TOPIC:

Hi all,

I recently took the bike, not on its longest trip, but probably the most demanding.
Speed limit was 70mph, and hills were steep both directions.
No problems on the way to the ocean, turned off, enjoyed time, turned on, and drove home.
Then at the first stoplight in my town, the engine cut out and it took the choke to get it to turn over which obviously would not be needed since it was warmed up.
This happened again as I was coming to slow down for a round-a-bout.

My first thought was a fuel problem. I checked the float levels, had to adjust a little.
Could turn it over, but the idle was jumpy, and if I tried to give any throttle it died.

So, I cleaned the carburetors, now there is no way there is something clogging the jets.
I was able to turn the bike over, but it was a fight this time. Even with the choke used at its fullest, I had to open the throttle. After it turned over the choke could go down and the throttle, but the idle was still not steady BUT better than before.
I could steadily give some throttle and it would go up, but the thing was backfiring like no ones business.

Bike has been running great since this trip.
Things I noticed were that the jets were shimmed by 3 washers! (bought bike used, also has aftermarket exhaust on it so maybe this was an adjustment?)
I don't have the pods, I made the custom air filter that's on this site.

I'm worried there is something going on with the engine, but that is an area I have yet since to touch in all my mechanical experience because I've never had to.
I checked the spark plugs to see for any issues, the side electrode went from black to white/grayish and the center electrode was white/grayish. And the threading was blackish.


I've checked everything to my knowledge so any suggestions are appreciated as the bike is not rideable :[

- Chris

Chris, are you talking about your 1980 kz440 LTD?
If yes, please add it to your Avatar Profil, we can´t read the cristal ball.

Scirocco wrote: Chris, are you talking about your 1980 kz440 LTD?
If yes, please add it to your Avatar Profil, we can´t read the cristal ball.

It is in his signature line.

Has valve lash been checked lately? Oil level?

Do you mean that the needles had three washers? If so, that seems like a lot.

It may be a fuel issue. Pull your fuel line and check to see if you're getting fuel to the carbs. Check to see that the vent on your fuel cap is working. Check your carbs with the bowls off to see if you're getting fuel into them.

It may be a spark issue. (but sounds like it isn't) Check your plugs to see if you're getting spark.

It may be an engine issue. Check your compression.

Thanks TexasKZ for the note, Mea culpa newkzrider18
I did miss something, time to get some sleep, i am in the Central European Time.

Scirocco wrote: Thanks TexasKZ for the note, Mea culpa newkzrider18
I did miss something, time to get some sleep, i am in the Central European Time.

You had a good day, and so did I

TexasKZ: I adjusted the valve clearances about two months ago when I was doing other timing adjustments, so I can check it again, although I don't see a reason it would change. Oil is good. Also did a change with that and filter at that same time (2 months ago)
Yes the needles had three washers. It did seem like a lot, I did take it to a mechanic 2 years ago when I first got the bike and couldn't figure out for a month why it wasn't running, and they rebuilt the carbs so...I guess those are supposed to be there??? Usually I thought there would just be one or two...

hardrockminer: It does seem to point to a fuel issue, I just wonder why a hard ride would have brought the issue out...I will look at your items when I have time this weekend.

Scirocco: All good!

Thanks all the for the replies.

Do you have a see-through fuel filter with pleated paper element? I had a similar issue with them. They are designed for cars with fuel pump. After a while they don't flow enough with gravity.

loudhvx: nope it is not pleated paper, thanks for the thought!

Ok did the suggestions and everything checks out...
I did take 2 of the washers off because I checked the spark plugs closer and they were riddled with black.
So now both needles have one washer.
Valve clearance is good.
Fuel cap is venting: I just emptied all the gas into a container and it all came out, so that's how I checked.

I was a little confused on how to tell if gas was getting to the carbs...I've checked the float level by priming the bowl and then unscrewing the overfill and checking the level in a clear tube. But how can you check it while it is running? The same method? Would that be "stealing" gas away from the engine and wouldn't it not run?
A suggested method would be nice.

It really seems like a fuel issue, but like I said, every fuel item seems to check out.
I attached a video of what is happening. You can hear that it's stumbling and when you open the throttle fast, it blipped the first time, then died immediatley the second.

Ok posting videos on this site has never worked out for me.
I don't understand why. I change it to a correct format, and downsize if necesasry.
So here is a link to a private google drive shared folder with the video...

drive.google.com/open?id=1hneKAU0InmQpRXjkxnXeU-ssfqZkYvoa

Which apparently you have to download....sorry.
I tried!
But basically my explanation above gets the point across.