Page 1 of 2 1 2 LastLast
Results 1 to 10 of 13
  1. #1

    01 GTS carb issues

    This GTS has the 720 with a single carb (with accel pump).

    Had it on the lake to tune yesterday.

    If you slowly apply throttle it will get to 1/4 throttle and stay there - going to WOT it will get to full speed, but takes forever - once at full speed it will go from 1/2 to WOT pretty decent. Once you go back below 1/2 throttle you're screwed and have to start the whole process over again to get to full speed.

    I messed with the low and high speed settings, motor is all stock. Stock low speed is 1 turn out - I went up to 1-1/2 out. Stock hi speed is 0 and has the restrict cap on it and I opened that up about 1/2 turn. A mild change was noticed, but no where close to where it should be.

    Crack it wide open from an idle and it will just sit there and probably die....

    Carb is clean, accel pump seems to spray a mist when operated by hand, fuel system is clean with new delivery hoses, fuel selector switch is clean - it will run full speed no problem once it gets there - so fuel is being deliverd.

    I know this is probably related to pop-off pressure but that's something I've never had to mess with yet. Seeing as this is a stock ski, can I just put a rebuild kit in the carb and call it good? Do the rebuild kits come with new springs and needle/seat?

    Thanks Everyone!


  2. #2
    Waterluvr's Avatar
    Join Date
    Mar 2015
    Location
    Northern Indiana
    Posts
    478
    +1
    69
    Different kits come with an assortment of springs, it's on you to check the pop off and make sure it's correct you'll see the canned answer of "just reuse the old springs to be safe" all over forums but how would you know what is really in there now and if someone changed it before you owned the ski without testing it to see in the first place?

    For the accelerator pump carbs of that era on a 717 you want to use a 115 gram spring and a 2.0 Needle and seat for a 32 psi pop off.

  3. #3
    wkuadam07's Avatar
    Join Date
    Feb 2013
    Location
    Bowling Green, KY
    Posts
    1,405
    +1
    170
    If you don't have a pop off pump you are wasting your time... You probably have a leak between the carb body and the pump block. You need a good pop off pump to leak test the carb at 10psi to find and correct this though. What you have is s common symptom of a leaky carb for sure... won't leak fuel out even, leaks vacuum in the mid range. Get a pop off pump if you are going to do carb work.

    The mikuni brand is expensive, but it's reliable to use as a pressure leak testor.

  4. #4
    We got the rebuild kit with needle and seat. I plan to rebuild the carb to stock form with new everything. Any need to do a pop off test at that point?

    Not clear what you mean by a "leak between the carb body and pump block" - There's a new gasket between carb and rotary intake....

  5. #5
    Waterluvr's Avatar
    Join Date
    Mar 2015
    Location
    Northern Indiana
    Posts
    478
    +1
    69
    Quote Originally Posted by raptorobbie View Post
    We got the rebuild kit with needle and seat. I plan to rebuild the carb to stock form with new everything. Any need to do a pop off test at that point?

    Not clear what you mean by a "leak between the carb body and pump block" - There's a new gasket between carb and rotary intake....
    It's really important to perform pressure testing at various intervals of a cleaning and rebuild, a hand pump with accurate gauge is a must for low pressure tests of the fuel pump and carb body seams combined with a low volume tester supplied from a regulated air source for pop off testing needles and seats properly.

    I get carbs in every week from DIY rebuilds and other shops that slap new kits in and they run worse after the rebuild for various reasons but air leaks always top the list along with circuit obstructions that weren't cleaned properly and made worse.

    Aside from proper cleaning of the places that matter which you can't see into, a completely leak free carb with the right pop off setting for it's intended application are critical if you want it to run right.

    In cases like your's with just a single carb it's cheaper to farm them out for a rebuild than buying all the tools to get it right.

  6. +1 by:


  7. #6
    Waterluvr.. What would you charge to rebuild a 95 gts 587 carb.have already purchased the rebuild kit.thanks

  8. #7
    wkuadam07's Avatar
    Join Date
    Feb 2013
    Location
    Bowling Green, KY
    Posts
    1,405
    +1
    170
    Quote Originally Posted by raptorobbie View Post
    We got the rebuild kit with needle and seat. I plan to rebuild the carb to stock form with new everything. Any need to do a pop off test at that point?

    Not clear what you mean by a "leak between the carb body and pump block" - There's a new gasket between carb and rotary intake....
    Yes... you ESPECIALLY need to test the pop off after you switch parts out. What you are describing (gasket between carb and intake) is a carb base gasket. What i am talking about is a leak in the carb itself... between the main body and the pump block... If you misaligned one gasket and don't have a pop off tester to leak test the carb it will never be right until you find/repair the leak. It may look perfect, but it's easy to make a mistake or use the wrong gasket, kits come with several duplicates that look alike, but they aren't. That thin rubber gasket that goes over top of the carb filter between the main body and the block causes most of the leak trouble that i see.

