If idle is uncontrollable like that I would suspect a vacuum leak. You need to spray Carb cleaner or starting fluid around all gasket areas. I had this once. It was a vacuum leak on the right Carb gasket. 82 450sc. On Feb 29, 2012 2:10 PM, "Ralf Oehlerich" <[email protected]> wrote:
> I set it at 3 turns out. > > On Wed, Feb 29, 2012 at 2:29 PM, Allen Thomas <[email protected]>wrote: > >> How many turns out on the fuel screws? Just curious. >> Sent via BlackBerry by AT&T >> ------------------------------ >> *From: *Ralf Oehlerich <[email protected]> >> *Sender: *[email protected] >> *Date: *Wed, 29 Feb 2012 11:46:14 -0500 >> *To: *[email protected]<[email protected] >> > >> *ReplyTo: *[email protected] >> *Subject: *Re: [Nighthawk Lovers] 81 CB750C Carbs idling at 3500??? >> >> Cb750 is all good. Had to clean out idle jets and bench sync carbs >> >> Sent from my iPhone >> >> >> On Feb 28, 2012, at 10:45 PM, "Allen Thomas" <[email protected]> >> wrote: >> >> PS the PO probably backed out the fuel screws to compensate for dirty >> carbs. Now that you cleaned them the cylinders are getting too much fuel. >> I'm not familiar with your specific model, but on later models about 3 >> turns out is about right, I'd start there. Of course I could be wrong with >> all of this, but we have seen that issue before. Let us know the fix when >> you get it sorted out. >> Sent via BlackBerry by AT&T >> ------------------------------ >> *From: *"Allen Thomas" <[email protected]> >> *Date: *Wed, 29 Feb 2012 03:26:45 +0000 >> *To: *Nightwawk Lovers<[email protected]> >> *ReplyTo: *[email protected] >> *Subject: *Re: [Nighthawk Lovers] 81 CB750C Carbs idling at 3500??? >> >> From the factory Honda sets them so lean that if you touch the throttle >> the engine will die. If you have to crack the throttle to get it to start >> then I'd say it is way too rich. When it warms up does the exhaust start >> popping? (Rich condition) IMHO you can't do an effective carb cleaning with >> out removing the pilot screws. That could be why #2 isn't firing, its idle >> circuit sounds clogged. +1 on doing a bench sync of the butterflies, it may >> not be perfect but that will get the carbs close enough for it to run right >> once you get the mixture correct. >> Sent via BlackBerry by AT&T >> ------------------------------ >> *From: *Ralf Oehlerich <[email protected]> >> *Sender: *[email protected] >> *Date: *Tue, 28 Feb 2012 22:14:41 -0500 >> *To: *<[email protected]> >> *ReplyTo: *[email protected] >> *Subject: *Re: [Nighthawk Lovers] 81 CB750C Carbs idling at 3500??? >> >> Worked on it more this afternoon. The trick with the sync screws did not >> help. Now the choke does nothing. I never touched air/fuel screws or idle >> jet. Now you need some throttle to start it and hold it for a while, then >> it idles again at about 2000+. Cylinder 2 is NOT getting hot still. I will >> pull the carbs again and try to sync the butterflies. I found an excellent >> article that discusses rebuilding these specific carbs. >> >> On Tue, Feb 28, 2012 at 7:55 PM, Allen Thomas <[email protected]>wrote: >> >>> ** >>> Has it ever run right to your knowledge. Did you do anything else done >>> besides cleaning the carbs? Did you count the turns on the fuel screws >>> before removing them? Will it start without the choke? >>> Sent via BlackBerry by AT&T >>> ------------------------------ >>> *From: *Ralf Oehlerich <[email protected]> >>> *Sender: *[email protected] >>> *Date: *Tue, 28 Feb 2012 03:17:39 -0500 >>> *To: *<[email protected]> >>> *ReplyTo: *[email protected] >>> *Subject: *[Nighthawk Lovers] 81 CB750C Carbs idling at 3500??? >>> >>> Working on a 81 CB750 custom and just cleaned the jets on the carbs. Put >>> everything back on the bike and she idles at 3500 rpm. Could that be a bad >>> fit/too much air? >>> Cables are free and idle screw is all the way out. Air box and filter >>> are in place. Plugs are NOT new. She runs fine, just WAY too high even with >>> choke off when cold. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Nighthawk Motorcycle Lovers!" group. >>> To post to this group, send email to [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]. >>> For more options, visit this group at >>> http://groups.google.com/group/nighthawk_lovers?hl=en. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Nighthawk Motorcycle Lovers!" group. >>> To post to this group, send email to [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]. >>> For more options, visit this group at >>> http://groups.google.com/group/nighthawk_lovers?hl=en. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Nighthawk Motorcycle Lovers!" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/nighthawk_lovers?hl=en. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Nighthawk Motorcycle Lovers!" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/nighthawk_lovers?hl=en. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Nighthawk Motorcycle Lovers!" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/nighthawk_lovers?hl=en. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Nighthawk Motorcycle Lovers!" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/nighthawk_lovers?hl=en. >> > > -- > You received this message because you are subscribed to the Google Groups > "Nighthawk Motorcycle Lovers!" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/nighthawk_lovers?hl=en. > -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en.
