1983 ZN1300 Street build.

Maybe I'm missing something here, but I'm not seeing how the GS500 carburetors would work. You'd have to run six carburetors since the GS, I believe, had one carb per cylinder (quite common). I don't know how that would even fit with the KZ's intake manifolds.
Then, even if you did get them to fit, how on earth would you sync them reliably? You'd really have to have two separate 4-port manometers and calibrate them to each other, and then tune each individual carb.

To me that sounds rather unpleasant.

brandonsmash wrote: Maybe I'm missing something here, but I'm not seeing how the GS500 carburetors would work. You'd have to run six carburetors since the GS, I believe, had one carb per cylinder (quite common). I don't know how that would even fit with the KZ's intake manifolds.
Then, even if you did get them to fit, how on earth would you sync them reliably? You'd really have to have two separate 4-port manometers and calibrate them to each other, and then tune each individual carb.

To me that sounds rather unpleasant.

Only three Carburetors are needed. There are three intake ports, each port splits into two intake tubes that lead to the cylinders. Only one tube is going to be on the intake stroke at a time per port.

Each cylinder is 216cc So i'm going to use carburetors that are made to feed at 250 CC cylinder.

Another way to explain it:

There are six intake tubes that go to each cylinder. Those six tubes are divided into three ports. Each port contains two tubes. And only one tube is going to be drawing air into one cylinder at a time on each port.

The way the firing order works on this motor, two tubes will be drawing air into the engine per intake stroke, but they will always be on different ports. Each port has its own Carburetor.

Both tubes on one port will never be drawing air in at the same time.

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And the way I would get them to fit is by using my CNC mill to make custom boots so the round carbs will fit the oval intakes.

Phil wrote:

aus_z1300 wrote: An adjustable fuel reg might be an ok dodgy fix for a drag car or bike running full throttle for 10 seconds or so but don't think for a second it is going to sort out the fuel mixtures for you they will be all over the shop.

It sorted mine, as verified by an exhaust gas analyser at the local bike dyno. The fuelling was pretty consistent across the board You also have to ask if adjustable fuel pressure regulators weren't a fix then why does such a huge aftermarket for them exist in the car world?

I wouldn't believe it unless i had seen wideband 02 readouts on the rd and watched for consistency as for dyno tuning that is another subject entirely.

As far as the aftermarket adjustable fuel pressure regulator... yeah that is the right way to do it. Lots of people have used them on project bikes and cars of all flavors. A number of guys use electric pumps and adjustable regulators over on KZrider for various projects with good results. That is pretty simple and dependable mod.

Your assumption about the carburetors is a bit too simple. The 1300 is fed with six 33mm chokes for a reason. Your analysis of one cylinder and then the other is somewhat valid at low RPM's but as engine speed increases the flow becomes more steady and the pressure drop through the venturi becomes constant, at that point your small 3 carb set-up will fall flat on its face. A stock bike runs all the way to redline at WOT, so your 3 carb setup would have the equivalent pressure drop of a 1/2 throttle or less... the engine won't get enough air. Your could use three 60mm throttle bodies or something of similar size. That may prove advantageous at high rpm but prove unstable at slower speeds.

You ZN is fuel injection system is not all too complicated to re-make harness for, or use a generic controller to fire the stock injectors. Or even modify the throttle bodies to install aftermarket injectors. Those options would be much easier IMO.

Tyler wrote: As far as the aftermarket adjustable fuel pressure regulator... yeah that is the right way to do it. Lots of people have used them on project bikes and cars of all flavors. A number of guys use electric pumps and adjustable regulators over on KZrider for various projects with good results. That is pretty simple and dependable mod.

Your assumption about the carburetors is a bit too simple. The 1300 is fed with six 33mm chokes for a reason. Your analysis of one cylinder and then the other is somewhat valid at low RPM's but as engine speed increases the flow becomes more steady and the pressure drop through the venturi becomes constant, at that point your small 3 carb set-up will fall flat on its face. A stock bike runs all the way to redline at WOT, so your 3 carb setup would have the equivalent pressure drop of a 1/2 throttle or less... the engine won't get enough air. Your could use three 60mm throttle bodies or something of similar size. That may prove advantageous at high rpm but prove unstable at slower speeds.

You ZN is fuel injection system is not all too complicated to re-make harness for, or use a generic controller to fire the stock injectors. Or even modify the throttle bodies to install aftermarket injectors. Those options would be much easier IMO.

I'll remember that logic. other poeople on the internet have done it so it's ok. Hey it's running too lean lets just put the choke on that will fix it . The only way to do it properly is with a programmabe ecu and a lot of hours road and dyno tuning. Or reprogramming the factory ecu That's if anyone has been smart enough to hack it yet. Like i said before rising rate rubbish is a band aid not a solution and fuel mixtures will be all over the shop dyno tuning is never the entire solution to a good tune. ANd last of all The majority of tuners are dodgy they throw it on a dyno tune the wide open throttle areas get you a silly figure with no load and send you on your way.

I got spark on the bike. But no power to the fuel pump.

I found some KZ1300 carburetors for the bike on ebay. So that is sorted for now.

The stock wiring harness is in very bad shape. I'll be using an older ninja 250 harness for the headlights, tail lights, turn signals, cooling fan, and ignition switch with the igniter box and wiring from the kz for the coils. The zn1300 harness has a ton of extra wiring that is no longer of use and I don't want to go through it.