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Author Topic: K75 neglected for two years  (Read 17701 times)

Offline Rokah

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K75 neglected for two years
« on: October 14, 2019, 06:46:11 AM »
Hi, I've been gifted with a '90 K75 that doesn't start. I don't know much about it, except that one day the bike stopped and the owner never bothered to fix it. It's been two years since that...

General state: Bad. broken foot rest plates (PNs 46711457234 & 46711454485).  Bent back brake foot lever. Rusted forks. Rusted gearbox oil plug (07119919143). Broken headlight glass. Bent front brake lever & handlebar. Cracked vacuum plugs (13547694924)

Rust in the battery strap (and installed incorrectly): PN 61211459044

Sulfate in battery holder and rusted Vibration dampers (PN61211233028 )

Petrol tank installed incorrectly, missing (PN 16112309163) vibration dampers and missing retention clips PN07129934336

Battery: around 5. (The clock is still running though)

Brakes. Front brake works, back brake doesn't. The reservoir is empty

Coolant level: low

Oil level: On the lowside but still has some.

Spark plugs: horrible condition, they had screw terminals and I believe this bike had a solid terminals (Bosch X5DC or NGK D7EA)

Fuses: all OK

The goal is to make it start before doing anything else; I have the feeling the last guy who worked on this bike didn't have a clue on what he was doing.
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  • Madrid
  • K75

Offline Rokah

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Re: K75 neglected for two years
« Reply #1 on: October 14, 2019, 06:46:31 AM »
I've purchased a new battery (EXIDE GEL 12V 19AH GEL12-19) and new spark plugs. they have been tested by connecting them to the HV leads and grounding them to the chassis. they all make a blue spark. Injectors have been removed from the throttle bodies and they all spit petrol. The bike still won't start

However, it now cranks with force and Injectors spit fuel

Bottom line: electrical systems seems in top condition and grounding of the battery looks ok.

I think the next step I will take is to remove all fuel in the fuel lines/injector rail.

What do you think I should test next? Fuel pressure or compression? Should I go directly for the compression test?
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  • Madrid
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Offline daveson

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Re: K75 neglected for two years
« Reply #2 on: October 14, 2019, 08:08:43 AM »
Fix all these faults you have found, especially the vacuum leaks. Put a bit of oil in the cylinders to improve sealing. Give it a service.
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  • Victoria, Australia
  • Current; '85 K100RT~100,000km; four other bricks. Past; Vulcan 1500, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline Rokah

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Re: K75 neglected for two years
« Reply #3 on: October 14, 2019, 09:00:57 AM »
Quote from: daveson on October 14, 2019, 08:08:43 AM
Fix all these faults you have found, especially the vacuum leaks. Put a bit of oil in the cylinders to improve sealing. Give it a service.
Will do!

Is this a regular cranking noise?

https://photos.app.goo.gl/ikKFshWSoBtZCKnE7
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Offline Laitch

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Re: K75 neglected for two years
« Reply #4 on: October 14, 2019, 09:25:41 AM »
Quote from: Rokah on October 14, 2019, 06:46:31 AM
Is this a regular cranking noise? Should I go directly for the compression test?
The sound it makes during starting is not unusual. Limit the duration to five seconds. Disconnect the battery or connect it to a tender when you aren't working on the moto.

A compression test is uncomplicated. Do it. Check each cylinder with the throttle wide open. After the first reading of a cylinder, repeat after spraying some oil into the cylinder to see if that raises its value significantly.

Top up the coolant. Change the oil and filter. The fuel tank should be cleaned. The fuel filter should be replaced. The tank interior fuel lines should be replaced with new 30R10 lines. The valve clearances should be checked and adjusted if necessary. The new spark plugs' gaps should have been checked before installation. The air intake and filter should be checked for restrictions; the muffler outlet should be checked for restriction. The z-tube crankcase-to-airbox connection should be checked that it isn't severed.

After doing all that, try starting it.
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  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles
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Offline K1300S

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Re: K75 neglected for two years
« Reply #5 on: October 14, 2019, 11:30:38 AM »
exactly what he said....perfect pre-start checklist.
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Project Thread "K75s Midlife Refresh"
http://www.motobrick.com/index.php/topic,7810.0.html

Offline Soggz

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Re: K75 neglected for two years
« Reply #6 on: October 14, 2019, 12:17:20 PM »
Good Luck. Mine was neglected since 2008.Getting there though.
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  • Down in Selwood Forest
  • 1986 K75C, 1982 Honda CX500EC Eurostreetbrat
One More Of These,One Less Of Those...

