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  • yamaha raider problems

    Hi
    I have a 1997 Raider 1100. Last year i took off one of my waterboxes. it has 2 waterboxes and i thought taking one off will increase my performance. i also rejeted the carbs with a 80 low and 120 high jets. it ran lean and then when i tried to adjust it ran rich. So I went back to my stock settings and to the 75 low and 107.5 high jets . Thats what it came with. My problem is that the compression dropped from 138 PSi to 130 PSI. When i was messing with the exhaust and the jetting the thing ran bad. I couldnt get the speedo to read over 60 or 61 MPh where before i messed with it It read a constant 69 to 71. I did minimal mods. I went to a pre mix ( didnt like the injection) and i had the head milled, because when it was brand new the compression was very uneven from one cylinder to another. I also had the prop repitched to a 17 21 pitch. i added some older ocean pro flame arrestors and thats about it for the mods. I had it radared at a high of 63 mph even though the speedo read 68. I also have another strange thing happening. If i take all the spark plugs out and crank the motor it cranks fine. if i try to put the compression gauge on a cylinder to get a reading the motor cranks a few times and the starter spins like the bendix is not pushing itself to the flywheel. If i put the other 2 spark plugs on, the starter works and i get a reading. Could you help me or am i a candidate for a new motor soon. i tried to maintain it really well, but I unfortunatley let my friend mess with it.
    Thank you
    Rob

  • #2
    I used to work on Jet skis with a friend who had a shop. i helped him out and got pretty good at diagnosing problems. This one with my raider has me baffled. i took the starter out and the bendix. i serviced them and even took the starter in to a shop tio see if it was bad. The connections were good and everything else seemed fine. The carb problem is no big deal i fixed it. i think I havent taken the ski out this year, but i cant understand the compression drop. i pulled the head to see if i scored the cylinders, but the compression drop is even all the way across. mabey i have a bad gauge? Id die laughing
    Thanx
    Rob

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    • #3
      First, you are right - removing one of your waterboxes will not make it any faster - just louder and off banance to one side or the other.

      Second, Yamaha staggers compression from the factory to balance cylinder temperature, to combat detonation - you didn't state what your original stock compression was, but it's normally a few PSI lower going towards the rear on the 1100.

      Third, you have to examine your pistonss and rings to see where you got blow-by and where you scored your pistons - if you were running lean and wore your rings down in a few spots this will not show on your cylinder walls. This is most likely the cause of your reduced compression and top speed.

      Forth, The bendix thing may not be a problem. It's perfectly fine to do a compression reading with the other two plugs in anyway. What could be happeneing is that when you only have the gauge in and no plugs, the engine has just the right lack of resistance that the bendix kicks back like the engine is starting - this is more likely to happen if you are getting severe blow-by and the engine is cranking at a faster than usual rate. The reason it doesn't kick back with nothing in at all is because it's spinning smoothly, without the momentary compression resistance. As the engine reached TDC on the cylinder you have the gauge in, the bendix feels the resistance and slowly kicks back, unitl after a few rotations it disengages. If you are getting severe engouh blow-by, that kick could be weak enough that it just lets the bendix mesh slip. Putting the other plugs in increases the compression resitance and keeps the cranking speed low enough to keep it engaged. I would wager that this did not happen before you scored your pistons/rings and lost some compression.

      You probably aren't due for a whole new engine, but most liikely need a top-end job - probably just a honing of the cylinders, new rings and pistons. That should cure your problems.

      Comment


      • #4
        Thanx for the response Bryan
        The raider when i got it it had the strangeast compression. it was a difference of almost 10 psi from the #1 to #3. like 135 #1 129 #2 and 125 #3/ I just wanted even compression. i went and rejetted to see if it would run better i went to 120 high and 80 low. it didnt help so i Went back to my stock 107.5 and 75. i have to take it out to see how it runs as i dont have a test tank. I also think that my gauge may be going bad. it got banged around a little and dropped a few times, but Im gonna have it checked. its just too weird that it dropped 8 psi on all 3 cylinders.
        Rob

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