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Overly Rich Mixture - idle to 1/4 throttle 17 Mar 2016 17:39 #715901

  • weales
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G'day - finally got to fire up my Z1-R last weekend - with mixed results.

Cranked the engine over several times for 15 seconds or so at a time to circulate the oil around,
then fitted the plugs and tried for a start. After several attempts with no firing happening I pulled the plugs and
they were completely dry - no fuel getting through. Also starter motor clutch sounded like it was slipping/not engaging so brought the kickstart into action.

Got some "Start ya bastard" (actually ether in a can) and sprayed some of this into the carb intakes.
After second kick it fired up but was very rich - black unburnt fuel coming out the exhaust and running very rough.
Tried adjusting the pilot air screw to lean it off but didn't seem to do much from 1-2.5 turns out!

Checked carb fuel levels and all were in spec. However, one of the drain screw threads in no3 carb has stripped out and I need a replacement float bowl - anyone got one to sell, please? There is no M6 x 0.75mm thread repair kit made so if I stick with this one I'll have to put in a M6 x 1.0mm thread repair and use a non-std drain plug (ie just a 6mm screw with a gasket/o-ring)

Have since pulled carbs off and suspect blocked pilot air passages, or extra fuel being sucked up through the bleed pipes - the new bleed pipe o-rings seemed a bit loose and to not seal properly where they screw into the carb body. Any other ideas would be appreciated!

Off to the Barry Sheene Festival of Speed at Sydney tomorrow - riders such as Freddy Spencer, Kevin Schwantz, and lots of others such as Graeme Crosby will be there! I was hoping and working towards riding the bike to the event but it's not gonna happen this time - bugger! Still, will get to watch some top riders and meet some old racing mates at least.
Current Project
1968 Norton P11A Desert Sled
Other bike (and daily ride)
2004 Yamaha FZR 600
Previous Bikes
78 Z1-R (resto)
91 Zephyr 750
73 Mach IV (Resto)
78 Z1-R
78 Z1-R (stolen)
76 Z900
76 Z650
73 Mach IV
72 Mach III

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Overly Rich Mixture - idle to 1/4 throttle 17 Mar 2016 17:43 #715903

  • SWest
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Sounds like pilots clogged. Trying to use mains to start. Guitar string to clear the pilots.
Steve
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Overly Rich Mixture - idle to 1/4 throttle 21 Mar 2016 15:07 #716594

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Have cleaned out and blown out the pilot passages and jets and tried again but same result -
starts on kickstart easily and briefly runs ok but very quickly runs rich with black smoke
coming out exhaust and soots up the plugs.
I think that rather than blockages/restrictions in the pilot air system,
it may be that just too much fuel is being supplied by the pilot system?
I replaced the pilot jets (size 17.5) which came with the bike, with the new ones
provided in the o'haul kits - these are size 15. I would have thought that the sizing would be similar
to the main jets - ie bigger the number = more fuel?
I note that the holes which appear to be to allow the air through from the pilot air jet
are much bigger on the size 17.5 than the size 15; the hole though the middle of the jet
appears to be the same on the 15 as on the 17.5
Any thoughts/experiences please?
Current Project
1968 Norton P11A Desert Sled
Other bike (and daily ride)
2004 Yamaha FZR 600
Previous Bikes
78 Z1-R (resto)
91 Zephyr 750
73 Mach IV (Resto)
78 Z1-R
78 Z1-R (stolen)
76 Z900
76 Z650
73 Mach IV
72 Mach III

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Overly Rich Mixture - idle to 1/4 throttle 21 Mar 2016 16:33 #716613

  • SWest
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Have you tried putting the stock jets back in? aftermarket jets can be all wrong.
Steve

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Overly Rich Mixture - idle to 1/4 throttle 21 Mar 2016 16:59 #716620

