I just purchased a set of 28mm keihin carbs (part no 29sb0) and they came with .135 main jets in them and I havent done any extensive searching but a few web searches and the biggest main jets I see for keihin carbs are .250 and I was running .340 mains in my stock mikuni carbs. Do I need to run close to the same size jets in these carbs as my stock carbs?? I appreciate any help...............

 

planet-sand is alot better for this question. but ill help ya, with the stock carbs at 340 your looking at around 190 mains on the new carbs. i have the same carbs but im at a 152 main. what elev are you at? im at 1600ft. hope this helps.

 

Thanks for the info. I am around 300 ft above sea level, I really dont think that I need to have that big of mains because I think I had an air leak around the carburetor cap or thats the only place I can find where it will idle down at all when I spray starting fluid on them. I keep melting my right side piston. I even put .380 mains in the second time to make sure I wasnt just running lean and I ran high octane gas and it is still trying to melt my piston but it didnt melt all the way through this time before I caught it. I have checked crank seals, intake boots, crankcase, reed cage gasket, base gaskets, hell I even checked the spark plug out of despiration. I have went through 3 pistons and about 5 cans of starting fluid so this is why I bought new carbs. How do you figure out what size jets to run in these carbs in correlation to the stock carbs because I am going to start out rich and jet down. I dont want to burn another piston up, I am afraid if I do I will have a solid black banshee instead of red and white one if you know what I mean. Thanks for your help. Oh yea I also need to know how to figure out how to compare jets in these carbs to stock for pilots.