Warm up procedure?

I've got my KZ750 running pretty good once its warm. It'll idle pretty stable around 1100 once it has warmed up.

Getting it to that point is a real bear though and I wonder if I'm doing something wrong. I'm new to motorcycling, wrenching and old bikes. So total noob here.

If the air temp is below 70 degrees F I put it on full choke, no throttle and it starts right up. The idle climbs up above 2000 pretty quickly and I start moving the choke down little by little.

It's really sensative at this point. If I let the idle fall below 1500 it'll quickly drop and stall.

It takes a minute or two but eventually I have the choke off and it's just barely staying running. In fact it'll usually stall on me at the first couple of stops.

After a few miles it seems to warm up and then runs fine. The idle is nice and stable right around 1100.

I've adjusted the air mix screws and idle set screw according to Tek9ine's very sound advice, which is what got me this far. It runs great when warm or when the air temp is above 70. Any colder and it's almost impossible to get going.

Am I doing something wrong or does my bike need some sort of adjustment?

ALL KZ's are known as being "cold blooded".

Each of us have our own "start up procedure" that we use. As long as it gets your bike running without damage or extreme effort and in a decent amount of time, then you're all good.

Sounds like my KZ900. Although the idle, once warm, should be about 900. Motorcycles are different than cars, in that the engine oil also lubes the transmission. In other words, they's more metal parts to warm up with the heat of the engine. Your bike is not totally warm till about twenty minutes into your ride.

Bill

So I've been tempted to adjust the idle stop screw to keep it from stalling before its warm. Bad idea or is that ok?

Any bike I have ever had I start it up, ease back the choke a bit and go ! With my 750/4 its probably on 3/4 - 1/2 choke pulling out of the driveway, a little less at the first stop sign and fully off about a mile later at the first traffic lights. I have never waited for a stable idle at no choke before going. I'm old enough to have done the same with cars which had manual chokes. The last part of choke travel is usually just a high idle mechanism.

Topper wrote: So I've been tempted to adjust the idle stop screw to keep it from stalling before its warm. Bad idea or is that ok?

That's a good strategy. After you've been riding a while you'll notice the high idle at a stop light and can easily turn it back.

Bill

You can also just manually hold the throttle open a little if it doesn't idle until warm. For the record, the KZ650 I ride all year around in all temps, although a piece of junk and a bear to start, once started I can ride immediately and turn the choke completely off in less than 1 block and it idles fine.

Ok, I was under the impression that riding with the choke on was bad. Sounds like it's actually pretty normal. That'll make things much easier. Thanks for helping a noob!

Start the bike up full choke and leave it there until it begins to stammer, then move the plunger in a small amount, and let the bike idle at around 2000rpm. Then once it begins to rise again, you can adjsut it back some more, still maintaining a higher rpm, and pull away choke on (if you like).

I've never had to ride a bike with the choke on that was tuned properly, but I always get the choke off quickly, and I can attribute this to a very good vacuum synchronization.

If you perform a vacuum sync, the bike wont stall when you go off choke. I can turn mine off right after I go to half choke for 10 seconds, then she will still idle at about 600-700rpm just fine and smooth. Wait till she comes up to regular idle (a minute), and then pull away.

To each there own, but a bike shouldnt be stalling, less you're really impatient, and if so, invest in some goood oil :laugh:

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Not saying that yours has an issue, but the leaner it is on the pilot system, or air leaks, will cause it to stumble/ stall without the choke being on a long time. Dirty passageways could be a reason for lean circuit, or the jet is 1 size to small. Air leaks at the carb holders, or pod air filters will lean out the fuel mix.

Previous owner had way too small pilot jets in there and i had a lot of popping. I've returned them to stock. When I set the air mix screws for highest idle they ended up almost all the way in, which fixed the popping.

Could that be a sign I need further pilot jet changes?