plug gap help

[chilly]

my brother in law just rang about his lads learner bike running rough. its a jinlun texan and is a 125 twin chopper styled thing . he has only had it a day and all is not well. it ticks over nicely and revs ok but when he rides it it is powerless and backfires all the time. i told him to check for leaks and look at air filter and clean and gap the plugs. other than that i dont really know. any ideas?

[Phil TK]

Sounds like intake leak leaning it off, hence no power under load. Loosening off the carb rubbers and jiggling the carb so that it sits nicely square in the rubber and then a good tightening up again is the first thing I'd do with those symptoms.