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Bike won't idle below 1700 18 May 2015 12:36 #672629

  • SWest
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And there's the problem. If it's a 750 twin, shims are hard to find. If it's a four, the job takes work,time and money. The way these bikes are set up, a valve adjustment can last for 3/4000 miles. If the owner is too cheap, lazy or stupids to do it, they should sell it and buy a 350 Honda or something a monkey can work on, let alone a more modern one and all that goes with it. :angry:
Steve

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Bike won't idle below 1700 18 May 2015 13:19 #672634

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New 750 wrote: I tested the battery voltage while running in is def in spec, both at idle and at rev, it's a brand new coil from eBay, it was only $20, I thought it could be oil but here is why I suspect it isn't, I can wipe it right off with a rag so I assumed it was soot from being rich, number two I literally use no oil, I run 20/50 Mobil 1 synthetic and change it every 1500-2000 and never need to add in between. Every 100-250 miles bike won't start so I pull the plugs wipe off with a rag and she fires right up! I'll order 50 pilot jets, how far out should my mixture screw be? I'm at 3 out from lightly seated, thanks Nathan . oh could someone point me in the direction of who sells jets, I saw them her. www.dimecitycycles.com/vintage-cafe-race...-jet-50-004-012.html. Are these correct

On mine the mix screw run about 2T out from lightly seated.
1979 KZ-750 Twin

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Bike won't idle below 1700 18 May 2015 13:21 #672637

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New 750 wrote: I tested the battery voltage while running in is def in spec, both at idle and at rev, it's a brand new coil from eBay, it was only $20, I thought it could be oil but here is why I suspect it isn't, I can wipe it right off with a rag so I assumed it was soot from being rich, number two I literally use no oil, I run 20/50 Mobil 1 synthetic and change it every 1500-2000 and never need to add in between. Every 100-250 miles bike won't start so I pull the plugs wipe off with a rag and she fires right up! I'll order 50 pilot jets, how far out should my mixture screw be? I'm at 3 out from lightly seated, thanks Nathan . oh could someone point me in the direction of who sells jets, I saw them her. www.dimecitycycles.com/vintage-cafe-race...-jet-50-004-012.html. Are these correct

I believe the PN for the pilot jets are Mikuni BS-30/96.

Tenth from the top on this page.

www.allensperformance.co.uk/mikjets.html
1979 KZ-750 Twin

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Bike won't idle below 1700 18 May 2015 14:27 #672643

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Steve, yes I checked the valves this morning, my manual says they need to be between 0.5-0.10 mm
Witch they all where, I assume those specs are for intake and exhaust? The only experience I have with adjusting valves was on my yamaha, those where super easy, just loosen the lock nut and that's about it, no shims. I have a propan torch, off (obviously) I sprayed the gas all around carb and boots, same with wd40 no change in idle,i know of no other way to check for leaks? I inspected visually, also I removed the boots and sealed them on the motor side with rtv type sealer, today I bought iridium plugs, they cross reference to ngk BR8ES, also I put my original coil back in just to see if there was a change, still no low idle.
1977 kawasaki KZ750

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Bike won't idle below 1700 18 May 2015 17:36 #672662

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The only thing I can think of, you set the idle too high while on the bench. One is the lead carb so you set it with a brill bit of the right size it in the middle of the adjustment range, then set the other to match.
Steve

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Bike won't idle below 1700 18 May 2015 20:33 #672686

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New 750 wrote: Steve, yes I checked the valves this morning, my manual says they need to be between 0.5-0.10 mm
Witch they all where, I assume those specs are for intake and exhaust? The only experience I have with adjusting valves was on my yamaha, those where super easy, just loosen the lock nut and that's about it, no shims. I have a propan torch, off (obviously) I sprayed the gas all around carb and boots, same with wd40 no change in idle,i know of no other way to check for leaks? I inspected visually, also I removed the boots and sealed them on the motor side with rtv type sealer, today I bought iridium plugs, they cross reference to ngk BR8ES, also I put my original coil back in just to see if there was a change, still no low idle.

Wrong plugs. The 750 twins use the NGK B6ES which are two notches HOTTER than B8 plugs. The stock plugs were not resistor type so you don't want the "R" plugs.
1979 KZ-750 Twin

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Bike won't idle below 1700 19 May 2015 05:41 #672705

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Wait so is it possible that the plugs are to cold thus not burning off all the carbon? I have ran those plugs or equivalent for a while.
1977 kawasaki KZ750

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Bike won't idle below 1700 19 May 2015 05:57 #672707

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That's the first and cheapest thing to do. I ran them when I was burning oil. I switched to BP8ES because I thought they were too hot. BP plugs have a longer reach so they wouldn't foul as easy. I also went one step down on the pilots to burn the oil. New valve guide seals and went back to normal plugs and jetting.
Steve

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Bike won't idle below 1700 19 May 2015 12:34 #672748

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New 750 wrote: Wait so is it possible that the plugs are to cold thus not burning off all the carbon? I have ran those plugs or equivalent for a while.

The B8 plugs are definitely too cold for the 750 twin in normal usage.
1979 KZ-750 Twin

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Bike won't idle below 1700 19 May 2015 16:30 #672774

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Had same problem....what I found on mine was the air screw o-rings damage..guess fro over the years of adjustments. Change them out ...sync carbs ..done
1982 GS1000sz Katana ( #15...17K Miles)
1982 GS1000sz Katana ( # 297....7100k Miles)
1978 Kz1000 Z1R. 10K Miles1
1978 kz1000 z1r 27k miles
1977 KZ 1000 A ( Project ) 54K Miles
1976 Kz900A4 (Red)21K miles
1976 Kz900A4 ( Red)7500 miles
1974 Z1 900 project

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Bike won't idle below 1700 24 May 2015 14:11 #673526

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Mine don't have any o rings or a washer it's only the needle and a spring? Should there be an o ring
1977 kawasaki KZ750

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Bike won't idle below 1700 24 May 2015 16:02 #673536

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Well ...I have never work on a kz750...but all of my cycles have oring on the air pilot .
1982 GS1000sz Katana ( #15...17K Miles)
1982 GS1000sz Katana ( # 297....7100k Miles)
1978 Kz1000 Z1R. 10K Miles1
1978 kz1000 z1r 27k miles
1977 KZ 1000 A ( Project ) 54K Miles
1976 Kz900A4 (Red)21K miles
1976 Kz900A4 ( Red)7500 miles
1974 Z1 900 project

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