R1150gs Alternator Swap

[Neil W]

Just a quick one, the 40a denso alternator on my 1999 1150 is overcharging @14.9 volts under load and I have in my possesion a shiny 50a Bosch one (its only done a 1000 miles ).

Before I mess about stripping out the old one I take it that they are a straight swap .

 

[littleredrooster]

Are you sure 14.9 is overcharging? If this measurement is taking immediately after starting, it could still be OK. After a few minutes of running (and assuming your battery isn't goosed and is therefore high resistance), it should settle down to 13.8 - 14.2v

 

[DrFarkoff]

Just a quick one, the 40a denso alternator on my 1999 1150 is overcharging @14.9 volts under load and I have in my possesion a shiny 50a Bosch one (its only done a 1000 miles ).

Before I mess about stripping out the old one I take it that they are a straight swap .

Yes they're interchangeable But a P.I.T.A to get it in and out

 

[Supertech]

14.9 is high, but not overly so. Is your meter a good calibrated one, a Fluke or an Avo? If not I wouldn't condem an expensive unit on the strength of its readings.

15.5 is dangerously high, more normal is 14.4, 13.8 is trickle charging and way too low a figure from the bike's charging system, a reading that low will mean a flat battery sooner rather then later. Don't confuse what a battery charger outputs for service charging with what the bike does, the battery charger isn't expecting heavy loads to be placed on it, the bike's system is.

 

[Stewart H]

if you check the charging voltage after fifteen or twenty minutes of running I expect it will be in the more normal range, automotive alternators (because thats what it is) tend to put back the juice from a cold start fairly quickly then ramp down to a lower rate.

Stewart

 

[Neil W]

14.9 volts with a professional meter on a fully charged battery after the bike has been running for 10 or 15 minutes with the lights switched off.
If they're interchangeable I think I'll change it anyway.

 

[ELIMINATOR]

Is your battery damaged or it's life shorter than expected?

 

[Supertech]

My R1150R charged the battery at 14.8 volts (cheapy maplin meter) from cold start. That was measured at the optimate lead, but only run it for 5 mins as it was on the bike lift still.

 

[johnhorsley5]

On the subject of swapping alternators,
I have Denso unit fitted, but bought a Bosch as a spare.
The diagrams suggest different part numbers for the Bosch belt and the Denso belt.
If/when I swap alternators, do I need to get a different belt and is the pulley different? Can the pulleys get swapped?

 

[johnhorsley5]

On the subject of swapping alternators,
I have Denso unit fitted, but bought a Bosch as a spare.
The diagrams suggest different part numbers for the Bosch belt and the Denso belt.
If/when I swap alternators, do I need to get a different belt and is the pulley different? Can the pulleys get swapped?

Anyone any ideas?

 

[Steptoe]

Anyone any ideas?

Therer are only two different types of belt. Both use the same pulley. The only difference is the length of the belts. The shorter one isn't adjustable, the longer belt is.

But on an 1150 you can use the longer belt on all models if need be. The shorter belt came in with the servo braked bikes. But you haven't said which year of bike you have and what year of bike the spare alternator is from.

 

[sockpuppet]

Remember there was a part change to a maintenance free belt which I think was a bit shorter than then original belt.

Edit: Steptoe beat me to it.

 

[johnhorsley5]

Mine is a 99T R1150GS with a Denso unit. I have no idea what year the Bosch unit came from, probably a bit newer.
I fitted a new belt a few years ago