Pod Air Filters...

[JC Viper]

Hey fellas. It's been a while since I posted anything but I was busy becoming an expert on Mikuni carburetors...

My 1984 GPz 750 ran fine when I bought it and brought it home only to find it leaking gas from the carb throat leading to the engine. With everyone's suggestion I cleaned out the carbs and got new float needles and cleaned out the jets.

Now the new problem: I managed to start the bike but it went into a high idle when I gave it some throttle or sometimes on its own. Also, the bike doesn't start consistently and sometimes it sounds like it's about to fire up only to die. The latter part is now a constant and the bike will not fire up.

The exhaust is stock but the air filter box has been replaced with pod K&N Air filters by previous owner. I have no idea if the jets are stock but the needle doesn't seem to be as it has 7 notches and it isn't really tapered like it says in the manual. Well I set the pilot screw 1, 1 1/2, 2, and 2 1/2 turns and no difference. Now when I push the starter constantly the carbs flood and brings me back to the gas leaking from the carb throat.

It ran fine with the pod filters before the carb got cleaned up. I cannot synch the carbs as the bike won't even start up and idle. So any ideas?

[JC Viper]

Okay, some more info:

Using the choke I get no indication of start up at all. Continue to crank and the carbs start to flood the intake area.

Opening the throttle and turning off the choke gets me better results but still won't fire up enough to idle.

Float heights are set to their specified setting

Pilot mixture screw is said to be an AIR screw but is located in front of the throttle bodies. Screws turned 1 whole (360º) turn, then 1 1/2, then 2 then 2 1/2. Unless they meant one half turn of the screw driver is one turn (range of motion).

Starter motor begins to smell a bit but I didn't hit the starter too long so hopefully I didn't burn it out.

[BuzZz]

That dam GPz still giving you grief? Sonofamotherfulbastard.....

Well you can't jet, sync or adjust dickall until it runs, so that needs to happen. I'd start by pulling the spark plugs and cleaning them well. They could be fouled from all that raw fuel. Adjust the gap to the higher end of the recommended specs, and while they are out, spin the engine over on the starter to make sure the cylinders are totally clear. While you got them out, ground the plugs against the engine and make sure you still have spark at each cylinder.

Once it's back together, try turning the fuel on to fill the floatbowls, then turn it off when you try to start it. There should be plenty of gas in the carbs to get it running. Once it starts and runs for 20-30 seconds, turn the fuel back on. If you have to crank it excessively trying to start it, open the fuel again periodically to make sure the carbs still have fuel in them.

Hopefully that gets it running and you can start messing with the carbs again.

[JC Viper]

Heh, thanks buzzz. I managed to ride the GPz a few times in the past months but the ride always ended up short because it would begin to idle in the higher RPM area, no matter what the idle screw is set to, and not come back down...

Cleaning the spark plugs have been a constant occurrence as well but it seems only 1 plug needs to be cleaned which happens to be carb 1, the carb that is lowest to the ground when the bike is on its stand. I also check for a nice fat spark from each and even went to the hotter plugs and gapped them to the max allowable per specs.

At this point is now sounds like it fires briefly but nothing else after. The firing order is 1-2-4-3. I'm not even sure about the air screw mixture because I've been told that it's a fuel screw if it's on the engine side of the carburetor, an air screw if towards the filter. Then I'm also told that pod filters are no good for anything.

The float bowls are always filled but for some reason gas pools up in the intake area of carb 1 if I hit the starter several times.

[PeterTrocewicz]

About 9 years ago, I had an '82 KZ750 (basically the same engine) do something similar after I'd owned it for a few years. It would suddenly decide to start pouring fuel out of the #1 carb, like when I was sitting at a stoplight in city traffic on a hot day. I must have had those carbs off and apart 6 times.
My appologies if you've already done these things, and for the wordy answer. I hope this helps.

Do you have the factory service manual? Clymer or Haynes is good too. Set adjustments to the recommendations there. When they say "1 Turn" of the fuel screw, they mean a 360 degree turn of the screwdriver blade.

When Kawi recommends float level level, they mean "service" float level: bike sitting upright and level, carbs on and full of fuel. Put a clear fuel line on the float bowl drain spout and open the drain screw. hold the fuel line upright against the carb and measure from the top of the fuel level in the line to the joint between the carb body and float bowl. The measurement should be the same, but this will probably give you a different reading than if you set it with the carbs apart. It is possible for a float to become "waterlogged' with fuel, or even develop a pinhole and fill up with fuel, causing them to ride lower in the bowl and allow more fuel in. Checking it this way and setting that carb's float height higher than the other 3 fixed mine.

You can can get very close to ballanced carbs without the bike running using a smaller sized drill bit or something like that. With the carbs off the bike, open the throttle stop screw until the drill bit will just slide in on the #1 carb This is the base carb. The others get set to it.
Now use the ballance adjust screws so that the drill bit will just slide in on the other 3. You'll find them pretty well spot-on if you recheck them with the bike running.

[JC Viper]

Thanks. I do have the Clymers manual and the fuel level is set right, the floats are still operable, ie. not filling up, and I actually synched the carbs using the visuals instead of vacuum so they're all evenly opened/ closed. I also tested the float needles and they do indeed stop gas from flowing and I've adjusted the float heights.

It seems that the constant cranking of the engine is squirting out liquid fuel but I'm not sure why as I have more air flow than gas at this point. The bike did run and start up right until I had a sticking/ worn float needle. The new problems came about after cleaning the carburetor.

I might do something gutsy and just rip out the 1 air filter and look into the carburetor while pushing the starter...

[JC Viper]

Umm... what's the sign of a burnt out starter motor? I've been cranking the bike a lot but not holding it straight through for more than 10 seconds. The box that contains the motor gets quite warm. Just wanna make sure I didn't blow the damn thing...

[Wrider]

As long as you let it cool down a bit between crankings it should be fine, and when it's blown it'll no longer crank, so that's usually a pretty big hint... haha
As for the carbs, what level is the needle clipped at? It sounds like you're running way too rich, so that clip should be at the highest level possible to sink the needle in as far as possible.
Try standing the bike up straight when you crank it.
See if you can't get it to bumpstart from a decent speed.

[JC Viper]

Bike ran fine before the stuck float needle when the clip was at the middle notch making it pretty high up. Considering the filters are high flow I guess it needs to be rich I thought the jet needle was only for throttle while idle relies on the pilot jet? The clips are now at the leanest position and still no luck. It started fine before but not sure what has changed after cleaning.

[JC Viper]

Okay, so the jets and easily clogged carburetor parts are soaking in carb cleaner. The pilot jets are stock sized and should only affect 0% - 25% throttle or something like that. The main jets are definitely not stock. The numbers on them are 185, a google search shows they go on Mikuni BS42 carbs while bikebandit.com shows the stock main jets are 107R - 112R.

Another thing is that the jet needle is a long even width stick. It's not tapered like the manual or bikebandit shows and it contains 7 notches. Should I be concerned and get the stock jets and needles? Bear in mind that the bike is using after market high flow pod air filters but stock exhaust (a bit asinine).

While the carb insides are apart (not gonna take apart the whole assembly) what else should I do while cleaning or assembling it?

Maybe spending another $2500 for a 1995 GPz 1100 sounds like a good idea...