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  1. #1

    Low Speed control on new re-build XL1200

    I just went thru a 2000 XLT1200 Yamaha. Re-built carbs, fresh top end, D-plate, temp sensor and removed the oil injection. I replaced the power valve lever with the aluminum lever links. I had one bad cylinder,so I had it re-plated. I also remove all the stock spark arrestor and replaced it with an R&D flame arrestor. I am all back together now and I got it to start, but the idle speed is way to high. The remote throttle stop screw had no effect on the rpm. The throttle cable actually had a little bit of slop in it as I left it at it's original adjustment. What do I need to do to get the low speed rpm under control? I saw that the carb adjustment screws have tamper proof caps and that most likely the carbs will have to come back off to get at them. That means the exhaust will have to come back off, which is a pain. By the way, when I took the power valves, apart they were trashed. They had a lot of build up and one was stuck. One of plastic coupler parts was broken. I replaced the couplers with Wave Eater couplers. Could the stuck power valves have messed up the power valve servo and could this affect controlling the low end speed?

  2. #2
    leejax01's Avatar
    Join Date
    Apr 2011
    Sounds like an air leak. Did you leak test the engine before installing it?

  3. #3
    Quote Originally Posted by leejax01 View Post
    Sounds like an air leak. Did you leak test the engine before installing it?
    I did not leak test. I got a reply from the same post on another forum. The "expert" says that the pop off pressure will need to be lowered due to the install of the aftermarket air box and the d-plate.
    He says that stock pressure is 60-75 and needs to be 45-50 to richen up the mixture and lower the RPMs. Any thoughts?

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