Help me diagnose my hesitation (video evidence included)


Information and questions on GL1500 Goldwings (1988-2000)
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LeYak
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Help me diagnose my hesitation (video evidence included)

Post by LeYak »



Hi all,

first of all, since this is my first post on this forum, let me say that I have made great use of the DIY articles and collective wisdom on this site since I aquired my first Goldwing in July. So a collective thank you to you all.
So I bought a 1994 GL1500 Aspencade in July, an American import in the Netherlands with 43000 miles on the clock. Hadn't been ridden much if at all the past years, and the PO obviously wasn't the most meticulous type (how else to explain the presence of what seems to be blue mouse poison in the airbox to accompany the newspaper bits, i.e. mouse nest, under the intake manifold? :shock: , or the 19y old tires?). But it ran on a bit of choke, was relatively cheap and low-mileage, and looked like it could use some serious TLC. And since COVID had foiled further vacation plans, why not, right? This is it after 8 hours of cleaning, most of it spent on surface rust:


I have already done quite a bit of overhaul, including the following:
- New air filters (main, sub, cc)
- New coolant, oil and brake/clutch fluid
- Carbs cleaned (except for the pilot screws since I lacked the d-shaped tool :? )
- Replaced carb boots and many vac lines
- Timing belts replaced
- New spark plugs
- New tires
- New brake pads
- New front wheel bearings
- And other small niggles

The reason for getting in the carbs was a surging idle, one leaner and one richer cylinder bank based on spark plug color, and an obvious vacuum leak. Turned out to be one of the carb boots being loose. So replaced those and like 20 vac lines, all the ones in blue here:


Reinstalled the cleaned carbs and airbox with new filter, synched the carbs and the surging idle is gone :D

However, and here is where we come to the problem, the bike runs fine at high rpm's but below 3000-3500 it still has a form of the dreaded hesitation/flat spot. Sometimes a stumble, sometimes a weird sort of low/no-torque fluttering depending on rpm's and, I guess, its current mood. Mind you, this is only under load, it does not hesitate when in neutral on the center stand! Here is what the hesitation looks like:

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I have scoured the interwebz for the right explanation, but I haven't found it yet. I have already done some of the often proposed solutions: timing belts, plugs, cleaned carbs, vacuum lines,... so I thought I'd do some more telling diagnostics.

- I checked the operation of the slide valves and accelarator pump, and they seem to be working as intended. Correct me if I'm wrong here:
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You can also hear that the bike has no problems revving in neutral.

- I thought it might be an ignition problem, so I checked to see if all spark plugs sparked by slowly removing the leads and all of them arced, and the further removal caused irregular running of the engine.

- I checked all the plugs again. They now look similar on both sides (so that left side vacuum leak no longer leans out one bank over the other), but they seem to indicate an overall lean mixture (white tips). They all look something like this:




Keep in mind that these plugs are about 150 miles old.

- I tested whether the mixture was lean or rich by blocking off the air intake at the airbox. rpm's increased when I blocked 80-85% of the intake opening. Bike immediately stalled when covered fully. See here:
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This seems to indicate a) that the bike is running lean, and b) that there are no other huge air leaks.

However, I'm at a bit of a loss as to what to conclude from all of this, and what my next steps should be. And so I turn to you, Goldwing guru's. Lend me your collective wits and insights, and we'll get it back to proper health (I hope)!



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bellboy40
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Re: Help me diagnose my hesitation (video evidence included)

Post by bellboy40 »

Well, sad to say, but it could be those pesky pilot screws you couldn't get out to clean. It appears the accelerator pump is working right, which was my first thought.

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Re: Help me diagnose my hesitation (video evidence included)

Post by bellboy40 »

Oh btw, that is a beautiful bike. Love the color.

