Author Topic: K1100 Intake Manifold Rehab  (Read 19858 times)

Offline mystic red

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K1100 Intake Manifold Rehab
« on: June 06, 2011, 04:57:01 PM »
If you suspect you have a vacuum leak on your intake manifolds build yourself a leak detector. Propane works great.
I used a 1# propane tank with a torch on top. Tape up the vent holes and add a length of flexible tube.
Turn the propane on and use the hose to find leaks by moving it around different areas while the bike is idling. RPMs will increase if there is a intake leak. By pulling the hose away and letting the engine slow down and the putting it back up to a suspected area you can pinpoint a leak.



I removed the knee pad and shoved the tube in and around the throttle bodies and sure enough a leak was detected.  Off come the fairing side lowers so I can pinpoint the leak. If you don't know how to do this you remove the knee pad (has the fuel gauge in it) the radio and radio box. If you have engine guards the left one has to come off. Then remove all the screws and bolts in the lower fairing. If you have a LT or a RT, a much more comprehensive fairing removal write up by frankenduck is here.
This what it looks like.



After exploring around I kept getting a leak from the rubber bushing ( as BMW calls it) on the #2 intake manifold. But it didn't look any different than the other 3 bushings. Bushings are the thick rubber boot that connects the throttle body to the intake manifold.

The fuel rail is in the way.
Blow out the area with compressed air and clean it up as good as you can before proceeding.



Note: It is recommended to depressurize the fuel system before unhooking the lines. The easiest way to do this is to unhook a fuel line while holding a rag around it to keep the fuel from spraying out. Just keep in mind that it is a pressurized system and will spray a some fuel. Plug the hose ends (if you're not replacing them) with golf tees.

So out it comes. You just unhook connectors and fuel lines. Cut the zip ties on the fuel rail that hold the wiring to the rail so you can get the wiring out of the way. The 2 bolts holding the rail on are the ones in the foreground in the above picture. Then pull gently (yea, right) straight out so you don't damage the injectors.

Here's a closeup of the injector connector. Push down on the wire while pulling gently to remove it from the injectors.



Fuel rail removed from the intake manifold.



Ready to take the injectors out so I can have them cleaned and serviced by Mr. Injector in Dalton Gardens, ID, about 20 miles from me. If you don't have them serviced by Bill at Mr. Injector then you will need to replace the o-rings before re-installation. Bill will have them ready to install if you use his service.




Use a pair of pliers to pull off the retaining clips. I'm holding the clips in the correct orientation so you can see how they came off and I will remember how they go back on the injectors. Clymers recommends marking the injectors so they can be reinstalled in the same order. I don't think it matters if you have them serviced but I marked them anyway with a black felt pen. We'll see if it survives the cleaning process.



Aha! Torn bushing. The other 3, while not torn completely through, were very close to it right where the clamps connected on each end. That's why I couldn't see any difference in the bushings. I would highly recommend replacing these rubber bits every 15 years or so. I could have done this last winter when I couldn't ride instead of missing a couple of weeks waiting for parts. Fuel lines also. I had a fuel line spring a pinhole leak last summer. There are three. Two come off the bottom of the gas tank, supply and return. Supply runs to the fuel regulator (which is behind the throttle body assembly) and the the third is a short hose that runs from the regulator to the fuel rail.
Note that I've cut off the "one time use" hose clamps and will replace them with good old worm drive stainless clamps. BMW put the "one timers" on one end and worm drives on the other end of the bushings for whatever reason.



Next comes the throttle bodies themselves. Remove the four hose clamps that hold the bushings to the airbox , throttle cable, idle advance cable (choke), cruise control cable and vacuum line (you've done Duck's cruise, right?). Remove the cables by rotating the throttle rail by hand. You will see a slot for the cable and nipple to come out of the assembly.
Don't forget to unplug the throttle position sensor located on the right end of the throttle bodies. It has a similar wire clip as the injectors. See below picture.



That's the fuel regulator attached to the throttle body assembly by fuel hoses. The shot of whiskey, straight from the freezer, is optional.



If you replace those fuel hoses make sure to cover the holes in the regulator with tape so dirt can't get into it until you reinstall the new lines.



When I get it out it's worse than I thought.



The intake manifolds are held in place with two bolts each and are made of plastic. There is a flexible o-ring under each one which will be dried out. Replace the o-rings for sure and the manifolds at your discretion. I'm going to replace both to be safe.
Here's a shot of the manifolds removed. The bolts are cleaned up in the parts tray to the left.



Heart ripped out of her.



