Fontyyy's right of course. The MC28 tach is a bloody liar! They seem to be at least 500rpm optimistic, so if it's hitting 12,000 on the tach then it's probably only 11,500 in real numbers.

We used to gear our race 28's used to hit about 12,600 on the tach. This was in SP spec, so no mods to the cylinders. Then we read the rules again....and again....and then tickled the exhaust and transfers to errrr NSR spec and we'd see a healthy 12,800 on the tach. Good job that the guv'na of Harc-Pro was on our team and he was best of pals with the MFJ scrotum'neer.

If a stock mota 28's hitting 12,500 on the tach then it's doing ok, but I'm talking a racer here, so it won't stay together if you hold it full volume for any serious length of time.

SS (Super Sprint) spec 28's will see 13,000+. But that's with a lot of engine work. Piston changes every race. Cranks every 2000kms etc etc.