Page 1 of 2 1 2 LastLast
Results 1 to 10 of 11
  1. #1

    1998 GP1200 not reaching full RPMs

    Good compression, checked it.
    Good spark, checked all three plugs and wires, and have new boots.
    No reason to suspect fouled fuel, was treated with Stabil and is pre-mix 40:1

    I bought the ski used 3 years ago and aside from handling issues which I fixed with trim tabs; all has been great.

    First, I don't think these are stock carbs; can someone please verify?
    It has primer kit installed only plumbed to first carb, and I see no provisions for choke plates.
    It has Tau Ceti individual flame arrestors too.




    Regardless, they appear to be all working fine. They are synced, and all flowing evenly.



    The ski ran fine all last year. For the hell of it, I decided to install a TDR waterbox at the end of last season. It ran fine on the hose/trailer, but I never water tested it.

    This year, I took it out for the first time after installing new NGK plugs. I had an issue with not reaching RPMs, and found out I had a spark plug tip come off in the spark plug boot. I destroyed the spark plug boot trying to get it out, so I replaced all 3 spark plug boots with new ones from NGK.

    It was still not reaching full RPMs. As soon as I squeeze the throttle to open the carbs just past 1/4 inch it sounds like it's banging on an electronic rev limiter.

    Tonight, I put the stock waterbox back in and tried to run it on the trailer/hose again. It still has the same issue where it sounds like it's banging on an electronic rev limiter.

    I also now have about 1/2" deep of oil in the bottom of the hull.



    I have a service manual. If anyone has any pointers on what to check first/primary; I am all ears and very thankful.

    Brian


  2. #2
    mudslanger's Avatar
    Join Date
    Jul 2010
    Location
    Huntsville Al
    Posts
    1,326
    +1
    49
    Those carbs have been modified. I think they have been modded to black jack but not sure. If your ski is hitting the rev limiter you should check your pump. Check clearance and for debris.

  3. #3
    Quote Originally Posted by mudslanger View Post
    Those carbs have been modified. I think they have been modded to black jack but not sure. If your ski is hitting the rev limiter you should check your pump. Check clearance and for debris.

    It's not hitting THE rev limiter.

    It sounds like it's hitting something much lower, like it is not firing correctly and only hitting about 5000 rpm. What in the electronics of the ski could be causing this?

  4. #4
    Pistonwash's Avatar
    Join Date
    Aug 2005
    Location
    Florida
    Posts
    3,595
    +1
    77
    I think those are Red Tops...good carbs but very sensitive. I don't think they are your problem...Mud is right..check your pump, you might have debris or jacked up prop. You might have an intermediate bearing housing problem. You might have a stator problem that has corrosion formed from sitting with moisture trapped in it.

    You will have to check one thing at a time. Compression is fine, then move to carbs then electrics then your pump/driveline. Pull the spark plugs out and see if the couplers spin somewhat freely. Pull the pump and check to see if prop spins freely. You will have to attack this by process of elimination.

    If your stator is bad, it will react this way or stop working all together and you will get no spark at all. It is in the front cover and will have to be removed but go through your checklist again..you seem to be doing that well.

  5. #5
    Thanks gents. No visual issues with the prop or pump. Clearance is exact as it has been since I installed the impeller/pump 3 years ago, albeit there is a little cavitation burn on the forward edges of the pump veins.

    The issue exists on the trailer in the driveway, as well as in the water.

    All three carbs are working properly as best I can visually tell. They are all flowing what appears to be evenly and fogging the fuel well when the engine is running and throttle is opened. IOW, I do not believe the cylinders are starved for fuel.

    This "seems" electrical to me.

    I am plumbing in a temporary tank of fresh fuel to check next.
    After that I'll pull the plugs and grate to check rotation.
    After that, the stator cover comes off.

  6. #6
    It was the stator. There was way too much buildup of grease and gunk in there, and the main culprit was two pieces of electrical tape that had come loose from the wiring harness and were dancing around inside the stator housing.

  7. #7
    Pistonwash's Avatar
    Join Date
    Aug 2005
    Location
    Florida
    Posts
    3,595
    +1
    77
    Quote Originally Posted by Sydwayz View Post
    It was the stator. There was way too much buildup of grease and gunk in there, and the main culprit was two pieces of electrical tape that had come loose from the wiring harness and were dancing around inside the stator housing.
    Yup...this is one of the main silent killers of the 65u. You done good hunting it down.

  8. #8

    Join Date
    Jun 2013
    Location
    St. Cloud, MN
    Posts
    23
    Well as I started reading this thread it was sounding exactly as the problem I'm having with the 98 GP1200 I just bought this spring. Took it out for the 1st time on Fathers Day and it ran great for hours of fun. Then went to take it out of the water and it would not start, turned out to be no spark - bad stator, mechanic replaced and it started fine but would limit RPM's as your machine was doing, turns out the brand new stator is also bad. Water Craft Superstore were I bought the SBT brand stator was going to send a replacement but found all in stock were also bad, so they did refund my money. Waiting now for OEM stator to be back in the water.

  9. #9
    mudslanger's Avatar
    Join Date
    Jul 2010
    Location
    Huntsville Al
    Posts
    1,326
    +1
    49
    One of the big problems i found with these stators is they somehow loose ground internally. i usually run a new ground wire from the battery to inside the electric box. but that may be a different issue than what you all are having.

  10. #10
    Well, ran great for about 30 minutes today today, the rest of the time it was acting up again. I am now looking for someone to test and diagnose the issue somewhere around Richmond, VA if anyone has any good shops or mechanics to recommend.

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: 11
    Last Post: 04-01-2014, 08:12 AM
  2. 00 gtx di not reaching full rpm
    By derekshep in forum 2-Stroke Performance
    Replies: 0
    Last Post: 07-26-2013, 09:10 AM
  3. 1998 GP1200 not reaching full RPMs
    By Sydwayz in forum Yamaha Old School Skis
    Replies: 3
    Last Post: 07-06-2013, 09:03 PM
  4. 03 msx 140 not reaching full rpm??
    By REG-DOG in forum MSX/Matrix
    Replies: 6
    Last Post: 08-10-2010, 08:24 AM
  5. 96 XP not reaching full RPMS consitently
    By DarthAWM in forum 2-Stroke Performance
    Replies: 14
    Last Post: 04-17-2008, 10:59 AM

Posting Permissions

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