New sprocket, Slugish bike ?

[Stag]

To begin with i owned a hyosung gt125r, I then bought a 250cc engine for it, and put it in the frame (Common knowledge this can be done easily for the series of bike) For the first 10 or so miles i rode the bike, with the same 125r sprockets and chain. 52 teeth for the rear and 14 teeth on the engine.

The acceleration was insane and really blew me away for a 250cc, Not sluggish at all. The new sprockets are much larger, The Front engine one being 15 teeth, and a overall much bigger sprocket; The rear being 42 teeth.

Are these new much larger sprockets the reason for my sluggish bike, If so can anyone recommend me a better sprocket set i can buy for a faster acceleration ? i dont care about top speed

[Kickstart]

Hi

Would make it a bit more sluggish in 1st (rest of the time you can just sit a gear lower for the same effect), but think stock gearing is meant to be 14:46. 14:42 would be 10% higher than standard

All the best

Katy
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Stag]

[Kickstart]

Hi

For more acceleration (if you don't want to play with the gearbox) you need a smaller front or larger rear sprocket. But 1 tooth on the front has about the same effect as 3 on the back. You might not be able to use a larger rear without a longer chain, but a smaller front means you probably can take up the slack with the adjusters

All the best

Kty
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[cresad]

Hi

The best way to think about gearing is to look at the front where the smaller the cog/sprocket ( no; of teeth ) the more times it has to turn to turn the rear , and the rear works the other way around - the smaller the sprocket ( no; of teeth ) the lower the gearing ( the slower it'll be ).

As you've dropped 1 tooth on the front and 10 teeth on the rear , I would be tempted to go to 46 / 48 on the rear to get better acceleration

Adam

[Rogerborg]

Yup, JT Sprockets confirms that the GT125R is 14/52 as stock, and the 250R should be 14/46.

Why did you change the sprockets, and why 15/42?

Also, you said that the new sprockets, plural, are larger than the old ones. How can a 42 be larger than a 52, if it has the same pitch?
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike