Voltage on 90 907ie

90_907ie · Post by **90_907ie** » Mon Jan 02, 2006 5:53 am

Hi all, I have an interesting issue. On my 907ie, I have noticed that when I put the brakes on or engage the turn signals it dims the headlight and other dash lights. So I am wondering if anyone has any issue like that. I have noticed it doesn't really seem to matter what RPM the motor is running at. although it's worse at Idle.

I am wondering if something is pulling too much current or there is maybe a short somewhere. I know we already discussed that the alternator barely has the capacity to run everything on the bike. But is my issue normal. Just curious and a bit concerned.

I was also wondering if anyone can give me some ideas on voltages at certain RPM's. I took some measurements and found that the engine has to run at least at 3500 rpm to make 12.5 volts. Any help or discussion would be appreciated.

Finnpaso · Post by **Finnpaso** » Mon Jan 02, 2006 4:50 pm

You have some bad now in Your bike! Voltage must rise somewhere close 13.5-14.0 V, if You rise rpm from idle little, like to 2000, or so. Normally in 907 voltage falls somewhere close 12.5 V, if it stays some time in idle, but MUST go up, if U accelerate more RPMs. Normally good charging voltage to 907 battery is very close 14V. But if voltage is more, than ab.14:4Volts, then its again wrong.

1. Check all battery connections
2. Check all charging connection
3. Change fuel filter(glogged filter takes too much current, what can be "too much" from 907 charging capasity)
4. Change battery, if Its over 3-4Years old, cause they least normally that age.
5. Good to check also main fuse and also other fuses and they holders

Ps. put digital multimer to Your loved bike, like to some dashboard and go to drive and look voltage, but BE CAREFUL with other traffic.

pencilbeam · Post by **pencilbeam** » Mon Jan 02, 2006 8:45 pm

Finnpaso wrote:You have some bad now in Your bike! Voltage must rise somewhere close 13.5-14.0 V, if You rise rpm from idle little, like to 2000, or so. Normally in 907 voltage falls somewhere close 12.5 V, if it stays some time in idle, but MUST go up, if U accelerate more RPMs. Normally good charging voltage to 907 battery is very close 14V. But if voltage is more, than ab.14:4Volts, then its again wrong.

1. Check all battery connections
2. Check all charging connection
3. Change fuel filter(glogged filter takes too much current, what can be "too much" from 907 charging capasity)
4. Change battery, if Its over 3-4Years old, cause they least normally that age.
5. Good to check also main fuse and also other fuses and they holders

Ps. put digital multimer to Your loved bike, like to some dashboard and go to drive and look voltage, but BE CAREFUL with other traffic.

All great advice, except driving around looking at a multimeter. You can just run up the rpm while the bike is on the stand in neutral to see what it will do on the road.

90_907ie · Post by **90_907ie** » Tue Jan 03, 2006 5:24 pm

Thanks for the reply, Finnpaso. I have wondered about the fuel filter. But it looks to me like it's very difficult to get to. And does anybody know what I should replace it with here in the US?

Finnpaso · Post by **Finnpaso** » Fri Jan 06, 2006 9:34 am

Maybe thats why nowbody havent changed it for long time? I have talked with some injection specialists and they say, that most of troubles in injected bikes have caused from glogged fuel filter and then pump start to take too much current and it drains battery down little by little.... Also its good to take sometimes injectors away to injetion maintainer, who check them, how they spray fuel and there is also small filters inside them, what U cant change without special tool. If injectors dont function well, then bike doesnt function also well. That check doesnt coast so much.

You can also measure fuel pump current by using multimeter. I think, here have been discussion about current amount long time ago...cant remember all...

GOOD ADVISE: Take Your old filter away from inside tank and put to that place suitable pipe. Buy new filter from Ducati, or BMW dealer and put new one to output line of tank to upper side of clutch cover, tight it to frame with Panduit from where it is very easy to change, when need to do it. I make such and i am very happy about that small modification

Take old filter to BMW mc shop(or Ducati surely) and they sell U new filter. You can maybe find it cheaper from car store, like i did.

Filter is made by KNECHT and code is: KL 145 This KNECHT is connected some way to MAHLE concern, i can read it from my filter package