    Bottom line...It's worth the money to either send the carb out to someone who knows what they are doing, or actually buy the tools that are needed and read the manual on how to do them properly.

  9. #8
    Yep I get it - I will do the leak test and pop off test! I've been into my share of carbs between quads, dirt bikes and skis and never had an issue cleaning or rebuilding. I think those gaskets and the diaphragm are wasted along with the needle and seat. We were told "the ski runs great" when we bought it - so tried to get away with a good cleaning.

    I would love to send it out to an "expert" but our local "expert" is half the reason this ski is in the shape its in!!!

    I will put in the homework and get it right - that's why I love this forum... thanks!

  10. +1 by:


  11. #9
    Waterluvr's Avatar
    Join Date
    Mar 2015
    Location
    Northern Indiana
    Posts
    478
    +1
    69
    Quote Originally Posted by Jordanjairin View Post
    Waterluvr.. What would you charge to rebuild a 95 gts 587 carb.have already purchased the rebuild kit.thanks
    That's better left to a pm than hijack Op's thread, but I no longer accept to many machines built prior to 1996 in for service. It is in the best interest of my customer's and their financial well being to not see them enter into a *Repairs exceed value* situation and for a machine of that class just a few hours shop labor does just that unfortunately.

    Your ski may run like new still yes? Or not, in the case where you are having some trouble and are considering a carb rebuild there's plenty of people that will take your money no questions asked and do the work if you bring the carbs in or ship them but is this in your best interest and have you really evaluated your engine at this point for other issues?

    Not at all uncommon to do a set of carbs for a 580 class ski and it runs worse when they come back because they are tuned properly and no longer dumping an excess of fuel down the throttle body that masked the extra heat generated from poor engine compression and blowby, worn grooved rotary valves and covers etc.

    Do the inner crank seals leak like the Titanic at this point dumping oil from the rotary cavity into the crankcases? If the crank hasn't been replaced they certainly will by now and those old leaky carbs were doing you a favor to wash some of that mess out of there oil burns pretty much not at all and I get calls all the time from people that don't understand how the carb rebuild they just did made the ski run worse.

    Again, this is for your benefit and others reading it but a carb rebuild is no magic wand on a tired old 2 stroke engine that has exceeded it's intended window of use. It is well worth taking some time to evaluate what you have before you start spending real money on it and a worn rotary valve engine is a worse case scenario.

    Prior to rebuilding the carbs on that particular ski unless it has a brand new motor from a reputable shop you should accurately test for cylinder compression, pressure test the rotary cavity, measure the clearance on the rotary valve and cover for wear and use proper tools designed to evaluate the ignition pulse or you'll be spending good money after bad without a positive result.

    If you can show me you have a healthy engine I'm happy to help you with a proper carb rebuild if you want to send them in but due diligence is needed in this case.

    ~Send me a PM if I can help you.
    Last edited by Waterluvr; 06-17-2015 at 12:49 PM.

  12. #10
    Still chasing the same problem after over a year!

    We finally got the ski that I originally posted about to run by purchasing a brand new Mikuni carb. It ran like a champ once new carb was installed - apparently I don't know how to rebuild one of these carbs - that's ok I'm good with that!

    Unfortunately, we have 2 of these skis that are exactly the same....The other ski wouldn't run right so we too the new carb and swapped it to that ski - now that ski runs awesome!

    Sooooo, we purchased a new Mikuni carb for the original ski - put it in and the ski ran like total crap - just like it did in my original post. It can't get out of the hole but when you feather it up to WOT it'll run there all day - no problem.

    Sooooo, we figured we got a bad carb out of the box......2 more brand new carbs later, we still have the same problem! Then, we put the carb from the other ski on and still the same problem (the ski used to run perfect with this carb installed).

    Anyone have any clues???? We don't have a fuel delivery issue - she'll run on top all day - the only thing that appears to happen is it seems to run slightly better when stone cold - also it always starts right up.

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. Common Carb Issues
    By OsideBill in forum Yamaha How To & FAQs
    Replies: 97
    Last Post: 11-02-2011, 04:34 PM
  2. gp1400r carb issues pleas help
    By gpr-sam in forum Yamaha PWC Performance (2-stroke)
    Replies: 9
    Last Post: 10-11-2007, 06:11 PM
  3. 2000 GR1200R Carb issue (could take all summer to repair)
    By havoc in forum Yamaha PWC Performance (2-stroke)
    Replies: 31
    Last Post: 08-26-2007, 12:45 PM
  4. 951 carb issues.....
    By sasage900 in forum 2-Stroke Performance
    Replies: 1
    Last Post: 06-24-2007, 11:49 AM
  5. Need 01 XLT CARB INFO
    By mt375hp in forum Yamaha PWC Performance (2-stroke)
    Replies: 6
    Last Post: 11-20-2006, 05:10 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
  •