1500 off idle stumble ?????

3441 Views 17 Replies 10 Participants Last post by dizzy, Apr 7, 2013

AJ1500

Discussion Starter · Apr 4, 2013

I hate to be rehashing an old topic BUT with all my research I haven't found an answer to my question

so I have an 88 1500 and it has the dreaded off idle stumble, it is a lot worse after it warms up

my idle is dead on and smooth, no searching or surging, my high RPMs are smooth

but if I sit at a light and go to take off if I don't rev it first it is VERY likely to stall out or jump to high idle rather than being a smooth increase
also if running at a steady speed for a while if I excel strongly it will stumble bad before it catches up and smoothes out
and one last issue which is the worst of all when slowing down to make a turn if I don't keep the idle up it will stall down some while leaned over and have a hard time revving back up to normal

on my choke there is a small distance that when you move it down there is NO resistance at all (I just figured loose or worn cable) then you begin to feel resistance,
so I use the choke to crank the bike when cold, it revs up as expected
moving the choke effects the running as expected except in the small area of no resistance, that appears to have no effect on the idle at all

BUT if once the motor is warm and I close the choke and roll it back down just a little into the area of no resistance all the above problems go away
I sort of found this out by accident recently

so I think it has something to do with the enrichment of the engine
as I understand that is how the choke works, but what I don't get is if the enrichment is being engaged why doesn't it effect the idle
it appears to have NO effect at all on the idle
But it sure cures all those NASTY off idle hesitations

I haven't noticed any adverse effects from running it like this like you would if the ehancment was actually engaged some

so the real question here is WHY does this seem to work and will it cause future issues if I keep doing it

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satan

· #2 · Apr 4, 2013

When was the last time you sync'd and worked an idle-drop idle mixture adjustment... If running the enrichmetn does improve your off-idle sag, then I'd suspect that the richer mix is helping ... this would indicate a too lean of an idle (something that could be discovered by workig a idle-drop mixture setting).

Generally, if the idle drop requires even a half-turn of modification toward the rich (more out after setting than before), and you have no reason to suspect that the prior idle drop wasn't done correctly, then you'll be discovering narrowed fuel passages (dirty low-speed jet and or passage) or a reduction in float height that is leaning your idle mix.

As far as running with the enrichment partially on... It would depend on how much extra fuel you're dropping, and if it's enough to cause dilutions/contamination of oils or fouling of plugs. Since the enrichment stuffis not terribly accurate at controlling fule flow - you may be over rich which could cause the typical over-rich symptoms (either immediate or long term).

get a good sync, set your idle mix, and you may wanna reach to one-step hotter sparkplug to see if you can manage your off-idle stumble without cleaning your carbs.

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DriverRider

· #3 · Apr 4, 2013

AJ1200 said:
I hate to be rehashing an old topic BUT with all my research I haven't found an answer to my question

and one last issue which is the worst of all when slowing down to make a turn if I don't keep the idle up it will stall down some while leaned over and have a hard time revving back up to normal

Some mechanics would raise float height from specs hoping for a richer mixture. Sounds reasonable except when bike is leaned over and then floods engine. Have you ever noticed an idle RPM change when lowering bike to side stand park position prior to shut down?

Straddle bike with engine idling and fully warmed up with side stand down on level ground. With hand and foot off brakes let bike drop on its own weight to side stand position from straight up. Any change in idle indicates float level too high.

Had this issue and if IIRC the float height was .5 or 1mm too high when opened up.

ALEX BERECZKY

· #4 · Apr 4, 2013

Suggestions:
-Adjust the cable to the choke, so that the slack is removed. Also clean/lube the lever at the lower end of the cable, so that the choke operation is reliable, especially reliably-closed.
-Tighten the clamps, that restrain the rubber isolators (between carbs and intake manifold). They may be loose and leaking, affecting the air/fuel mixture.
-Inspect the vacuum line used to set vacuum advance... it's the notorious one with the 90-degree bend that breaks; running from left side of intake manifold, to the ECM on right.

glhonda

· #5 · Apr 4, 2013

Changing the float level, shimming the needles, resetting idle speed only masks the symptoms. The bike didn't run like that new, or they never would have been able to
sell any.
Over a period of time, soft carbon deposits form on the back side of the intake valves.
This carbon absorbs fuel, causing a slight lean condition, giving you your stumble. The fact that the choke improves the condition verifies that it is too lean. Most engines are overly rich at idle for smoothness, so it's not as evident.
You can fatten up the carbs, and do work arounds, but all your doing is sacrificing fuel economy for driveability. For most, that's a fair trade. If you to FIX it, use a chemical cleaner like BG or JB. Use in on the intake side BETWEEN the carbs and the cylinders, to work on the back side of the valves. DON'T put it in the tank.
Chemicals caused the condition, chemicals can resolve it.

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Bellboy40

· #6 · Apr 4, 2013

I think this is the hose Alex is referring to. It is located under the insulator beneath the carbs.

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DriverRider

· #7 · Apr 4, 2013

glhonda said:
Changing the float level, shimming the needles, resetting idle speed only masks the symptoms. The bike didn't run like that new, or they never would have been able to
sell any.

But

This was an 88 and a fair number were produced with problems and not all got the fix back when it was available. The OP has a 25 yo ride with 200k on the clock. You cannot expect an older engine with now small leakages here and there, degradation and wear of components and increased tolerances not to mention our crummy fuel of today to run at exactly the same fuel/air mix when it rolled off the showroom floor with the exact same performance characteristics today. A slight hesitation when new would probably be described as a moderate hesitation by today standards and are no fun to ride. From reading here some original owner buyers that had the fix done admit it was not 100% effective.

