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The TTR250 FAQ web pages -> TTR250 -> Sprockets, chains and gearing -> Unusual (or maybe not?) gearing 1994 raid
Post Info TOPIC: Unusual (or maybe not?) gearing 1994 raid
deefer


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Unusual (or maybe not?) gearing 1994 raid
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Morning all,

I was doing a bit of reading on the TTR gearing and checked what is currently fitted to the bike i've recently bought  for comparison. It appears i have an 18 front and 57 rear sprocket which seems at odds with a lot of the discussion threads i've seen on the subject of gearing. I was wondering how an 18/57 sprocket combination compares to the more common combos mentioned here like 14/52, 13/50 etc

I've also seen standards gearing is 14/44 so confused why something that different has been fitted in the first place.

The chain and sprockets look in good condition, so if it'll work ok for mainly off road riding and a little on road to get to lanes i'd be reluctant to change it at the moment. I've have however just fitted a 110/100 rear wheel and whilst it doesn't look like it's going to rub there's bugger all clearance so would an different configuration (or just switching out one sprokcet on the existing setup help gain some additional clearance



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TTRfan


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18/57 is the original Yamaha gearing for the Raid. 

The sprockets and chain are 428 and not compatible with the more usual 520 chain & sprockets as fitted to the OEs.

See http://www.ttr250.com/#Pre-Y2K_white_models

Brian



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ttr steve


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Every day is a school day smile



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deefer


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Thanks guys, seems very strange for Yamaha to bring out two very similar variations of bike at the same time but then go to the effort of a different swingarm, chain and sprockets, doesn’t make a lot of sense to me from a sourcing and assembly perspective but I’m sure there was method in the apparent madness 😁

Does anyone know if a 520 chain and sprocket set up would fit or would it interfere with the frame, Speedo pickup etc? I would imagine the speedo wouldn’t read correctly due to the different in front sprocket size.

Or if there are smaller 428 front or rear sprockets available that would then provide some more clearance for the tyre ?

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mossproof


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18/57 is very close to the OE 14/44 ratio so should not make much difference to the speedo if you stick to that. Changing tyre sizes would have more effect I think.
It is quite common to swap to a 520 chain and sprockets I believe.
I would ride it as-is to see if the ratio suits the trails you want to ride, and change if you are riding more technical stuff that requires a bit more finesse.

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Mortown


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I have the 18/57 set up on my 96 Raid..

I'm not overly fussed on swapping it out for a 520 chain if I don't need to, however I'm struggling to source the 18/57 sprockets!

Does anyone have a link to these? Or better yet, a chain/sprocket kit.

Regards,
Scott

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96 TT250R Raid

87 Kawasaki KX500 
ttr steve


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ive never seen a 18 front sprocket or a 57 rear one and I took over from Brian 7 years ago now. I'm suprised an 18 and 57 actually fit, unless the 428 are actually smaller confuseconfuseconfuse

photos please for me edumacation biggrinbiggrin



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mossproof


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428 links are shorter Steve, so you need more teeth for the same circumference sprocket.
The mystery of why Yamaha made the 2 bikes so different remains though. Were they expecting the Raid to have gentler use than the Open Enduro, so a weaker chain would do?

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Mortown


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This is a real headache!

Some models of the DT125 have the same 18/57 arrangement with a 428-134 chain.

The rear sprocket is a perfect match but the front unfortunately has a different shaft size.

The Part No, For the 18T Raid front sprocket is: 4GY-17460-10, there is potentially one available on eBay but it is priced over £100, so no doubt would be more cost effective to do the chain upgrade.

Other than this, it looks like this part isn't common across any other model.

It is insane that Yamaha would produce a one off consumable part just for the Raid.

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