ok so i have a yamaha srv 540. i am not sure what the last owner has done, but i hear the stock jet is a #150 or 155. well i need a new jet mine broke at the threads, problem is it says 135! the snowmobile does seem to be a bit lean (spark plugs brown and no black in exuast at all) should i go to the stock size? or keep 135? or maby just go up a little? i am not sure what to do any help would be great