As noted above, you are supposed to clean the area all up before you do any of this which is nearly impossible with all the ch!t in the way so I covered the holes with duct tape and really gave it a thorough cleaning. I used CRC Lectic-Motive from NAPA. Don't spray it on the plastic parts as per the warning label. It just melts the grease away! Then blow it out with your compressed or vacuum the area.  You don't want to get anything in the engine.  Now it looks like this waiting for her transplant.





Parts on the way:

1. Fuel lines part numbers:
  a)13541461494
  b)13311461973
  c)13311461971

2. Intake manifold part number:
  11611461621

3. Bushings (rubber boots) part number:
  11611461739

4 .Manifold seals ( O-rings) part number:
  11611465169

5. Worm dive stainless steel clamps for fuel lines and bushings

6. Sparkly clean injectors.

All fer now.....I'll update this when all goes back together.


Picked up my cleaned and serviced injectors today The felt pen marks I made on each injector to identify their position did not survive the cleaning process. Bill said, as I suspected, that position doesn't matter after he services them. They all have identical flow now.
He tests them before cleaning.
The pattern was good on two of the injectors and fair on the other two. No leaks detected on any of them.
Flow was:

   Before    After    Increase%   
1.   40         41          3
2.   38         41          8
3.   39         41          5
4.   38         41          8

He said that wasn't too bad for a set that had 80K on them but I'm glad I had it done.
Also advises to use plenty of lubrication on the upper and lower o-rings. Motor oil is what he recommends.






Offline mystic red

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Re: K1100 Intake Manifold Rehab
« Reply #1 on: June 19, 2011, 02:52:59 PM »
My parts finally arrived so I went about the business of putting it back together.
The new o-rings looked nothing like the ones that fell out of the old intake manifolds. I wish I had taken a picture of them but they had been cooked down to about half the size of these.



The first step is install these into the intakes. I blew off the top of the engine again to make sure nothing could get into the engine after I pulled the tape off the holes. They friction fit in, no need to apply grease to get them to stay.
Then install the intake manifolds. Torque the screws to 80 inch pounds.



Then install your new fuel lines on the regulator because you can't get at them when the fuel rail is installed.
I bought a bag of hose clamps at the parts store for fuel injection systems. Don't like worm drive on fuel lines.

Supply and return hose with M&Ms, a Max BMW tradition.



The supply hose is the longer of the two and hooks to the regulator. You can do the return hose after everything is back in. The 7 inch  hose also attaches to the regulator and will connect to the fuel rail. All of these hoses come with a preformed 90 degree bend otherwise you could buy regular hose at you parts store. I did use a straight hose for a year when I sprang a leak in the return hose but I made it a little longer so it didn't have a sharp bend in it.





Now install your "bushing" onto the throttle assembly with new hose clamps. They are marked so you don't reverse them.



Then lift the throttle bodies on top of your installed manifolds and secure with clamps.
Note the short supply hose coming out underneath the throttle bodies. This the hose that connects to the fuel rail.

Then hook your throttle cable, choke cable, and cruise control. You can also hook up the throttle position sensor that BMW quaintly calls a switch.
Loosening the rail that connects the throttle bodies together makes it much easier to hook up the throttle cable. Make sure the screws are tight when you done. It's the rail right above my nut driver.

 
Slip a hose clamp over each hoses coming off the air box and force them over the top of the throttle bodies. Make sure your supply fuel hose routes up through the #3 and #4 air box hoses. I ended up lubing them up with some silicone grease and pushing them way back over the TB's to hook the back edge and then worked a screwdriver around to get them on. Slip clamps down and tighten.

Now the fuel rail. Lube up the o-rings on the injectors with some motor oil and gently push them into the fuel rail. Don't forget to install the clips that retain them.



Lube the other end and carefully push in all four at once into the intake holes. Give them a little turn once they are in there in each direction in case one of the o-rings twisted on you. Put the two bolts that hold the fuel rail on into their holes and tighten to 62 inch pounds. Clymers says to tighten by staggering in two or three stages.
Hook the electrical connectors back up to each injector and zip tie the wiring harness to the rail.
Then hook up the fuel hose that comes out the bottom from the regulator to the fuel rail.



Connect the return hose to the other end of the rail. The 90 degree end fits to the bottom of the fuel tank on both hoses.
You routed the supply line through the back two air intakes so you have enough length to slide your tank back into position. If you missed that step above you can feed it back through and grab it with some needle nose pliers. DAMHIK



Now you can hook your new fuel lines to the tank and check for leaks. If you disconnected the fuel pump/sending unit plug under the tank to move it hook it back up.
Check for leaks by turning on the key and letting the system pressurize for a couple of seconds and then turn it off. Do this 2 or 3 times. If you have any leaks DON'T START THE BIKE. You get to pull the rail back off and probably replace the o-rings on the injectors. Lots of oil on these when you install them.
If you passed that test start the bike and let it idle a few minutes and check for leaks again. No leaks then sync your throttle bodies and your done (except for putting all the Tupperware and engine guard back on the bike.

