Greetings all,
I have been using the Motobatt batteries for my last few replacements, finding the double terminal setup to be really convenient(see my post about installing a Fuzebox), and the batteries had previously been long-lasting. Unfortunately, the last one I had purchased failed after only one season, and the two local dealers no longer carry Motobatt, as they had issues with their dealer servicing.
I wanted to stick with an AGM type battery, so decided a Yuasa would be a good choice, as they have a good reputation here in the states. Calling them and receiving excellent customer service, I discovered the original battery in our bikes was a YB14LA2, supplied by Yuasa. This has been replaced with a newer AGM type, which is a YTX14-AHL-BS. It has 210 CCA, and has the positive terminal on the left as you face the front of the bike, which is where I need it on my bike.
The very nice lady at Yuasa told me that they sell the exact same battery to Battery Mart, part #MOSM62H4L, where it is known as a Motocross brand. Price was only $89.95 with free FedEx shipping (you have to choose it from the drop-down menu as UPS is the charged default), which is about $40 less than most other retailers. I have one on the way, and will report back in the future as to its longevity.
The most important thing is to have a good charge in the battery when starting, so the Sprag clutch doesn't die. Better to replace an average brand every few years than flog one to death. I had a MotoBatt on mine for a few years, and it was OK, but when it died, it wasn't worth the differential to a midrange AGM.
I bought a Motobatt once & it lasted just over a year on my 955i. Replaced with a Yuasa battery & it's still going strong after 3 years.
I also had (briefly) a second 955i that came with a Motobatt. Don't know how old it was but it held a charge for less than a week if not used. Replaced with a Powerline battery, which lasted 2 years with intermittent use.
Currently have a Yuasa battery on my Trophy 1200. 3 years old & still going strong.
To be fair, as London_phill says, any mid-range AGM battery will do the job. If you think about it, the charging circuit was made for a lead-acid battery, and the AGM battery is essentially a non spill lead-acid battery, so you can't go far wrong.