaust chapters, so it isn't as helpful as it can be. Those are the most important chapters imo..

Where can I get my hands on a Kawasaki Service Manual? Are they available anywhere for free?

Where can I get my hands on a Kawasaki Service Manual? Are they available anywhere for free?

Put the cursor over "Forum" above
Click on Search
Search for any recent post by user name loudhvx
loudhvx is the resident kz550 and electrical expert. His signature has links to a ton of 550 information including manual
Good luck

No eBay APP ID and/or Cert ID defined in Kunena configurationHere's one at a pretty good price (free shipping) that covers the 1981 KZ550-C2. The back cover shows the models in it. Offer him $25 and he may take it. Ed

JR wrote: Put the cursor over "Forum" above
Click on Search
Search for any recent post by user name loudhvx
loudhvx is the resident kz550 and electrical expert. His signature has links to a ton of 550 information including manual
Good luck

Found his page on TK carbs and realized none of my carbs have the choke flaps :ohmy:

The choke still works, just not as well as it should I imagine.

I don't think this is my problem, is it?

I should also mention the engine bogs if I'm cruising at moderate or high RPMs, above 2nd gear, and I open the throttle suddenly. Don't know why this happens.

I haven't ridden it (due to broken clutch cable) since cleaning the carbs yesterday, so I can't say for sure whether that solved the problem. With #2 still leaking and cold starts still being difficult I am not expecting the bogging to have disappeared.

Do a compression test before going any further. Since all the flaps are missing, they likely went through the motor. Most of the time they make it clean through, somehow. But sometimes one will get stuck in a valve. then the valve won't close all the way. That can lead to backfiring. So you want to check the motor before spending a lot of time tuning.

If the compression shows good, like all cylinders around 150 psi or so, thenmove on to ignition and carbs.

If the valve clearance is out of spec, other symptoms will show up after you start riding. That will tell you to check the valves. Make sure to read the valve warning before doing anything with the valve cover.

Also there is a link regarding the clutch adjuster, since you will likely be dealing with that soon.

those links are in my signature

By the way, after you get the cable and check compression, you can always choke it by putting something over the airbox opening. That will do the same as the choke, but you have to let some air in right after it starts to fire up.

Thanks loud, I'll try to do the compression test today. What other symptoms would bad valves cause?

I'm already intimately familiar with the clutch adjustment on my bike (in part thanks to that link in your sig ). Previous owner used a clutch cable that was too long and everything had to be adjusted out and was very finicky. I can't wait for the new cable, I want to get back on the road.

Compression test showed 150-160 PSI in all cylinders! And now I have a compression tester kit I also have a full service manual.

After a bit of running (mostly at idle, some revving, not too much so I don't piss off the neighbors) it seems to be a lot smoother. I can still get it to bog, but the engine has to be cold and I have to really try. Haven't tested it at speed yet.

It started pretty easy, minimal popping.

I will get some clear tubing and check the carb fuel levels tomorrow. I'd like to get to the bottom of why #2 is leaky (only leaks when it's running).

Addendum: the plugs, which were changed in the past 50 miles, had the first few threads blackened and the tips were white/gray.

The valves stretch when they get hot, and when there is not enough clearance between the cam-follower (called a bucket) and the cam, the valve does not close all the way.

Often, (but not always) the clearance between cam and bucket gets smaller over time. I think it's because the valve starts to sink into the valve seat more . The valve stretches most when going fast on the highway. So the usually the first initial symptom is that the bike will start and run fine until you go on the highway for twenty minutes or more at high speed, then if you come to a stop, it will stall. It will usually start right up, and will stay running if you give it throttle, but it will not have a steady idle until the motor cools down.

It only takes a few minutes for the motor to get cool enough that the bike runs normal again. If you stay off of the highway, after that, the symptom won't come back until you do another high speed run.

If the valves are not re-adjusted right away, the problem gets worse with more miles, and eventually symptoms will start to show up even in normal riding as the bike warms up.

For the fuel leak, you will want to look at the needle valves. If the tips have a noticeable ridge forming a ring around the tip. You probably need new needle valves and seats. Then you will have to re-set the fuel level. The TK22 website shows how to set it for new valves, dry, in the maintenance section.