At this point I could tear out what little hair I have left. What the hell are you doing to check for ignition ? It doesn't have to be running. Just take the plugs out and connect the plug wires to them and lay them on the engine. Turn key and push button. Observe business end of plugs to see if there is a spark occurring. Yes ? No ? Really, it's that easy. You didn't have a .0011" wire ? You had your carbs out and missed a vital step ? gee... You think I pulled that figure out of the air ? I did say it was the only way to insure that the jets are completely open. I have taken the time to measure ALL the jets in the spectrum and record the sizes. I buy my wires from a piano repair place. Fishing tackle, musical intrument, etc.... this is my 9~5 job and I must do it. No excuses, no returns. Results count. .0011" IS the size of the slow jet in a 700s. I don't have the luxury or the inclination to do a job more than once. Now, the sudden drop in performance. Unless I missed that the first time or you wern't explicit... I'm going to stay with a loss of two cylinders untill you say otherwise.
# a tech tip for all of you who are dealing with R&R of carbs in the bikes that use vacuum petcocks. Instead of wearing down the battery while you wait for the carbs to refill, Pull off the vacuum line to the petcock.Insert a small syringe in the vacuum line to the petcock and pull back the plunger. That will open the diaphram and allow the carbs to refill. Open the drain bolt in the bowl and check for fuel flow. close it back up and allow a minute to complete refilling. Now start the bike. --- On Fri, 5/29/09, Dennis <[email protected]> wrote: From: Dennis <[email protected]> Subject: [Nighthawk Lovers] Re: 700SC carbs question To: [email protected] Date: Friday, May 29, 2009, 2:23 AM Message Dennis, Any thoughts on how to arrange things so that I can run the bike with the fuel tank removed? I'm doubting that it'll run long enough with what's in the bowls for me to test all four plug wires for spark. What do people normally do to be able to run with the tank off? Dennis - Seattle -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Dennis Hammerl Sent: 28 May, 2009 21:29 To: [email protected] Subject: [Nighthawk Lovers] Re: 700SC carbs question That's scary stuff... flash point is too low. You could be hurt. After a few minutes of run time, shut it of and open those screws a bit (the one you sent a picture of) and see if fuel runs out. this way we insure that each bowl is filling. I'm assuming that you passed the .0011 wire through each slow jet ? I'm starting with some basic stuff here. Does this pop or anything? just sounds flat ? --- On Thu, 5/28/09, Dennis <[email protected]> wrote: From: Dennis <[email protected]> Subject: [Nighthawk Lovers] Re: 700SC carbs question To: [email protected] Date: Thursday, May 28, 2009, 11:51 PM Dennis, It is very flat seeming when it runs. I haven't run it long enough to let it fully warm up. But, during the time I have run it, I use about half choke and a bit of throttle to keep it running or else the RPMs drop so low it stops. When I've got it going and I give it throttle, it comes up slowly and with little enthuiasm. I've run it up to about 3500 and it sounds pretty different than it would if it were run up to 3500 when it is running right. I have some spray starter fluid - would that do? Dennis - Seattle -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Dennis Hammerl Sent: 28 May, 2009 20:39 To: [email protected] Subject: [Nighthawk Lovers] Re: 700SC carbs question Your plugs are indicating a lean condition.(ideal is somewhat brown) Not unexpected given being loose. Loose plugs do not transfer heat as they should. Effectively rendering them about one heat range more than they should be. It would appear that they all were firing. However, I will wait to see what you have to say about that. A 700s running on two out of four would be a very flat sounding, poor running thing. Do you have a spray carb cleaner ? Idle the motor and push the boots aside a tiny bit and spray a bit into each carb throat and observe the reaction. If it picks up or garfs a bit. --- On Thu, 5/28/09, Dennis <[email protected]> wrote: From: Dennis <[email protected]> Subject: [Nighthawk Lovers] Re: 700SC carbs question To: [email protected] Date: Thursday, May 28, 2009, 11:17 PM Dennis, Thanks as always for sharing your advice. Tommorrow, I'll see which plug wires are sparking. I did use the strong light method of evaluating the butterfly valves and the one I adjusted was a better match when I was finished. I wondered if taking the cables off at the grips was the right thing to do to gain extra length. I didn't do it that way and it was a very tight business to do it the other way but, ultimately, it worked. Next time, I'll take the cables loose on the other end and make things easier. I just walked out and had another look and now I see where to connect the manometers. Does make a lot more sense than trying to connect them to the bottom of the float-bowls, eh <smile>? Dennis - Seattle -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: 28 May, 2009 19:53 To: [email protected] Subject: [Nighthawk Lovers] Re: 700SC carbs question The OEM exhaust is a balanced affair. So dismiss any thought of a diagnosis in that fashion. Please do check for spark at all plugs before we go tearing into anything else. When you have determined that, get back to me. The procedure to check out an ignition issue on a system like that is something that will take time to write out. Only if I have to. The vacuum take-off point is at the screws on the intakes. Same place as the vacuum take-off that is used for the petcock. The hoses are plugged into adapters on one, three and four, the petcock take-off on two. Understand ? You have to remove the screws and thread in adapters. Did you use a strong light to determine that a throttle plate needed to be moved ? Graham, the "pressed in jet" is not to be removed. There are only two. Remember to clear the slow speed jets with the .0011" wire. As far as R&R of the carb pack, it is best to start at the grip and remove the cables to insure enough slack at the carbs. The air box can be slid back quite far to allow space, just takes some effort. Liquid soap, WD-40, or silicone spray makes for a much easier time popping the boots and intakes off and on. Kyle takes the bolts out and pulls the intake manifolds out with the pack. I have no problem with that method. --- On Thu, 5/28/09, Graham Rogers <[email protected]> wrote: From: Graham Rogers <[email protected]> Subject: [Nighthawk Lovers] Re: 700SC carbs question To: [email protected] Date: Thursday, May 28, 2009, 10:17 PM I haven't put the carbs back on my 700SC yet - I'm afraid to! I put the carbs back on my CB750F and it ran like before! Graham On May 28, 2009, at 9:28 PM, Dennis wrote: Well, I finished putting my 700SC back together today and started it up - and it ran just as before. It feels like I have two cylinders firing and two not - but that's a guess - I haven't watched the spark plugs spark to prove it. I have the stock dual exhaust and it seems to me like both mufflers feel the same. So for either muffler, one cylinder's hitting and one's missing. Does that make sense? Dennis, I'm keen to focus now on the coils if you still think that's the most likly target to investigate, Can you tell me your thoughts again about how to test them out? I had a look at them today but I didn't see anything obvious like broken or shorted wires. Cheers! Dennis Gallagher - Seattle - '85 & '86 CB700SC --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. 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