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85 GPz 750 Cafe Project 03 Oct 2016 19:42 #744403

  • ajsfirehawk
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Patton wrote:

ajsfirehawk wrote: . . . pulled the pods off and shot starter fluid in, took off running light a bat outa hell. Possibly the paper filter on my baby bottle is clogging the passage of fuel to the bowls? . . . .


To just rehash some basics ---

Ability to run on starter fluid but not otherwise indicates an imperfect pilot circuit. And that for whatever reason fuel mixture isn't being provided by the carb.

Even with a perfect pilot circuit, sufficient fuel must flow into the carb, through the float valve, and into the float bowl.
A restrictive in-line filter can prevent fuel from being furnished to the carb, same as a kinked fuel line, or for whatever other reason why the carb thinks you're out of gas.

Be sure to use the type of in-line filter designed for gravity flow (such as for lawn mowers), and not an in-line filter that's designed for use with a fuel pump.

After an unsuccessful effort to start the engine due to lack of combustion, the spark plugs should be wet with fuel. Which indicates that the starter circuit and/or pilot circuit are providing fuel mixture from the carb that's being sucked into the cylinders.

And of course, remember to not touch the throttle grip when attempting to start a cold engine.

Good Fortune! :)


The plugs are not wet after an unsuccessful attempt to start the motor. I am using a gravity fed style filter which flows freely into a container on the bench. The carbs bowls are filling and the floats have been verified to be in spec with the clear tube test.

Final note, in the link you sent me to the 85 GPz carb exploded diagram, it shows caps over the pilot screws. I do not have caps over the pilot adjustment screws.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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Re:85 GPz 750 Cafe Project 03 Oct 2016 20:20 #744408

  • GPzMOD750
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Those caps were a import emission control requirement. To keep dealers and users from making adjustments, at least not easily. Completely unnecessary especially since gas formulation has changed so much over the years.

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85 GPz 750 Cafe Project 03 Oct 2016 20:33 #744411

  • Patton
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The idea is to blast carb cleaner through the tiny passageway into the pilot jet, in order to clear any obstruction in the tiny passageway.

Even without blocking the air jet, needle jet and idle jet while spraying into the main jet, if the tiny passageway is clear, enough spray should go through the tiny passageway to reach the mixture screw.

Here's a method I think might work to determine whether the spray is getting through the tiny passageway and on up to the mixture screw.




If spray is exiting through the open mixture screw hole, then screw the mixture screw back in, and re-spray to see if the spray gets into the carb bore.

Could try using toothpicks as temporarily jet plugs in order to concentrate the spray force through the tiny passageway.

Good Fortune! :)
1973 Z1
KZ900 LTD
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85 GPz 750 Cafe Project 04 Oct 2016 06:13 #744432

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Yet another exercise -- blast backward.







In this spraying backward exercise, spray exiting though the jets (air jet, needle jet and main jet) is to help clean the small passageway and show that spray is passing through the small passageway.

An ancillary benefit -- the hopefully -- is to help clean the orifices in the top of the carb bore just underneath the pilot screw.

Good Fortune! :)
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KZ900 LTD
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85 GPz 750 Cafe Project 04 Oct 2016 16:38 #744487

  • ajsfirehawk
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Stripped the paint off of everything. Boiled all pieces in the ultrasonic cleaner (30% Krud Cutter) for 40 minutes at 70" C. Rinsed everything with hot clear water, blasted all passages with compressed air. There isn't any connection between the nozzle (main jet)and the pilot circuit on these carbs. That means no cap should be over the pilot jet on these carbs per the footnote in your post. I've verified airflow and carb cleaner through the enricher circuit, the pilot circuit, and the main jet circuits. I started assembly. I'll finish assembly and installation tomorrow. Thanks for the guidance.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1
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85 GPz 750 Cafe Project 05 Oct 2016 14:33 #744557

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It lives, interesting journey to get there. With #40 pilot jets I needed to back out the adjustment screw to 3 full turns coax this puppy to life. Even with that and the choke on I had to bump it with starter fluid to get it to light. Then dial in the idle adjustment. Once I got some heat in it, I can get it to start on it's own. No doubt getting things hot and circulating for the first time in nearly 15 years doesn't hurt either. With the pilot adjustments screws fully backed out (3 turns is as much as one should go, yes?) I think that suggests I should go to a #42 pilot. Agree? I don't want to dork around with vacuum syncing if I'm going to open the carbs up again to load new pilot jets. I'll do a legit cold start in the morning to see how well it starts without a taste of starter fluid on full choke.
It was 6 months ago when I rebuilt these carbs. I don't remember every move I made, but it makes me wonder: If I ultrasonic clean with a 30% mixture of Simple Green and water, then rise with hot water and let it sit am I exposed to Simple Green residue clogging the small carb passages? I used Simple Green then, I am currently using Krud Kutter as it doesn't dull the aluminum. Meaning I think my recent process of 30% Krud Kutter and water, high temp ultrasonic clean, then blast all passages out with high pressure air, and follow that with carb cleaner may be a better way to go. That way ensuring there isn't any cleaner that could create enough 'crust' to block a passage? I'm speculating of course, but it seems possible. (FYI I posted this on KZ650.info as well.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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85 GPz 750 Cafe Project 05 Oct 2016 17:07 #744558

  • Nerdy
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ajsfirehawk wrote: I used Simple Green then, I am currently using Krud Kutter as it doesn't dull the aluminum.



There's a purple version of Simple Green that is supposed to be safe for all metals. I haven't tried it yet on a carb body, though.

Non-corrosive formula safely cleans aluminum, stainless steel, polished steel, chrome and other metals

1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R

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85 GPz 750 Cafe Project 06 Oct 2016 10:00 #744605

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I was unsuccessful in my attempt to post the video. I went through the rules and didn't see any guidance, what is the proper way to post a short video on this forum?
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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Re:85 GPz 750 Cafe Project 06 Oct 2016 11:41 #744611

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I don't think you can directly upload a vid. They have to be hosted by YouTube or some other site. You can't even do gifs without hosting. Some forums I've participated in don't even let you do pics directly.

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Re:85 GPz 750 Cafe Project 17 Oct 2016 16:35 #745485

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Bike up and running, now I'm down to wiring in the new gauges and lights. Got out the black ruler and starting tracing some things out. Headlight switch, tach, neutral switch etc.
Questions:
1) What is a "Reserve Lighting Device" and where is this mystical box located?
2) The fuse block and associated relays and fuses are all in a block called "Junction Box" that doesn't show the internal fuses or relay connections. Anyone have the internal wiring diagram for the Junction Box or is it somewhere else in the Kawi Service Manual?
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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Re:85 GPz 750 Cafe Project 17 Oct 2016 18:55 #745497

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Are you doing a harness from scratch or are you using the existing wiring?

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Re:85 GPz 750 Cafe Project 17 Oct 2016 19:01 #745498

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I'm using the existing harness. It appears most of the 'extra' wiring that will not be used will tuck up under the tank fairly easily. I'm not dead set on that, but that is where I'm headed now.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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