'89 R100GSPD - Battery Options

Hi all, I'm in the market for a replacement battery for my '89 GSPD and after having searched on here and googling the subject I
realise that there are loads of options.

But, could anyone advise me of the biggest battery it's possible to fit whilst retaining the original battery holder.

My bike is a poor starter when it's cold and often requires a lot of cranking. I've reconditioned both carbs and set them up as per the manual but it still struggles to start easily. Once warm it starts and runs fine.

Motorworks list quite a few airhead batteries HERE and the 30Ah jobbie looks huge but I don't want to have to alter the battery holder or the under seat storage bin. The bike is almost 100% original (apart from a couple of small spotlights added by the original owner) and I'd like to keep it that way.



The current battery (see what I did there?) is the one pictured below. I'm not sure if it is big enough or up to original spec.



Any advice appreciated. Steve.

Hi Steve, I buy lawnmower battery's for them! £30 from motor factors and they last forever, I've never had any issues with them at all.

I like Florences post above. I replaced my old un with an oddessey and it has run well, even with 2 months layoffs in winter times without hick ups or poor starting and thats with a seibenrock coversion. WHOOPS shouldn't have said that eh. good luck

I have a Motobatt in my R100 GS , the 20 ah size , and it spins the bike over fine. Importantly it keeps the volts well over 12 even when cranking under the starter load, which helps starting. Leaves a bit space in the tool tray for a compressor and extra tools too.
And is a bit cheaper than the 30 AH size or the G/S type.
The GS was a reluctant starter when I bought it, and not long after a tooth broke off the starter ring and jammed the starter so I replaced it with a cheap Valeo copy from EME and HD battery lead leads from the same source. Has started fine ever since.
I too have found the garden tractor batteries will do the job much better than you would expect considering the low price, but they are usually a wet battery so you have the palaver of topping up, corroding terminals and battery carrier, etc,etc, that you dont get with a AGM like the Motobatt.
Couple of things to check re the starting, one is the wiring harness earth to the frame up near the voltage regulator,never seems to get a clean and tighten up like the other earths, and the plug caps, particularly if you still have the OEM Beru type.
The OEM Crack-o-matic coil will fail sometime if it hasnt already been replaced, and may be on the way out.
EME has sensibly priced plug leads, coils and adjustable voltage regulators which give the modern batteries the extra volt or two that they seem to require.
As it takes me weeks to get parts to Oz I usually just bite the bullet and order everything I might need at the same time - with bikes that are 20 to 40 years old I know I will have to replace them one day so I just get it over with and do the lot, and I hate a bad starting bike!

I have a Varta 30amp on my 1990 R100gs, fitted with HD battery leads from Motorworks, coupled to the Hitachi starter motor. No issues at all.

Steve
Have you checked the valve clearances, as my R80ST became a poor starter until I redid the valves.... now starts fine, hot or cold.

Good luck

Hi all, sorry for the tardiness of my reply I've been very busy of late.
Thanks for all the suggestions above, I've settled on a 30Ah Exide AGM battery from Motorworks as well as a set of HD copper battery leads and new plugs and plug caps.
Apparently these will all help with the poor starting. Bubb, I checked the valve clearances quite recently when I refurbed the carbs but as it's so easy to do I'll check them again.
Beemerboff, does the Crack-O-Matic coil give any symptoms before failing, or does it just generally stop working?
All I'm really trying to do is create a bike that starts easily when hot or cold. This thing has a kickstart but I've never been able to start it using that method even when warm.
I'm no expert on carbs but I can follow instructions and I cleaned and set them up meticulously using the standard settings according to the Bing carburettor manual I got from Motorworks at the same time as I purchased the refurb kits.
Below are some gratuitous pictures of the bike in the garage, because everyone like pictures.



What goes in this hole?

That space is useful for alternative Dyna coils or twin coils for twin plugged bikes.
I have never had a OEM coil fail - I do a fair bit of riding a long way from a repair shopall my parts have to come from overseas, and I had a Dyna lying around, so it went on as soon as I bought the bike.
Some signs of ,er, aftermarket wiring on your bike, including to the starter relay, so might be worth a check to see what the problem was - on my G/S the same pin that the non stock red wire goes to on your bike is the earth for the switch feed, and a intermittent failure in that wire was a exceedingly hard to locate starting problem for me! Harness/ wiring had seen 440,00 hard KM and wast just about at the end of its useful life . Kinda like its owner, if I ever had one!
Ended up replacing all the wiring, relays, minor switches, PCB and bulb holders, VC unit, etc, etc, and for the first time ever everything electrical on the old girl works as intended. DAHMIC -----------.

SteveM said:

What goes in this hole?

Click to expand...

Mine has a nice framed view of the air box lid in the hole?

And a mystery connector just behind it. What can it be for?

Olde bikes by mark jackson, on Flickr

I had a lawnmower battery fitted to mine, a 895 if I remember correctly, 30a, it didn't quite fit fully into the holder, but sat on the rear top edge, it was cheap though £43 I think