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  1. #1
    Senior Member GOF's Avatar
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    1987 carb questions.

    Have a kit coming with stock jets as well as all the other assorted parts needed. Will be riding in the 6-700 foot above sea level range. At least for the most part. So any reason to change the jetting? If so what jets would be better? Mind you I am not as young as I once was. Won't be wailing on the old girl like back when. And any longer road trips will be on the bigger bike. Perhaps an occasional short hop on the highway for an exit or two. Mostly around town and light trail riding.
    1988 Suzuki Savage
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    Senior Member CJ7Pilot's Avatar
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    Although the stock jets will run fine, they do run a little lean at lower elevations.

    The '87 I got from Little Tommy has a stock carb,which was professionally rebuilt and re-jetted for lower elevations (Seattle), and it runs great here in Northern California (Sacramento Valley)!

    Without taking it apart, I can't tell you exactly what was done to it... but if I were trying to reproduce it, I'd start with one size larger main jet, shim the jet needle, and properly adjust the idle mixture screw.

    You need a good baseline though, so maybe just install the kit as-is, and see where you want to go from there.

    Have fun!
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    Super Moderator littletommy's Avatar
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    Quote Originally Posted by CJ7Pilot View Post
    Although the stock jets will run fine, they do run a little lean at lower elevations.

    The '87 I got from Little Tommy has a stock carb,which was professionally rebuilt and re-jetted for lower elevations (Seattle), and it runs great here in Northern California (Sacramento Valley)!

    Without taking it apart, I can't tell you exactly what was done to it... but if I were trying to reproduce it, I'd start with one size larger main jet, shim the jet needle, and properly adjust the idle mixture screw.

    You need a good baseline though, so maybe just install the kit as-is, and see where you want to go from there.

    Have fun!
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    Senior Member elime's Avatar
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    A brand new #114 high speed jet can works wonders on a carb that old.

    Jets wear out. The hole in the center gets bigger with use and age. Don't be fooled thinking the old jet is OK just because it looks OK. Replace it. Set the idle mixture screw to around 2.5 turns out, adjust to your liking, thoroughly clean the inside of the carb and you should be good to go.

    I have tried a couple of different carb kits and found them both to be junk but that was a few years ago and maybe they have improved. Good luck and report back your results.
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    Senior Member CJ7Pilot's Avatar
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    Quote Originally Posted by littletommy View Post
    It was more than that, but it's top secret...
    Well, now I might have to peek inside....
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    Super Moderator littletommy's Avatar
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    It if ain't broke, don't mess with it!! It was and still is the fastest stock 87 on the forum!!
    Quote Originally Posted by CJ7Pilot View Post
    Well, now I might have to peek inside....
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    John 3:16
    For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.

    John 3:17
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    Senior Member GaryL's Avatar
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    700 feet above sea level is nothing! I live at 1400 feet above and still nothing as far as the carb and jets are concerned. Get up in the mountains where 6,000 and above and you might want different jetting. All "Carb Kits" are not created equal so it will depend on which brand of kit you bought. I hear good things from members who bought the Pro Cycle kits and bad things from those who bought the Ketster and other low quality kits. Yamaha proper does not sell a "KIT" for rebuilding these carbs but they do sell all the internal parts separately and I stick with original OEM stuff whenever possible.

    GaryL
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    Senior Member GOF's Avatar
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    Well, We shall see what I get when the kit arrives. I am sure that it will be an improvement over the fuel dripping on the floor.
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  10. #9
    Senior Member GaryL's Avatar
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    Quote Originally Posted by GOF View Post
    Well, We shall see what I get when the kit arrives. I am sure that it will be an improvement over the fuel dripping on the floor.
    Fuel not shutting off is a very common issue almost always related to the float valve sticking. I have seen this in brand new bikes and newly rebuilt carbs with new float valves freshly installed. A prudent preventative for this is to always shut the petcock off while not in use. Sometimes a light tap on the side of the carb will free the sticking valve so it does shut off. When your new parts arrive make sure the float level is set top the correct height and the needle is installed right and freely moving. The tab you adjust the height with could have a slight burr or deposit on it so be sure to inspect it closely. This is one of those unsolved mysteries around carbs and I installed a brand new OEM carb once and took the Tdub for a cruise. All was running fine and with no issues at all. I then had the bike on the lift to adjust the chain and do some other checks and had no leaking fuel from the overflow. The next day I went to the shed to find half my fuel leaking onto the floor. Hard to say why but I had not shut off the petcock and I suspect some atmospheric change caused the float valve to stick. I tapped the side of the carb with the rear of a screw driver and it immediately stopped dripping. When you get the old valve seat out take note of the fine screen above it as this is often where crud gets caught so it does not enter the carb float bowl.

    GaryL
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    Be 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.

    1987 Yamaha BW350 Big Wheel
    2017 Snowdog Track sled tow motor for ice fishing
    Kubota BX2370 Subcompact tractor with snow blower
    Wilderness System Ride 115 fishing Kayaks

  11. #10
    Senior Member GOF's Avatar
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    I have rebuilt many carbs over the years. But few on bikes. I had this one apart to clean whatever crud may have built up over all the sitting and whatever rust may have found its way from the tank. Found a few flakes in the filter screen at the inlet. I suspect that the 32 year old seal on the seat didn't like being disturbed. In 15 minutes i developed a wet spot of fuel under the bike a little over a foot in diameter. Other than that it was running well. At least for the couple of blocks I rode it. So I figured I'd replace the gaskets and seals and needle and seat. Started this thread wondering if changes to the jetting might be worth while.
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