I've got 14, 15 and 16 cs sprockes, and 45 and 47 at the rea, so lots of possible choices. I also have a new did vx chain lying around

The plan was to ride 15/47 for everyday, and change the cs to 14 for some really fun (used that gearing for an enduro = perfect) and 16/47 for roadtrips on the highway. I bout a chain with extra lengt.

The time will tell what i figure out, i just know its nice to have options. I''ve modfied the Cs sprocket-cover so I wont have to take the gearlever off, saves time and effort.

I'd say go with a 14cs and try it out, it wont kill swingarm or its protection, and you can use stock chain. The bike doesn't gain "much" but it gives it more lov end grunt, and makes the bike more rev-able. A 15/47 is not as agressive as 14/45. btw 15/47 can be done with stock gearing to.

Just to be controversial: I have gone down one tooth on the gearbox sprocket on a couple of bikes (one an XT660R) with no ill effects at all. It will wear the chain slightly faster, as each link turns through a bigger angle, but that's all. No new chain to buy, and it's an easy job to change. It's one of the cheapest and easiest ways to enhance performance that I know of.

Simple way to see what the effect of a change is - divide the rear sprocket teeth by the front. Standard is often 15/45, which gives you 3.00. Going to a 14T on the front would give you 3.21 (lower gearing, better acceleration, lower top speed). Incidentally, that's a change of about 7%, which is quite noticeable, believe me. The only advantage to changing the rear is that you get to make a finer change, as one tooth on the front is equivalent to roughly three on the rear. 14/47 would be a ratio of 3.36, which is 12%, quite a difference.

Fantastic, thanks both for the information.
7% better acceleration is definitely worth having and will suit me better as I don't enjoy the XT on motorways and prefer the twisty county lanes at a lower speed.

I have scrapped the 13 tooth front sprocket idea and ordered 14/47 sprockets earlier today. I will do the front sprocket alone first and add the 47 later. Tyres should be here tomorrow too.

Gearing Commander: Motorcycle Gearing Ratio Sprocket RPM Speed Chain Calculator

I've added the 1990 xt600e, the gearing should be the same from 1990 and up.

Very helpful tool.

Now that is a very clever tool, I like it.

It also confirms the 7% and 12% changes to be expected.

[phew] My maths is still up for it, eh?

:-)

Yes your maths is good :)

My sprockets arrive tomorrow and as I still have the back wheel off from changing the tyre I could fit both sprockets.

Obviously the chain will still fit if I fit the 14 tooth front sprocket but will the existing chain still fit with 14/47?

Jens you mentioned that you have modified your front sprocket cover so that you don't need to take the gear change lever off. Did you just cut off the piece of plastic where the bolt hole is?

My boddy helped me make a new cover in aluminium. Will post a pic on monday :)

I wish I had buddies like that :)

Fitting the header pipes, marving silencer and pipercross filter did not make a noticeable difference to the performance but the second dyno next week will be able to tell for sure one way or the other.
On a 30 mile ride last week it runs fine, acceleration is as smooth as before, no lurching, no hesitation but there were a couple of pops/small backfires on deceleration so it might have leaned out a bit with the modifications.
Maybe I need to wind the mixture screw out 1/2 a turn?

It's possibly because there is no gasket in between silencer and headers. I bought a graphite one but there is no room to get one in as the parts are a tight fit without.

Gotta say I am loving the 14/47 sprockets, just what I wanted. It's great up hills in every gear.

I've been looking at silencers, how do you find the marving silencer?

Did you need to buy a new chain when you changed the sprockets?

You can use he following on a stock chain for sure (i've tried)

15-45 (stock)
15-47
14-45
14-47

ANd ofcourse thing in between, as 15-46 and 14-46 aswell. You can probably gear it a bit higher asweel, but i havent tried. 16-45 should fit to.

I forgot to take photos of my cs-sprocket cover tho' :(

xtremity afaik the marving is not performance enhancing. It should pass the M.O.T though and I like the chrome look. It's a couple of kilos lighter than the stock but no way to get inside the marving if you wanted to.

I used the same chain with the 14/47 sprockets.

For me I love to ride on twisty country lanes, there are loads near me. I am not interested in high speeds. Just to test it today it goes 80 at 6000 RPM but I spend most my time at between 30 and 60 mph.
I actually want to try 13/50 sprockets if they do them to fit the XT600E, anyone know?

Bike runs smoothe, throttle response still feels good after the modifications (headers, silencer, snorkel off, piperx filter, iridium plug), no lurching or stuttering. Just the occasional pop when riding downhill with no throttle and when letting off from full throttle.
It may be because there was no room to fit a gasket between headers and sliencer but the clamp is very tight.

My air/fuel screw was exactly 4 turns out, I tried 4 1/2 and 5 turns out.
Still runs the same.

i assume your talking about the whole exhaust system? the law has no say in what downpipes you use, its the endcan that is stamped and thats not important these days, its the testers "opinion" that counts

i have the motad pipes with lazer pro'duro can, the packing has blown out long ago and its well loud but when the tester questions it its fully stamped up and ive kept the certificate from lazer so he says "well thats fair enough then...."

and, performance wise, dont expect much whatever you spend on it, its a 40hp on a good day air cooled single. if you want performance get a KTM husky husaberg competition bike and service it every 1000mi

Well, here it is, "slightly" delayed. Its nicely made by my mate, and it makes it a lot easier to change the sprocket.

http://peecee.dk/uploads/042010/DSC00631.JPG
http://peecee.dk/uploads/042010/DSC00632.JPG

I have the kedo/devil headers, piperx filter, snorkel off and a marving silencer which I bought because it is road legal and will pass the MoT.

But the marving silencer is restricting the bike so I need a second hand performance enhancing silencer before the next dyno in 11 days time.
So if anyone is selling one or sees one on Ebay for a 4PT please let me know.