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won't run w/o choke

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won't run w/o choke - 5/9/2008 4:00:47 PM

amacadams

Posts: 9
Joined: 5/9/2008
Status: offline

Hello all, here's my problem:

1991 1000F (Red/Blk). Just pulled the bike out of storage. When I put it away, it wouldn't run without the choke on basically all the way. Even with the choke on, if I gave it any gas it would immediately die.

So I pulled the carbs last week before starting it up again and cleaned them out - I'm not a carb guru at all, but darn if they don't look REAL clean to me. Then again, I'm not a carb guru. ahem. I re-installed everything, started the bike, and it starts right up with full choke and runs fairly smoothly. But I still have the same problem. Start pushing the choke up, revs lower and quickly dies. Give it any gas, even with full choke, and it cuts right out.

I haven't done anything since, b/c I live about 30 minutes away from where I'm keeping the bike. I was thinking of changing the plugs and running some more carb cleaner through it, or seafoam, or something along those lines. Could this be a vacuum issue? Anyone have this problem? Any ideas?

Thanks,
Aaron

Post #: 1

RE: won't run w/o choke - 5/9/2008 8:17:13 PM

MarkR

Posts: 690
Joined: 8/20/2005
From: Gold Coast, Australia
Status: offline

How old is the fuel

(in reply to amacadams)

Post #: 2

RE: won't run w/o choke - 5/9/2008 9:00:27 PM

Shadow1

Posts: 1607
Joined: 12/21/2007
From: Pinetown, South Africa
Status: offline

Good Point, MarkR - I sometimes forget that you guys up north have to pack your babies away for winter. I once had similar issues with a GSX1100, and had the carbs off THREE times before I resolved the problem. The tiniest particle of dirt in the wrong place can be a real pain, but I suspect that you may have leakage around your rubber carb boots. Try tightening the clamps on both ends, and see if it helps.Maybe raise the idle a bit, to see if that helps...
Having to run the bike on a fully rich setting, ie choke on, indicates some sort of mixture problem....There was another post like this a couple of days ago........
Let us know what you find, please.

(in reply to amacadams)

Post #: 3

RE: won't run w/o choke - 5/10/2008 3:08:21 PM

Dean0

Posts: 78
Joined: 9/22/2006
From: Preston, UK
Status: offline

I'm going to suggest a simple check first - Is the idle adjuster up high enough for the bike to run off choke ?

I would try winding it up a turn and see if the bike then runs off choke. You can always lower it if the idle is too high.

Second suggestion is the float heights. if a carb is stored for a time with full float chambers - the springs/needle supports are permenantly under load and bend/weaken slightly.

The new float height would be wrong and allow too much fuel through.

(in reply to Shadow1)

Post #: 4

RE: won't run w/o choke - 5/12/2008 9:20:51 AM

amacadams

Posts: 9
Joined: 5/9/2008
Status: offline

Update:
The gas was old, so I removed and drained the tank. Ran some straight carb cleaner through the bike for a few minutes and played with the idle adjust. Result: seemed to run smoother, and I was able to turn the choke off - ALMOST. Idle dropped, which I was able to compensate for somewhat via idle-adjust, but the engine wouldn't be running as well and would want to die again unless I gave it more choke. Huh.

Checked the plugs - they look good.

Basically ANY throttle and it immediately dies.

So, I'm left thinking that Shadow is right about this being a mixture issue.

Another question: At the petcock there are three hose attachments. 1 is fuel, and one of the other two is vacuum. What should the third be attached to? Also, there are two hoses coming from the carbs that go around the tank (each from its own side), and seem to end at the back of the tank. What are these? Should they be blocked or attached to anything?

Anyways, what do you guys think? What should I try next...I have tomorrow off, so it looks like i'll be pulling it apart again.

