Hall Effect Sensor replacement - use same alignment position?

[schrocketeer]

When replacing a Hall Effect Sensor, if I carefully mark the orientation of the old one, and line up the new one to the same marks, do I have to re-time it?
1986 K100RT OEM sensor, replacing with new Euromotoelectrics BOIgnSen-K033EDL

Related: is the bike's timing tightly coupled to the sensor itself, or the position of the sensors relative to the bike's rotating, timing disk?

[Laitch]

You shouldn't need to time it again if you've been careful during your replacement procedure, and the initial timing before the procedure was ok before everything went haywire. Maybe, you have read EME's instructions. If you have, you can take 'em or leave 'em. That's free will! If you have not, you should so you can take 'em or leave 'em.
 

Timing is governed by the position of the crankshaft. The position of the crankshaft is signaled to the ICU by the position of the window in the rotor cup during crankshaft rotation relative to the magnets of the Hall effect sensor.

[frankenduck]

Easy peasy. Align the notch on the HES with the arced notch on the engine block.

[daveson]

When replacing a Hall Effect Sensor, if I carefully mark the orientation of the old one, and line up the new one to the same marks, do I have to re-time it?

No. But if it isn't at the factory setting, as with the photo from duck, you want to ignore the original position, and go with the factory setting. Some people deliberately advance the timing for improved fuel economy or more power, at the cost of increased engine temperature, amongst other drawbacks. If the bike has a temperature gauge that's about forty years old, it might give a reading well below the actual temperature, and the engine might pack up.

I serviced a car once that was the same model as mine, the timing was advanced five degrees over stock, apparently without issues, so I did it to mine. I got my car to 570,000km with the original engine, and got better fuel economy after the change, but six weeks later it packed up, a valve guide dropped, so the valve couldn't close. I think it was due to the increased temperature. The car I serviced had a low mileage compared with mine.

[daveson]

Related: is the bike's timing tightly coupled to the sensor itself, or the position of the sensors relative to the bike's rotating, timing disk?

Yep.

[schrocketeer]

Installed the new Hall Sensor from Euromotoelectric (BOIgnSen-K033EDL). Contact cleaner on both sides of the connection, dielectric grease. Now it won't start enough to stay running.
It will bark for half a second, then the starter just grinds. If I hold the Starter button down with my left hand, and run the throttle from full, to partial, it act like it wants to start, but won't stay running if I let off the Starter. Disconnected the fuel rail return line, to make sure the system was pressurized and no junk.

The reason I installed the new HES, was that it was hard to start when warm, and would not accelerate smoothly. Understand it's Fuel Injected, but it responded like junk in the carb that needed blown out.

1986 K100RT, 53k miles, less than 300 miles on NAPA fuel filter. 91 octane, ethanol free gas, averaging around 40mpg.

For reference, previously had a '85 K100RT I put 25k miles on.

[Laitch]

It's okay for you to loosen the two holding screws of the sensor mounting plate and rotate the plate not more than 1 or 2 BCH units in either direction to see if that makes any difference in starting and idling.

[schrocketeer]

Okay thanks. I'll play with advancing or retarding a bit.
Would you please tell me what a BCH unit is?

[frankenduck]

Some people deliberately advance the timing for improved fuel economy or more power, at the cost of increased engine temperature

Please explain how changing the timing impacts the temperature at which the radiator thermostat opens.

Also, the spark plugs fire the same number of times and cause combustion regardless how far advanced or retarded the timing is. Why would advanced timing generate more heat?

[Laitch]

Would you please tell me what a BCH unit is?

It's a hair's width of a certain caliber. 

If moving it slightly one way or another doesn't improve things, maybe you could summarize what other elements you've may have explored that could cause these symptoms such as:

• Throttle body manifolds or the z-pipe crankcase breather containing cracks that open when the parts are heated.
• A dirty ignition control unit plug pins and their sockets.
• Clogged injectors.
• Failing or loose interior fuel tank hoses.
• A failing ICU.
• Coils and secondary ignition wires.

[Laitch]

Please explain how changing the timing impacts the temperature at which the radiator thermostat opens.

Also, the spark plugs fire the same number of times and cause combustion regardless how far advanced or retarded the timing is. Why would advanced timing generate more heat?

These guys seem to believe the state of timing makes a difference in heat generation but we really don't know who they are, do we? They could be adolescents churning out websites for fun that are financed by Temu sales.
 

[daveson]

Please explain how changing the timing impacts the temperature at which the radiator thermostat opens.

Also, the spark plugs fire the same number of times and cause combustion regardless how far advanced or retarded the timing is. Why would advanced timing generate more heat?

I think I agree with what I think you're saying, that there's not much of a relationship between the timing and the thermostat. I was thinking that the earlier the combustion happens before top dead centre, the more it fights against the crankshaft rotation. This would make the engine run hotter.

