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  #1  
Old 21 Jul 2007
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Airhead prep

I have a 1993 R100GSPD which I have ridden far places and without much for problems. It's a Canadian model with 40mm carbs.

Because the shift pawl spring broke, I have the tranny out and getting a rebuild: seals, bearings, springs, inspections and the circlip.

Tis summer I've rebuilt the carbs and installed a new rotor in place of a fried stock unit. 18 months ago I installed a rebuilt shaft (old one looked good). Also a year ago last winter, a rebuilt Bosch replaced the still-working Valeo, and a Thunderchild Diode board with metal mounts replaced the stock board with rubbers. I have a 2 year old Wilbers shock, the stock one is on the shelf with the old diode board, shaft and starter.

I have a steering head bearing kit to install this winter.

To anyone who knows these beasts: any advice as to travel prep? I want to ride to Mexico next May and have an unlikelyhood of bad surprises.

Tom
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  #2  
Old 22 Jul 2007
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travel prep

I'd say you've covered most of this bike's weak points. If the tranny's out, why not consider a lower first and a higher fifth gear, but only if you think you'll need it? I guess your rebuilt drive shaft is greasable? Personally, I'd fit a single seat, bigger windshield, louder horn(s), washable air filter and oil filter (no spares needed), reinforced rear sub frame (simple job), and a better front brake and brake line. Plus of course decent tires (take your pick) and aluminum panniers with matching mounts (take your pick). I'd also have the sump off to check and clean the bottom end, fit new fork seals, fit new brake seals, fit new push rod seals (while you check the heads and valves), grease the wheel bearings with a marine type grease, clean and grease the paralever bearings (probably done already) plus 2 new rubber boots. If you haven't got heated grips then get some.
Do all of that yourself or get someone to show you and take the extra tools with you.

And don't forget to go!
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  #3  
Old 22 Jul 2007
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If you ever need to replace the rotor, don't. Use the new permaneant magnet rotor. This eliminates both the slip rings/brushes and diode board. ( it also chucks out power at lower rpm up to 450watts.
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  #4  
Old 22 Jul 2007
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Magnetology ,beemerology .

I'm not a beemer bloke but I agree with oldbmw, permanent magnet alternators are great ,especially for those flat battery mornings !
I'm working on a conversion for my Yamaha using a Lucas style alternator and solid state reg/rect .
You are luckier because there are already ones out there that will fit an airhead .
Have a good trip !
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  #5  
Old 23 Jul 2007
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Magnet alternator ?



Hi

I am very confused and scared about facing a rotor problem with my R80 on the distant road.
I know I must change the rotor but how?
Can you tell more about permanent magnet alternators and where to find/buy one? Does it solve the problem forever?

Regards,

Samy
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  #6  
Old 23 Jul 2007
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Quote:
Originally Posted by Samy View Post

Hi

I am very confused and scared about facing a rotor problem with my R80 on the distant road.
I know I must change the rotor but how?
Can you tell more about permanent magnet alternators and where to find/buy one? Does it solve the problem forever?

Regards,

Samy
Hi Samy , I did a quick search and found this :
Welcome to Euro Motoelectrics! EnduraLast BMW
Which shows what is needed to do the conversion .

I'm not a BMW expert so my advice is about all bikes in general .
Permanent magnet alternators are better because they do not rely on a battery to be able to work .All you have to do is spin the engine and you can produce electricity to start chargng your battery and get your bike going .
If you have a capacitor wired into your bike you can start your bike [kickstart or bump start ] fairly easily even if the battery is dead.
The regulator/rectifier units that are supplied with them are more reliable too .
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  #7  
Old 23 Jul 2007
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This is the site for Euro motoelectrics Euromotoelectrics: charging and starting systems for motorcycles
Here you will find the charge system. It is very easy to fit and comes with lots of connectors etc. to help with the rewiring. If you are not electrically inclined you can take it to any auto electrician and with the clear instructions supplied, they will be able to sort it out it no time.
The rotor and stator fit easily in the place of the old gear but the regulator need a new place as it is to large to fit in the place of the old one plus it need more cooling.
On the GS I have found that fitting it in the same position as the diode board by mounting it on a plate sideways is the best. You will have to drill some holes in the top of the engine cover to provide air for the cooling.
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Old 23 Jul 2007
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"Permanent magnet alternators are better because they do not rely on a battery to be able to work .All you have to do is spin the engine and you can produce electricity to start charging your battery and get your bike going."

This is not entirely true as damage to the charge system can be caused if it is not connected to a battery. The system might not need the battery to be in good shape but it does need a battery none the less. a generator system like the one fitted by HPN can actually operate without a battery in place. This system is often used for racing where one wants to eliminate the possibility of battery or charge system failure. It is very expensive and involved modification and even need a different crank.
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  #9  
Old 23 Jul 2007
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I did not suggest that the bike should be run without a battery or that the battery should be disconnected , only that the alternator is self exciting and not dependant upon having a charged battery to excite it .
Therefore it will be more reliable .

To illustrate my point : My Norton has a bad battery but it has a perm magnet alternator AND a capacitor and starts first kick !


An expensive racing system is irrelevant for a traveller .
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Last edited by Dodger; 23 Jul 2007 at 08:53.
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  #10  
Old 23 Jul 2007
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Alternators, magnet vs brush?

Don't know about the alternators on airheads, but I'd never go for underpowered permanent magnet alternators.

