Front sprocket torque?
 

I'll be changing the front sprocket later today and was wondering if anyone knows how much torque to use?

Hi,
it's 120 Nm.

Thanks!

So, I finally got to change the front sprocket. 14T down from 15.

I dunno.. Maybe I was expecting too much, but I can't say I notice all that much of a difference. My motivation for changing it was making it go slower in first and second gear, making offroad a bit easier on the clutch and such (hey rhyme!). I guess it must go a bit slower, but my initial test driving around the parking lot wasn't all that great.

It did however feel a bit friskier going from 20-100 km/h

And now a question - Where does the bike get its speed reading from? Before changing the sprocket I was going somewhere around 105-110 km/h at 4000 rpm. With the new sprocket, it's more or less exactly the same?

Gearbox output shaft, so nothing you do will change the ratio between indicated speed and rpm. You aren't doing the same real speed as before though.

5'ish hour highway haul today, and yeah... I'm NOT doing the same speeds as before :D
I brought a GPS along and it seems like I'm roughly 15 km/h lower than indicated on the speedo.

Since 1st and 2nd gear aren't as slow as I was hoping for, I'm kind of regretting changing the sprocket. Those 5 highway hours were tiresome. 5k+ rpm all the way. Nonstop rain didn't help, though. Hopefully the offroad trip planned for this weekend will make up for it!

I'm pretty sure you will notice the difference once you take the bike off road - you'll stay in second rather than chopping down to first more often. The down side is it will ware more quickly than the 15th. More miles on the engine will also help that ability to stay in a higher gear + any mods on the air and exhaust side - sorry not sure what mods you have already done to the engine performance.

I have no mods to the engine and it's as quick as a modded bike. lol. 14 teeth is a must for off road. If you do mainly tarmac miles I wouldn't bother. Again, if you do mainly off road, you don't need a power mod anyway, it has plenty power for that. :happy5:

It aint all about power - its also the ability of the engine to pick up at low revs.

This.

i feel the same. my problem is though im 50% off road.... and 50% on road.

This is why i cant decide on a 14T sprocket :)

Going from 15:45 to 14:45 is only about a 7% difference in ratio. Therefore, if you just learn to ride 7% faster off-road, you won't need to change your gearing and compromise the bike for road use :D

Or, do the fuelling, filter and exhaust mods and you'll find the bike will pull from ~2000 rpm rather than ~3000rpm, which is the same as dropping your gearing by ~30% (which probably isn't even possible) and again, doesn't compromise the bike for road use.

+1 on that. I found that sorting the fuelling made the huge difference to tractability and flexibilty on and off road. That extra 1K rpm makes a really BIG difference.

To back up the last two comments - at 50% and 50% I would stay with the 15th. The first thing I did was fit the 14th because at the time most of the riding I was doing was off road and as I have said in the past it was a good and cheap idea at the time. I then fitted the kev mod, stage 2 and have recently gone back to the 15th as I plan to spend more time on long tarmac runs rather than off road and because of ware issues with the 14th.
Now I find that with more mileage on the engine, the standard 15th and the mods I can get the same performance down low off road without the 14th fitted. In my instance the off road issue was with low down grunt not power.
I can fully understand why anybody who does a lot of 'technical' off road stuff would wish to fit the 14th - but............if you are also doing a lot of tarmac miles consider putting more miles on the clock and doing the air and exhaust mods as a long term 'fix'. Yes a more expensive fix probably, but over the life of the bike ...well who knows?

i get what you guys are saying about if you sort the fueling it changes the bike just like changing the sprocket does...but...i cant "sort" the fueling as that means changing the zorst...which makes it louder...and i HATE loud zorsts....

......am i right in thinking my only other option is to cut the CAT out of the standard pipe? (i know this makes it a bit louder but not "single MTC loud")

Tar

Earplugs!

I can understand that - I am always aware of noise when off road and would love a quieter one.

Mines quiet because I have not felt the need to change it. I'm happy with the way the bike performs and I like the 14 tooth sprocket. Each to their own I suppose.

You'll find the biggest gain comes from the air filter and fuelling mod, less so the exhaust, so you could fit a DNA filter, remove the snorkle, add a Kev mod and gain flexibility without noise. Such mods won't break the bank either!

In fact the two things you'll need are in the for sale section here

oh right...i think ive miss understood all this then as i thought you couldnt do the DNA filter, snorkel removal and a Kev mod WITHOUT changing to a free flowing exhaust?? hence me enquring about cutting the CAT out to make it free flowing???

Phil, shove a 14 tooth sprocket on to try it. A cheap fix for me.

phil ten, I have just done this mod and can confirm that the extra low down grunt is well worth it.
A couple of weeks ago I got in touch with the 'Captain' and he arranged a filter, but I was running out of time before a trip around Ireland.
I got in touch with Kev who advised me not to run the new filter without the 'Kev mod' because of the increased airflow.
One very kind forum member saw my dilema and gave me a Kev mod which I fitted very easily.
Then I fitted a brand new pair of tyres (TKC's) as I knew I would put some serious mileage on my bike for the trip.
This was a camping trip down from Yorkshire to south Wales, over the ferry to Ireland, up the West coast to meet up with some Thumper club members in Northern Ireland for a couple of evenings and then ferry back over to Scotland for a haggis in 8 days!

1500 miles and I've nearly wrecked the rear tyre!!!:120:

Anyone that knows me will tell you that I do not travel lightly and like to ride with enthusiasm. The engine characteristics have really changed, the bike will pull from 2k up to fourth gear and goes like stink now. Anyone who has travelled in Ireland will know that there are very few dual carriageways especially in the South so when I hads to overtake I just gave it plenty.:o

Should have put road tyres on really but didn't expect to appreciate such an improvement. I did the mod the day I set off so I did not have time to assess the situation. I do have a standard exhaust by the way.
I set the fuelling mod at the 4 o clock position and the bike still pops on the overrun. Despite the feel of an increase in power I was still getting a good 200 miles before reserve which I always did which was also a concern. It really does appear that the engine is just working better and not stifled.

