One of the nice things about synthetic oils is its nature to produce cleaner exhaust and will over a peroid of time start to clean the piston tops, cylinder heads, exhaust ports - so don't be to much of a hurry to put a finger on Klotz.
A Sea-Doo service tech once told me that the Sea-Doo's will carbon up running the Rotax oils, that they use Johnson outboard engine tuner, spray it in the carbs and on top of the piston tops and let sit overnite, pull the plugs out,turn over the engine several times, reinstalled the plugs, start the engine up a let idle for up to 30 minutes (don't do this time all at once, break it up) keep the rpm's under 5500 for the first 30 minutes and all the carbon deposits are gone - it works I tried it - just take it easy for the first 30 minutes, so you don't scuff the pistons. be aware that there will be a cloud of smoke both at a idle and on the trail until all the engine tuner is burnt out !!!
A Sea-Doo service tech once told me that the Sea-Doo's will carbon up running the Rotax oils, that they use Johnson outboard engine tuner, spray it in the carbs and on top of the piston tops and let sit overnite, pull the plugs out,turn over the engine several times, reinstalled the plugs, start the engine up a let idle for up to 30 minutes (don't do this time all at once, break it up) keep the rpm's under 5500 for the first 30 minutes and all the carbon deposits are gone - it works I tried it - just take it easy for the first 30 minutes, so you don't scuff the pistons. be aware that there will be a cloud of smoke both at a idle and on the trail until all the engine tuner is burnt out !!!