(in reply to Dean0)

Post #: 5

RE: won't run w/o choke - 5/12/2008 11:39:06 AM

Shadow1

Posts: 1607
Joined: 12/21/2007
From: Pinetown, South Africa
Status: offline

Here's a link to download the manual. May help you
> http://members.iinet.net.au/~cbr/Honda_CBR1000F_Service_Manual.pdf>
OR
http://myweb.tiscali.co.uk/midlife/images/Honda_CBR1000F_Service_Manual.pdf
Hope it works -

(in reply to amacadams)

Post #: 6

RE: won't run w/o choke - 5/12/2008 2:29:32 PM

idodirt

Posts: 627
Joined: 8/14/2006
From: South Florida, USA
Status: offline

quote:

ORIGINAL: amacadams

Another question: At the petcock there are three hose attachments. 1 is fuel, and one of the other two is vacuum. What should the third be attached to? Also, there are two hoses coming from the carbs that go around the tank (each from its own side), and seem to end at the back of the tank. What are these? Should they be blocked or attached to anything?

The 2 hoses that come from the carbs that wrap around to the rear of the tank are ambient pressure hoses and should not be connected to anything, nor should they be blocked with anything.

_____________________________

On the shore of Lake Okeechobee.

(in reply to amacadams)

Post #: 7

RE: won't run w/o choke - 5/13/2008 6:45:45 AM

paul6585

Posts: 31
Joined: 8/4/2005
Status: offline

To find a possible air leak in carb boot or vacuum line, spray WD40 on boot or vacuum line while engine is running. If idle changes, then you probably have an air leak.
Is air filter clean?

(in reply to idodirt)

Post #: 8

RE: won't run w/o choke -UPDATE 5/26/08- - 5/26/2008 3:34:37 PM

amacadams

Posts: 9
Joined: 5/9/2008
Status: offline

UPDATE:

Pulled carbs apart again. Cleaned out with carb cleaner and compressed air. There's nothing in there now - they are C L E A N. I know i haven't missed anything.

While they were apart I noticed some slight rubber "cracking" on the airbox where it connects to the carbs, so I fixed that with high heat silicone/gasket maker (in case of leaks).

Emptied and cleaned out fuel tank - filled it with a couple gallons of 92.

Air filter is clean (not new, but I do have one on order that should be coming end of the week).

Put in new plugs.

She started right up, as usual.
I played with the idle adjust, as someone suggested, and was able to ALMOST get the choke off and still have idle close to 1000 rpm.
The problem remains the same, however:I can ALMOST get the choke off after it warms up for a few minutes, but i can't give it any gas. RRRRR!!!! Virtually any throttle at all, and it almost seems like it's fighting itself - sort of like a timing issue. Makes it to ~1500 rpm, then she just dies.

I haven't played with the timing at all - she was running fine when initially stored.

Here's a short video:

http://www.youtube.com/watch?v=_NpW0b7ospI

This is so frustrating! Any more ideas, guys??!

-Aaron

_____________________________

1999 Ford Ranger XLT
1991 Honda CBR 1000F
1972 Ford Mustang Mach 1

(in reply to paul6585)

Post #: 9

RE: won't run w/o choke -UPDATE 5/26/08- - 5/26/2008 5:48:29 PM

vl5150

Posts: 39
Joined: 4/9/2008
Status: offline

Dumb question: When you cleaned the carbs, did you actually pull the jets and inspect them?

(in reply to amacadams)

Post #: 10

RE: won't run w/o choke -UPDATE 5/26/08- - 5/26/2008 7:47:01 PM

amacadams

Posts: 9
Joined: 5/9/2008
Status: offline

I'm not a carb expert, so there can be no dumb questions! Anything you guys think it could be I'll check and re-check. I want to get her on the road again and try out the new Metzelers!

I've now pulled the carbs apart three times in the last two weeks... on the positive side i can now disconnect, disassemble, reassemble and connect them fairly quickly...

but I'm beside myself trying to figure out what's wrong, and it's probably some stupid little thing! (i hope!)

Anyways, i've checked out all the jets, floats, etc... i've soaked them in carb cleaner for hours, blown compressed air through them, etc. They're not blocked in any way. The nylon filters aren't clogged. All the circuits seem clear. I do wonder if through storage the floats (or the little metal clips) have bent a little - but I don't know how to check float level (any good how-tos out there?) However, would float level cause what's happening in that video?

