Katana Cold Start Frustration

[no_morelipfrom_you]

I'm trying to get my 2000 Katana 600 to cold start more easily/reliably so that I can start riding it to work.

I have read all the way back through something like 24 pages looking for "starting trouble" threads to get as much info as I can.

First off I'm in San Diego and its like mid 70's right now so cold weather is not an issue. If it has been ridden within 15 hours it starts ok. After that, here's what happens:

With the choke off, and no throttle (throttle completely closed), pressing only the start button, the motor turns over aggressively and will usually "putt" a few times while turning over, sounding like its going to start but doesnt. It just goes back to the motor cranking over.

Sometimes it will start, and I let it run for 4 or 5 seconds and then try to give it a little gas. As soon as I give it gas, it dies. Doesnt matter if I give it a lot of gas or a little. Of course if I dont give it gas then it will eventually die on its own after about 9 or 10 seconds.

Bike will NOT cold start, or even "putt" with the choke on.

Bike will NOT start, or even "putt" with the choke off, if I give it any throttle at all while pressing the start button.

Changing to petcock to "PRI" makes no difference.

Eventually, after repeating the start process and recharging the battery 2 or 3 times in between, I'll get it started and then throw the revs up, put the choke on, and once the engine is warm, no problems at all.

Here is what I've done: I've changed the inline fuel filter and made sure the tank has no rust. I pulled the plugs and made sure they all have spark. They do. All plug tips are chocolate brown.

Have a new air filter in, so its clean, and the airbox is securely connected to the throttle bodies? or carbs. Whatever its suppost to be connected to, its locked tight.

The fuel lines all seem fine (no creases or pinches or anything) but I didnt suspect that anyway since everything runs ok when the engine is warm.

I *believe* fuel is vacum fed.

I've ordered a service manual but they didnt have it in stock, I should be able to pick it up this weekend.

I'm trying not to clean the carbs if I dont have to. The bike has less than 5k miles but it is also 5 years old. I dont know if it was stored properly or if there is anything I am supposed to check/change/fix, and also dont know how much of that the dealership handled and I wouldnt trust them to tell me.

Sorry this is so long winded, I am at the end of this post now. I'm thinking that probably the fuel/air ratio needs to be adjusted. I'm thinking it is running too rich. Anyone have an opinion on that?

I found a thread that mentioned turning both screws off, and then back on 2.5 turns, and then "Adjusting from there". But I dont know what "adjust from there" means or how to properly do it.

Thanks for any help or advice, it's really appreciated.

[enos]

I think your carbs are fine. If you have nice looking plugs and the bike runs good once warm, the mixture is probably right. If you still have stock exhaust and intake and nobody messed with the carbs, they're probably right (they don't change themselves). If it idles smoothly once warm, your idle screws are fine. All these also suggest that the carbs are clean enough, and all the rest of the fuel and air delivery (filters, lines) is fine.

It's not too rich, because when the engine is cold you NEED it rich (that's what the choke does). So if it was rich, it would start right up, then get worse and worse as it warmed up.

The weird thing is that the choke doesn't have the effect you'd think it should have. I've had a bike with similar starting problems, and it was the valve clearance. All the valves clearances were too tight, so the valves weren't closing all the way. For some reason, this made choke not help, and I'd have to give it half throttle to start, especially in the winter. After setting the clearances, it started at the first touch of the starter, and the choke acted like it should. The weird thing is, your bike is fairly new, and it shouldn't need valves adjusted at 5k miles. Mine was an '82 with 20k miles. But if you don't get any better leads, might as well try it.

[eddie13231]

Yeah I have the same problem. A mechanic friend of mine told me it was fuel/air mix (carb tuning) and not to worry about it since it would be warm soon. If you want to, i'm sure you could re-adjust them so your bike is richer.

[no_morelipfrom_you]

So this is it? NOBODY has any more suggestions? I'm not even going to try to check valve clearances by myself. I'm not a mechanic. Does anybody have any ideas of something I can try before sending this off to a bike shop??

[Jackal79]

You don't need to be a mechanic to check valve clearances. You'll need a set of feeler gauges (like what? $5?). Pop the head cover off, and move the bike around, check X locations, move the bike around again, check Y locations, move again, check Z locations and so on so forth. If your 600's valves are setup like my old 750's was, checking and adjusting clearances doesn't get any easier.

Anyway, thats probably what it is. If you put your petcock on PRI and leave it for a while and it makes no difference, it isn't a fuel delivery problem (and also because it runs "fine" when warm). Lean problems get better whan an engine is warm, but its not a mixture problem because 1) choke has no effect and 2) it runs "fine" when it is at op. temp. (temperature won't make that dramatic of a difference). Maybe take a quick look and see if the choke cable is actually connected to the carbs?

Of course theres a million other things it could be, but valve clearances is a good bet. Does it REALLY run "fine" when it is at op temp?

[enos]

I'm wondering about the battery. Maybe it's so bad that it can't give a descent spark with the extra fuel from choke or extra air from giving it gas? Of course if it does start then you have the alternator putting out juice and it works fine. Try jumping it with a non-running car.

[no_morelipfrom_you]

Okay then I'll check both suggestions, the valves, and first, I'll try jumping it from a non-running car again. I havent done that since changing the fuel filter out.

Enos you might be onto something because when I checked all four plugs for spark, they did spark but the spark was small and red, on all four plugs. And I remember hearing somewhere that the spark should be blue, which is hotter.

Maybe the spark isnt strong enough to really ignite the mixture well until the cylinder gets hot which would then help it ignite a bit better.

As for whether it *really* runs fine when hot, I can only go by my very limited experience, since this is my first bike. I mean I havent even ridden 50 miles yet. I just bought this bike and I have spent more time working on it than actually riding it. It does stall pretty easily but I assumed that was just newbie error and so I compensated by giving it more gas and just let the clutch drag out a bit longer.

If it does stall abnormaly easy then maybe I can blame my first drop on that - since it was a slow speed launch into a left turn

Thanks for the help guys.

[enos]

Yeah, red spark is no good. Don't bother tearing into the valves until you have a nice blue/white spark.

[5thDementian]

Like enos said... a red spark is bad... You may wanna try new plugs.

And... I'd take care of this ASAP, because you're putting way too much strain on your starter. That will quit on you soon, too.