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82 Gpz 750 will not start. 02 Jan 2012 19:30 #495895

  • HAILCON71
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You guys seem knowledgable and may have come across my problem.
I have an 82 GPz 750. Bs34's. Each carb was soaked in Berrymans'. New jets all around. New o-rings all around. The first time Carbs were installed nothing happened. Checked plugs, had an ignition problem, I fixed the wires...ignition good. Hit the starter....nothing. Checked spark again noticed that the plugs should be wet, but the weren't. I left the bike over night and gave it a whirl and it started. but only for a few secs. I believe that the weight of the fuel in the lawn mower tank I have been using dribbled fuel into the bowls and overflowed into the intake manifolds. (I have used the bikes tank also hoping the lawn mower tank was the culprit) So i know the valve train and ignition systems are working. What would keep the cylinders from sucking fuel through the carbs. The Starter circuit is preety stupid proof isn't it. All new rubber boots and Carb holders. I plugged all ports to eliminate the fresh air crankcase vent valve for troubleshooting.
I have blown air into every hole and air always comes out from where it is supposed to. My best guess for idle is that the float levels were not right. I checked the float heights and they were all jacked up, even though using the clear tube method for fuel levels was not that bad. I now have the right fuel levels in the bowls.
Stock air box and new stock air cleaner.
Stock exhaust.
New air box boots.
New ----37.5 pilots all plugged and o-ringed, float valves, 110 mains, mixture screws and o-rings (out 2.5 turns). Stock needle for needle jet, one clip type needle. Diaphragms supple and soft no tears. Compression and timing good.(Runs with starter fluid)
With my hand on the engine intake and the starter pressed the engine sucks pretty good on my hand.
I would love to hear from other GPz R1 folks, Or BS-34 guru's. I have been to other forums and they were very knowledgable and helpful. But they were stumped also. I thank them for their help.
I'm hoping to thank you guys for getting this bike running.
HAILCON71




I have been through the enrichment circuit with air, carb cleaner and plastic wire.
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82 Gpz 750 will not start. 04 Jan 2012 13:53 #496282

  • Patton
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For reference, see also www.kzrider.com/forum/3-carburetor/48930...and-its-carbs#490326 and the links therein provided.






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Good Fortune! :)
1973 Z1
KZ900 LTD
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82 Gpz 750 will not start. 04 Jan 2012 14:39 #496286

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Given good intake suction, but dry plugs, yet runs with starter fluid -- indicates absence of fuel mixture entering carb bore through choke orifice or pilot circuit orifice, for whatever reason.

Could be blockage in the pilot circuit, or too low fuel level, or maybe something else

Was engine running before the carb work?

Did engine sit without running and allow carb fouling due to fuel evaporation?

Good Fortune! :)
1973 Z1
KZ900 LTD

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82 Gpz 750 will not start. 04 Jan 2012 15:43 #496296

  • HAILCON71
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Patton,

Excellent Diagram. I'll give it shot on monday my day off! The bike ran before I rebuilt the carbs. This is why I'm worried that Soaking them in Berrymans may have some how effected them. When I sprayed down from the enrichmnet chamber I noticed if I didn't get the straw directly in the hole of the enrichment circuit to the enrichmnet tube, fluid would come out around the enrichment tube and not through it.This also makes me wonder if Berrymans somehow dissolved sealant where the brass post is pressed fit into the carb base from manufacture. Possible? When I pull off the carbs I think I will try to plug off both end of each Carb and look to see if the butterfly shafts are leaking. I have cleaned the Enrichment circuit countless times, and spray always comes out where it is supposed too. I know the enrichment circuit helps to start the bike, does the pilot only kick in once started. I took the top off of number 1 carb and turned over the engine and I could see the pilot spraying.(I believe this is only because the diaphragm and needle were removed) So if the enrichment circuit does not start the bike, then there is not enough vacuum to raise the needle just enough for the pilot to kick in) . By removing the needle I allowed the pilot jet fuel and the engine suction did the rest. Am I on the right Track?

The entire top end of the engine was rebuilt. Timing, compression and spark and Valve clearance are all there.(Engine runs on starter fluid, and gas) So the Carbs have not sat more than a few days between removal.

Thanks for your help.
I'll open the carbs and give you detailed info on work accomplished.

HAILCON71

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82 Gpz 750 will not start. 04 Jan 2012 16:13 #496300

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I would shut off the fuel petcock then proceed to drain one carb at the time. You should get plenty of fuel from each float. If not, chances are that the carbs will not fill. That has happened to me many times, although I cannot explain why. Having a vacuum operated petcock will make it next to impossible to fill the floats without sucking on the vacuum pipe, but the resistance to filling can happen with normal petcocks as well.
1977 KZ650B1
1980 F1 engine
B1 3-phase alternator
B1 Points ignition

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82 Gpz 750 will not start. 04 Jan 2012 17:00 #496308

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yep, most simple way to check and make sure fuel is getting to the carbs is to crack the drain scews loose and see if gas is flowing out. If not, check your needle and seat to make sue the needle isnt sticking. If you do think you have a stuck needle, try whacking the carb with a rubber mallet.. If the needle comes open, it really saves you the hassle of removing/disassembling the carbs. If you do get it running at all, even crappily, keep it going as long as you can and then see which header pipes are cold and which are hot so you can determine which carbs need work. If you pull the carbs off again, try blowing air through the intake side of the carbs with a compressor and see if your diaphragms go up.
1981 Kawasaki KZ1000-K LTD
1983 Suzuki GS300L-D
1982 Suzuki GS300L-Z sold:(
1976 KZ400D3
1973 Z900... I WISH

DO A BARREL ROLL!!

