just changed to an Andrews EV27cam /adjustable pushrods/ Jim's hydliftersin my just stock '93 Evo... rejetted cv carb with 45 slow 180 main jet...exhaust is unrestricted/ stock air filter (so far)/aftermarket ignition module...my problem is bike starts fineand runs at idle butbegins to backfire at fairly low rpms when given fuel...guess I need a few hints at where to look for the problem...I'll start with a compression test and new plugs but like to know what else to check if that doesn't fix things...

 

should have mentioned, backfiring is through exhaust, not carb