Offline Rokah

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Re: K75 neglected for two years
« Reply #7 on: October 18, 2019, 12:46:11 PM »
Hi everyone! I followed some of Laitch's advice but i have bad news

Spark Plugs were set somewhere around 0,6&0,65

These are the compression tests I did:


TestCylinder 1    Cylinder 2    Cylinder 3   
Without adding oil75 PSI0 PSI150 PSI
Adding 5cc of oil to each cyl100 PSI0 PSI160 PSI

As you can see, cylinder #2 is dead, and cylinder #1 is low on compression.

regarding the valves I measured the following clearances:

TestCylinder 1    Cylinder 2    Cylinder 3
Inlet0.15-0.200.15-0.200.15-0.20
Exhaust     0.20-0.250.25-0.300.15-0.20

As far as I understand I have to change the shims on the exhausts valves of cylinders #1 and #3

I am thinking I will have to dismantle the head of the engine and check the condition of the head gasket, hopefully my its not the piston rings.

What would you do?


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Offline Laitch

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Re: K75 neglected for two years
« Reply #8 on: October 18, 2019, 01:10:27 PM »
Quote from: Rokah on October 18, 2019, 12:46:11 PM
TestCylinder 1    Cylinder 2    Cylinder 3
Inlet0.15-0.200.15-0.200.15-0.20
Exhaust     0.20-0.250.25-0.300.15-0.20
What would you do?
I don't understand your measurement results. There should be one value for each valve, not a spread of values. Because these figures don't make sense, I wonder if your compression technique might be flawed also

Explain exactly how you tested the compression and exactly what type of tool you used to perform the test.
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  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline Rokah

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Re: K75 neglected for two years
« Reply #9 on: October 18, 2019, 01:30:47 PM »
Sorry I didn't explain. My gauges go in 0.05mm increments, the first value I was able to fit and the second I wasn't, therefore I know the gap must rely somewhere between the two values.

Compression I measured using this https://www.amazon.es/gp/product/B074CT56FF/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1. Removed all the sparkplugs, and then fitted the gauged and cranked the engine with the throttle open until the gauge reached a maximum. Then, repeated for the rest of the cylinders
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Offline Laitch

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Re: K75 neglected for two years
« Reply #10 on: October 18, 2019, 01:57:09 PM »
OK. All the intake valves are good. #1 and #3 exhaust valves need adjustment.

You need to do a leak-down test if you don't have a camera like the one in the attached video that can look around via the spark plug hole. These cameras are surprisingly inexpensive. They are called borescopes. #2 and #1 might have severely damaged valves and/or valve
seats.
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  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline Rokah

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Re: K75 neglected for two years
« Reply #11 on: October 18, 2019, 02:21:01 PM »
Do you think its worth testing? I mean, i know there must be something wrong with the valves. I might as well just disassemble  the engine head and take a look with my own eyes and fix it while its open. Don't you think?

Thanks for the help!
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Offline The Mighty Gryphon

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Re: K75 neglected for two years
« Reply #12 on: October 18, 2019, 02:26:36 PM »
I'm guessing that you have some burnt exhaust valves.

If it were mine, I'd pull the head and take a good look.  If there's damage, I'd be looking for a used head at ebay and a new head gasket.
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  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline Laitch

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Re: K75 neglected for two years
« Reply #13 on: October 18, 2019, 02:51:28 PM »
Quote from: The Mighty Gryphon on October 18, 2019, 02:26:36 PM
I'm guessing that you have some burnt exhaust valves.

If it were mine, I'd pull the head and take a good look.  If there's damage, I'd be looking for a used head at ebay and a new head gasket.
I agree. The odd part is valve clearance is good on the worst cylinder. There could be broken valve springs in the mix.