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Re: Help me diagnose my hesitation (video evidence included)

Post by ct1500 »

Your RPM went up about 200 with the partial intake air block so it is running very lean. The lean running condition needs to be diagnosed whether it is one, the other or both engine banks which are causing the problem. Doing a sync on an engine with running problems is bass ackwards. :)
Carb cleaning and no parts only goes as far as the doer knows. Replace parts for the chance of a more successful outcome next time. :idea:
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LeYak
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Re: Help me diagnose my hesitation (video evidence included)

Post by LeYak »

bellboy40 wrote:
Wed Sep 09, 2020 6:45 pm
Well, sad to say, but it could be those pesky pilot screws you couldn't get out to clean. It appears the accelerator pump is working right, which was my first thought.
Yup, thought it was just the vacuum leak that caused the surging at the time so left them well alone. But now that I think about it, I of course have no idea if they've been fiddled with to try and solve the issue in the past. I ordered a d-shaped bit so I should be able to check next week. I'll have to get the carbs back out if I don't want to wait that long :geek:
ct1500 wrote:
Wed Sep 09, 2020 7:14 pm
Your RPM went up about 200 with the partial intake air block so it is running very lean. The lean running condition needs to be diagnosed whether it is one, the other or both engine banks which are causing the problem. Doing a sync on an engine with running problems is bass ackwards.
Carb cleaning and no parts only goes as far as the doer knows. Replace parts for the chance of a more successful outcome next time.
Ok, thanks for the confirmation that this indeed means a significant lean condition, so that is a piece of diagnostic info I can definitely work with! And even if it is not the cause of the stumble, it needs to be fixed anyway!
I did the sync because some people seemed to think that could cure the issue. Obviously, it hasn't. Did make it idle a lot better though :lol:
Two questions:
1) How would I go about testing if one bank is causing the issue? I'd think looking at the plugs, but can't see any real difference there. Is there a home garage method to do this (manifold temps or something)?
2) What carb parts do you mean? I've replaced most gaskets and O-rings, except for those on the pilot screw (obvs) and those on the accelarator pump (because they weren't in my Honda kit). The latter did get a new diaphragm and seems to work well, and would not be the cause of a lean condition at idle, right?

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LeYak
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Re: Help me diagnose my hesitation (video evidence included)

Post by LeYak »

Okay, okay... baby steps.
Took the carbs out since I'd wanna check if the passages for the pilot screws were clear anyway and how many turns the pilot screws were out. My d-shaped bit arrived today so thought I'd take the latter out. Well, let's just say that everyday is abit of an adventure...

The right one came out without much of an issue. The left one though, that's a different story. The screaws had been touched before, as edges were not very sharp anymore, but could still get grip. Nevertheless, a bit of pressure and before I knew it, the head was 'rounded' :( . So what to do (aside from continue to soak in penetrating oil)? Tried the 'dremel a groove into it' method but just ended up breaking the resulting 'tabs' without effort. So, continue to soak, take a flat screwdriver bit, sharpen it into a miniature chisel and hammertime! So I drove it into the pilot screw, put a lot of pressure on it and twisted. It finally gave after 20 minutes of intermittant hammering and internal profanities. Result:


You can tell it took a bit of persuasion..
But, luckily I was able to clean up the threads with the other pilot screw and I'll be ordereing a new set later today. Also, I could make sure that the internal passages were clear, so that's another plus.
So that's another step in the direction of a well-running bike.

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Re: Help me diagnose my hesitation (video evidence included)

Post by FM-USA »

.
Being soft metal I'd file that head to a HEX. Take maybe 20-30 mins.
;)
.


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LeYak
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Re: Help me diagnose my hesitation (video evidence included)

Post by LeYak »

FM-USA wrote:
Sat Sep 12, 2020 12:32 pm
Being soft metal I'd file that head to a HEX. Take maybe 20-30 mins.
.
DAT PHOTOSHOP THOUGH :lol:
I hadn't even considered reusing it by recreating a different head. Still, I think I'll just order new ones. I have no idea if I buggered them up in ways I don't yet know about, and don't feel like finding out :roll: It's true that they are not cheap, but they are a darn bit cheaper than the whole carbs my worrying brain was making me imagine ordering!

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Re: Help me diagnose my hesitation (video evidence included)

Post by FM-USA »

.
PHOTOSHOPPED? NO WAY!!!
Microsoft Bitmap, sure.
I've resized many a hex heads by filing from Metric or British to SAE and that's usually due to the heads getting BOOG'd up.

.

