Page 1 of 2 1 2 LastLast
Results 1 to 10 of 11
  1. #1
    Lightning1's Avatar
    Join Date
    Mar 2013
    Location
    Illinois
    Posts
    367
    +1
    29

    Breaking up in high RPM

    I am having an issue with getting my ski dialed in. Over the weekend, I was running around and blew off an intercooler hose. This is the third time it happened this year. (once broke a constant tension clamp, the other 2 were the same t-bolt clamp that will be replaced) Once the clamp was done, the ski would run up to 8300 rpm and felt real solid. This was with the finger throttle at 3/4 down and really, it is running where the ski should be at WOT. If I go past that, it will go from 8300 to 7500 and back and just jump around. The ski was at 12.5 at 3/4 down, then the WOT would go from 14 to 10 (obviously it is breaking up)

    What do you guys think this could be? I was going to look for other boost leaks this week, but don't know where to go from there. Any ideas would be great, my mods are in my sig.

    Thanks,

    Jeff


  2. #2
    imp0ster's Avatar
    Join Date
    Dec 2011
    Location
    Palm Harbor, FL
    Posts
    5,037
    +1
    672
    The ECU pulled your timing due to detonation (Knock Attack) and you're having trouble recovering after the attack (knock decay). Get that 14 WOT crap under control and give it another go.

    Make sure your fuel pump is doing its job and that the Walboro is a real walboro. I just had an issue where my brand new walboro sucked up the rotten strainer sock and ruined the impeller. I compensated it with my fuel map and now I need to basically redo my entire IFR map.

  3. #3
    Lightning1's Avatar
    Join Date
    Mar 2013
    Location
    Illinois
    Posts
    367
    +1
    29
    The walbro is a real walbro pump, we use them at my work all the time. My Rotax ECU does not have a knock sensor program on it, so that should not be the case. My ski should run right around 8300-8400, so I am not too far off, but yes, I do believe the ECU is pulling timing at some point.

  4. #4
    imp0ster's Avatar
    Join Date
    Dec 2011
    Location
    Palm Harbor, FL
    Posts
    5,037
    +1
    672
    I missed the fact that you're running this with 48s. You need a minimum of 60s. You might have a injector hanging open from going static.

  5. #5
    Lightning1's Avatar
    Join Date
    Mar 2013
    Location
    Illinois
    Posts
    367
    +1
    29
    hmm, never thought I was running out of injectors. I thought the 48s were good for the 137 wheel. Do I need the 60s since I am spinning the motor faster now?

  6. #6
    imp0ster's Avatar
    Join Date
    Dec 2011
    Location
    Palm Harbor, FL
    Posts
    5,037
    +1
    672
    may as well go for 80s man. That way you have compensation room plus room for 9K

  7. #7
    Lightning1's Avatar
    Join Date
    Mar 2013
    Location
    Illinois
    Posts
    367
    +1
    29
    Yeah, I was looking in the store and it says the 60s are for the rotax ecu. I guess I suck at doing research lol. I am thinking I am just going to jump to the 80s so I don't need to worry about this again. Thanks for the input, I would have never guessed on injectors. Looks like some 48s will be for sale soon.

    Thanks imposter for the input.

  8. #8
    Site Admin Green Hulk's Avatar
    Join Date
    Apr 2005
    Location
    Morgan City, LA
    Posts
    36,398
    +1
    2,524
    Check your intercooler for a leak... The symptoms you have are classic symptoms of a leaking intercooler... runs fine at lower RPM, but when you get under boost and higher RPM water gets mixed with the fuel mixture and the engine will start to sputter/cut out

  9. +1 by:


  10. #9
    Lightning1's Avatar
    Join Date
    Mar 2013
    Location
    Illinois
    Posts
    367
    +1
    29
    Yeah, I can do that as well. I hope that intecooler is fine, I have low hours and only fresh water on it, but I will look anyways.

  11. #10
    Site Admin Green Hulk's Avatar
    Join Date
    Apr 2005
    Location
    Morgan City, LA
    Posts
    36,398
    +1
    2,524
    Quote Originally Posted by Lightning1 View Post
    Yeah, I can do that as well. I hope that intecooler is fine, I have low hours and only fresh water on it, but I will look anyways.
    chances are it's fine then. But check anyway!

    by chance have you tried a fresh set of spark plugs?

Page 1 of 2 1 2 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Replies: 9
    Last Post: 05-06-2011, 07:53 AM
  2. Will crack in impeller housing cause rpm not to go up as high??
    By vwmikey99 in forum 2-Stroke Performance
    Replies: 0
    Last Post: 07-30-2010, 12:42 PM
  3. loss RPM's but gain hook up in chop
    By Tanny in forum Yamaha PWC Performance (2-stroke)
    Replies: 7
    Last Post: 02-23-2008, 03:14 PM
  4. Replies: 3
    Last Post: 11-08-2007, 05:06 PM
  5. Hook-Up in Ocean (High Speed)
    By RXP PIT BOSS in forum 4-Tec Performance
    Replies: 4
    Last Post: 09-10-2006, 12:20 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •