Slow Starting R1150RT

Roger, I just went to the nearest parts supply store and bought a 4 ohm resistor then wired it up with a couple of large gauge wires and ring terminals. You weren't kidding that it would get hot. I measured 250 degrees.

After the first discharge I realized that I needed better records if I wanted to see if there was improvement. After that I tried to get a voltage every 30 minutes.

I left the battery unattended on the bench since, well, whenever it was I posted last (been out riding a different bike). The voltage today, after sitting was 12.8 V. The bike turns over faster too, but I suspect maybe my starter needs to be looked at as well. That's for another day...

August 8, 2013

When I tested an R1200 GSW the other day, one of the improvements is that cold the bike seemed to start like, er, er, vroom. My 04RT is more like er, er er, er, er, er, vroom.

...

bike runs great except the slow first-start-of-the-day. I've GS-911ed all the sensors, looked at the LC-1 AFR charts, nothing seem to be wrong and the Motronic seems to be computing reasonable first injection times.

...

Any thoughts in how to get my bike to start faster 1st time in the morning? Er, Er Vroom!

August 24, 2015

Two years later, my '04 R1150RT (dual spark) now starts in about 1 second after sitting overnight and in about half to three-quarters of a second once the engine has warmed up (>40C). The final pieces of the puzzle were wiring the stick coils through a relay, directly to the battery (last month); and replacing the starter (last week). I’ve made it to Er, Er, Vroom!

Since it seems I'm at the end of this project finally and have learned a lot about what it takes to get the dual-spark 1150 to start quickly, I want to summarize the various improvements and repairs that I’ve made to reach the present state.

1) The Motronic, injectors and stick coils are voltage sensitive and the Motronic MA 2.4 doesn't fully compensate for low voltage. I experimented a lot by powering the electronics separately and the bike always started well when I did. A good battery, good starter and properly powered stick coils are all key.

--Odyssey PC-680: My battery had been chronically undercharged due to short trips, the 1150RT's alternator being a lower voltage than the PC680's spec, and my use of a Battery Tender Jr. with low voltage output. The battery was successfully rejuvenated by discharging and recharging 5 times, the BT Jr. was replaced with an AGM charger and I boosted the alternator output with the addition of an internal diode. I also modified the Kisan Signal Minder Flasher so that there was no key-off current drain on the battery.

--The stick coils were powered from the key switch and its contact resistance seems to have increased over the years. Later model dual-spark bikes power the stick coils with their own relay, called Load Relay II. Recently I added a relay and rewired the stick-coils (and while I was at it the secondary coil too) directly to +12V through the relay. It improved starting, idling quality and (surprisingly) top-end smoothness.

--The planetary gear cover inside my starter had fallen onto the armature a couple times causing serious internal arcing. I replaced the cover and the starter seemed fine but after fixing everything else in this summary, I got to the point where some starts were still slow and I knew it was related to the starting dip in the +12V. It seemed there must be excessive draw from the starter some of the time, causing the voltage dip and upsetting the Motronic, injectors and coils. After replacing it the motor spins faster, and quieter during starting and the bike starts very quickly whether cold or hot.

—To idle well in cold weather immediately after starting, the alternator needs to start charging the battery ASAP. I noticed from GS-911 logs that the alternator sometimes would take up to half a minute to start charging the battery. During that time, voltage at the injectors could be less than 12 volts, resulting in a lean, rough idle. This is caused by a much slower injector turn-on time at the lower voltage. The alternator starting current is supplied by the Batt/Alt bulb. By replacing the stock 1.7W annunciator bulb in Batt/Alt with the 3W bulb from the High Beam annunciator, the alternator always starts immediately and cold-idle is smoother.

2) All 4 spark plugs need to fire well for a quick start.

--Both stick coils were found to be sub-par and although the bike ran well, replacing them improved starting and idling quality, as well as top-end smoothness.

--The lower plugs seem to foul easily and although I didn't notice it while riding, fresh lower plugs made a difference to starting and cold idling. I've gone up in the heat range on the lower plugs to try and keep them cleaner.

3) The Hot Idle Speed, TPS and Fast Idle Lever need to be adjusted correctly for best starting.

—The BMW procedure for setting the Fast Idle Lever results in the throttle being opened about 4 degrees when the Fast Idle Lever is in the mid-detent position. Mine was at about 1.92 degrees, and many I’ve seen in GS-911 logs are lower, some as low as 0.64 degrees. Although the bike will start with that little throttle, 3-4 degrees open leads to faster starting. The adjuster for the fast idle lever ran to the end of the threads at a little over 2 degrees so a spacer was manufactured to sit in the bottom of the ferrule & adjuster to add adjustment range. After trial and error, 3-3.5 degrees when the Lever is in the mid-dent leads to a fast start but not too high a warm-up idle speed.

—Oddly, but confirmed on several bikes, if the Hot Idle Speed is set above 1100 RPM, the cold-start enrichment with the Fast Idle Lever OFF is too lean. This is because there is more air entering than expected at closed throttle while Open Loop. By reducing Hot Idle to 1100 RPM, the bike’s Cold Start AFR is slightly richer.

—TPS: Although a longer topic, I realized along the way that the closed throttle voltage expected by the Motronic is 340 mV. It was also discovered that the infamous zero=zero procedure results in the throttle being opened too far. The correct zero degree voltage is 250 mV.

Summary

Although everything on the list above contributed improvement, I found the most important were: 1) a fully charged, properly conditioned battery; 2) a starter that didn’t glitch the battery voltage badly, 3) separately powered stick coils and 4) good spark plugs. Although many in the forum helped I want to especially thank DR, GS Addict and terryofperry who provided valuable advice on debugging, starters and AGM batteries.

" I noticed from GS-911 logs that the alternator sometimes would take up to half a minute to start charging the battery." per roger 04RT

Roger,

I've always heard that automobile alternators will not (usually) begin charging until the engine is revved to 2k as a delay to keep the extra load off during cranking and warm up. Could these alternators be doing the same thing??

 

I've always heard that automobile alternators will not (usually) begin charging until the engine is revved to 2k as a delay to keep the extra load off during cranking and warm up. Could these alternators be doing the same thing??

Evening Lowndes

That is not the case, they want system voltage up so the coils are working correctly & injectors are getting good voltage.

There is no or so little alternator output during engine cranking that there is no reason to shut off the alternator during engine cranking. (now shutting the head light & accessories off during engine cranking is a big gain).

Some of the very new vehicles do use a (computer controlled) ramped charging algorithm to take the load off a low idling engine & do ramp the charging up as needed.

On the older systems Like the BMW 1100/1150 (& most cars of that era) there is no charging delay built in as the rotor excitation if pretty straight forward.

Now there are a number of vehicle charging systems that will delay the charging until a higher RPM is reached but this is due to a fault in the system (like burnt out dash light bulb or high resistance in the dash analog volt gauge). In fact years ago GM put a shorting resistor inside the alternator to start the charging earlier in the revv range if the dash light bulb failed.

BMW did approve the use of a dash light bulb in the gen light socket for a quicker start-of-charging (I believe the BMW parts book now shows the lower resistance bulb as correct now with the older higher resistance bulb not being offered anymore)

I have seen charging systems that had issues & wouldn't start charging until 2000 RPM + due to the above mentioned problems & those could run the battery completely dead if the engine was started & allowed to idle with the AC on & fan on hi & head lights on. All those accessories puled power out of the battery with no replenishment from the charging system.

+1 to DR.

THANKS, DR!!

I got to the "diode" project over the weekend. The alternator is now charging at 14.75 volts. Many thanks to GSAddict for his valuable help, often on a moment's notice at the crack of dawn.

 

While the project seems a success, it is a bear of a job. At this point I can't say for certain that it won't be bad for the bulbs, or other electronics. Nor do I know for sure that the higher voltage won't be bad for the ABS or Motronic. I don't know that I've selected the best diode, and I don't know how long the diode will last. If the diode fails, the alternator will stop charging. (But often overloaded diodes short out in which case the alternator will operate but at its original voltage.)

 

The first time I reassembled, the diode interfered with the alternator body causing two internal pins on the voltage regulator to touch. This happened because I attempted to do the work without pulling the alternator. You really have to remove the alternator to do a good job, which I did the second time. (It would be better to find a voltage regulator that was adjustable or a higher voltage, then swap regulators. I haven't found one yet.) Removal of the ABS system takes a great deal of care.

 

RB

 

If I haven't scared you off from trying, and you're willing to take all the risk yourself, and you want to install a diode, here is a brief outline of what I did:

 

Step 1

Remove the alternator by removing:

-Seats, left and right fairing and fuel tank

-Alternator Belt Cover

-Battery

-ABS (requires bleeding all circuits afterward)

-Motronic

 

 

Step 2

Remove the Voltage Regulator from the Alternator by:

-Removing the black cover on the alternator

 

And then:

-Drill out the spot weld on the ground lug

-CAREFULLY remove Ground Lug. (Note in the photo below that I have started removing the ground and it is bent upward.)

-Save ground lug to shim the underside of the regulator when you reinstall it.

 

 

Step 3

Boost the Voltage by Adding:

-One NTE 5812 Diode in series with the internal ground

-Reinstall Vreg

-Reinstall Alternator

-Reinstall fuel tank and battery

-Test alternator output

 

 

Step 4

-Pull fuel tank and battery again

-Reinstall and Bleed ABS system

-Reinstall everything else

 

There are a lot of steps and skills needed for this project. It would be easy to do it wrong and cause serious damage. This outline and the photos should be sufficient if you have the right skill set to take this on. Otherwise, if you have an Odyssey PC680 battery and want to keep it 100% charged, consider charging your battery with an approved Odyssey charger every few weeks. Or at your next battery change consider a regular lead acid or Gel battery, both of which are fully charged with the standard alternator.

I've got a 2001 R1150GS now that came with an undercharged, but still serviceable PC680. I ran it through several discharge cycles (see posts earlier in the thread) and then after each ride attach it to my charger. Every time I return from a ride, no matter how long or short, the battery requires charging (drawing 2 amps for half an hour) to get back to 100%, even though the stock regulator and alternator is working properly and the grounding system is in great shape.

Yesterday I decided I was tired of having to keep the battery on a charger and began the voltage regulator diode mod. I'm updating this thread because I was able to remove the voltage regulator without removing the alternator, which suits me since I loath bleeding the ABS system. Here's the additional detail.

—remove the battery, remove the Motronic, remove all bolts holding the ABS to the tray.

—remove the three nuts/bolts holding the alternator to the engine.

—remove the bolt and spacer from the top of the alternator. This allows the the alternator to be rotated in place.

—remove the rotor excitation pigtail, remove the main alternator wire.

—remove the two bolts that attach the right mounting arm, and tension adjuster to the alternator in that order. This allows the alternator to be freely rotated so that the screws holding the back cover can removed.

—remove the three back cover screws, remove the rear cover. You have to fiddle with the alternator to get the cover off—patience.

—with the rear cover off, push the ABS back about 1/8”, the alternator can now be rotated so that its pulley is facing down and the voltage regulator is facing up. This makes removal of the voltage regulator easy.

With the regulator out, solder the diode in place, and then as BMW is fond of saying “Installation is the reverse of the removal process”.

The key to this procedure is patience.

Update:

The modified VR for my Odyssey PC 680 has been in for a month now. What a pleasure, no more use of a trickle charger. I had to let the bike sit for several days after a trip to the airport but measured the battery this morning—12.94 V, 100% charged.

Under similar conditions with the stock regulator I'd be measuring 12.7x V much less than a full charge. For me, the mod is well worth the effort. Either the diode I used or a higher voltage regulator does the job, prolonging the life of the battery and improving starting.