Think this sprocket is due for replacement.

[JeffK]

After 20 K it looks like it is time for a front sprocket replacement.

I bought from my dealer an original 12 t front sprocket.
Number SL-07-12

It looks like a renthal 287-520-12
can anyone verify?

I kept the original chain and rear sprocket (only 20 K on them)

[kingcharles]

I thought the original sprocket was a 14 tooth?

[kingcharles]

Can you check if the measurements match up with either of the attached pictures?
Thanks

[JeffK]

I thought the original sprocket was a 14 tooth?

You are right, I was distracted by the serial number 12.

So 14 T it is.

[JeffK]

Can you check if the measurements match up with either of the attached pictures?
Thanks

Nope they do not match
25=22
21.7=19

[kingcharles]

Hmm, the attached is the best I could find, what do you think?

[JeffK]

Hmm, the attached is the best I could find, what do you think?

Yes, I think this will be good enough...
Looks like Suzuki, right?

[kingcharles]

Yes, I think this will be good enough...
Looks like Suzuki, right?

Good enough is a bit dangerous. Did you measure with a calliper (Schuifmaat)?
Can you also check how thick the sprocket is and if both sides are equal?
Sorry for being such a pain...
Thanks

[JeffK]

Good enough is a bit dangerous. Did you measure with a calliper (Schuifmaat)?
Can you also check how thick the sprocket is and if both sides are equal?
Sorry for being such a pain...
Thanks

yep, but the 19mm could just as well be 19,5
The sprocket is 6 mm thick, and symetrical.

[GSX750ES]

Hmm, the attached is the best I could find, what do you think?

JTF 1439 is the one that fits?
(stock part suzuki GSX R250 R '89)

[Shinysideup]

Sprocket Center in U.S. lists the JTF 1439, but they do not have it, nor do their suppliers. Before I order if from Europe (ebay UK lists it), I want to see what others think about the I.D.

The original is 19 mm I.D. & 22 mm across the base of the splines.

If the JTF 1439 is 22 mm but 19.5 mm I.D., then would not the splines be 0.5 mm more shallow and therefore possibly more likely to strip under full torque?


Why in the hell did Brammo specify such an oddball size, from a Suzuki of 1989??

[JeffK]

I installed the JTF 1439, perfect fit,
On the bike for 5K now, no problems

[Shinysideup]

Great news JeffK! Thanks. I think I'll order 2 or 3, since they're a bit rare.

[Shinysideup]

Great news JeffK! Thanks. I think I'll order 2 or 3, since they're a bit rare.

Amazing, the sprocket came to California from UK in just a couple of days. I noticed it does fit with a little more "slop", but I hope JeffK's experience holds true and it doesn't strip out over time.

I'd be up for having the OEM sprocket copied by CNC if it the price were reasonable. Maybe we could do a group buy? Anybody know a good provider of this service?