F 700 GS 18 tooth front sprocket upgrade

[Ash]

A chap in the United states posted how he had changed his front sprocket on his 700 GS to an 18 tooth.
From the standard 17T.
He's said the revs dropped by 500+ Rpm in top gear & bike fealt mush less harsh at motorway speeds.

Last week I did 2600 miles across Holland, Germany, Czech Republic, Poland and also fealt the lower revs would be a bonus not to mention the fuel savings.
So ordered an 18T sprocket via eBay for £24 incl p&p.
Hardly going to break the bank.
I will report back once it's fitted.
I am aware I will lose a bit if exceleration, but it's got plenty of spare power low down, so I'm hoping it's a worthwhile upgrade...

 

[slparry]

I have an F700GS 17 tooth one awaiting fitting on my F800GS for the same reasons you mention, I will get around to fitting it one day

 

[dmilne]

I was just reading (yawn) through the many pages of my insurance policy to see what was and was not covered. Under MODIFICATIONS one of the items mentioned was changing the sprockets.
So.... don't shout about it...?

 

[frenchy3]

I have been meaning to do the same thing

I have an F700GS 17 tooth one awaiting fitting on my F800GS for the same reasons you mention, I will get around to fitting it one day

 

[Smythson]

The AFAM no longer fits - they changed the splines by a few mm in the last few years. That sprocket (if the same as the one I got this year) is intended for an Aprilla with similar but not exactly the same splines.

If you do go for it you'll have to remove a bit of the swingarm guard as the sprocket is too wide but as i said it probably won't fit. (on an '09 658)

If it does fit do post up because it means my splines have changed shape in the last few years!

Best,

S

 

[Ash]

Well took bike & 18th AFAM front sprocket to my mates workshop.
For him to fit, well he did offer & my u/s hands & arms make spannering somewhat a chore
Pic 1 old sprocket on floor.
Pic 2 new sprocket fitted.

 

[Ash]

No trimming of plastic chain / sprocket gaurd was required.
New sprocket fitted straight on.

Revs have been reduced by between 500 & 600 RPM's

60 MPH in 6th gear is now just over 3k RPM
70 MPH in 6th gear is now just under 4k RPM
A tad under 80MPH is now just over 4.2k RPM.

Pictures are of the speedo / rev counter after change over of sprocket.

No problem at very low speed in 1st gear.
Pulls cleanly through all gears & no noticeable loss in acceleration.

It has made riding much better, last week during my 2600 mile Euro blast cruising at 70 - 85 MPH seemed a tad harsh even with the Rox Anti-Vibration risers I have fitted.

This afternoon I cruised one the A34 at 70 - 80 MPH for about 16 miles & the bike seemed much happier / smoother.

Of course now it's reving between 500 - 600 RPM less than b4 fuel consumption must improve.
500 to 600 little squirts of fuel less per minute must equal better MPG.

All in all very happy with the result & methinks I will get back my £24 sprocket cost back PDQ.

Last week I went abroad with an F 800 GT & although he is a few stone lighter, has a belt driven bike & has a full fairing he saved between €3 & €4 per fill up, thats quite a saving over 8 days during between 2 & 4 fuel ups per riding days.

I know the GS is duel use so can never equal a road bike in economy but if I can get closer the the RT's fuel economy & smoother bike then a happy bunny I will be...

100% recommend this simply upgrade & in total took less than 20 minutes to compete...

 

[JJH]

All things beeing = the fuel consumption would improve. All things are not = and just because you are running at less rpm does not nescessarley mean better mpg. Why? Because you may have to use larger throttle openings to pull the higher gearing. Good and interesting post. I done the mod myself on my GSA 16 tooth to 17 if I remember correctly. Didn't notice much improvement in mpg but the lower rpm made it worthwhile. Gone back to 1200 so gearing left alone. JJH

 

[Reggie P]

All things beeing = the fuel consumption would improve. All things are not = and just because you are running at less rpm does not nescessarley mean better mpg. Why? Because you may have to use larger throttle openings to pull the higher gearing. Good and interesting post. I done the mod myself on my GSA 16 tooth to 17 if I remember correctly. Didn't notice much improvement in mpg but the lower rpm made it worthwhile. Gone back to 1200 so gearing left alone. JJH

Sorry , if this was true .... why would car manufacturers put incredibly tall gearing on their products ?
My car does 1900rpm at 90 mph... its all about emission figures.

Like you I have the 1200 now ( though miss the sheer joy and playfulness of the 800 !)
If i still owned one I would do as ash did... and get better economy too !

 

[JJH]

What size is the engine in your car? To take your arguement to its logical conclusion why not make the gearing even taller? How come a escort 1100 was less fuel efficient than a 1300? Because it wasn't able to pull the gearing. Don't forget I'm talking from experience. JJH

 

[Ash]

Even if the fuel consumption stays the same.
Smoother running engine is a big bonus to someone like me that has hands that are semi numb 95% of the time.
So I will be more than happy for 24 notes & 20 minutes of my mates time....

 

[Norfolk Tiger]

Even if the fuel consumption stays the same.
Smoother running engine is a big bonus to someone like me that has hands that are semi numb 95% of the time.
So I will be more than happy for 24 notes & 20 minutes of my mates time....

Good work just make sure you keep the old sprocket should the future owner wants it back standard

 

[Ash]

Good work just make sure you keep the old sprocket should the future owner wants it back standard

Baaaaaasstaaaaaaard

Made I larf though " future owner "

 

[smudger64]

No trimming of plastic chain / sprocket gaurd was required.
New sprocket fitted straight on.

Revs have been reduced by between 500 & 600 RPM's

60 MPH in 6th gear is now just over 3k RPM
70 MPH in 6th gear is now just under 4k RPM
A tad under 80MPH is now just over 4.2k RPM.

Pictures are of the speedo / rev counter after change over of sprocket.

No problem at very low speed in 1st gear.
Pulls cleanly through all gears & no noticeable loss in acceleration.

It has made riding much better, last week during my 2600 mile Euro blast cruising at 70 - 85 MPH seemed a tad harsh even with the Rox Anti-Vibration risers I have fitted.

This afternoon I cruised one the A34 at 70 - 80 MPH for about 16 miles & the bike seemed much happier / smoother.

Of course now it's reving between 500 - 600 RPM less than b4 fuel consumption must improve.
500 to 600 little squirts of fuel less per minute must equal better MPG.

All in all very happy with the result & methinks I will get back my £24 sprocket cost back PDQ.

Last week I went abroad with an F 800 GT & although he is a few stone lighter, has a belt driven bike & has a full fairing he saved between €3 & €4 per fill up, thats quite a saving over 8 days during between 2 & 4 fuel ups per riding days.

I know the GS is duel use so can never equal a road bike in economy but if I can get closer the the RT's fuel economy & smoother bike then a happy bunny I will be...

100% recommend this simply upgrade & in total took less than 20 minutes to compete...

Yep, exactly the same experience as me! Smoother and less frantic at 70-80. Can still get the front wheel up, so low down is still more then usable. Well worth the cost and time.

 

[Stevie4scoops]

I changed the front sprocket on my 800GS which for me made it much better. Wish I coud add an extra gear on my XR

 

[Colin]

Is the front sprocket bolt left or right hand thread? what is the torque setting?