ChinaRiders Forums - View Single Post - ATA-250D with Mikuni 30mm

Rule308 · 10-03-2015, 07:27 PM

The flexible R&D fuel screw didn't seem to want to screw in though the thread pitch and diameter looked identical and seemed to line up with the stock screw side by side, you could feel the number of threads were the same, I think, but when screwing it in it caught and went in about 1/2 turn then stopped, giving me impression it was going to cross thread, so didn't try to push it. It said it was for the Keihin FCR carbs but looks like it will be correct for the Mikuni VM26 PZ30.

Used the extended pilot screw version instead, and had a ton of spitting through carb and sputtering, eventually walked the pilot jet size to largest I had which is the 30 pilot (slow jet) and I'm ordering 35, 40 , 45, 50. Seems like the larger pilot jets finally got it running fairly well.

Does running lean sound louder, noisey, and rich sound lower and more quiet?. The reason is, the ATV has been getting quieter as I go up in pilot jet size. Think I still have to go bigger. Plug looks lean and too clean. White and clean, way to clean. Using new plugs every few jet changes.

What theoretical pilot size should I be running at ~80 degrees, 200 above sea level, K&N with UNI sleeve, add on Walker Sound FX muffler after the stock system connected with flex pipe. This is the 230cc Rhino 250 ATA-250D.

Remember this is the odd ball VM26 PZ30 30mm Mikuni carb.

10-03-2015, 07:27 PM	#17
Rule308 Join Date: Aug 2015 Location: Houston but will ride in Llano Texas Posts: 52	keep increasing pilot jet size to get rid of spitting through carb. The flexible R&D fuel screw didn't seem to want to screw in though the thread pitch and diameter looked identical and seemed to line up with the stock screw side by side, you could feel the number of threads were the same, I think, but when screwing it in it caught and went in about 1/2 turn then stopped, giving me impression it was going to cross thread, so didn't try to push it. It said it was for the Keihin FCR carbs but looks like it will be correct for the Mikuni VM26 PZ30. Used the extended pilot screw version instead, and had a ton of spitting through carb and sputtering, eventually walked the pilot jet size to largest I had which is the 30 pilot (slow jet) and I'm ordering 35, 40 , 45, 50. Seems like the larger pilot jets finally got it running fairly well. Does running lean sound louder, noisey, and rich sound lower and more quiet?. The reason is, the ATV has been getting quieter as I go up in pilot jet size. Think I still have to go bigger. Plug looks lean and too clean. White and clean, way to clean. Using new plugs every few jet changes. What theoretical pilot size should I be running at ~80 degrees, 200 above sea level, K&N with UNI sleeve, add on Walker Sound FX muffler after the stock system connected with flex pipe. This is the 230cc Rhino 250 ATA-250D. Remember this is the odd ball VM26 PZ30 30mm Mikuni carb. Last edited by Rule308; 10-04-2015 at 01:50 AM.
	0