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  1. #1

    Lower RPM's since Pump Upgrade

    Hello all. I just didthe pump upgrade to my 250x. I took her out yesterday and the max rpm's I saw all day was 5050 with a top speed on the dream-o-meter at 54 mph. Any ideas why? The pump was put back together right (I believe) and the obvious was checked.....s/c belt tension, hose clamps, etc. What else am I missing?

    Another question, the pump ring (???) Has an offset. Is the thinner part of the ring supposed to be on the bottom or the top? That was the only thing that I was confused on when reassembling the pump. Couldn't remember the way it came off


  2. #2
    nicjak's Avatar
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    if the pump had a wedge the thin section goes to the top did you only have the pump out? did you install the large rubber seal? seems very odd you lost rpms by just doing the pump!!

  3. #3
    Yes. I made sure the large rubber ring was is place. The only other thing I did was deburr my impeller with a small file. The impeller had a few small dings that I filed down straight.

  4. #4
    By the way, just for the hell of it, I took out my IC to check for oil but it is clean as a whistle. I'm in the process of putting it back in. I also checked the wedge, its installed correct.

    Can sealing the intake grate and ride plate with silicone have anything to do with it? I siliconed the grate and plate with silicone but I made sure not to put too much. The bottom of the ski is smooth cause I took real care in applying the silicone. Maybe I didn't seal it enough???

  5. #5
    nicjak's Avatar
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    did you smooth the silicon off inside the shoe? if you had anything wrong in the pump area it would be cavitating and on the rpm limiter!! did the pump spin free when you torqued the prop up? if all this was correct you problem is elsewhere, check the usual areas, intake trumpet, plugs, boost air leaks, belt slippage. does it feel real sluggish? are the max rpms from observing the dash or recalled amount? what was the boost at max rpm? answering these will give us better ideas of where to look. you didnt change the prop did you?

  6. #6
    No. I didn't change the prop but just filed down the little nicks. I didn't smooth out the inside the silicone in the pump area. Gotta check that out. The numbers I'm getting are from thding e recall. I remember seeing 6900 rpms while riding though. Gonna change out plugs. Checked all hoses and belt and everything was ok except I was able to tighten up (1/2 turn) on those 2 little plates on top of the motor (I believe they are BOV's????)

  7. #7
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    You have to look at the actual the recall is not accurate.

    Plates on top of the valve cover do nothing was for old emissions stuff

  8. #8
    nicjak's Avatar
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    no those valves arent the BOV's, they are egr type valves for exhaust gases. that wont be a problem. sounds to me your ski is running fine very confusing because in your first post you state max rpm all day was 5050 now you say 6900??? this is what confuses us at times the perimeters always change which means alot.
    your dreamometer could be out and you can only ever get max rpm whilst you are riding the ski the dash kind of logs it back to front on the recall it will log highest rpm once the wheel maxs out.
    make sure you smooth that silicon out in the shoe if its squeezed out the joins.
    enjoy your ski

  9. #9
    Thanks for all your help fellas. I will smooth out the silicone inside the shoe tomorrow. By the way, what rpm/mph should I be looking for with a 08' 250x with the following mods......Riva intake, Riva ride plate/wedge, and Riva exhaust?

  10. #10
    nicjak's Avatar
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    at a guess around 7600rpm+ mid 60's but you will need a gps, next time your out take note of the max rpms and boost.

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