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I have recently purchased a 1981 KZ750. When I went to look at the bike the previous owner had relatively little problem starting it. I bought it and brought it home and have not been able to start it. I took the air filter out and it was dirty, I blew it out and replaced it because I have to wait 2 weeks for the new one I ordered to arrive. Still won't start. So I took out the old plugs and replaced them with new ones. Nothing, no go. I checked to make sure that fuel was moving through the lines. All good. Everything seems to be fine but I still can't get it started. Before I did all this I had it on a battery charger and it wanted to start but would just putter and stall after running for a few seconds. I am going to put it on the charger and try to get it running this evening but I would like some alternate advice to fall back on if I can't get it going. Any advice would be appreciated.

First thing, are you using the choke. I pull the choke all the way and then crank. If the bike has been run recently it starts and the rpm's will run up to about 3k and then I shut down the choke. If I haven't started it in about a week it spits and coughs and may die. I just keep after it till it's running on all 4.

I bet the bike was warmed up before you showed up.

BTW the choke is really an enricher. (it adds more gas instead of choking the airway.)

Your carbs might be clogged, or the petcock.

There's no OFF position on your petcock, is there? If so, and it is turned off, you are trying to start with no fuel. If the engine is cranking but not turning over, that is a fuel issue, most likely.

KZ750 is a triple/2-stroke, correct?

--Dave

It is an inline-four/four stroke. I am figuring that it is probably a fuel issue. The guy has an in line fuel filter between the tank and the carbs and the whole setup is a mess with bends in the line and uphill flow. First i am going to check to see how much fuel is making it through to the carbs and I am also going to check the float valve on the carbs. One thing that is bothering me is that the day I checked it out it was sunny and about 7 degrees celsius outside. Since I got the bike it has been around 0 maybe going up to 3 or 4 for a while mid day. Does anyone think that this could be a factor. I don't see why it would but I am just wondering. Any other suggestions on things I should do would be helpful.

My Ninja 500-R is not the happiest bike it's cold. It is hard to start, definitely needs the choke. When it gets running, the carbs can freeze up when it is wet/misty out.

I missed that you mentioned getting gas through the lines. Sounds like a carb scrubbing might be in order.

Also, is there a kill switch on the handle bars? Brake side. My '86 Kawa would crank but not turn over if the kill switch was turned to off. Sometimes that is the last thing people check. I have been there a few times

I love the looks of the KZs. I hope you get it going.

--Dave

I have the bike running now but the problems persist. I can get it started and as long as I am manipulating the throttle it runs but it will not idle if I am not giving it gas. I guess later in the week I will take the carbs out and give them a good cleaning but I don't think that is going to solve the problem. I am assuming that I need to set the idle. Anybody have any advice?

On my 87 Concours there is a knob on the left side of the carb bank that controls the idle.

Now this sounds like a problem a guy is having in the "Troubleshooting" forum.

Maybe your idle is set too low, or the adjuster screw has come out? Although you have four carbs... Hmm... Is there and idle adjustment linkage between the carbs (never had to set the idle on the multi-carb bikes I have had).

If your idle is closed, you are getting no gas when you don't twist the throttle. Since you do get gas when you twist the throttle, you are getting gas to the carbs and the cyliders, your are getting spark, and you likely have good compression.

See if you can find how to adjust the idle. If there is a screw adjustment, tighten for more gas, loosen for less. You might as well open it up a bit and then bring it down to where you want it. Not sure what RPMs you'd want, but you'll know when you hear it.

Likely, the idle adjuster is near the throttle arm. Typically a screw that moves it open or closed. Follow your throttle cable back to your carbs and look for a screw there. It is probably about as wide as a pencil. I'll take a look at my Ninja today and see if I can give you a better idea where things are.

--Dave

Is your bike fuel injected or carb?

I agree with the idle set screw/knob. I have a 75 KZ400, and I had a similar problem... Also, are you using the electric start? or the kick start? My KZ was having electrical problems and the battery would die, but as long as I kept the RPM's up, it would run but would not idle.

You wouldn't happen to be from Edmonton would you? Maybe we bought our bikes from the same guy...