  • weales
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That's the current plan - hope to do that tonight.
Did some reading up on carb jet numbering Vs Size and apparently, the bigger the number the richer the mixture in all cases - except for the cutaway which is the reverse. Happy to be corrected though.
Current Project
1968 Norton P11A Desert Sled
Other bike (and daily ride)
2004 Yamaha FZR 600
Previous Bikes
78 Z1-R (resto)
91 Zephyr 750
73 Mach IV (Resto)
78 Z1-R
78 Z1-R (stolen)
76 Z900
76 Z650
73 Mach IV
72 Mach III

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Overly Rich Mixture - idle to 1/4 throttle 31 Mar 2016 04:39 #718431

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Have done some research on Mikuni pilot jets (of which there are many!).
Looks like the pilot jets I've got may not be the right ones - although stamped with "15" per the spec these appear to be quite different
to those shown in the Z1-R parts book and the service manual which covers Z1000 and Z1-R models.
Could someone please post some pics/diagrams of the correct pilots?
Carbs are Mikuni 28mm without accelerator pump and with air screw only, no fuel adj screw.
Thanks!
Current Project
1968 Norton P11A Desert Sled
Other bike (and daily ride)
2004 Yamaha FZR 600
Previous Bikes
78 Z1-R (resto)
91 Zephyr 750
73 Mach IV (Resto)
78 Z1-R
78 Z1-R (stolen)
76 Z900
76 Z650
73 Mach IV
72 Mach III

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Overly Rich Mixture - idle to 1/4 throttle 31 Mar 2016 04:52 #718436

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Overly Rich Mixture - idle to 1/4 throttle 31 Mar 2016 14:18 #718550

  • missionkz
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swest wrote: My 28's have 17.5 pilots.
Steve
jetsrus.com/a_jets_by_carburetor_type/je...i_VM28-486_pilot.htm

My 26mm carbs have those exact looking pilot jets too but I'm running #20s.
Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado
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Overly Rich Mixture - idle to 1/4 throttle 04 Apr 2016 06:36 #719167

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Steve, those jets look just like the ones fitted to my carbs and the ones that came in the overhaul kits. However, they look nothing like the ones in the Z1-R parts manual or the service manual which are really short and screw right up into the carb body and do not protrude like yours, adjacent to the bleed pipe and main jet. Is there any chance that the jets I need are the short ones? Maybe this is why I'm getting too much fuel on the idle? My parts book has Kawasaki P/N 92064-1003, the long jets like yours are 92064-1017. I've found 1 of the 92064-1003 so far and will try to get 3 more.
Current Project
1968 Norton P11A Desert Sled
Other bike (and daily ride)
2004 Yamaha FZR 600
Previous Bikes
78 Z1-R (resto)
91 Zephyr 750
73 Mach IV (Resto)
78 Z1-R
78 Z1-R (stolen)
76 Z900
76 Z650
73 Mach IV
72 Mach III

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Overly Rich Mixture - idle to 1/4 throttle 04 Apr 2016 09:57 #719215

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Overly Rich Mixture - idle to 1/4 throttle 04 Apr 2016 20:37 #719311

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Yes, that's the same as the ones shown in the service manual and the parts book for the Z1R.
Something that concerns me is that the thread on the 92064-1017 is a finer pitch and size to the 92064-1003.
(Hopefully the threads in the carb bodies haven't been damaged already.) I didn't notice any binding or stiffness
when I unscrewed the original jets and fitted the new ones (92064-1017 type).
If you or anyone can help with my confusion over these pilot jets I'd be very grateful







as I'm pretty sure that this is the root of all my rich mixture at idle/small throttle opening problems!
Pics confirm different part number and physical construction of the jets.
Current Project
1968 Norton P11A Desert Sled
Other bike (and daily ride)
2004 Yamaha FZR 600
Previous Bikes
78 Z1-R (resto)
91 Zephyr 750
73 Mach IV (Resto)
78 Z1-R
78 Z1-R (stolen)
76 Z900
76 Z650
73 Mach IV
72 Mach III
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Overly Rich Mixture - idle to 1/4 throttle 04 Apr 2016 20:51 #719313

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I'd like to see pics of the underside where the jets go and the jets in them.
Steve

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