[align=left]Hi, I'm all new to this forum here...
I've been looking through all the problems everyone else is having and don't seem to see one like mine...

I have a KZ900 engine on a modified suzuki frame. Problem is that it keeps sputering out like it's out of gas. It'll idle like a charm, but when I accelerate it tries to die out. On the road, it'll start to do this and I have to choke it to get it up to gear speed. Soon as it's there, I can usually let the choke off. But not this last time. I had to ride home as quick as I could with choke on full.
This bike was a prject bike I traded an older Katana for and am not sure what all is going on with the bike.
What I'm thinking is Fuel Pump. Does the older KZ900 engine come with a fuel pump origianlly? Would putting one on solve the problem or am I looking at a possibly valve clearance issue? Ahhh!!! I appreciate any feedback from you guys.

Tattoo
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Welcome to KF! I dont know enough to help you out tho.

 

That's alright, I'm sure someone on here knows, or has a better idea than I do of what is going on.
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If it runs better on choke then my guess would be the carbs. Sounds like when you open the throttle its getting too much air and not enough fuel and the choke is compensating. You shouldnt need a fuel pump for a gravity feed system. But like I said blind leading the blind.

 

have you ever cleened the carbs on the bike what about the tank? it dosent take much to plug a jet

 

Sounds like it is a jetting problem. I'm guessing the previous owner installed the "obligatory"aftermarket pipe and either 1.) didn't rejet the carbs, or 2.) did rejet the carbs and botched the stage 3 install job, or simply installed jets of the wrong size and didn't feel like taking the time totroubleshoot the job properly.
How old is the fuel you're using, and (I'm assuming) you've drained the bowls of the old stuff? The "sputtering" is my clue on the old gas.
Another thing to look at, are the plugs. What do they tell you in terms of color, wetness, etc.?
You may also want to look at the fuel delivery. Is the gas tank full of rust down at the petcock? Is the petcock in good shape/clean (inside)? Is there a fuel filter in-line to the carbs? Fuel lines clean? Any hoses missing or misrouted? Electronic ignition or points? Double check your marks/gaps/etc.
The KZ's are kinda like old tractor engines; beautifully simplistic, which makes the troubleshooting job much easier. Just check your fuel pathway, from start to finish. It's all air, gas, and spark.

 

[align=left]Let's see....There's alot that I know isn't the case, and some that I'm getting ready to go check out. I know the gas is good. Trust me the prices at the station are sure to let me know.
The carbs? Maybe, I'm ripping those off today. I thought that I had done that, but I guess I didn't. I did my other two bikes (78, 80 Yamaha triples) and somehow left out my baby.
There is no in-line fuel filter.
The pipes seem original guessing by the manner he mounted them to the frame.
It is electric ignition. Like I said, it starts up beautifully. But when you run it hard, or just more than idle, it tries to die.

There is one point that I kinda doubt is an issue, but possibly. My valve cover gasket is slightly leaking. I haven't got around to ripping it off yet and replacing it. But that shouldn't cause this kinda problem, should it?
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how long dose the bike sit between rides with fule in it do you live in the section that has ethonal blened into the fules if you do the blened fule olny lasts 30 days then its junk. Great stuff ant it

 

[>:]No such thing as luck today...I tore the carb off...cleaned it throughly...One jet was a little dirty, but the other 3 were good. Found the vacuum line? from the tank to be kinked and full of gunk...cleaned it out best I could. May still need to rip the petcocks off and check them.

Here's my dumb question of the day...
The vacuum lines from the carb, where do they attach to. From the carb to???

Maybe this guy that gave me the bike had it crossed before he handed it to me. I don't know. He thinks it needs a fuel pump. Another friend of mine whose quite knowledgable disagrees and thinks it's the valves. WHAT DO YOU GUYS THINK? Ya'll are the experts that have probably had the same issue.
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the valve on the tank most bikes have a vacume shutonn bilt into the valve