Single can next methinks!

My thanks to Kev, Captain and Dave.:wub:

Will post pics of 'damage' to tyre.

Hope this helps.

Is it worth changing to a 14 front sprocket when doing about 70% offroading? How much different would it be?
Is there any difference between changing the front or rear sprocket??

i "think" the difference is just wear rate?? i also "think" that 1 tooth down on the front is 2 up on the back? which will need a longer chain.. i "think".

I "think" i may be wrong though :) :) usually am :022:

Based on having fitted a smaller front sprocket to several bikes, and specifically my old 2004 XTR:

1. One tooth on the front is equivalent to three on the back. So changing the front sprocket is a relatively coarse adjustment, and if you want to fine tune the final drive ratio you will need to change the rear by one or two teeth.

2. It makes the bike noticeably livelier off the mark and more responsive on the road. It also reduces top speed a little, and increases engine revs for any given cruising speed. As the top speed on any naked bike is limited by your neck muscles, the reduced top speed may not be relevant.

3. My 2004 had quite bad snatching at low revs and it definitely improved with the smaller cog.

4. Fitting a smaller front cog, you will almost certainly not need to alter the chain (I didn't). With a larger rear, you may have to. It will depend on the wear of the existing chain and how much movement you have left in the adjusters.

5. Either change will ****** up your speedo reading, making it over-read by around 7% (on top of any existing inaccuracy). This can be rectified by fitting a speedo healer (���).

6. Theoretically, as the smaller sprocket makes the chain articulate through a bigger angle every revolution, it will increase chain wear, and fitting a larger rear would be kinder to the chain. However, I doubt if any increased wear is significant (bearing in mind the multitude of wear factors on an exposed chain) and I certainly didn't notice any ill effects.

For the modest cost and ease of modification, I reckoned this was well worth while on my 04. As the 06 doesn't have the jerkiness off idle, and I don't do any technical off-road stuff, I won't be bothering with it on the new bike. I like the long-legged feeling of the standard setup, and the nice 15/45 or 1:3 satisfies my inner OCD.

Hope that is some help.

I'm like you , I hate loud bikes..but the Metal Mule 2 into 1 system
is not to loud with the baffle in... And they save a lot of high weight &
give 50mm more ground clearance with skid/bash plate fitted...

I run a 14T sprocket.. I fined it great...makes a big diffrent's on river crossings..
you can go that bit slower in 1st...

I already has the MTC Single can, and I would order the DNA Stage 1 & Stage 2 (3) filters including the DNA airbox cover, and also Kevs fuel mod this week. Has anyone tried the 14T sprocket with this combination of mods?

I've spent a bit of time lately riding an MT-03, which is the same motor but has 15:47 gearing as stock (not far off the 14:45 you are proposing). It's funny for about five minutes, then you just keep trying to change up another gear, and being annoyed when there isn't one.

If you've got the filter/fuelling/exhaust mods, you've already got far more bottom end than the sprocket change will give you.

And ultimately, you don't need to be riding that slowly. Really.

Mt-03's really do wheelie quite well though

I like 14 off road and 15 for open road work,but saying that 14 better around town.:023:Open pipe power difference to standard pipe N/A noise its great,but the best improvement is the weight loss its great.:mbounce:Iv had snorkel in out shake it all about .Change fueling is best mod,:sweat:

I only tried once, but didn't think so. Stiff shock and more than half the weight on the front wheel, as opposed to the height, squishiness, and rearward weight distribution of the Ten. I can't wheelie for **** though, as you know - but the best I can do is on the Ten.

HERE'S A QUICKIE
Just read all through this post and very interesting BUT anyone gone UP to 16t on the front ? Just a thought but would it give better fuel consumsion ?
Cheers Phil

This has come up on virtually every forum I have been a member of. I would reckon the answer is very little. All that raising the gearing does is slow the engine revs down for any given speed. This will reduce the frictional losses in the engine and transmission, but at any decent road speed these are a small proportion of the total work done by the engine, the vast majority of which is in overcoming air resistance. Let's say you raise the overall gear ratio by 10%, and thereby reduce the engine and transmission losses by 10%. If 90% of the engine's power goes into overcoming air resistance, then raising the gear ratio only reduces the engine's workload by 10% of the remaining 10%, i.e. 1%.

To reduce fuel consumption, lie on the tank, fit a fairing, or just ride 10 mph slower, but your overall gearing ratio will make little difference. You are also raising the road speed at which peak torque is reached, meaning that the bike might struggle to maintain a decent cruise.

Two examples from experience (both car-related, but the principle is the same):

Series 2 Land Rover - fitted Fairey overdrive, quieter at speed but only 1 mpg improvement in fuel consumption.

Range Rover 4.6 V8 - towing a caravan on French autoroute, left it in 3rd gear rather than Drive by accident for 200 miles approx. Expecting massive fuel penalty, in fact it made no difference at all.

It's pretty much energy in = work out, and for a bike most of that is air resistance.

Just some thoughts. I am not an expert.

Than settles it then !!!!
It was more of an idea than a reality as once or twice a year i blast back to the UK to see family , around a 2000 mile return and i only really stay there for a long W/E
Phil

at some point in the near future im going to need a new chain & sprocket set. Was thinking of going just 1 up on the back..so 46? (45 standard isnt it?)

will the OEM chain length be ok?

Late answer, but no, you will need a 112 length chain if you got 1 tooth up on the rear sprocket.

I have just ordered 15/46 with a DID VX2 520, 112 length chain.