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82 Gpz 750 will not start. 04 Jan 2012 17:14 #496309

  • Patton
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The pilot circuit is supposed to function at fully closed throttle position, which is the situation with a warm engine at idle rpm.

Adding "choke" introduces additional mixture, especially when the throttle is closed (but also when the throttle is partially open). In other words, adding choke adds additional fuel mixture to the fuel mixture already being supplied by the pilot circuit.

So the problem at hand might be largely attributable to failure of the choke circuit (would assure clear fuel pipe to starter jet -- see image posted), but would seem that spark plugs would not be completely dry where pilot circuit is supplying at least minimal fuel, regardless of a failed choke circuit.

That's why thinking there's blockage in both choke and pilot circuits thereby preventing any fuel mixture at all from entering the combustion chamber.

Good Fortune! :)
1973 Z1
KZ900 LTD

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82 Gpz 750 will not start. 04 Jan 2012 17:21 #496310

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Would again assure that the tiny short passage into the pilot circuit is clear.

And that the plugs are properly installed at bottoms of pilot jets.

The plugs are essential, as the pilot jets must not be "open" to the float bowls (which would inhibit mixture flow through the pilot circuit).




Good Fortune! :)
1973 Z1
KZ900 LTD
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82 Gpz 750 will not start. 04 Jan 2012 17:36 #496312

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If not already done ---


1973 Z1
KZ900 LTD
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82 Gpz 750 will not start. 05 Jan 2012 22:14 #496587

  • mtkawboy
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Have you set the petcock on prime so your sure its getting gas ? Also make sure the vacuuum hose is on the petcock. I always fill mine on prime after any work on the carbs. Nice job on the carb circuit drawings Mr Patton
78-KZ1000/1105, 80 KZ1000, 82 Kawasaki GPZ750, 95 Harley Fatboy, 80 Suzuki GS1100ET, 81 GS1100E parts bike, 83 GS1100SD Katana/1394,78 Yamaha XT500, 81 Yamaha XS650, 78 Yamaha XS650E, 48 Whizzer model J motorbike, 71 Honda CT70H, 71 Honda CT70, 81 IT 250 Yamaha,82 Honda XL100S owned

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82 Gpz 750 will not start. 05 Jan 2012 22:51 #496603

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Follow Patton's cleaning diagrams for sure. I found blocked passages even after a major cleaning with method the he is suggested to you. But I would also point out that you don't forget the passage for the coke circuit located in each float bowl. These jets have a high probability of clogging when fuel sits and gunk's up the bowls. Carburetor cleaner and compressed air weren't enough to clear mine. Had to use an appropriate size wire before they opened up an then was able to confirm the are open by spraying more cleaner. Like Patton said, its sounds like its both the pilot and the choke circuit. But just thinking it may be worth checking the choke bowl jets to help the coke along. Good luck.

Current project 76 KZ900 (This was a Vetter model)
76 KZ900
81 XJ550H SECA (Current Project)
82 XJ550R SECA
Past:
86 FJ1200
74 Z1900
72 CB450
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82 Gpz 750 will not start. 06 Jan 2012 04:22 #496659

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KZJOE900 wrote: ...don't forget the passage for the coke circuit located in each float bowl...Carburetor cleaner and compressed air weren't enough to clear mine. Had to use an appropriate size wire before they opened up an then was able to confirm the are open by spraying more cleaner...worth checking the choke bowl jets to help the coke along...


Excellent suggestion! :cheer:





Here's a link to the tutorial among the "Not model-specific" files in KZr's FILEBASE:
Click here > www.mtsac.edu/~cliff/storage/gs/Mikuni_B...Rebuild_Tutorial.pdf

And here's a link to another helpful tutorial:
Click here > www.thegsresources.com/gs_carbrebuild.htm

Both tutorials include helpful pics.

Z1 Enterprises offers a wire cleaning tool.
Click here > www.z1enterprises.com/Carburetor-Cleaner-wire-set-236.aspx

Others may use a wire strand pulled from a wire brush.

I like using a short length of a small Guitar E string.

Be gentle with whatever wire might be employed, as the idea is to assist clearing the crust from an existing orifice, and not reaming out (enlarging) the orifice or damaging the contour of the orifice.

Good Fortune! :)
1973 Z1
KZ900 LTD
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