Blame all problems on Honda? No.

Some will need finessing to be better than new.

http://www.goldwingfacts.com/1500 Service Bulletins/1500SB2.pdf

glhonda

· #8 · Apr 4, 2013

DriverRider said:
The OP has a 25 yo ride with 200k on the clock.

My mistake, he couldn't possibly have deposits on the valves.

77Pinto

· #9 · Apr 4, 2013

I messed around with "easy" ways to fix the symptoms, but in the long run there were still issues and the only way to REALLY get the carb.s right was to pull them.

The OP seems to be looking for someone to tell him to run with the choke on and all will be well with the world....

BTW: My 88 had 20(something)K when I got it when it was less than 10 years old, and I put up with the off idle thing for WAY TOO LONG. Maybe miles and age have LITTLE to do with the problems that SO many 88s have.

Bill

busdriver

· #10 · Apr 5, 2013

Has the bike always had this problem since you bought it. or is this a recent development?
If recent could be something as simple as a dirty sticking carb slide(s).

AJ1500

Discussion Starter · #11 · Apr 5, 2013

well some good info and suggestions, Thanks to all that have posted so far

No I am not looking to be told if I run the choke all will be good
my question was why does that seem to fix it but not effect my idle, adding enrichment I thought would always have an effect on the idle

the bike has done this since I bought it, in my research long before I bought the 1500 I was aware of the poential of this problem but was willing to buy one anyway
I picked this thing up for a song and had not test drove it

I have no problem tearing into it to fix it, I just don't want to disable it untill I feel sure I know what I'm looking for

So again Thanks for the suggestions, I think I found my answer

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Bellboy40

· #12 · Apr 5, 2013

If you decide to remove the carbs for a thorough cleaning here is a link that will be of great help to you.

http://www.jmartino.me/carb/index.htm

77Pinto

· #13 · Apr 5, 2013

AJ1200 said:
....it sure cures all those NASTY off idle hesitations...

......I haven't noticed any adverse effects from running it like this....

......will it cause future issues if I keep doing it

AJ1200 said:
.....No I am not looking to be told if I run the choke all will be good.....

You had asked if it was safe to keep doing it, not just to do it until you fix the problem. The choke helps minimize a symptom, its not a fix.

AJ1200 said:
....my question was why does that seem to fix it but not effect my idle, adding enrichment I thought would always have an effect on the idle...

It does, but not enough for you to notice without either a very sensitive tachometer, vacuum gauge, or a wide-band O2 sensor.

The early 1500s were too lean coming off idle, with the choke you are adding just tiny amount of fuel at idle that the engine has avalible when you twist the throttle; thats all. You can do similar with the air screws, but its not ideal either (trust me on this one; been there, done....).

Glad you have found info, and plan to dive into the real fix!

My thread: http://www.goldwingfacts.com/forums...-recall-carb-upgrade-parts-trigger-wheel.html

Bill

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OnaWingAndaPrayer

· #14 · Apr 6, 2013

as for the enrichment circuit , consider this . Push the choke lever down and it opens the enrichment circuit . If you only partially use the choke , you add fuel but do not add any airflow to increase RPM . When you fully apply the choke it does advance the idle speed as well as open the enrichment circuit.
Also look on the left side of intake manifold at the center and rear cylinder runners . IF like my 94 , they both have a vacuum line . Its a problem point as the hose tends to crack and leak vacuum .

AJ1500

Discussion Starter · #15 · Apr 7, 2013

just a quick update
I have the covers off as I replaced both cam seals yesterday, left one was leaking bad and right one just enough to see under timing belt gear
the right pully bolt was VERY tight and I ended up having to hit it straight on to help loosen it, I saw the cam move when doing this, how much end to end play should there be in the cams

on the original issue, I inspected all the vacume hoses I could see while the covers are off, looked at the hoses under the flap as well. those almost look as if they have been replaced as they lok different from the rest
I did find a small vacume hose going to the little module on the left side frame rail the was collapsed right where it hooks to the fitting in the block and one line at said module broken loose

not sure what it's for but hoping the cruise as it stopped working recently

it might be a while before I dig into removing the carbs as this is my primary ride but thanks to everyone I will have the info to get it fixed

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DriverRider

· #16 · Apr 7, 2013

AJ1200 said:
the right pully bolt was VERY tight and I ended up having to hit it straight on to help loosen it, I saw the cam move when doing this, how much end to end play should there be in the cams

No more than the left side which didn't take a beating.:?

AJ1500

Discussion Starter · #17 · Apr 7, 2013

:ROFL: I should have thought of that

dizzy

· #18 · Apr 7, 2013

In my experience...88's run really nice with clean carbs, no vacuum leaks and mixture screws richened up from the stock setting. The off idle stumble 88's are known for is hardly noticable. There was a product update campaign for 88's which included richer carb jetting but it wrecked the gas milage...I did at least a few of those. The time limit on Honda buying that repair was done years ago.

However, you mentioned stalling when the bike was leaned over? You might want to bring your VIN to a Honda dealer and have them run it to check for recalls that haven't been done. One recall was for the Bank Angle Sensor (some call them tip over sensors) to be replaced. The symptom is stalling when the bike is leaned over. There is no time limit on recalls so if it hasn't been done, a Honda dealer can still do that at no cost to you.

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