.
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ct1500
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Re: Help me diagnose my hesitation (video evidence included)

Post by ct1500 »

ct1500 wrote:
Wed Sep 09, 2020 7:14 pm
Replace parts for the chance of a more successful outcome next time. :idea:
Pilot jet replacement strongly recommended.
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754
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Re: Help me diagnose my hesitation (video evidence included)

Post by 754 »

I know that sound and chased that exact same problem for months! My wing had no low end torque until you got rolling, launching from a stop was almost impossible. I finally found the problem to be the electric fuel pump not working well enough to get the fuel up hill to the carbs. That was after doing everything that you have up to this point. Now that opens up a whole other can of worms. After the failure of several aftermarket fuel pumps from Carter, I ended up with picking up an Airtex fuel pump and have not had a single problem since.

If you search here for fuel pump threads you will find several from me.

Hope this provides so insight for you.

Travis
1992 Goldwing Gl1500 Interstate

1978 CB750 Supersport

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LeYak
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Re: Help me diagnose my hesitation (video evidence included)

Post by LeYak »

754 wrote:
Sun Sep 13, 2020 8:30 pm
I finally found the problem to be the electric fuel pump not working well enough to get the fuel up hill to the carbs. That was after doing everything that you have up to this point. Now that opens up a whole other can of worms.
Thank, Travis! I'll add a fuel pump flow test to the list of things that need doing. Question: did it make a difference for you whether the bike was hot or not?

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Re: Help me diagnose my hesitation (video evidence included)

Post by newday777 »

Welcome to the forum LeYak
The bike cleaned up very nicely.

Reading through your posts in this, it sounds like you didn't mention your process of cleaning the carbs. You need to fully field strip the carbs of all parts and o-rings and then either do an ultrasonic cleaning or boil cleaning to get rid of the hardened old gas in the tiny fuel ports in the carbs along with the jets(all brass parts are cleanable and reuseable, that is unless buggered by someone.....).
Did you closely inspect the rubber of the vacuum slides and accelerator pump for tiny cracks? Look for cracks holding to light. Replace if cracked or deformed/hardened. These are key in these carbs.
Yes fuel pump flow test is necessary. As is inspection of the tank while the pump is out for rust and debris. Rust can be mitigated from the tank, in place, by electrolysis cleaning.

This is a good carb overhaul tutorial

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

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newday777
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Re: Help me diagnose my hesitation (video evidence included)

Post by newday777 »

The other possible cause of the fluttering idle is a leaking vacuum petcock that can be rebuilt. You can do a vacuum leak down test or pull it apart and closely inspect for cracks in the rubber.
The kit here in the states is @ $20 USD.

Did you put on a new fuel filter?

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754
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Re: Help me diagnose my hesitation (video evidence included)

Post by 754 »

LeYak wrote:
Mon Sep 14, 2020 3:35 am
754 wrote:
Sun Sep 13, 2020 8:30 pm
I finally found the problem to be the electric fuel pump not working well enough to get the fuel up hill to the carbs. That was after doing everything that you have up to this point. Now that opens up a whole other can of worms.
Thank, Travis! I'll add a fuel pump flow test to the list of things that need doing. Question: did it make a difference for you whether the bike was hot or not?
It made no difference if the bike was hot or cold. There is no real flow or pressure information for these bikes. What I noticed was there seemed to be just enough flow to get to the carbs and keep them filled but, there was just not enough pressure behind that flow.
1992 Goldwing Gl1500 Interstate

1978 CB750 Supersport

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Re: Help me diagnose my hesitation (video evidence included)

Post by LeYak »

newday777 wrote:
Mon Sep 14, 2020 7:26 am
Welcome to the forum LeYak
The bike cleaned up very nicely.

Reading through your posts in this, it sounds like you didn't mention your process of cleaning the carbs. You need to fully field strip the carbs of all parts and o-rings and then either do an ultrasonic cleaning or boil cleaning to get rid of the hardened old gas in the tiny fuel ports in the carbs along with the jets(all brass parts are cleanable and reuseable, that is unless buggered by someone.....).
Did you closely inspect the rubber of the vacuum slides and accelerator pump for tiny cracks? Look for cracks holding to light. Replace if cracked or deformed/hardened. These are key in these carbs.
Yes fuel pump flow test is necessary. As is inspection of the tank while the pump is out for rust and debris. Rust can be mitigated from the tank, in place, by electrolysis cleaning.