That's all for now........








Offline johnny

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Re: K1100 Intake Manifold Rehab
« Reply #2 on: June 19, 2011, 03:58:14 PM »
  • i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin...

Offline frankenduck

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Re: K1100 Intake Manifold Rehab
« Reply #3 on: June 19, 2011, 03:59:52 PM »
And use black zip ties. ::)
93 K11LT
94 K11RS- "Kato"
86-97 K75F (K75/100/1100 Frankenbrick)
86 K75C w/ paralever, high perf. cams,TURBO!
91 K1
86 custom K100
and 2 more
IBA #17739 (SS1K, BBG, 50CC)

Buy parts HERE

Offline Scott_

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Re: K1100 Intake Manifold Rehab
« Reply #4 on: June 19, 2011, 04:01:01 PM »
And use black zip ties. ::)
I was thinking that, but wasn't going to say anything.....................
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Offline mystic red

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Re: K1100 Intake Manifold Rehab
« Reply #5 on: June 19, 2011, 06:51:37 PM »
And use black zip ties. ::)

I'm tearing it back apart right now cause I found some black ones. Sheesh, you guys are hard to please. ;)

Offline johnny

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Re: K1100 Intake Manifold Rehab
« Reply #6 on: April 07, 2012, 01:49:36 PM »
so... how did this work for you there mr... have you ridden it since you did this critical service...

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

Offline mystic red

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Re: K1100 Intake Manifold Rehab
« Reply #7 on: April 07, 2012, 02:02:59 PM »
so... how did this work for you there mr... have you ridden it since you did this critical service...

j o

Yessiree. And it runs like new after the addition of Magnacor full on red spark plug wires. No black zip ties yet to appease all the OCD types that lurk here.

Offline tsbt

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Re: K1100 Intake Manifold Rehab
« Reply #8 on: June 03, 2012, 10:39:53 AM »
Thanks for documenting this procedure so well Mystic, thinking this'll be my winter project.

92 K100RS 4V
75 KE125

Offline billday

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Re: K1100 Intake Manifold Rehab
« Reply #9 on: June 03, 2012, 11:32:15 AM »
Yes, thank you for taking the time and trouble. Great pics, clear descriptions. I just synch'd my throttle bodies and found myself gazing at those rubber boots, wondering.... my bike's running great but like tsbt says, this looks like a great winter project.
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Offline mystic red

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Re: K1100 Intake Manifold Rehab
« Reply #10 on: June 03, 2012, 01:14:07 PM »
Yes, thank you for taking the time and trouble. Great pics, clear descriptions. I just synch'd my throttle bodies and found myself gazing at those rubber boots, wondering.... my bike's running great but like tsbt says, this looks like a great winter project.

Yeh, mine was running great last summer until I jumped on the throttle hard and evidently the boot popped. Not a gradual thing at all.

Offline Lawrence

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Re: K1100 Intake Manifold Rehab
« Reply #11 on: July 03, 2012, 11:22:42 AM »
This is a little late for your purposes since you've completed the replacement of the rubber intakes, but perhaps others will benefit from what I learned (finally).  As Dr. Duck noted, there is insufficient room to fit the intake components.  This finally worked for me -- after too many unsuccessful tries!  Coat the rubber tube ends very liberally with silicon grease.  Fit the tubes to the plenum first, then fit that assembly to the throttle bodies. After you have pushed the parts as far together as is humanly possible, use a large screwdriver to force the rubber connectors home (seating the internal bead).  It's possible to catch the outside with the screwdriver blade and move the connectors the final 2mm -/+ home.  Failing to do this will result in an air leak, provoking coarse language and perhaps major depression in the mechanic.  :loopy:
1985 K100RS

1982 Laverda Mirage 1200TS
1983 BMW R100RS

Offline Lawrence

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Re: K1100 Intake Manifold Rehab
« Reply #12 on: July 04, 2012, 12:08:21 AM »
Oh yes, one other trick that may have helped me finally get all that stuff reassembled without leaks was to heat the rubber connectors with a heat gun. 
1985 K100RS

1982 Laverda Mirage 1200TS
1983 BMW R100RS

Offline lukeman

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Re: K1100 Intake Manifold Rehab
« Reply #13 on: July 05, 2012, 11:08:58 AM »
Good advice, I made sure I swore in German so my bike would know that I was not pleased with her.  Nervensäge!  That and the airbox I could use on my car...


