Anybody had experience with getting a bit more road speed out of a XT 600E by changing the sprockets? The bike will be loaded and travelling from UK to Faro for the bike rally in July, any tips would be appreciated or should I really be using my Trans Alp for this trip? mmmm?

__________________
'We are all in the gutter, but some of us are looking up at the stars' Oscar Wilde

I would think very carefully before doing this. My own bike (2005 Enfield Electra X) has a one tooth bigger gearbox sprocket fitted by the PO, no doubt done with the intention of increasing the cruising speed by 5%.
Unfortunately it does not really improve things overall. It dislikes long inclines and headwinds and I spend a lot of time in fourth instead of being in Fifth gear. It also makes low speeds ( 30 mph limits) nigh on impossible in top gear.
In a very real sense it detracts from the riding experience. In the next few weeks despite the amount of work involved I will replace that sprocket with the original size one prior to making any lengthy trips.

This move also is not so likely to give any mileage increase commiserate with the higher gearing because although at any given speed it may be revving slower, it also need a corresponding wider throttle opening.

I personally haven't but it's a matter of how you like to ride you XT...

There is a calculator on here somewhere that you can enter the sprocket sizes you want that it'll tell you how many chain links your chain has to be, what the ratio will be, what speed you should obtain and the difference in % of RPM you will get at a determinate speed...


Someone post it on here as I don't remember where it is!!

btw, what is the actual date of the bike festival in Faro?
I might consider on going with a friend on his Virago 650


Vando

oldbmw at a given speed it would need LESS throttle... not more... at a determined throttle position because if he gives it more throttle, at the same RPM as with the stock gearing he would be going somewhat faster

no?

No. OldBMW is right. The engine is revving slower and therefore making less power (power = torque x revs), so you have to open the throttle to compensate. This negates any advantage of using a higher gear.

Illustration: I once towed a caravan for about 300 miles in France in an automatic V8 Range Rover. For the whole of this stretch, I accidentally left the autobox in 3 rather than D. When I came to fill up, I was expecting a massive rise in consumption. In fact, the fuel consumption was exactly the same, to one decimal place. The engine had done more revolutions, but had used the same amount of fuel, i.e. each revolution of the engine used less fuel, which indicates that the throttle was not open as wide.

(For the curious, the fuel consumption was 14.7 mpg or 19.2 litres per 100km. Ouch.)

__________________
2006 XT660R daily ride, 1994 XT600E about to be reborn, Blog: http://goingfastgettingnowhere.blogspot.com/

humm... think of it like this:

with 15/45 at full throttle max RPM...hypothetically making 160km/h top speed..........the carburetor is giving the maximum fuel it can give!

now with 16/45 at full throttle max RPM...hypothetically making 170km/h top speed .........again the carburetor is giving the same maximum fuel it can give which is the same amount as with 15/45!

ok...

now with the 16/45 at 160km/h you won't need full throttle and the revs will be lower!

The whole point on going with a taller gear is to give the same fuel consumption, at the same RPM but at a faster speed!

Which is the same as saying that at the same maximum speed as you can get with a 15/45 but with the 16/45 gear it will need less revs which means less throttle soooo less fuel consumption (in terms of km per litre or mpg)

THIS IS IF you don't always ride like.... if you were in 4th gear at slow speeds and always give full throttle for hard acceleration...NOW this defeats the whole purpose of having a taller gearing which is also not an engine-saver way to ride....

The link to the sprocket/chain calculator is Gearing Commander: Motorcycle Gearing Ratio Sprocket RPM Speed Chain Calculator

Cheers.

The rally in Faro is 15th to 18th july, if you are going let me know maybe we can meet for a . Thanks everone for the info, i take it on board that messing with the gearing may not make that much difference and after riding my XT earlier today (which is quite new to me) I think that changing the gearing might not be the best idea after all. I was interested to hear about the Enfield experience and putting it back to standard speaks volumes. Thanks everone a good cheap lesson... I think I will spend my money on making that seat a bit more comfortable!

__________________
'We are all in the gutter, but some of us are looking up at the stars' Oscar Wilde

Standard is 15/45 (if i recall).. Thats good upto 65-70mph on a loaded bike.

I tried LOADS of combos on this bike.

15/43 gives a cruising speed of about 80 mph but the engine really isnt powerful to pull it smoothly. You end up over revving 4th gear to get enough revs to handle 5th at top speed. It doesnt work well at all.

15/44 was the best in my opinion. The bikes suspension, height and handling really isnt upto any higher cruising speed. Enjoy 70 mph !!

If you have a 650 tranny, take that if its a road ride through Europe !

__________________
Did some trips.
Rode some bikes.
Fix them for a living.
Can't say anymore.

Thanks for the info Ted, I know the Tranny is probably the most sensible option but there is a strange draw to the XT, I was planning doing some light off roading on the way down too but nothing the transalp wouldn't manage with ease.. plus it's also a lot more comfy. I'm not one for the easy life but logic might have to prevail... for this trip at least!

__________________
'We are all in the gutter, but some of us are looking up at the stars' Oscar Wilde

My 600e had 16t front and 45t rear when I got it and it struggled to get enough revs to produce enough power in top gear, I dropped to 15/45(std) and it holds a speed much better and gets there easier, it actually goes faster with the lower gearing as the engine needs to rev to pruduce the power to get you there.

No

try this. get your torque wrench out and holding it on the end turn it to 65ft lbs. Now do the same holding half way along the handle. That is how the engine feels IE to travel at the same speed you will need a wider throttle/more pressure. This is because the leverage is less advantageous to the engine, just like holding the torque wrench handle closer to the pivot point.
For any given speed it is a balance of the pressure in the cylinder(s) versus the leverage and the resistance.
at the same speed the resistance is the same. so you are down to balancing the cylinder pressure against the leverage.

Regarding cruising speeds, often I hear here that people want a bike that will cruise all day at 100 mph.
There is no such bike.
not even half a day.
probably not even six hours.
Most bikes struggle to run for much over three hours before needing to stop at a garage.

I like to use the smaller roads, here in France the speed limit for any non dual carriageway is 56 Mph. This is precisely where the Enfield is happiest. Dual carriageway speed limit is 65 Mph which the Enfield can just manage without any drama. Only on the peages (motorways) which I try to avoid can I legally ride faster than my bike is happy. I think this is close to the situation in most of Europe with a few minor differences.
My bike can manage to run for nearly eight hours before needing to stop at a garage. Which means the bike is capable at covering 400 miles legally in the same time a Hyabusa could only cover 382 legally (due to fuel stops). Sadly I could never prove this because I would need to stop before the 400 miles were up

This is gonna be one of those debates - :confused1:


My brains aching with all the possibilities



If you do loads of high speed/motorway riding - and you think its screaming too much - gear it up

If you do more town/backlane riding and its sluggish, gear it down

Simples

This is the whole point,as also made by OldBMW and others. The gearing (gearbox and final drive)is carefully matched by to the engine design so as to enable the best compromise of acceleration, MPG and cruising speed. The only way to make a success of gearing up is to increase the available torque from the engine, usually done by improving the gas flow but also by raising the compression ratios or boring out the engine to a bigger size. There have been many discussions on here about how to release more power from the XT engine, and what the gains might be, especially those to be made by a freer air filter and exhaust system. So unless you're planning to do this kind of work I suggest you leave well alone.

Geoff

I would agree, with one small observation. Manufacturers these days are not free to engineer an ideal compromise between performance and economy, because of noise and emissions laws. Two bikes I have owned recently (Ducati 1000 and Yam XT660R) were both badly over-geared in stock form. This is, I understand, to pass noise regs which measure noise at a certain road speed. Gearing the bike up makes it quieter at the measured speed.

Both bikes had useless 1st gear (the Yam wouldn't plod on a trail, and on the Duke I had to feather the clutch on a tight low-speed turn) and a pointlessly-high top speed. I fitted a +1T sprocket to the gearbox on both bikes and they were transformed from a riding point of view, with a useable 1st gear and much better acceleration through the 'normal' road range. It was interesting that, in both cases, the bigger sprocket was available from the manufacturer as an accessory part.

I would argue that, by doing this, I returned the bikes to the gearing that was best for normal use, and that without the noise/emissions regs that is what the manufacturers would have given us in the first place.

__________________
2006 XT660R daily ride, 1994 XT600E about to be reborn, Blog: http://goingfastgettingnowhere.blogspot.com/