_____________________________

1999 Ford Ranger XLT
1991 Honda CBR 1000F
1972 Ford Mustang Mach 1

(in reply to vl5150)

Post #: 11

RE: won't run w/o choke -UPDATE 5/26/08- - 5/26/2008 10:59:34 PM

Aracanth

Posts: 89
Joined: 2/10/2006
From: Aberdeen, N. Scotland
Status: offline

Morning!,
Just read through what you've tried. Silly question, but are you absolutely sure that you are getting enough fuel down to the carbs when she is running? You can suck on the fuel taps vacuum line and see if fuel comes out of the main feed, and I mean RUNS out of there, not a little dribble. When its running, does it "feel" like its running on 4 cylinders, or is that only maybe 3 are running and thats stopping the beast from idling properly? Might be as simple as a dead plug. Do they 'fire' against the engine with them out?

COULD also be a sticking valve, unlikely but you never know.

Ara

(in reply to amacadams)

Post #: 12

RE: won't run w/o choke -UPDATE 5/26/08- - 5/27/2008 5:55:04 AM

vl5150

Posts: 39
Joined: 4/9/2008
Status: offline

I had mine running on 3 cylinders and had to clean the carbs over an over again. They must have narrow galleys in the circuit. I would pull the carbs and remove the mains and pilots (also the vacuum diaphrams up top). Triple check them. Take out the floats by removing the metal pin. The needle valve should come out too. Note how the needle valve attached to the float. Take 2 cans of carb cleaner and using the red tube, get into every hole, orifice, vent, etc. Spray again and again, and again and again.. Run compressed air in all the holes both in the top, but in the float area as well. Spray again. Inspect the needle valve and brass seats.
Since this looks to be a pilot circuit issue, pay careful attention to the tiny hole(s) in front of the butterfly valve. When you spray carb cleaner where the pilot jet goes, you should see cleaner coming out of those tiny holes

Put in the jets and floats/needle valve. Get a metal ruler that measures MM's and to check the float heights. The measurement is taken from the line on the float up to the bottom of the carb body (the flat part where the bowl bolts on). What you're looking for is the point where the needle valve stops moving up and is fully seated. The float will move higher than this so this measurement is tricky. Check this against the bike's spec. Put the carbs back together.

Open the tank and run low pressure air in the tank vent--you should see bubbles.
Drain gas tank and inspect/clean the petcock. Make sure vacuum will open the valve. Use the nipple that faces the rear of the bike for vacuum (ask me how I know this). Inspect the vacuum line-if it has cracks, etc, ditch it.

Start there and see where that gets you. I just had the same issue and I read a post about cleaning, cleaning, cleaning.

Check out this thread from my ZRX buddies: http://zrxoa.org/forums/showthread.php?t=163000

(in reply to Aracanth)

Post #: 13

RE: won't run w/o choke -UPDATE 5/26/08- - 5/27/2008 7:03:14 AM

Shadow1

Posts: 1607
Joined: 12/21/2007
From: Pinetown, South Africa
Status: offline

I'd check the vacuum on the petcock diaphragm to make sure it's not stuck.....first. If no go, then +1 all of the above.....

(in reply to vl5150)

Post #: 14

RE: won't run w/o choke -UPDATE 5/26/08- - 5/27/2008 10:42:59 AM

bigape

Posts: 27
Joined: 3/30/2008
From: Cary, NC, USA
Status: offline

Here is another quick test. Along with my carb stix (for synchronizing), I have a small fuel bottle which hangs from the handlebar while I am tuning. This functions independantly of the motorcycle tank (most mechanics remove the tank when sync'ing the carbs). See if you can get your hands on one. Remove the fuel line from the petcock and attach it to said external fuel source. Then start the engine and see if she'll run and idle without the choke. If it works, then the fuel tank petcock is the problem.

I removed my petcock and cleaned it thoroughly only to find that the valve assembly in it was bad. A replacement petcock solved my fuel delivery problems.

(in reply to Shadow1)

Post #: 15