This is a good carb overhaul tutorial

http://www.jmartino.me/carb/index.htm
Brass parts buggered by someone? Who could you possibly mean :lol: ?
You're right, I did not specify how I cleaned the carbs. I'm afraid it was the old carb cleaner (lots of it) and compressed air method. I have to say though that the carbs were surprisingly clean inside. No blocked jets as far as I could see either, and definitely not after the cleaning. I did check the slide valve diaphragms for cracks/holes but found none. It is of course possible that I made some during reassembly but then I'd have to have been pretty symmetrical about it given my current slide operation :p The accelarator pump got a whole new diaphragm and it does work. I also placed a new fuel filter. It is in the same orientation as the last one, and I don't suspect it to be the cause o f the issue since the Wing had the hesitation before that change as well.

So, as you and Travis indicated, I did a fuel pump flow test. Two outcomes: the fuel pump does not prime/pump for a few seconds on turning the ignigiotn. I thought it should, or am I mistaken here? The flow of the pump itself was good: an estimated 1200cc/min, which is well above the 640cc minimum that Honda prescribes. I did hook the pump straight to the battery to test it though, so I only know that the pump works, and not if there is a problem with the ECM/bank angle sensor/other shenanigans in that system. I can't measure the voltage it gets while running yet, because the carbs are still off while waiting for the replacement pilot screw, but it does get about 10v while cranking.

I have a vacuum gauge on the way, so I can soon test the petcock and the solenoid valves on the right of the bike, and maybe the Air shot valve too.

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754
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Re: Help me diagnose my hesitation (video evidence included)

Post by 754 »

There's the catch that caught me off guard. My old original fuel pump had enough flow to barely get by on but, there was just not enough pressure behind it especially since it has to be pumped up hill against gravity. If I remember right per the factory manual (which I have a copy of) my pump had the right amount of flow but, no numbers are given for pressure. I swapped the pump based on those findings and it was a different machine after that.

I can't say if this is indeed what the problem you're having but the sounds and symptoms seem to line up with what I had going on.

Travis
1992 Goldwing Gl1500 Interstate

1978 CB750 Supersport

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Re: Help me diagnose my hesitation (video evidence included)

Post by bigsteveswing »

the fuel pump does not prime/pump for a few seconds on turning the ignigiotn. I thought it should, or am I mistaken here?
Someone will verify this but I believe the fuel pump only "primed" on ignition in the 80's models, after that the fuel pump is controlled by the ECU and only pumps when cranking/running.
Big Steve
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Re: Help me diagnose my hesitation (video evidence included)

Post by LeYak »

Thanks everyone for thinking along here!!
Okay, my vacuum gauge arrived just before dark, so went ahead for some quick tests (don't have power in my rented garage). This is what I did:

- Tested fuel pump flow with the end of the first fuel hose as high up as I could get it (above the fuel filler cap). Basically the same result, so around 1000 cc/min flow. I do have to say that the tank is like 80-90% full. Does that colour my results? Bike has the problem whether the tank is full or not though..
- Put 200mm vac on the petcock, which it held. So petcock diaphragm is intact.
- I then put the container at the fuel line that goes from the petcock to the carb and put the same 200mm vac on the petcock. Powered the pump and still got something like 1000cc/min of flow.
- I then released the vacuum from the petcock and powered the pump. No fuel released.

So seems like both the fuel pump (I guess, or am I still being too generous towards these results? Travis got me worried now :p) and the petcock do what they are supposed to.

The only thing I could test with the air jet solenoid valves is whether they held the 400mm vacuum on the lower opening. They did.
bigsteveswing wrote:
Tue Sep 15, 2020 1:01 pm
Someone will verify this but I believe the fuel pump only "primed" on ignition in the 80's models, after that the fuel pump is controlled by the ECU and only pumps when cranking/running.
That is reassuring!