In the example I mentioned I think the temperature gauge wasn't accurate. I got a good improvement in fuel economy (back to where it used to be) and the car was on its last legs, so I thought, I don't care if it only lasts a year, the fuel savings would be more than what the car is worth. But it only lasted six weeks, so then I thought, well that was one more silly idea I've tried. Another modification I did on that car was to install a bypass oil filter. I only changed the oil and original filter at 50,000km intervals. It did about 300,000km like that, and it clocked up over 570,000km.

[schrocketeer]

A second new HES does NOT make the bike start.
Putting the OEM sensor back in the bike starts, but hesitantly.

Any guesses as to why two new HES would not work, but the old one will?

Is the timing angle really sensitive? Understand previous post about advancing/retarding a few degrees.

Shoutout to Euro Moto Electrics for 2nd day shipping another HES to me, based on my theory that the 1st new HES was defective.

[Laitch]

Is the timing angle really sensitive? Understand previous post about advancing/retarding a few degrees.

It's fair to say that something that is adjusted in one degree increments is sensitive. I wasn't kidding when I recommended moving the angle 1 or 2 BCH units to test the effect, but I can understand if you believed I was. Do I understand correctly that you didn't try moving the HES sightly before you ordered and installed the new HES? There seem to be gaps in your narrative.

[schrocketeer]

Did Not mark the OEM sensor before I pulled it.
Tried to make protractor small increments on the 1st new HES, and went up and down maybe 5 degrees. Apparently I was using too Coarse of increments.

For a new install, is it important for the first starting to have Cylinder #1 at TDC?

BTW, thank you for your awesome help!

I'm having a feeling that getting my '86 RT going will help me with my '85 RT (he says hopefully).

[Laitch]

For a new install, is it important for the first starting to have Cylinder #1 at TDC?

The #1 piston does not need to be in that position before cranking the engine after the new HES was installed. It's important that the timing was correct before the replacement.

Remove the HES cover and photograph the position of the notch of the HES plate and include in the photo the pointer on the timing cover below the notch. Take the photo directly above the notch in full light with as little shadow as possible, then post it here You've installed this part and indicated that it didn't help start the engine. Did you move it slightly in either direction and try to start it again before you made your last post here?

[schrocketeer]

Finally made and connected the HES test light set up, I found here. Very helpful and easy to use, once I got it set up (electrical photo).
Trying to back off 0.24mm from TDC on Cylinder #1 was troublesome. Acknowledged that my dial indicator set up is very questionable. I ended up finding TDC, then backwards, backing the backlash off.

[daveson]

I don't think it's been verified yet that the problem is with the hall sensors. Maybe there's nothing wrong with the original hall sensors. Maybe it's just me but I don't like the thought of dielectric grease on electrical connectors, I'd wipe and spray them clean and try again.

It's an '86 RT, but maybe it's an '85 RT that was first registered in '86, at least that's sometimes an issue in OZ. If it has a seven litre fuel level light and grab handles on the seat, they point to it being the earlier '85 model.

Often the earlier model had issues with the coils. I think there are tests for the coils in the guide you're using.

The hall sensor signals might not be reaching the injectors and coils. Here are some simple, easy, tests to check for that, using a computer safe 12V LED test light, clamped to the positive terminal of the battery. They might pass the test when cold, but might not when the engine is warm.

https://youtube.com/shorts/2cXY21Zu3Z0?si=_v75umlADcHvkJ_Z

https://youtube.com/shorts/5VrtFtr07-4?si=XDsprvcOJm3lh-Yx

[schrocketeer]

Using VIN WB105140XG0053944, https://www.realoem.com/bmw/enUS/select?vin=0053944 says it was produced in 11/85.
Yes it has both the 7L and 4L Low Fuel Level lights on the cluster, and as you noticed, grab rails on the rear cowling.

Thanks for the tips and videos on the coils. I've got a spare set that came with my last Brick trade I can use to troubleshoot.

[schrocketeer]

For the two different cutouts on the "timing disc" (rectangle and wide-bottomed V), which should be aligned with the pointer cast in to the block? (please see attached phot)

[Laitch]

This photo shows the simple method within circle for making reference marks on a HES plate before removing it.



The pointer to align with the rotor mounting disk isn't cast into the block; it's cast into the timing chain cover.


Cylinder 1 at TDC on the compression stroke should align these circled elements. The marks reflect the same alignment as corresponding marks on the crankshaft and engine case beneath this assembly. This alignment is the jumping-off point for testing and photos showing it are found in Clymer, Haynes and BMW's K75/K100 workshop manual downloadable from this site. Some disks don't have the squared notch; they only have the V-notch. The V-notch is used for alignment.