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  1. #1
    Randy Walker
    Join Date
    Aug 2006
    Location
    Roseville
    Posts
    27

    2006 250 HPDI - loss of top end speed

    Hey All,
    Recently lost cylinder 2 and decided to have both 1 and 2 rebuilt. The tech different pistons that I guess do better under heat. He also had all fuel injectors rebuilt. He has done this same job on several Yamaha's with good success including for my buddy 2 years ago.
    I had several issues during and after the break in hours. REALLY rough idle and running overall, burned thru a ton of gas and oil in 2 hours of part of the break-in time, HORRIBLE hole shot (seemed like it took a minute to get on pad) and lost top end speed.

    * so, I adjusted the idle and I'm good there now
    * replaced plugs since all were fouled which I figured was the cause of all the other problems. (fouled from the heavy lube used for rebuild I guess)
    * felt like a shimmy, prop slip or plug missing while running - even after replacing all plugs (kind of felt like running thru current eddy - was on CA Delta with strong current but never felt that before the job was done?)
    * Top end speed loss - still not corrected.
    * compression matched in both new cylinders at 110 and all other cylinders were at 116-117

    Took it back to the tech and he hooked it up to the computer. He said it sounded like a possible coil problem... but, he tested all the coils, injectors and basically checked all motor stats and said EVERYTHING looked good. He suggested to change props (mine had some damaged blades - but was that way prior to losing cylinder), he also adjusted my hot foot (maybe the cable had been stretched) and he said that he noticed my motor bushings were worn and he thinks I may have lost some trim range.

    So, here's where I'm at as of running it yesterday on Folsom Lake (CA):

    * idles good in neutral and in gear (after adjustment)
    * swapped props to non damaged (same prop - Yamaha Ti 25)
    * very good hole shot
    * very good mid range power
    * NO top end - can't get over 60 MPH (5400 RPM max)
    * back to normal fuel and oil consumption (been using Lucas oil products)

    Anybody ever had the same problem or any Yamaha mechanics out there have any idea's of what's going on?

    Also, if I have lost say 1/4 inch of trim range, would this be enough to lose that much top in speed?

    Thanks much for any thoughts

    Randy

  2.  
  3. Member
    Join Date
    Dec 2004
    Location
    Kingsport
    Posts
    343
    #2
    Quote Originally Posted by onewalker View Post
    Hey All,
    Recently lost cylinder 2 and decided to have both 1 and 2 rebuilt. The tech different pistons that I guess do better under heat. He also had all fuel injectors rebuilt. He has done this same job on several Yamaha's with good success including for my buddy 2 years ago.
    I had several issues during and after the break in hours. REALLY rough idle and running overall, burned thru a ton of gas and oil in 2 hours of part of the break-in time, HORRIBLE hole shot (seemed like it took a minute to get on pad) and lost top end speed.

    * so, I adjusted the idle and I'm good there now
    * replaced plugs since all were fouled which I figured was the cause of all the other problems. (fouled from the heavy lube used for rebuild I guess)
    * felt like a shimmy, prop slip or plug missing while running - even after replacing all plugs (kind of felt like running thru current eddy - was on CA Delta with strong current but never felt that before the job was done?)
    * Top end speed loss - still not corrected.
    * compression matched in both new cylinders at 110 and all other cylinders were at 116-117

    Took it back to the tech and he hooked it up to the computer. He said it sounded like a possible coil problem... but, he tested all the coils, injectors and basically checked all motor stats and said EVERYTHING looked good. He suggested to change props (mine had some damaged blades - but was that way prior to losing cylinder), he also adjusted my hot foot (maybe the cable had been stretched) and he said that he noticed my motor bushings were worn and he thinks I may have lost some trim range.

    So, here's where I'm at as of running it yesterday on Folsom Lake (CA):

    * idles good in neutral and in gear (after adjustment)
    * swapped props to non damaged (same prop - Yamaha Ti 25)
    * very good hole shot
    * very good mid range power
    * NO top end - can't get over 60 MPH (5400 RPM max)
    * back to normal fuel and oil consumption (been using Lucas oil products)

    Anybody ever had the same problem or any Yamaha mechanics out there have any idea's of what's going on?

