It sounds like it's not getting enough gas. Have you adjusted the carbs with
the screw adjustment? Have you checked the screen in the petcock to see if
there's any debris? Is the air filter clean? I like to start with the little
things before I go into major surgery. HotrodMamma..
----- Original Message -----
From: Graham Rogers
To: [email protected]
Sent: Friday, March 06, 2009 5:59 AM
Subject: [Nighthawk Lovers] Re: Nighthawk S starting problem
This bike CB700) is on hold for a little bit. I'm having to make the
difficult decision to sell one of my Hondas. So I'm going to sell my 1980
CB750F. But first I have a problem. I restored this bike as much as I can
(paint job, new decals, new seat cover and detailed clean, including carbs).
The bike runs good as long as I keep the choke on some. The bike breaks up and
dies if I do not use the choke. Here's what I suspect may be the problem and
this is where I need help. I could not find a vacuum leak by spraying around
the carbs while it was running. The bike has a 4 into 1 exhaust system. That's
how I got it. Should the carbs have been modified/adjusted for the change from
the original exhaust system and had they not, would that cause it to run lean
and so need the choke activated? If that's the case what do I need to do?
Installing stock exhausts/mufflers is too expensive. Thanks guys, Graham
On Feb 26, 2009, at 12:38 AM, Dennis Hammerl wrote:
They are your carbs. Investigate what passages are blocked. It would
seem that you have sufficient intake vacuum, Hand choking increases that. If
all was well, after hand choking, the plugs would be saturated. Because they
aren't, the path from bowl to intake via choke valves must be blocked or the
choke valves don't work properly. They can be removed without too much trouble.
Very simple devices.
--- On Wed, 2/25/09, Graham Rogers <[email protected]> wrote:
From: Graham Rogers <[email protected]>
Subject: [Nighthawk Lovers] Re: Nighthawk S starting problem
To: [email protected]
Date: Wednesday, February 25, 2009, 5:46 PM
I cranked the motor over - it tried to start, at least on one or
two cyl. Then I checked the plugs. They were dry on the tips and porcelain but
a little wet on the rim of the plug. It didn't smell like gas however. I then
tried to start the bike with my hand restricting the air flow at the air
filter. It did start but died when I moved my 'hand choke' I probably could
have gotten it started that way. So, it looks like the choke isn't working eh?
Now what?
Graham
On Feb 25, 2009, at 12:21 AM, Dennis Hammerl wrote:
Spraying it optimizes the conditions needed for starting.
Which... means the chokes aren't working. If it has a strong vacuum when
cranking if you hold your hand over any carb throat, the chokes aren't passing
any fuel. WHY ? The "gas chokes" are very simple valve devices. If they have
access to fuel from the float chamber and they are open to the bores when
activated, all should work. With the throttle plates closed, the high vacuum
(or , more properly, low pressure) should draw fuel up through the choke
circuits and into the motor. It's as simple as a faucet. I don't want to get
into any abstract at this point. Are the plugs getting wet when you crank the
motor with the chioke operated ? Knowing that is a must before proceding. If
they are, we look elsewhere. If not, we stay in the carbs.
--- On Tue, 2/24/09, Graham Rogers <[email protected]> wrote:
From: Graham Rogers <[email protected]>
Subject: [Nighthawk Lovers] Re: Nighthawk S starting
problem
To: [email protected]
Date: Tuesday, February 24, 2009, 8:05 AM
Tried starting the bike this morning and there doesn't
seem to be any improvement. It would 'bubble' along like it was trying to
catch (it acted like a weak spark) but again it took starting fluid and the
choke seemed not to play apart. Once it had 'caught', restricting the air flow
through the air filter with my hand significantly increased the rpms. Maybe I
should also check the state of the battery huh?
Incidently I noticed the fuel gauge didn't work until I
revved the engine significantly and held the revs. That was a new one to me,
Graham
On Feb 23, 2009, at 11:02 PM, Dennis Hammerl wrote:
Let us know how that works out. The neutral
wiring is grounded and that's why it always shows N / green light. Let's get
into that later. You have multiple issues. One at a time.
--- On Mon, 2/23/09, kiwi <[email protected]>
wrote:
From: kiwi <[email protected]>
Subject: [Nighthawk Lovers] Re: Nighthawk S
starting problem
To: "Nighthawk Motorcycle Lovers!"
<[email protected]>
Date: Monday, February 23, 2009, 1:16 PM
Blasted those tiny holes that allow the gas through when using thechoke with
compressed air and spent 2 hours reinstalling the carbs. Itstill took starting
fluid to get the bike started BUT, not very muchand the choke worked a little.
I'll see how it starts tomorrow whenit is back to winter temperature.Second
problem with this NH is the neutral/gear indicator. It reads Nall the time and
won't show what gear the bike is in. I found a littleblack box under the tail
section that I think is part of the N/gearindicator system. Is there a way to
check it?Third problem should be
simple. The left front turn signal is'bright' when ignition is on but will
not blink when it should. Theothers work as they should. That left one
shines a lot brighter thanthe right front when ignition is on.On Feb 22, 11:11
pm, Dennis Hammerl <[email protected]> wrote:> I will assume your carb clean
was a complete operation. Let's examinehow the choke works. The cable opens
valves that will permit raw fuel to besucked into the motor during cranking.
Now, lets say that works fine.Your plugsshould be wet after cranking for a
short while. Y-N ? The most common cause ofthe plugs being dry after cranking
is the throttle plates being open too far andcausing insufficient vacuum. Same
as opening the throttle while trying to start.When the intake air flow is too
low, no fuel will be drawn in from the chokecircuit. If the plugs are wet,
you're flooding the motor.> We start
here. Additional checks of compression and a leak-down may be inorder.> This
may take time to resolve. Get at it. >> --- On Sun, 2/22/09, Graham Rogers
<[email protected]> wrote:> From: Graham Rogers <[email protected]>> Subject:
[Nighthawk Lovers] Nighthawk S starting problem> To:
[email protected]> Date: Sunday, February 22, 2009, 6:18 PM>> I
have a 1986 Nighthawk S. It ran before I got it but always took > starter
fluid in the air filter to get it going. I pulled the carbs > and thoroughly
cleaned them and used to compressed air in all the > holes. However the bike
still will not start without stater fluid > and even then it takes along time
with the fluid. I noticed that >
using the choke seemed to make no difference at all so, thinking that >
perhaps the choke isn't working at all I removed the carbs again > (they are
terrible to remove) and did what I could toi ensure the > choke was working
right. The mechanism moves as it should and I used > compressed air in the
holes to the where I presume the choke opens. > Now, before I reinstall the
carbs, any suggestions? Could the > problem have been the choke or is there
something else that would > cause the same problem. By the way, once the bike
was warmed up, it > ran fine - just when it's cold I have to use starting
fluid, Graham
--~--~---------~--~----~------------~-------~--~----~
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
-~----------~----~----~----~------~----~------~--~---
