Author Topic: Light popping/burble on acceleration  (Read 881 times)

Offline Laitch

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Re: Light popping/burble on acceleration
« Reply #25 on: August 31, 2023, 06:08:06 PM »
Darkness warshed over him when he went to the dark side.
That could actually have been a drenching in sheep dip.
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline daveson

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Re: Light popping/burble on acceleration
« Reply #26 on: August 31, 2023, 06:26:07 PM »
Actually I should have said darkness warshed over the dude, without even going to the dark side.
  • Victoria, Australia
  • Current;'85 K100RT~100,000km; four other bricks. Past; 1500 Vulcan, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline Laitch

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Re: Light popping/burble on acceleration
« Reply #27 on: August 31, 2023, 06:30:10 PM »
You're such a stickler for details.  112350   Your prose fully conveyed the salient pointóit's dark in there, wherever it is.  :tinhat2:
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline daveson

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Re: Light popping/burble on acceleration
« Reply #28 on: September 01, 2023, 08:15:08 AM »
I felt like posting the YouTube clip, but I found the will power to resist the urge.
  • Victoria, Australia
  • Current;'85 K100RT~100,000km; four other bricks. Past; 1500 Vulcan, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #29 on: September 04, 2023, 07:55:43 AM »
I installed NGK plugs and wires last night and Iím hoping to take the bike for a spin later today.  My plugs looked great, a nice tan color, but I figured since I couldnít test the stock plugs, I should probably buy some that could be tested.  I did notice a difference when goosing the engine in neutral, with it responding much smoother and faster than before.  I will report back later today.
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Offline Laitch

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Re: Light popping/burble on acceleration
« Reply #30 on: September 04, 2023, 12:00:09 PM »
Did you measure the electrode gap before you installed them? Did you measure the gaps of the plugs you removed?
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #31 on: September 04, 2023, 12:01:07 PM »
I did measure the new plugs and if I recall the old plugs were in spec too.  The old plugs were Bosch. 
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Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #32 on: September 04, 2023, 01:54:46 PM »
Did you measure the electrode gap before you installed them? Did you measure the gaps of the plugs you removed?

Do I need the terminal plugs if Iím using NGK plugs and wires?
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Offline Laitch

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Re: Light popping/burble on acceleration
« Reply #33 on: September 04, 2023, 02:45:02 PM »
It's likely you will need terminal nuts. You can determine that by looking into the opening in the wire that receives the spark plug terminal. Is it the width of a bare terminal screw or the width of a terminal nut?
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #34 on: September 04, 2023, 02:47:01 PM »
Thanks.  It obviously needs the terminal nut.  I also found out that the NGK wires seem to lock on the terminal nut, but in actuality they need a real good push to get that ďpopĒ when the cap seats on the plug.
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Offline Laitch

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Re: Light popping/burble on acceleration
« Reply #35 on: September 04, 2023, 02:48:24 PM »
That is a typical good fit.
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #36 on: September 04, 2023, 11:41:13 PM »
Well, the plugs and plug wires didnít change anything.  Still has the hesitation and popping on acceleration. 

Two things I did find out while fiddling around today. 

When the bike is left on its side stand while idling, it will eventually die.  I never use the side stand, so this is new to me. 

Second, when I pressed the starter button while the bike was running around 1k rpm, it attempted to engage the starter button.  I just recently cleaned the switch, and from my reading it the starter switch runs through the ICU.  The ICU, if I am correct, should. It allow the starter to engage if the rpm is above 770.   

Iíve cleaned the ICU plug with DeOxit and the grounds under the tank.  Is it possible that I may need a new ICU?

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Offline Martin

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Re: Light popping/burble on acceleration
« Reply #37 on: September 05, 2023, 12:53:29 AM »
On a K75 the revs need to be over 1000 RPM otherwise the starter will engage.
Regards Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline daveson

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Re: Light popping/burble on acceleration
« Reply #38 on: September 05, 2023, 01:06:47 AM »
It dies if left on the side stand.

I feel that if there is water in the tank, it might double the amount of water under the pump while on the side stand cause they're both on the left.

This could be another good reason to double check if the replaced fuel filter is partially blocked.

Water in the tank might be difficult to see, especially with fuel circulated and mixed by the pump.
  • Victoria, Australia
  • Current;'85 K100RT~100,000km; four other bricks. Past; 1500 Vulcan, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #39 on: September 05, 2023, 01:22:52 AM »
It dies if left on the side stand.

I feel that if there is water in the tank, it might double the amount of water under the pump while on the side stand cause they're both on the left.

This could be another good reason to double check if the replaced fuel filter is partially blocked.

Water in the tank might be difficult to see, especially with fuel circulated and mixed by the pump.

There is no water in the tank.  I emptied completely, took everything out and cleaned it.  I just filled up today with Chevron 92 and I did take a peak inside with the cap off while it was running to see if I could spot any bubbles or gushing fuel. 

The filter is a BMW one that was quite easy to blow through. 

I feel like it runs great under 3k and that is when the popping starts and the hesitation.  Maybe I need to go over the TB rubbers again and spray some carb cleaner or the like. 

Many moons ago, there was this great group of airheads that would get together here in PDX.  I donít know if any brickhead gatherings in the area. 

I guess Iíll keep chugging along until I figure it out. 
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Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #40 on: September 05, 2023, 01:23:28 AM »
On a K75 the revs need to be over 1000 RPM otherwise the starter will engage.
Regards Martin.

