85 GPz 750 Cafe Project

  • Stosho
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Re: 85 GPz 750 Cafe Project

29 Jun 2017 18:31
#765694
That is fine work my friend.
Stosho
1978 KZ 650 B (x2)
1976 KZ400 AHRMA Racer
1966 Honda Cub
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  • DoctoRot
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Re: 85 GPz 750 Cafe Project

29 Jun 2017 23:49
#765710
beautiful work
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  • ajsfirehawk
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Re: 85 GPz 750 Cafe Project

30 Jun 2017 09:23
#765741
Thank you Gents. It isn't perfect, there is a small spot (large pinhead size) on the right front where I got a paint spit and it looks like maybe an 1/8 inch fiber fell off the rope it was hanging from while I shot it. For $150 in paint products, I'm quite pleased.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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Re: 85 GPz 750 Cafe Project

07 Jul 2017 17:49
#766346
Say hallelujah! Guess who fired up today. Did the vacuum sync on the carbs and moved on to Colortune. Everything blue throughout the RPM range except...no idle combustion on carb #1. Dark. Once the RPMs come up it is a beautiful blue. #1 is the carb body I tried to fix and ultimately replaced for the broken float pillar. I replaced it with a slight earlier version of the BS34s. Meaning is does have the passage between the main jet and the pilot jet. Meaning the pilot jet must be capped to function properly. (see the drawing from Patton below) I checked resistance on the plug wire. 4.9ohms. No issues with #4 so it isn't a coil issue. I re-re-re-removed the #1 carb, broke it down and shot carb cleaner through every passage. All clear. Any thoughts on next steps are greatly appreciate.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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  • ajsfirehawk
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Re: 85 GPz 750 Cafe Project

07 Jul 2017 19:34
#766355
I should remind any readers: 42.5 pilot at 2.5 turns; 135 mains. Stock cams and pipes and those damnable pods.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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  • Patton
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Re: 85 GPz 750 Cafe Project

07 Jul 2017 20:04 - 07 Jul 2017 20:04
#766365
ajsfirehawk wrote: . . . no idle combustion on carb #1 . . . isn't a coil issue. I re-re-re-removed the #1 carb, broke it down and shot carb cleaner through every passage. All clear. Any thoughts on next steps are greatly appreciate. . . . .

Does spraying some starting fluid into carb #1 intake produce momentary combustion? If so, would suspect that the carb pilot circuit is still failing to provide fuel mixture into the carb bore despite all the cleaning effort. :pinch:

Could remove the #4 spark plug immediately after the lack of combustion scenario during the starting procedure to determine whether or not there's fuel on the business end of the spark plug, which would indicate that fuel mixture is indeed entering the combustion chamber but for whatever reason isn't combusting.

Good Fortune! :)
1973 Z1
KZ900 LTD
Last edit: 07 Jul 2017 20:04 by Patton.
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  • ajsfirehawk
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Re: 85 GPz 750 Cafe Project

09 Jul 2017 10:33
#766483
I'll be out there this afternoon Patton. Good thought on the starting fluid. Also had a recommendation to open the enricher circuit and see if I get combustion. Same thought as yours "introduce fuel another way to prove fuel is the only missing element". I will advise later today.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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Re: 85 GPz 750 Cafe Project

09 Jul 2017 13:42
#766493
I uncapped the pilot jet and I now have a pilot circuit functioning on #1. Letting the bike fully warm up it is back to tuning. What now becomes clear is I'm running too rich on the main jets. I've dropped the needles all the way down and any application of throttle makes it go yellow and when the RPMs flatten out it bounces between yellow and blue on the Colortune.. The plugs after running for many minutes come out black and sooty. I fine tuned the pilot circuits. I could never get them to go white with the color tune, but when they got too lean they would misfire (dark). I've got to see if I have 130 main jets and pull these suckers apart again.
Meanwhile I'm not confident the ignition system is 100%. Stock coils and wires that measure good but I'm skeptical. I don't even remember if I did the Wired George mod to apply battery voltage to the coils. I'll do that at a minimum and possibly order new Dyna coils and wires.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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  • ajsfirehawk
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Re: 85 GPz 750 Cafe Project

09 Jul 2017 15:33
#766508
No joy, I don't have 132.5 or 130 mains.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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Re: 85 GPz 750 Cafe Project

10 Jul 2017 18:44 - 10 Jul 2017 19:28
#766618
I went to Tri City Cycle chasing main jets. They had three 132.5's (as useful as balls on a priest) and four 130 main jets. I installed the 130's to see how it responded. Spins like crazy, but doesn't light. I'm ever more convinced the ignition is sub par. 13.2 volts on the coils at rest. I have not done the Wired George mod. This puppy should light. Great compression, (145 to 150) I watched the enricher function properly with the Colortune. Pull the enricher and each cylinder turns bright yellow. I've got air, fuel, compression...I have to believe the spark is weak. It should fire up immediately and just nothing. Not even a cough. I'll work through the ignition diagnostics in the service manual and then if nothing jumps out as a problem I think I'm going to order Dyna coils and new plug wires. Do the Wired George mod. Get another 132.5 jet and give it a go. Back to waiting for parts. JFC this just never ends.
79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1
Last edit: 10 Jul 2017 19:28 by ajsfirehawk. Reason: Added detail

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Re: 85 GPz 750 Cafe Project

11 Jul 2017 18:11
#766723
I'm going to call this a starting problem. It flatass won't start cold, won't even cough. But bump it once with starting fluid and it runs like a deer. Also starts very well once it is warm. I'm at a loss regarding how to make this puppy start on its own.


79 KZ650 SR
80 KZ1000 Z1 Classic
83 KZ1100 LTD
Z900RS
23 Mach 1

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