Engine warm-up

83 KZ550m1 13,000 miles,

When cold: it starts right up with choke out all the way out, but likes to rev around 4500 rpm's until its warm enough to push the choke back in. The time that it takes to do this seems considerable to me(2-4 miles down the road). Is this normal?

These bikes can take a while to warm up. If I were you I would let the bike warm up before taking off. If the bike is idling around 4500 and you shift into 1st it must be a hell of a shock on the tranny/clutch! I live in a colder climate and now that temps are dipping to around freezing at night I let it idle on full choke for about 15 seconds, then I push the choke in half way and rpm's go to around 1500. I go inside and put my boots/jacket/helmet/gloves and glasses on. This takes me a few minutes, then I push the choke in all the way. My idle drops to around 700, and I take off. I think it is probably better on the motor to get a good chance to warm up and get oil flowing before riding away.

Like our Viking friend says, push the choke back in until it's idling about 1500. You can ride when it will idle without the choke.

Thank you for the info you two. Do your bike idle this high though when you start them? 4500 rpm's seems and sounds like a lot to me for. I know it will hold this rpm for at least 5 minutes or more... I got tired of it and rode it for 4 miles and when returning home it seemed to idle just fine then. Maybe I'm being just too picky... Thank in advance for any further insight.

Scott

I found a plastic round turn-knob underneath and right in the middle of the carbs. Is this the idler screw? I can get a picture of it later if needs be.

Thanks,

Scott

83kaw550 wrote:

I found a plastic round turn-knob underneath and right in the middle of the carbs. Is this the idler screw? ....

Yes, that's used to set the idle speed at desired rpm when the engine is running at normal operating temperature.

The bell-crank (where throttle cables attach) stops when it meets the tip of the adjuster screw, which prevents the carb slides from lowering any further.

Good Fortune!

RPM of that range when the choke is on sounds like its got a vacuum leak at the manifolds. Check for vacuum leaks and repair as necessary.

How could I be sure there is a leak? How do I check?

Some spray WD-40 around the boots and look for smoke at the exhaust. Me I use brake clean or carb cleaner and spray it around the boots and check for a RPM change.

I appreciate the tip. Thank you.

If everything checks out well, and you don't have a vacuum leak. I would install some larger pilot jetts, it would cut down on the amount of choke needed.

since it is cold out now I need full choke to start my bike, and it will initially be up there somewhere around 4000 rpm's, but give it like 20 seconds at that speed and it starts to bog hardcore, way too rich, then when it goes in halfway it idles at 1500 nice and smooth, gets the oil flowing and doesn't bog. Just for curiosity if you let it idle for a minute at full choke what happens? These old bikes need some time to warm up, give them a couple minutes...my carbonated pickup takes a really long time to warm up in the winter, and since it has an automatic pedal style choke you can't just close it early, so a couple minutes for the bike is nothing.