My TX250 with a 156cc (200 piston) converision started knocking yesterday during a trial. It was fine when cooled down again but knocked like hell on the over run when hot. dong dong dong. Big end or piston slap?

Info, What does the plug look like? Has it been sitting a long time? If the rod or bearing is bad, it cares not if it is hot or cold.

Edited December 31, 201312 yr by lineaway

Sounds like she's getting hot, Possibly clogged exhaust? Maybe too lean on pilot jet? Ty350's do that if you try to trail ride them,if allowed to cool off just a bit as if walking a section they do fine.

knocking / pinging = most cases too lean.

- right gasoline with enough octane?

- clogged carburator, here the jets?

- could be ignition, may be to early?