Sito plus exhaust

what changes need to be made to my carb before i fit a sito plus exhaust to a PX200?

You may wont to go up a few sizes depends on what you have in the carb already if it hasn’t been fiddeled with already you should have either a 116 or 118 depends if its auto lube or not.
If i was you and wanted better performance fit a 118 if not already there check the timing 23 BTDC marks on stator (A) also check with strobe, disconect auto lube and mix oil in the tank, if your up to it port the barell, very easy to do most of the work on the exhaust, don’t go any higher just wider, you looking for between 60 - 70% of the bore diameter, on the exhaust i get good results with 65% ( if the bore is 66 then 65% of 66 is 42.9) take off barrel, scrib down to the edges of exhaust using tee square-measure this distance- i use a peace of solder wire- its easy to bend- this may be 35-37- you know you want 43 so cut a peace of soldering wire to this length find the centre, position it over the lines you have already in the barell and mark new edges of the port, then with (whatever you have) file or die grinder remove metal up to new lines, your want a nice rectangular port the centre slightly higher than the corners (top nearest the head) to aid rings back into grooves. Remember to shamfor edges of ports. Rebuild, with new base gasket and see what a differance it makes. You may want to go up even bigger jet, ive used up to a 133 in a standard tune with a few other mods to inlet and a better exhaust should have put on a 30mm but customer wanted to keep standard air box. If you want to tune the inlet then thats a lot longer process and will need to strip the motor.
Pilot jet should be a 55 air screw 1 1/4 to 1 3/4 out.

many thanks, someone said they had put one on with no changes and the engine siezed up, so i may go for the safe option.

thanks again

steve beech
armed forces scooter club (UK Division!)

absolutely none.if youre a bit wary and want to play it safe go up one size on the main jet

stroud valleys(midnight hour)sc est 1984