Outside of putting the carbs back in and seeing if the reset pilot screws have the desired effect:
- What are the things that I need to test before putting the carbs back (e.g., PAIR valve?)
- I do sometimes get pressure build up in the tank, even if the bike is just in the garage. Does this indicate possible trouble with the gas cap?
- Can the air shot system cause a vacuum leak that can cause this? Or does that only affect the exhaust side of things?

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Re: Help me diagnose my hesitation (video evidence included)

Post by wingdings »

Hi - There saw your post there !! - Before you tear anymore into your bike there - Please may i suggest you watch this vid there fella !! ?? .

It explains in full the induction systems on your wing there and how each system is linked to the other and how the vac line colour coding works as well too - A fact that is often missed out in a lot of vids i seen on youtube over the years .

IF one part of your induction system is down it can cause trouble in other parts by understanding how the whole system works can help get to the root of the problem more faster and save a lot of time too !! .

Hear is the vid to watch -



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If you still feel / need that you want to tear down your bike then watch these vids before you do !!



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Best rebuild carb kit on the market is - this - https://www.randakks.com/randakks-own-g ... ing%2F1989

Also check out there web site too !! - https://www.randakks.com/motorcycles/Ho ... odels/1989

Hope this helps :D :D :D :D :D :D

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newday777
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1975 CB750 K5 Planet Blue 7,800 miles

1976 CB750 K6 Anterris Red 25,000 miles

Past rides
1999A Restored from PO neglect & sold at 19,000 miles

1999SE Totaled by cager at 105,000 miles

Re: Help me diagnose my hesitation (video evidence included)

Post by newday777 »

Wingdings
I sure do miss the old gwfacts forum and it was a pleasure listening to Steve again in that video. I dropped that forum about 6 months after the m c . com took it over and screwed the pooch.

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Re: Help me diagnose my hesitation (video evidence included)

Post by ct1500 »

LeYak wrote:
Thu Sep 10, 2020 1:37 am
Ok, thanks for the confirmation that this indeed means a significant lean condition, so that is a piece of diagnostic info I can definitely work with! And even if it is not the cause of the stumble, it needs to be fixed anyway!
I did the sync because some people seemed to think that could cure the issue. Obviously, it hasn't. Did make it idle a lot better though :lol:
Two questions:
1) How would I go about testing if one bank is causing the issue? I'd think looking at the plugs, but can't see any real difference there. Is there a home garage method to do this (manifold temps or something)?
2) What carb parts do you mean? I've replaced most gaskets and O-rings, except for those on the pilot screw (obvs) and those on the accelarator pump (because they weren't in my Honda kit). The latter did get a new diaphragm and seems to work well, and would not be the cause of a lean condition at idle, right?
Your ride did a good deal of inactivity as you wrote so the pilot jets are more than likely partially plugged with cement like residue which NO amount of carb cleaner and compressed air will remove. If both jets (banks) were equally plugged a sync would not have much of an affect on its' running. I would be leaning towards one bank being the major offender but still replace both pilot jets. When using sync gauges you are measuring the amount of intake manifold vacuum that the engine can produce which is dependent on compression quality, ignition quality and fuel mixture quality. Any problem with one or the other of the preceding will show up as reduced manifold vacuum and when adjusting sync screws you are dialing the weak bank down and opening the predominate bank which gives the illusion of running better by masking a problem. If no one had previously messed with the sync screws furthering an incorrectness, I would bet you turned the screw at least a half-turn to equalize the gauges? Your normal running engine would never need more than an eighth or a quarter turn at most to bring back into spec. :)
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Re: Help me diagnose my hesitation (video evidence included)

Post by LeYak »

Thanks Wingdings, those are some valuable sources. Had come across most of those already on my search for info, but the Honda one I only discovered day before yesterday, actually. It has been really helpful, generally speaking, although the actual links between the systems remain a bit vague to me.
If all my testing and vacuum-setting and everything fails, I might indeed need some extra parts, as CT1500 clearly leading me towards.

