It really sounds like you have two issues the battery being one of them. If my battery is at all low the bike is hard to start even if it will spin the engine. Modern gas doesn't sit well and it doesn't take long for a nonrunning bike to gum up some and some of these bikes are known to have could starting issues like below even 50 degrees F. So take your pick there are threads covering all these issues in depth.

 

Mine is a an older Schumacher Battery Companion. It looks similar to the Deltran "Battery Tender". I also have too newer Schumachers and a cheap Motostance which has a maintenance voltage of 14.5 volts which is too high IMO. I will charge a batt with it but never leave it connected. The maintenance voltage of the Schumachers is 12.9-13.2.

 

True. The first thing I did when I bought the bike was install a Dynojet kit with a 116 main jet. Before that the bike was hard to start and took 5 minutes to warm up. The ethanolized gas seems to turn to ditchwater in two weeks. It doesn't bother my 3 FI bikes nearly as much as the KLX.

 

A guy on a car forum was having the same trouble and got some replies it might be the key switch.

 

Battery tenders have come a long way in the last 10-15 years. I use the Battery tender juniors for all three my bikes as well as one on the Dodge Diesel with the dual batteries. I have that wired in with the block heater so that on really cold days, it charges the batteries and heats the block. Both the KLX and the XT have been on tenders for 5 years now, and they crank like new. I still have the original battery on my KLX from November of 05.

Here is what I decided long ago though. As some of you know, I wired in a 12v socket on both bikes to run things like a GPS and charging a phone, but more importantly so that I could jump start the bikes if one went dead in the field, but even more importantly I did this so that I could use the tender to reverse charge the battery with a simple plug and play reverse engineered connector.

This has worked flawlessly for over 5 years. But here is the difference with me. I don't leave it on the bikes all winter in fact I only have two chargers between all three of my bikes. What I do is every 3 days or so when I'm tinkering in the garage I pull the plug out of the KLX and plug it into the XT and back and forth every few days, that way in a sense the battery gets a break from what some folks call an overcharge potential situation. I don't really think that these chargers overcharge anymore like they did back in the day, but I thought since its working so great, why not stick to the plan put in place.

Here are a couple of pictures of the charger and the cable I made to jump start the bikes if the need arose, and it did once, because someone used the kill switch she was taught to use in the bike class instead of never touching it and only using the key like I told her too....LOL

 

There is a power/charging plug on my 07 back by the helmet lock, which I use for charging once a month for 1 day. Works great.