What size pilots and mains are recommended for a stock motor with uni pods on stock carbs, points, and spec II classics? Engine runs good and plugs a tad rich during break-in on 40 pilot and 160 main with stock pipes but may go to chambers. Currently running premix @ 35/1, but may go back to pump. Start with same jets and check plugs, or go up a size or two first?
on r5 or rd cabs? need more detail
Unless you do a lot of freeway riding, or live way out in the boonies, most modern oils will support 40:1 mixture.
Chuck
id probably stick with 160 or 150 mains with chambers on the pump.
oil doesnt make it rich, it makes it lean. by moving it to the pump, you will be adding more fuel through the jet (not displacing it with oil). If you leave it stock pipes, id drop it a size on the main, check the needle position as well. (should be #3). IF chambers, then specII's on stock carbs, they seem to like it one lean on the needle with larger mains, in my experience, but its been so long, take that with a grain of salt. :twocents:
Mine, with K&N and Spec II ran good, if a bit rich, on the 160's. I'm running Milleniums now and 155's, always on the pump.
Autolube is your friend,
if you run pre-mix, carry a set of spare plugs!
The stock airbox is actually quite good and makes jetting really easy, just use stock jets.:)
Yamaha knew what they were doing when they engineered the airbox: it is part of the tune of the bike and the jet needle taper and the carb design is for a stock airbox. The restriction in the DS7 and R5 is not the airbox, or the filter, it is the intake port area, so bigger carbs don't help very much at all unless you do a bunch of porting, and then you have a bike that is more suited for the track than the street.
For jetting, simple rule, go way too rich and then work back down one jet size at a time. This is the safest way because there are too many variables like milled heads (compression) porting, type of air filter, type of exhaust, ignition timing...they all have an effect so it is impossible to give you exact jet sizes for your custom set-up. Sounds like you are close however, so see what size jet makes it go rich and start working backwards from there.
BTW, more oil does not equal less power, but it does equal more cooling and lubrication. I run 16:1 in my Yamaha KT-100, as it turns over 15K, any less oil and it seizes! All too much oil will do is foul plugs, but that is better than seizing due to too little oil.
So Jay...When do you not run wide open throttle with a KT100 with a slipper clutch? A blip for a second to hit brakes then instantly wide open again? so yeah 16:1 is needed. I run 20:1 on my roadrace RD engines so I get it.
Chuck