In my use there's:

Headlights: 2x50W=100W
2 heated vests for me and g/f: 2x75W=150W

Add the consumptions of battery recharging, bike starting, ignition, EFI, (ABS if you have one), standard heated grips on BMWs, the rest of lights and gizmos if you have and you're already exceeding 450W alternator which is already considered very high output in permanent magnet alternators field on motorbikes and needs around 5000rpms to produce it. Normally they're around 300-400W max, presumably around 300W or less average because you aren't revving your boxer over 5000rpms most of the time.

My R1100GS stock brushed alternator does 700W which is sufficent for my needs with a bit of reserve and creates 70-80% of it already from 2000rpm or so.

Never replaced anything on two bikes done over 120,000kms, not even the alternator belt that has service interval of 60,000km. So it needs very little maintanance. I do lot of offroad and bad roads here. On travels just in case I carry alternator belt with me that takes very little space and costs little.

Yeah, someday you have to replace the belt, and pulleys + brushes too in more extreme usage, but it's a dead easy job and costs very little.

Considering the surprisingly big amount of problems I've seen with permanent magnet alternators on offroad/big trailie oriented bikes (normally the magnets get cracked because of bike taking constanty bumps, vibrations on bad roads and also bigger output alternators tend to have bigger magnets - more mass makes it more vulnerable to bumps or gyroscopic forces and the magnetic materials used in the alternators aren't exacly very resistant ones), then in my point of view looks like permanent magnet alternator isn't always justified compared to more powerful brushed alternator, especially if you have above average wattage needs like I do (i.e. heated vests, a bit more powerful headlights).

So if you need relatively healthy amount of power, there's no real escape from brushed alternators anyways.

Thus figure out your needs first.

Last edited by Margus; 23 Jul 2007 at 12:05.
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  #11  
Old 23 Jul 2007
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Quote:
Originally Posted by Dodger View Post
I did not suggest that the bike should be run without a battery or that the battery should be disconnected .
I am aware of what you meant but seen in another context the next guy might try to run the bike with the battery disconnected.\

The system from HPN is not so much a expensive racing system but rather a generator system found on most single cylinder off road bikes. It saves weight and is very reliable but if I am correct does not supply a large amperage so will be unsuited for electric suits etc.

What make it expensive in the HPN case is the extensive modifications needed to install the system on the airhead boxer.

Last edited by gsworkshop; 23 Jul 2007 at 16:35.
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  #12  
Old 23 Jul 2007
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Quote:
Originally Posted by Margus View Post
Don't know about the alternators on airheads, but I'd never go for underpowered permanent magnet alternators.

In my use there's:

Headlights: 2x50W=100W
2 heated vests for me and g/f: 2x75W=150W

Add the consumptions of battery recharging, bike starting, ignition, EFI, (ABS if you have one), standard heated grips on BMWs, the rest of lights and gizmos if you have and you're already exceeding 450W alternator which is already considered very high output in permanent magnet alternators field on motorbikes and needs around 5000rpms to produce it. Normally they're around 300-400W max, presumably around 300W or less average because you aren't revving your boxer over 5000rpms most of the time.

My R1100GS stock brushed alternator does 700W which is sufficent for my needs with a bit of reserve and creates 70-80% of it already from 2000rpm or so.

Never replaced anything on two bikes done over 120,000kms, not even the alternator belt that has service interval of 60,000km. So it needs very little maintanance. I do lot of offroad and bad roads here. On travels just in case I carry alternator belt with me that takes very little space and costs little.

Yeah, someday you have to replace the belt, and pulleys + brushes too in more extreme usage, but it's a dead easy job and costs very little.

Considering the surprisingly big amount of problems I've seen with permanent magnet alternators on offroad/big trailie oriented bikes (normally the magnets get cracked because of bike taking constanty bumps, vibrations on bad roads and also bigger output alternators tend to have bigger magnets - more mass makes it more vulnerable to bumps or gyroscopic forces and the magnetic materials used in the alternators aren't exacly very resistant ones), then in my point of view looks like permanent magnet alternator isn't always justified compared to more powerful brushed alternator, especially if you have above average wattage needs like I do (i.e. heated vests, a bit more powerful headlights).

So if you need relatively healthy amount of power, there's no real escape from brushed alternators anyways.

Thus figure out your needs first.
I accept that the car type alternator will output more power but they are not easy to fit to an airhead. In my view the system I proposed offers the most gain for the cost and hassle involved. The 450 watts is more than an airhead would consume even running your heated vests and two headlights.
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  #13  
Old 23 Jul 2007
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Great,

fré
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  #14  
Old 23 Jul 2007
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Thumbs up Permanent magnet alternators

Never heard of the before, but it seems a good alternative to the standard alternator. My diode board and regulator are still fine after nearly 120,000 Kms, but I shot the rotor at 60k, so I'm expecting the current one to last not much longer.

@Margus, I don't think you can really compare the alternators of the old beemers and the later 4-valve generation. I reckon most elements are much more robust on the 1100 or 1150.

Hans
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  #15  
Old 24 Jul 2007
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Exclamation Everything fails at some time

Failure can and do happen on both alternator types -
excited rotors fail open circuit on airheads (happens to a lesser extent on other vehicles too)

Permantat magnet rotors have failures of the rectifire/regulator (all one box). Keep these cool and they last longer.

As for the power requirements .. an airhead G/S or GS in standard condition outputs around 240 watts .. max total .. for get the oilheads 700 watts .. Various people have come up with ways of increasing the electircal power on an airhead .. the most secessfull replace the alternator in total. 450 watts on an airhead is total luxury in terms of electrical power!

--- On my airhead - replaced 2 or 3 rotors .. now carry on bolted to the left crash bar. The old grey ingition coil still works ... and they are supposed to fail .. carry a sapre for that too, but it is considerably smaller and weights much less.
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