Good to know.  Thanks.
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Offline daveson

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Re: Light popping/burble on acceleration
« Reply #41 on: September 05, 2023, 02:25:34 AM »
One of the other suggestions was to check the fuel pressure, it might be low.

One of the things I'm thinking is does it only happen when the engine is warm? Or does the fuel pressure drop when it happens, like say a hose has a temporary kink, since it seems to be temporary, but dunno how long it lasts before it comes good, or when it comes good.
  • Victoria, Australia
  • Current;'85 K100RT~100,000km; four other bricks. Past; 1500 Vulcan, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #42 on: September 05, 2023, 10:14:12 AM »
One of the other suggestions was to check the fuel pressure, it might be low.

One of the things I'm thinking is does it only happen when the engine is warm? Or does the fuel pressure drop when it happens, like say a hose has a temporary kink, since it seems to be temporary, but dunno how long it lasts before it comes good, or when it comes good.

Iím hoping to get a fuel pressure gauge in the next few days. 

I think I will go back and check the fuel lines, as I just replaced them with regular fuel pressure rated hose. 
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Offline daveson

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Re: Light popping/burble on acceleration
« Reply #43 on: September 05, 2023, 06:37:05 PM »
The original hose has a formed 90 degree bend near the tank, check it out. If that's the problem you might be able to fix it with a spring type thing, If that fixes it, you probably don't need to check the fuel pressure.
  • Victoria, Australia
  • Current;'85 K100RT~100,000km; four other bricks. Past; 1500 Vulcan, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline Laitch

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Re: Light popping/burble on acceleration
« Reply #44 on: September 05, 2023, 09:15:48 PM »
You should be able to borrow fuel pressure gauges at no charge from Advanced, AutoZone or NAPA. If the fuel pressure at the rail is okay, the next step is clear.

Back in Reply #1, Mighty Gryphon asked if you had checked the valve clearances. You didn't respond. It's time to get the materials together to do that; it's an essential task with a newly acquired used Brick because inaccurate clearances and poor throttle balance affect both performance and engine lifespan. Gryphon made a post describing an effective homemade balancing rig. Once it is established that clearance are in spec, you'll need to balance the throttle bodies. Put this off no longer. clearance check Instructions abound. Among them is this one.
                   
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #45 on: September 06, 2023, 11:49:47 PM »
Fuel pressure regulator tested perfectly. 

Throttlebodies have been synced. 

I canít find my feeler gauges, so I decided to order some for k bikes along with some consumables.  Valves were checked at dealer and were within spec 10k miles ago. 

I still feel that the idle drop when on the side stand may have something to do with the main issue. 

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Offline daveson

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Re: Light popping/burble on acceleration
« Reply #46 on: September 07, 2023, 07:39:58 AM »


I think I will go back and check the fuel lines, as I just replaced them with regular fuel pressure rated hose.

Did you use special hose inside the tank suitable for being submersible in fuel, and has this problem occurred some time after you replaced the hose? If not small bits of rubber might be floating around inside the rail and/or the injectors, or along the supply and/or return line.
  • Victoria, Australia
  • Current;'85 K100RT~100,000km; four other bricks. Past; 1500 Vulcan, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #47 on: September 07, 2023, 09:22:24 AM »
Did you use special hose inside the tank suitable for being submersible in fuel, and has this problem occurred some time after you replaced the hose? If not small bits of rubber might be floating around inside the rail and/or the injectors, or along the supply and/or return line.

I only replaced the exterior fuel lines.  I inspected the lines in the tank and they were fine.  There has always been this light surging since I bought the bike.  Iím just trying to track it down as everything else on the bike seems great.
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Offline Laitch

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Re: Light popping/burble on acceleration
« Reply #48 on: September 07, 2023, 11:48:55 AM »
If, as you seem to be indicating, you can induce surging by leaning the Brick onto its side stand, that is BIG news. Replication is a key element of proving an hypothesis. All you need to do is consider which elements could be affected by gravity, or G-forces (as in the case of occurrence at speed). Pick one after anotherówiring, hoses, switches, for exampleóand wiggle or move them attempting to cause an effect while the engine is running in neutral on its center stand.

The pedestrian element of a defective fuel pressure regulator should be resolved. Verification of work claimed to have been done, such as valve clearance measurement, should be undertaken. Many owners seem to have been disappointed by BMW service centers.

Obstruction in the air snorkel should be investigated. Another element to consider is the air flow meter. Is there obstruction in its intake; is its air temperature sensor dirtyóthere is a dedicated cleaner for that; is its electrical connection compromised, does the movement of its internal vane appear to drag or is the movement unregulated?

Diagnosing an ailing Brick should be an orderly process of system-by-system investigation. Preconceptions and assumptions made without sufficient depth of experience can stall resolution. It can be tedious but it should be focused. Appearances can be deceiving.
  • Along the Ridley in Vermont.
  • 1995 K75 86,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline Lbxpdx

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Re: Light popping/burble on acceleration
« Reply #49 on: September 07, 2023, 12:19:55 PM »
Can I use Air Mass Meter cleaner on the air temp sensor? 

Iím wondering if the barn door moves when the bike is on its side. 

My school day just started, so Iíll be checking stuff when I get home tonight.  I think Iím going to pull the pump and lines from the tank and check them again too.

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