Sprocket sizes - Horizons Unlimited

**zorro** · #1 4 Apr 2003

I have just recieved a chain and sprocket set for my 3aj tenere, the sizes are 15t front and 45 t rear but the old set had a 40t rear on , what is the correct size.
Thanks, Bob.

**KlausXT600** · #2 4 Apr 2003

that depends on the year of manufacture.
first make of 3AJ ratio was 15:40
then yamaha changed the primary ratio and some gear ratios and hence the sec. ratio changed to 15:45.
latter one has the additional oil pipe on top of rear crankcase (b/w gearbox and oil filter).
regards
klaus

**Barry Johnson** · #3 23 Jun 2003

Hi Klaus

My 3AJ has the oil line mentioned above - does this mean it's a Mark II? I know Mk II's have longer oil coolers, but looking at photos of various 3AJs it seems that mine is a 'shorty', though it's hard to tell.

Engine/VIN number is 3AJ-006878. There's no 'date of manufacture' on the compliance plate.

Also mine has 15/40 sprockets fitted at the moment. I'm about to replace the chain with 15/45 sprockets however I recall a previous post from you (which I can't find) recommending one rear sprocket size over another for the effect it has on the fifth gear. My 5th does not sound at all happy below 4000 rpm (hence I only engage it at just over 5000rpm in 4th) and I'm worried that a taller sprocket combination will not help the situation.

This question is about sprocket sizes and model versions, NOT 5th gear - I don't want to raise that old chestnut ;-)

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Barry
3AJ Tenere

**FredXTZ** · #4 23 Jun 2003

The 45 makes the final transmission shorter, which is better for the engine/gearbox/wheelies/sand etc.

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Fred, XTZ660, Holland.

**KlausXT600** · #5 24 Jun 2003

if your bike is mkI and sec. ratio is 15/40, the engine should rev at appr. 4200 when speed is 100 km/h.
if it's mkII with this ratio you will get significantly lower revs with this speed.
than you have to use 15/45, or, even better, 14/45.
also for mkI 14/40 is the better choise (see fred's statement).

regards
klaus

**Barry Johnson** · #6 24 Jun 2003

Cheers guys, I'll have a look at my speedo/tacho on the way home tonight, however as 4500rpm equals 110km/h (my current highway speed) I suspect I've got a MkI.

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Barry
3AJ Tenere

**bolla** · #7 15 May 2006

I have to order another chain and sprockets for my 3AJ after being sent the wrong size.
My sprockets are 15/45 and chain length is 53 side plates so 106 links, supplier seems to think this is not right.I will count again but does any one the correct amount of links for 15/45 sprocket set up?
Thanks

**winmac** · #8 16 May 2006

106 is correct.
I currently have 104 links 15/45 on a 34L (don't ask why...) but I find the suspension acts differently with the rear axle far ahead in the swingarm.

**captain haddock** · #9 21 May 2006

Don't get tempted to gear it higher for speed, mine had a 16tooth front sprocket and struggled to hold speed in 5th, I changed it for a 15 tooth and it is now faster with the lower gearing, before it couldn't get up to the revs required to produce the power so kept dropping off.
Happy to say it will now pull 100mph (just...with tail wind) but would struggle to get over 85mph before, not on a public highway you understand as that would be illegal

**goodwoodweirdo** · #10 8 Jun 2006

I currently have a 15/40 and cruising above 100 / 110 kph isn't great.

I guess I have a MK1........

Current speeds are (with 15/40)

100 kph = 4000 rpm
110 kph = 4500 rpm
120 kph = 5000 rpm

I'll go for whatever makes the gearbox happy, but will a 15/45 make it better at crusing speed 120 KPH or worse ?? I guess not from what FREDXTZ says, then from Klaus comment should I go 14/45 ......

Sorry for all the quesitons

Salut Matt