well I will let you know in about 3 weeks time what performance I get out of it - stock sprockets and 15T/39T combo

 

Guys will chain lenght need to be changed?

 

That question was answered in my first post to this thread. See the linked thread.

 

16-42? Dude you would have to get a running start down hill just to be able to take off in first. 6th gear would be worthless unless again the downhill part.

 

Agreed.

 

Where is a good place to buy a 15T front sprocket? I can't remember where I got mine and I need a new chain so I want a new front sprocket to go with it though the old one looks OK.

 

Renthal website.

 

Deej, that's essentially the same gearing some run on the SF. Not that a 16 can be fitted, but the pure numbers have a 39/15 = 2.60 final drive where the 42/16 = 2.625, actually making it a shade higher. I've run the 39/15 on my stock engine that is jetted and has the KDX snorkel. On reasonably flat ground I could roll along at 70 not going higher because I like both my money and my license in my wallet, those sneaky patrol show up when you least want it. I wouldn't shift into sixth until over 60. It is kind of like driving my 4.0 Ranger pulling a trailer. I have to let it rev higher in fourth going up freeway grades (hills) but running fifth the rest of the time. You do what you have to do.

If I was running an SF and only doing roads for 90% of the riding I'd do the 39/15. Top gear would be pretty much an "over drive", which it actually is on the 09 and newer with a 21/20 gear, the drive being more teeth than the driven. Run top gear on the flats when it can be run, go to fifth otherwise. What is given up is the lower gearing doing dual sporting needs and the quick acceleration some riders like. Once into the middle it's pretty much normal, you're just in a different gear than you might ordinarily be. Rev all the gears out to higher speeds and use top gear whenever possible, after all there is no mechanical reason to have to run sixth.


I snagged my JT sprocket either on ebay or Amazon, both the front 15 and rear 39.

 

I prefer JT sprockets. I usually buy them on eBay. It's always a good idea to replace the chain with new front and rear sprockets at the same time. They wear together and just replacing one will cause accelerated wear on the new chain or sprocket if you don't replace them at the same time.

 

This might sound thick but what are the signs that your chain and sprockets are wearing out?
Only been riding for less than two years (less than one off-road).