Sprocket Size Change

Questions regarding the DR800

Sprocket Size Change

Postby Chris BIG » Tue Jul 30, 2013 11:12 pm

Currently running 15 /47 teeth on 92 800, want to try out 16 / 44 combo to bring revs down at 120 km/h. Anyone done that? Advice please. Thx
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Re: Sprocket Size Change

Postby BigBob » Wed Jul 31, 2013 8:41 am

The gearing you suggest is way too high
For a start a 16 won`t fit in the front, not unless you lose the case saver, which would be a really stupid idea, as if the chain breaks you will end up with a huge hole in the crankcase. This has happened far too frequently with Bigs for this to be a hollow warning, so please take note.
I`ve tried smaller sprockets on the back and you just end up losing all flexibility and the ride becomes really snatchy if you go down too far.
A 15 front and 46 rear will make a surprisingly big difference even though it`s only 1 tooth, and will feel way more relaxed at cruising speed.
I`m currently running that on one of my SR42 800s and it`s dropped the revs from about 5000 to about 4500 at 70 mph (110 kph).
I would imagine that going to a 16/44 combination would make it completely and utterly unrideable.
I also found that with a 15/46 combination I could use a 114 link chain, though I think the SR43 s/arm is longer so wouldn`t be possible.
I wouldn`t recommend a 15/46 on the 750 as it doesn`t quite have the grunt of the 800, and 15/47 is best.
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Re: Sprocket Size Change

Postby Chris BIG » Wed Jul 31, 2013 11:44 pm

Cool! 15 / 46 it is then, pity I only read some of your advice on the chains too late, first chain snap I was fortunate as the chain flew out the back (luckily no car behind me...) the second time it did damage the engine bay etc. and left me stranded a 100 km's from home. Put a Tsubaki on and it has been holding well, so well that I have now worn my sprocket down to the bone, used to think it was just my weight, length and driving style counting against me until I read some of the posts. Blessings.
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Re: Sprocket Size Change

Postby nug » Wed Jul 31, 2013 11:56 pm

Good choice with the Tsubaki chain :tup: I swear by them. Good chains still need lube though so make it a routine to check your chain & lube it. Most big singles are tough on chains & I have seen chains with over 50% of the side plates starting to crack & fail so keep an eye on them :tup:
Last edited by nug on Thu Aug 01, 2013 12:02 am, edited 1 time in total.
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Re: Sprocket Size Change

Postby Chris BIG » Wed Jul 31, 2013 11:59 pm

:tup:
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Re: Sprocket Size Change

Postby BigBob » Thu Aug 01, 2013 8:26 am

I lube my chain after every ride........you can`t be too careful.
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Re: Sprocket Size Change

Postby Chris BIG » Thu Aug 01, 2013 6:33 pm

Unfortunately I do not get to do "pleasure" riding much, but I do use her every day for commuting on highways (+-52km per day) so lubing takes place weekly. Tried getting a 46 today but what a mission here in CT still no luck but will keep trying.
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Re: Sprocket Size Change

Postby dave#22 » Fri Aug 02, 2013 8:53 pm

Hi Chris, On my mildly tuned SR41 I have got down to a 15/42 (DR 600) (120/90/17 tyre) after some experimentation over the years and I find it quite acceptable for normal use and relaxing on motorways....I think 80mph 5000rpm.
On my SR43 with a 750 crank (727cc) I run a 16/47 (525 chain) with 43 primary gears and that is around the same RPM/Speed. I recently went to Germany on it, two up with luggage and 60mph is about as low as you can go in top, but it made a big difference on the Autobahn criusing @ 130kph, but acceleration in top is best descibed as pedestrian.
And before anyone asks....I fitted a 750 crank because I prefer the smooth 750 engine to the vibrations of the 800, but I do miss the extra few horsepower.
Over to you BigBob,
Dave.
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Re: Sprocket Size Change

Postby BigBob » Fri Aug 02, 2013 9:48 pm

If you prefer it to be geared that high Dave then that`s fine, but personally I hate motorways so gearing that high really doesn`t suit me.
I also prefer the 750 for its relative smoothness
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Re: Sprocket Size Change

Postby nug » Sat Aug 03, 2013 9:53 am

I prefer the smoothness of the 750 as well compared to my 800. Although its not really smooth is it ? just smoother. Having sorted out my exhaust & airbox I find there is not much difference in grunt between the 750 & my SR43 I had.
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