Technical Rotax 125 chain

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Bullseye

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Hi
I have a rotax 125, I’m a bit of a novice and need some help.
Can someone help me in telling me How I work out what size sprockets goes with 108 link chain
Or explain to me how I work it out.
Cheers
 
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Adam

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As a rough guide or example - Front sprocket teeth (12) + rear sprocket teeth (89) + 10 = 111. Round it up = 112 Link Chain.

Use the correct gearing you want both front and rear sprockets, then get a chain to suite the gearing.


 

Bullseye

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Ok thanks mate .
 
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Adam

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What track are you going to test/drive at? Might be able to help you out with correct gearing and chain.
 

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I go to Angmering race way at the oval
 

Bullseye

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I have a 12 tooth engine sprocket u said a 89t sprocket and 112 link chain would that be best . Because every time I put a new spoket on it just rips it up and now it’s done it to my engine sprocket
 

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I have a 12 tooth engine sprocket u said a 89t sprocket and 112 link chain would that be best . Because every time I put a new spoket on it just rips it up and now it’s done it to my engine sprocket
89t rear was just an example how to work out what chain length you need. I don't have a clue what gearing you need to Angmering tbh! Bets off doing some testing to see what ratio works best for you. Ask some of the other lads at the track and see what they are running. You can use our gearing calculator to estimate top speeds etc etc.

With chewing up sprockets it could be a few things. Chain too loose or too tight. Sprocket carrier out of alignment. Bent axle. Axle moving/loose. Damaged chain. No chain lube/spray.
 

Bullseye

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Ok thank u for your help really appreciate it . I’ve just put a new axle on last weekend so will try all the things u have suggested . I’m probably going to sound really thick but how do u find out what gear ratio I have
 

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Ok thank u for your help really appreciate it . I’ve just put a new axle on last weekend so will try all the things u have suggested . I’m probably going to sound really thick but how do u find out what gear ratio I have
No worries! Defo check the alignment and also check to see if the grub screws are still tight! I always lock tight them in.

Keep the 12t on the front. Check to see what rear sprocket you have, should have a number stamped on it, which will be the amount of teeth it has. If you want more acceleration then add a bigger rear sprocket. If you want more top then add a smaller rear sprocket. A few teeth make quite a bigger difference.

What engine are you using? Rotax I assume?
 

Bullseye

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Ok will do thanks . I have a 88t sprocket on with 12t engine sprocket. It’s a rotax 125 senior max . Where u based and what tracks do u use
 

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