CT1500, I did have to adjust the sync screw quite a bit the first time, but that was when I had the carb boot leak on the left side (so little surprise). I can't recall whether the second sync after the replacement of vac hoses and boots got it back to a similar position. I just put the carbs back on to see how the situation has evolved with the new pilot screw (not screws, because my stupid *ss thought a 'set' was two screws rather than one screw, spring, etc. when I ordered it).
So, now that the carbs are on anyway, next step is to install the air box and go for a spin, see if it is any better. BTW, if carb cleaner and and compressed air won't restore the jets, I'm assuming no amount of something like seafoam will either, right? I set the pilot screws at 2.5 turns out, so already half a turn more rich than they are supposed to be. I'll also double check again for vacuum leaks. With all the fussing around, I may as well have made a new one :roll: .
Then, before I take the carbs off again, I'll test the Air jet valves, since they are the main systems for leaning the mixture. If those pass the test, I guess it's back into the carbs again, and for an ultrasonic clean this time, and new pilot jets (which are luckily still available and not prohibitively expensive).

For a while, I was considering whether this could be an ignition thing, but then I should not have lean-looking plugs, right?

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newday777
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Re: Help me diagnose my hesitation (video evidence included)

Post by newday777 »

LeYak wrote:
Wed Sep 16, 2020 4:06 pm
Thanks Wingdings, those are some valuable sources. Had come across most of those already on my search for info, but the Honda one I only discovered day before yesterday, actually. It has been really helpful, generally speaking, although the actual links between the systems remain a bit vague to me.
If all my testing and vacuum-setting and everything fails, I might indeed need some extra parts, as CT1500 clearly leading me towards.

CT1500, I did have to adjust the sync screw quite a bit the first time, but that was when I had the carb boot leak on the left side (so little surprise). I can't recall whether the second sync after the replacement of vac hoses and boots got it back to a similar position. I just put the carbs back on to see how the situation has evolved with the new pilot screw (not screws, because my stupid *ss thought a 'set' was two screws rather than one screw, spring, etc. when I ordered it).
So, now that the carbs are on anyway, next step is to install the air box and go for a spin, see if it is any better. BTW, if carb cleaner and and compressed air won't restore the jets, I'm assuming no amount of something like seafoam will either, right? I set the pilot screws at 2.5 turns out, so already half a turn more rich than they are supposed to be. I'll also double check again for vacuum leaks. With all the fussing around, I may as well have made a new one :roll: .
Then, before I take the carbs off again, I'll test the Air jet valves, since they are the main systems for leaning the mixture. If those pass the test, I guess it's back into the carbs again, and for an ultrasonic clean this time, and new pilot jets (which are luckily still available and not prohibitively expensive).

For a while, I was considering whether this could be an ignition thing, but then I should not have lean-looking plugs, right?
You are still trying to do it without a good cleaning of your carbs...and no synchronize before riding??? Uffdah....

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LeYak
Posts: 17
Joined: Wed Sep 09, 2020 1:12 pm
Location: Nederland
Motorcycle: 1994 GL1500 Aspencade, 1995 VFR750, 2013 Honda MSX125, 2013 Triumph Bonneville

Re: Help me diagnose my hesitation (video evidence included)

Post by LeYak »

newday777 wrote:
Wed Sep 16, 2020 4:18 pm
You are still trying to do it without a good cleaning of your carbs...and no synchronize before riding??? Uffdah....
Yeah, I guess looking back I should/would have done a better job on the carbs the first time around. I did take my time and a lot of effort to try and get them as clean as I could with the means that I had available at the time, but apparently my impatience was not rewarded :lol: .
I'm well aware now (in part thanks to the learning process that I am going through by trying to parce and prioritise all your suggestions) that the ultrasonic cleaning is almost certainly in my near future. But basically, I wanted to know what effect this most recent round of interventions has had. Likely, very little. But given the state of the pilot screws it was possible that they were at least partially to blame for this.
So, while the carbs are on anyway, might as well perform those little diagnostics before tearing into the carbs again (which, I'll admit, I'm not looking forward to), and more thoroughly this time. And as far as syncing is concerned, I'm afraid I am not yet the proud owner of a set of gauges, so I'd have to wait for one of my buddies to have theirs available. So might not be worth it for this short test ride. If there is no difference to before, at least I'll know that it wasn't the pilot screws.



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