Take your time. Use plenty of heat, penetrant and impact on the head bolts before attempting to loosen them.
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  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline Rokah

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Re: K75 neglected for two years
« Reply #14 on: October 18, 2019, 03:40:27 PM »
Quote from: Laitch on October 18, 2019, 02:51:28 PM
The odd part is valve clearance is good on the worst cylinder.

yuuuuuup that I find weird as well! I'll get back with updates!
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Offline The Mighty Gryphon

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Re: K75 neglected for two years
« Reply #15 on: October 18, 2019, 04:06:54 PM »
Make very sure you have a new tight fitting Torx wrench of the proper size to remove the head bolts. There are two types of Torx wrench, regular and heavy.  Later model bikes use the heavy.   The head bolts have a lot of torque on them, and the heads are easy to strip out. 

You don't need to know how I know this.
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  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline Rokah

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Re: K75 neglected for two years
« Reply #16 on: October 30, 2019, 05:33:35 AM »
Quote from: The Mighty Gryphon on October 18, 2019, 04:06:54 PM
Make very sure you have a new tight fitting Torx wrench of the proper size to remove the head bolts. There are two types of Torx wrench, regular and heavy.  Later model bikes use the heavy.   The head bolts have a lot of torque on them, and the heads are easy to strip out. 

You don't need to know how I know this.

I doged that bullet!


It looks like I've found the reason for the missing compresion on cyl#2



should I worry on how bad the cylinders look?



To replace the valves, should I replace all of them, or can I just replace the broken one/ones?
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  • Madrid
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Offline Laitch

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Re: K75 neglected for two years
« Reply #17 on: October 30, 2019, 09:00:57 AM »
 Cylinder #1 compression is poor; the reason should be sought.
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  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline johnny

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Re: K75 neglected for two years
« Reply #18 on: October 30, 2019, 10:00:05 AM »
greetings...

you sparker orientation looks like a you gotts a low and a high simotaniously on the weather map...

that caint be good...


* 20191030_085315.jpg (32.12 kB . 324x576 - viewed 586 times)

j o
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  • :johnny i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin  :johnny

Offline Laitch

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Re: K75 neglected for two years
« Reply #19 on: October 30, 2019, 11:03:57 AM »
omg :-)
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  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline Laitch

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Re: K75 neglected for two years
« Reply #20 on: October 30, 2019, 11:43:42 AM »
The difference in compression values after adding oil is probably symptomatic of stuck piston rings, which happens after neglect and usually ends after the engine is run in again.
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  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline Rokah

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Re: K75 neglected for two years
« Reply #21 on: October 30, 2019, 12:20:31 PM »
Quote from: johnny on October 30, 2019, 10:00:05 AM
greetings...

you sparker orientation looks like a you gotts a low and a high simotaniously on the weather map...

that caint be good...


* 20191030_085315.jpg (32.12 kB . 324x576 - viewed 586 times)

j o
Quote from: Laitch on October 30, 2019, 11:03:57 AM
omg :-)

Calm down gents, those spark plugs are loose! I put them in just to take the picture.

I'm going to buy a new valve and get a quotation for a head and valve resurface

Any more suggestions?!
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  • Madrid
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Offline Chaos

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Re: K75 neglected for two years
« Reply #22 on: October 30, 2019, 12:53:49 PM »
Quote from: johnny on October 30, 2019, 10:00:05 AM
greetings...

you sparker orientation looks like a you gotts a low and a high simotaniously on the weather map...


j o

Does anyone index spark plugs anymore?  Does it even matter?
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  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
sold 6/23
2023 Ural 2WD sidecar (BMW's bastard step child)

Offline johnny

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Re: K75 neglected for two years
« Reply #23 on: October 30, 2019, 01:55:59 PM »
greetings grandpa...

it matters... thats why i use e3 exclusively...

that and 10 moar horsepower with diamondfior technology...

thats 2.5hp a hole... you would getts 7.5hp combined on your minibrick.. itsa game changer for sure...


* Screenshot_20191030-125443.jpg (30.66 kB . 403x576 - viewed 554 times)
 
j o
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  • :johnny i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin  :johnny

Offline Chaos

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Re: K75 neglected for two years
« Reply #24 on: October 30, 2019, 04:14:35 PM »
do they make them for chippers?  mine bogs down with fat people
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  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
sold 6/23
2023 Ural 2WD sidecar (BMW's bastard step child)
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