Offline GasStation

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Re: K1100 Intake Manifold Rehab
« Reply #14 on: August 02, 2012, 06:25:03 PM »
Can I backup to the top of this thread...I would really like to test my bike for an air leak considering most of the German rubber is more than 20 years old. However, I am somewhat reluctant to using propane to test for an air leak as I fear death more than I fear air leaks. Is this method of using highly inflammable gas around a running engine really safe?  :yow

Obviously, it works, but I need to know as I don't want to be a "star" on the TV show: "1000 Ways To Die".  :yes
93 K75S Mystic Red
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Offline frankenduck

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Re: K1100 Intake Manifold Rehab
« Reply #15 on: August 02, 2012, 06:39:43 PM »
Yes, it's safe.  I've sprayed tons of starter fluid in around there on numerous Ks and it has never ignited.  The only sparks that occur are in the combustion chambers.

If you're paranoid then do it outside with a fan blowing and wear a firefighting outfit.
93 K11LT
94 K11RS- "Kato"
86-97 K75F (K75/100/1100 Frankenbrick)
86 K75C w/ paralever, high perf. cams,TURBO!
91 K1
86 custom K100
and 2 more
IBA #17739 (SS1K, BBG, 50CC)

Buy parts HERE

Offline mystic red

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Re: K1100 Intake Manifold Rehab
« Reply #16 on: August 05, 2012, 07:27:37 PM »
Can I backup to the top of this thread...I would really like to test my bike for an air leak considering most of the German rubber is more than 20 years old. However, I am somewhat reluctant to using propane to test for an air leak as I fear death more than I fear air leaks. Is this method of using highly inflammable gas around a running engine really safe?  :yow

Obviously, it works, but I need to know as I don't want to be a "star" on the TV show: "1000 Ways To Die".  :yes

It's actually the recommended method. If the torch did catch it would be a flame at the end and you  could just blow it out.

Offline ReneZ

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Re: K1100 Intake Manifold Rehab
« Reply #17 on: August 24, 2012, 08:30:48 AM »
For the total AR under us; they call the TPS a 'switch' as that was what it was on the first K's. Later it became a potentiometer and was called a 'sensor'. Both called TPS, but different things.

Cheers, Rene
Greetings, Rene

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Offline Filmcamera

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Re: K1100 Intake Manifold Rehab
« Reply #18 on: August 06, 2017, 04:54:47 PM »
Arrgh I am in the middle of doing just this job and all the photos are missing!

F**K photobucket!!

Still very useful though, thanks  :2thumbup:
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Offline Freelancer

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Re: K1100 Intake Manifold Rehab
« Reply #19 on: August 13, 2017, 12:10:16 AM »
Hey Guys,

Just had a thought and the measurements worked out.

Instead of grabbing BMW's pricey one timers for the top of the manifold tubes or using failure prone worm drive hose clamps.

Standard stainless steel zip ties that you can get at NAPA fit in the "top" clamp position dead on.

They are about $9 for a pack of 10. Probably can  find them cheaper elsewhere.

Seem like a good emergency repair item to have in the " 'ol get ya home kit".

What do you guys think?

Freelancer
1991 K100RS

Offline alabrew

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Re: K1100 Intake Manifold Rehab
« Reply #20 on: August 15, 2017, 03:11:13 PM »
What a coincidence that you would ask this Freelancer. I looked at mine over the weekend and noticed that the '91 had black zip ties (the appropriate color =-} ) holding on the intakes. Was going to post and ask if I really should replace them with the "proper" metal clamps.
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Current:
2005 K1200LT
1991 K100RS 4V
1985 K100 Standard
1979 R65
2006 525i
200,000 miles on BMW motorcycles

Past:
2002 K1200LT
1988 K100LT
1985 K100RT
1982 Yamaha Vision 550
1979 Yamaha R5C 350

Offline Freelancer

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Re: K1100 Intake Manifold Rehab
« Reply #21 on: August 16, 2017, 10:05:15 AM »
Hi alabrew,

If you r bike runs fine (no vacuum leaks) then I'd say leave the zip ties for a winter/non riding season project.

If your ride stumbles when throttle is closed quickly or shows other vacuum gremlins then this would be a good thing to take care of along with a full manifold rehab (New Gaskets, Rubber boots, and if necessary new manifolds).

The Stainless Zip Ties can be installed without having to use the specialty tool. Just takes a pair of cutting pliers and a pair of long needle nose pliers.

Here is a Youtube link that shows how to lock them in:



Hope this helps,
Freelancer
1991 K100RS