I've read a ton of posts regarding battery cable issues and startup. My 06 ST3 had these symptoms: Slow motor turnover and after about 4 seconds the starter didn't want turn over the motor. The battery was less than a year old, so the first (and easiest) thing I looked at was the power feed cables to the starter.
As I read through post after post, the gist of guidance is to buy a cable kit. Since I'm a cheap red-neck from east Tennessee, I did it with home-made tools and repurposed wire for about $12. Bottom line is that after the project the ol' ST acted like it had a new battery. The starter speed improved somewhat, but the biggest difference is that the motor continued to turnover much longer with the new cables, which tells me that the circuit wasn't heating up and losing current.
First, some observations on the stock starter wiring. It's my opinion, the stock cable (looks like 6 gauge) should be adequate. The issue I have is that the crimped connectors are marginal and the crimp itself is exposed and susceptible to oxidation due to it's location. In fact, the ST had a loose fitting rubber cup cover that covered the starter connection upside down (like a tea cup). Any water that got in this area would collect and submerge the connection until it evaporated.
This is what I found when I removed the old cable:
Not only was the post corroded, the crimp in this location had bad oxidation that made the original cable a lost cause.
First thing was to procure/repurpose/reuse/dig through the garage suitable 6 gauge (or 4 if you prefer) multistrand wire. I dropped by one of the local overstock stores (aka glorified indoor flea market) and picked up an oven/range wiring kit:
6 gauge multistrand - check; UL rated - (it can't hurt) check; rated at 250C temp - check. Heck, I had enough wire to fix a dozen Ducks... $8.00
However, that crimp connector had to go. Hardware store had the brass connectors ($4 for a 5-pack).
Well, now the issue is how to make an adequate crimp without the fancy $50 crimp tool for low gauge wire. I'll let the pics do the rest:
Cut a steel sleeve with an internal ID close to the connector OD -
The crimp is solid. Hint: Don't overtighten the crimp and destroy the connector, the connector is soft metal.
I also took Mapp gas and some solder to the connection. Before any NASA scientists starts flaming about the use of solder in a crimp joint, I did it for two main reasons; to improve the mechanical integrity of the connection (vibration resistance) and to eliminate oxidation of the joint -
Add some heat shrink, and the final result -
Here is the installed look (battery - solenoid - starter) -
The result is that I went from having to jump the bike off if it sit for longer than a week to not having to worry about it. I could have added a ground from the starter, but wanted to try this first (this was good enough for me).
Hope this helps.