A top end rebuild is required when compression is low on your cylinders. You'll need to get yourself a Compression Tester from someplace like Supercheap Auto, to check the compression. A rebuild kit is around the AU$400 mark).

You can get an HRC 030 card by contacting the guys from TYGA Performance or TSR-World. Even though it's not listed on their website, they may still be able to source it for you. Expect to pay around the AU$400 mark for one of these cards. A wire splice is required after fitting the card. Read here for more info.

Keep your stroker maintained; feed it quality fully synthetic 2 stroke motorcycle oil like Motul 600/Castrol Race2/or other quality 2T oil... and not lawn mower oil!

Ensure your Power Valves are opening and closing freely. They tend to get carbon build up and can get stuck which can cause a loss in power.

I'm sure there is more, but I can't be arsed reciting them all now as I actually have work to do that I can't put off any longer
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Jerry Lai
NSR250 [MC21SP]