    Also, if I have lost say 1/4 inch of trim range, would this be enough to lose that much top in speed?

    Thanks much for any thoughts

    Randy

    If he put Wiseco pistons in those two cylinders, then that could be the problem JTM, Stroker guy who builds high performance Yammies, has had a ton of issues with them. They tend to swell with heat and essentially keep the engine from turning higher RPMs. They tore one engine down multiple times and keep re-boring beyond what Wiseco recommended, never could get them to run right. Switched back to Yamaha oem pistons and ran great. Just a thought. You might could try and message him.

    Another thing to look at, make sure butterflies are opening all the way up. When I got mine back from Hydrotec, mine had nothing on top end. Turns out the arm that goes to the oiler that has two holes was in the wrong position, so at full throttle it was hitting the stop pin on the oiler keeping it from opening all the way up. Good luck!

  4. Randy Walker
    Join Date
    Aug 2006
    Location
    Roseville
    Posts
    27
    #3
    Thanks for the info... I will see what pistons he used for sure!! I know he has been using whatever they are for years on several other motors including my buddies, but his 2005 yammi did not have the same problems as mine.. same exact pistons and same 2 cylinders... but interesting about those pistons. I will follow up with him on those as long as having him check the butterflies that you mentioned.

    Thanks much for the reply.. much appreciated.

    Randy

  5. Member
    Join Date
    Feb 2013
    Location
    Birmingham
    Posts
    512
    #4
    Does sound like you are running on 5 cylinders. A faulty ignition coil may not show up on computer.

  6. Member
    Join Date
    May 2006
    Location
    Clarksville
    Posts
    202
    #5
    Had the same problem, top speed was only 60, ended up being the throttle cable inside the cowling, whole cable would move while pushing on the hotfoot. The bracket that secures the cable was loose, ended up tightening it up with a zip tie, speed it back up 80mph again! Finally a quick and cheap fix!!! Good luck

  7. Member
    Join Date
    Oct 2011
    Location
    Livermore CA
    Posts
    121
    #6
    I had similar symptoms on my HPDI and it was a bad spark plug boot. Got a new boot and it ran on all six cylinders again. I hope it's something simple for you.

  8. Randy Walker
    Join Date
    Aug 2006
    Location
    Roseville
    Posts
    27
    #7
    Awesome.. Thanks for your input and prior experience... I HOPE it's a loose bracket or bad boot.. be happy with either one of them!! Keep you posted incase anybody else runs into this situation.

  9. Member
    Join Date
    Oct 2010
    Location
    Rockwall
    Posts
    3
    #8
    Any one know how to get a hold of Stroker

  10. Member
    Join Date
    Oct 2010
    Location
    Rockwall
    Posts
    3
    #9
    like to talk with him about wisco piston I had same issue

  11. BBC SPONSOR Rich Z's Avatar
    Join Date
    Jun 2004
    Location
    Apex, NC
    Posts
    4,294
    #10
    Most use WSM pistons with good results.

  12. Member
    Join Date
    Oct 2010
    Location
    Rockwall
    Posts
    3
    #11
    who builds those pistons

  13. BBC SPONSOR Rich Z's Avatar
    Join Date
    Jun 2004
    Location
    Apex, NC
    Posts
    4,294
    #12
    HQ office is in NY but as far as where they are actually made idk.

  14. Randy Walker
    Join Date
    Aug 2006
    Location
    Roseville
    Posts
    27
    #13
    update...
    Yes Wisco pistons used..

    * Spark plug boots appear to be fine.. no corrosion and all plugs show signs of combustion/usage.
    * Cable bracket is secure.

    Going to have TPS checked next...

    Does anybody know if intermittent sluggish hole shot and no top end speed can be caused by exhaust blow back into the cowling? Someone was telling me that leaking exhaust in cowling might cause symptoms. Would that gag the engine?

    Thanks,
    Randy