More than ever I see I need to richen my bike. It runs better with the choke on. I'm guessing the cooler dense air is leaning the mixture out even more. There is so much info on tuning my 87 carb that I get confused reading about it. What is the stock main and pilot jets? Also what carb is on my 87?
I've been needing it for transportation. I smile everytime I go out to the drive at 4am to go to work and it lights by the 2nd kick.(I still haven't installed my starter clutch ) I wish my wife would deal with my mental abuse as well as my TW can deal with my physical abuse
1987 Yamaha BW350 Big WheelBe Decisive! Right or Wrong just make a decision. The road of life is paved with flat squirrels that couldn't make a decision.
Since light travels faster than sound, some people appear bright until you hear them speak.If I agreed with you, we'd both be wrong.
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It is possible that the jet has been changed by a prior owner and should be changed back to stock, as well as doing the recommended 2.5 turns out on the pilot jet. You can turn the carb after loosening and take the float bowl off, then with a bright light you should be able to read the jet number. I'm not sure of the stock number for the '87, but someone else surely will. (114, maybe?)
2014 BMW R1200GS LC
Cold air is denser than warm air given the same elevation (lower elevation=denser).
With correct jetting, an engine will make marginally more power with denser air vs thinner. However unlike EFI carbs do not compensate for this automatically, so as temp/elevation changes, fueling does not.
If it runs notably better with the choke partially on, you're now too lean. Turn the pilot screw in until it lightly seats and count the number of rotations. Now back it out that same number, plus 1/2 turn more to compensate for cooler air. If that's more than 3 turns total, you probably should swap the pilot jet for the next larger size (effective adjustment range is from about 1-3 turns- less than 1 turn, go down a size on the pilot- more than 3 turns, go up a size).
To "set" the pilot screw, have the bike fully warmed up and idling. Turn the idle speed up a bit faster than normal (this exaggerates changes and makes it easier to detect). Set the pilot screw to 1.5 turns as a baseline, then adjust it in 1/8 turn increments giving a couple seconds after each adjustment. Just listen to the engine speed. You're looking to find the spot engine RPM is fastest. There may be a small range where there seems to be little or no effect, that's normal. For an air cooled engine I shoot for the richer end of that range. Then turn the idle speed back down to normal.