Carb question

[liljerry564]

Hey guys got my first customer today its a buddy of mine. Its not an xs its a kz400 but I figured id ask. He says it stalls out and won't stay running. Today we couldn't get it to start. Do u think it sounds like a carb problem or should I start with something else.

 

[Downeaster]

Carbs/fuel are a possibility, but start with the simple stuff.

Does it have (fresh) fuel in the tank?

Is the fuel getting to the carbs (petcock on, filter not plugged)?

Does it have spark?

Are the plugs fouled?

Is it getting air (filters not gunked up)?

 

[racerdave]

First guess, plugged pilot jets.

 

[liljerry564]

Im gonna start trouble shooting after work. First thing i noticed it that the wire going to the battery is 18g. Is this ok? I would think it needs to be thicker.

 

[gggGary]

Your first "customer"? And you have no idea how to start troubleshooting a won't stay running bike? You're scaring me.
Three things for an engine to run; gas, spark, compression. All three need to be the correct amount at the correct time and it will run.
Proper procedure is to go through all the systems checking for clean and correct operation of all parts involved once you are done it will run.
You need to find the specifics for that bike model and year. Poor technique can easliy turn an "almost runs" motorcycle into scrap. For instance a crankcase of half oil half gas can ruin an engine in seconds. A hydrolock will bend a connecting rod on the first kick or crank. Good luck to you and your "customer".
To the others on this thread: this may sound a bit harsh but there is some history here.

 

[liljerry564]

I never said I don't know how to trouble shoot it. I know what an engine needs to run. But I don't know a lot about carbs yet. Iv always delt with injection. I'm just askin if u guys think it is the carbs. The previous owner said the carbs were rebuilt but he didn't know if they were done right. I haven't touched the bike yet but my buddy couldn't get it to start last night.

 

[gggGary]

We don't have the bike if we did we would TROUBLE SHOOT it and know where the problem lays. It's the term customer that has me going off here. I understand and sympathize with two buddies thrashing through a "won't run" bike situation. But once you have a "Customer" you have a duty to at least "have a clue". Again all troubleshooting involves finding out what does work and then fixing what doesn't, problem solved.
Like a doctor your first duty is to not make things worse. That is so often the dummies bane, creating a second problem before fixing the first one. Yes, I have done that bunch of times. Cluelessly thrashing about is almost guaranteed to make things worse. We CANNOT tell you if it's the carbs, because we have not done the troubleshooting to narrow down the likely cause of "won't stay running". A combination of carb issues and less than stellar ignition often is the bane of a won't stay running bike. The fuel system needs to be cleaned systematically from gas tank to intake. That is gospel.

 

[liljerry564]

The customer is a friend. Im not charging him for the motor work. I'm charging him for paint and bodywork and a few other stuff I'm fixing for him. I told him I would look at the motor for him because I would like to service bikes in the future.

 

[gggGary]

I'm good with that! Now go to troubleshooting in the tech section or a Clymer's and go through all the steps one at a time and it will run. Again old bikes in the Midwest always need the fuel system cleaned. Since you are painting the tank we can assume you want to clean the inside anyways. All new fuel lines and overhaul the petcocks and carbs if the owner wants a starts every time reliable ride. You will need to have the correct specs for the Kwak to get the carbs set up to run right. The carb guide in the tech section here will help you through the basic overhaul proccess. There is a pretty good site for the Kawasaki twins that should be able to help you out with specifics. Some of the early points type KZ twins had very weak coils that would go up in smoke just by leaving the key on for 15 seconds or so....... Guess how I know? Watching me watch the little mushroom cloud in my garage was priceless.

 

[retiredgentleman]

Im gonna start trouble shooting after work. First thing i noticed it that the wire going to the battery is 18g. Is this ok? I would think it needs to be thicker.

Any wire to the battery should be a minimum of 14 gauge, for kickstart operation. If you are using a starter motor, then the ground cable must be much heavier, similar size as the cable running to the starter motor itself.

No one on the internet can tell you its a carb problem. However, we can all guess, because carbs and ignition are common problem areas.

I did some work on a KZ400 a while back. It had some nice Kiehin carbs which had 2 main jets per carb as I remember, a primary and a secondary main jet as well as the pilot jet. It would start but it would not accept any throttle. The pilot jets were almost completely blocked. That's just an example, it does not mean that you have the same problem.

If I obtained a bike, with no history, and it ran like crap, I would take the carbs apart, check float levels and float operation, compare jet sizes to stock size, clean the jets,choke circuit etc. Once the carbs are known to be in working condition, you can proceed onto other areas that are suspect.

 

[liljerry564]

Cool thanks. Its just a kickstart. I'm gonna have to upgrade his wires. My buddy said it ran great but would stall out when he's ridin. He also has a brand new coil and wires. O and I forgot is also 30 degrees here in ohio.

 

[gggGary]

Check the gas cap for a clear vent. drain the float bowls into a plastic container see what crude comes out with the gas.

 

[XSLeo]

A repair manual that covers the bike is a good place to start. It has specs and procedures that are correct for the bike.
Yes, carbs are carbs ignition is ignition. Most knowledge can swap from bike to bike but some things are very specific. Float hieght is one.
With the repair manual and the carb guide I'm sure you will hear it run well.
Leo

 

[liljerry564]

did some trouble shooting and its not getting spark.

 

[CDNTX650]

Dont you own a shop?!?

check the obvious, points if equipped, gapped and clean, check the + to the coil make sure it's got 12v when the iggy switch is on.

 

[gggGary]

did some trouble shooting and its not getting spark.

Dry the plugs with a torch, wire brush em, check for spark again. New plugs are never a bad idea. Is the bike points or electronic ignition? I like to jumper from battery directly to the coil + terminal. I even keep a jumper with an on off switch in line in my parts bin. If that makes a difference I can go looking for a bad switch, connection, or wire problem.
That doesn't mean it's not the carbs too.
"A combination of carb issues and less than stellar ignition often is the bane of a won't stay running bike."
The thing is keep troubleshooting, assume nothing, Keep at it you'll get there if you keep troubleshooting.
While you are at do a compression test.

 

[liljerry564]

Coil has 12v. Im not sure how to check the points yet. My buddys dad said he can get it to start so Im working on some other stuff he wants done to the bike.

 

[liljerry564]

I got some new plugs.

 

[littlebill31]

This is s good "Points" thread. You'll see my little test light. Good thing to have with points.
XSLeo has great test instructions too on the second page.

http://www.xs650.com/forum/showthread.php?t=12670&highlight=points

 

[liljerry564]

Well i was trouble shooting the bike today and it started. There was arcing on the contact. From what I read this is bad correct? Could this be why its stalling out on him?