Popping Brick, Only kinda runs on Starting fluid?

[schrocketeer]

Would you please help with a K100 that only attempts to run on Starting fluid (short cough), then backfires?
  (You can hear backfire in attached .wav)
I've never heard this project Brick run, but put 25k miles on my previous K100RT.

1985 K1000RT (35k miles shown - before odometer quit)
New fuel filter
Fuse #6 good
Good fuel pump output (temp clear vinyl hose attached for testing)
Fuel rail cleaned (good flow out the back)
Previous Owner replaced the S-air vent (capped off, small K&N on the Return input)
All four injectors cleaned and functional (applied 12 volts, and sprayed carb cleaner through. respectable nozzle spray x4)
All four plugs cleaned and re-installed (cylinder #1 strong blue spark)
Throttle position sensor disconnected (photo of backside for reference)
Airbox disconnected
93 octane fuel (with Ethanol :-( ), fresh within a few weeks. 7 Liter light barely on.
Handlebar Fast Idle lever to On (throttle valves cracked open)
Good battery (load tested around 250 CCA)

[Martin]

After failure to start are the plugs wet or dry?
Regards Martin.

[Laitch]

What the feck is this about?

The Brick likely won't start or run well at all without accurate data coming from the air flow meter, and its temperature sensor, being input into the LE Jetronic fuel injection control unit for calculation of correct fuel mixture, but the meter in this Brick can't transmit doodely-squat to the LE Jetronic because the feckin throttle bodies are disconnected from the air box that is connected to the airflow meter, and that condition means that the fuel mixture computation is fecked from lack of sufficient air flow being drawn through the meter by the air pump that is otherwise known as The Engine.

The Service Bulletins~Brochures section contains the LE Jetronic training manual. Point #4 in the list on p.8 explains part of the situation. Necessary parts seem missing, decoupled or generally fecked, but Hope is eternal.

[The Mighty Gryphon]

+1 on Laitch's reply.  The engine won't run with any of the air intake stuff disconnected.  It'e impossible to get a proper fuel/air mixture without a sealed air intake system.  There can't be any air leaks between the air flow meter and the cylinder head.

When you say "S air vent" do you mean the Z tube that connects the air box and the engine block vent?  The Z tube is important to getting a good idle and proper throttle response coming off of idle.

I'm sorry, but the previous owner is a moron when it comes to fuel injected engines.

[schrocketeer]

Wasn't sure if the bike would run without the Mass Air Flow and Temperature sensor?

One of my intake manifold to airbox boots (officially listed as a "bearing" at Max's) was blatantly cracked. I'll get those ordered and installed, and report back.

BTW, is there a special tool for the one-time steel clamps that go top and bottom of the airbox boots?

Thanks

[Laitch]

Your 2V Brick has an air flow meter, not a mass air flow sensor.  A mass air flow sensor operates differently. Happily, the difference was explained to me by an experienced BMW auto aficionado. Knowing the difference between the two can lend to observers the impression that a feck concerning the engine management system is given, regardless of whether it actually is given. You never get a second chance to make a first impression.   

Anyway, without the data provided by the air flow meter, performance of the Brick's 2V engine is usually fecked-and-a-half.  Luckily for us owners, it is an unusually sturdy unit seldom needing service beyond ensuring that its air vane moves freely, its air temperature sensor is not coated with detritus and that its electrical connector is plugged into it to enable the sending of data to the LE Jetronic.


I strongly suggest that all owners of 2V Bricks not already having done so, read the LE Jetronic training manual—available in the Service Bulletins~Brochures section of this site—to understand how the engine works and to help them unravel messes like the one schrockteer is encountering.

[schrocketeer]

Is there a special tool for the one-time steel clamps that go top and bottom of the airbox boots?
It looks like a pliers (pull the tab taught) and punch (smash down the locking rectangle) operation, but I don't want to mangle brand new parts.

[frankenduck]

Their name is Oetiker clamp. There pliers are made for them.



I replace them with worm drive hose clamps and hide the worm drive part on the back.

[schrocketeer]

Thanks, I'll go with the radiator clamp approach.

[although I'm intrigued by a groovy new tool!]

[schrocketeer]

How do the custom brick modifiers bypass the air flow sensor?
I've seen some builds that only have velocity stacks attached to the throttle bodies.

[Laitch]

How do the custom brick modifiers bypass the air flow sensor?
I've seen some builds that only have velocity stacks attached to the throttle bodies.

So far, the only K100 2V Bricks I've seen with velocity stacks were using dummy velocity stacks that hid the fuel injectors. Like these at the Cafe4Racer site.

Post some photos of the Bricks to which you are referring.

[Laitch]

Brick modifiers that have replaced the LE Jetronic with a different engine management system could possibly be able to use v-stacks for their artistic creations.

[The Mighty Gryphon]

It could also be that bricks without airflow meters were built just to be static sculptures intended to be photographed for magazine articles.

[sooprvylyn]

How do the custom brick modifiers bypass the air flow sensor?
I've seen some builds that only have velocity stacks attached to the throttle bodies.

They are 4v K1100s.  There is no airflow sensor, just an air temp sensor, and the earlier jetronic EFI was replaced with a motronic EFI.  I made a bracket that holds my air temp sensor right between the pod filters I put on mine when I did my airbox delete.  I notice no real difference in performance with this method, and I assume the Motronic is able to adapt to the small difference this setup makes.


BTW- V-stacks are a BAD idea on a bike you actually plan to ride regularly.  Zero filtration is pretty dumb.

[sooprvylyn]

You can see the air temp sensor cord sticking out behind pod 4 in this photo....the sensor sits right between pods 3 and 4. 

If anyone puts pod filters on their bike, make sure you oil them so they can do their job.  Also, know the environment you ride in.  If its a dusty area, probably dont use pods.

You cant do a similar setup on a 2V K bike.