Page 1 of 4 1 2 3 ... LastLast
Results 1 to 10 of 31
  1. #1

    Join Date
    Apr 2015
    Location
    Albuquerque, NM
    Posts
    13

    Inherited 750 SLT Project

    Well, I've managed to find myself in the possession of a 95ish 750 SLT which is in need of some work. After doing a lot of reading on the web about these ski's, it seemed like this was the best place to come for some assistance. I haven't actually gotten the thing from my uncle yet, but hopefully in the next little while I'll pick it up and start working on it.

    My uncle has had it for only 2 or 3 years, and in that time it ran great after he originally had the carbs rebuilt along with some other work, but in the last year or two its been very down on power and takes forever to get up to any kind of speed. Having ridden it a lot myself during this time, I'd say it will probably only get up to 22 or 23mph, and takes a long time getting there.

    Based on what I read online, I'm guessing this is likely the symptom of at least one or two of the cylinders not running very well, although the thing doesn't noticeably bog or anything like that. I've been told it tends to foul one plug, so I'm betting that's probably where the issue is.

    The carbs have been rebuilt, although they're probably going to require a good cleaning again as the start of my work. I'm not sure if the fuel pump has been replaced/upgraded with the 3 output unit, so I plan on doing that immediately if it hasn't been done already, along with the replacing of most of the fuel line, as I've read they also tend to be problematic.

    I have a lot of spare parts for the thing, including a good (but somewhat rusty) spare cylinder and head, an entire spare tailshaft and impeller which is in absolutely perfect shape, a spare CDI box, and a few other things. I'm basically just posting this to introduce myself, see if anybody has suggestions on other items that I should check, and to keep track of what all I will be, or have already done. Any tips would be very appreciated. I've got a lot of experience working on 4 stroke engines, cars mostly, but I have never worked on a 2-stroke before and fear I'm getting myself in over my head with this project. Hopefully I'm wrong!


  2. #2
    Banned User
    Join Date
    Jun 2010
    Location
    Milwaukee WI
    Posts
    16,708
    +1
    1,324
    I would first check compression on the engine. That will give you a clue where to look. Pull the carbs and check them out too. Make sure they are clean internally.

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,595
    +1
    1,276
    Quote Originally Posted by bman22 View Post
    ... this was the best place to come for some assistance.
    Welcome

    Be sure to click on my signature links. Lots of useful info.

    As noted, compression text is a good check. Throttle held wide open, all spark plugs out, strong battery.

    Note that Polaris watercraft really like a strong battery. Weak batteries can cause all sorts of starting troubles and confound diagnostics.

  4. #4
    jajardas's Avatar
    Join Date
    May 2014
    Location
    Racine, WI
    Posts
    535
    +1
    19
    Always a good idea to update your profile and list where you are. Some of the Polaris guru's on here may offer assistance in your diagnosis/or repair.
    JJ

  5. #5
    Resident electronics hacker UnityRacing's Avatar
    Join Date
    May 2007
    Location
    Va Beach, VA
    Posts
    1,425
    +1
    28
    Probably the rings - I'll bet they were never replaced. 2 strokes down on power that's usually the case. As stated, do a compression check, that will tell you.

  6. #6

    Join Date
    Apr 2015
    Location
    Albuquerque, NM
    Posts
    13
    Alright, that will be first on my list of to-do items. I'm assuming I can use a normal automotive compression tester?

    Also, another issue I neglected to mention, when you run the tank out, the fuel system will not prime again properly without pouring a little gas down the carbs. Leads me to believe there are fuel pump issues, unless this is relatively common on these engines?

  7. #7
    BlueFishCrisis's Avatar
    Join Date
    Aug 2011
    Location
    Medina, Ohio, United States
    Posts
    4,988
    +1
    140
    It takes some work to prime the new lines on a new build, or in your case, an empty tank. I usually use a small electric pump to get everything filled. Pouring some gas down the carbs gets the motor to fire and increase the RPM and the draw through the pump. Using just the starter motor to try and prime the lines will take a while, drain the battery, and overheat the starter if you are not careful...

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,595
    +1
    1,276
    Quote Originally Posted by bman22 View Post
    ... when you run the tank out, the fuel system will not prime again properly ...
    Did you replace the fuel sector valve?

    If original, it is likely the valve rubber seals inside have hardened and the valve is leaking air into the fuel system under suction from the fuel pump. Often the fuel pump will eventually draw fuel through but any air leaks impede fuel pressure and reduce flow to the carburetors.

    The recommendation for original fuel selector valves is to replace with new. Not expensive.

  9. #9

    Join Date
    Apr 2015
    Location
    Albuquerque, NM
    Posts
    13
    Well, I finally picked the ski up. First thing I did was pull the carbs so if they needed parts, I could get them ordered. The base gaskets will need to be replaced, but I'm hoping I can just make some out of gasket paper. The diaphragms in all three seem rather stiff to me, and they make a light crackling noise when handled. I'm guessing they'll need to be replaced. I know the consensus is that the genuine Mikuni rebuild kits are superior, but considering I will need all three, and they're more than double the price, I'm hoping I can get away with the aftermarket brand.

    I'll also go ahead and order the 3 output fuel pump, and work on redoing the fuel lines. I'll pull the fuel selector valve tomorrow and see about replacing the O-rings as well.

    The next order of business is to check the compression and crank timing. I'm sure I can, but just to be sure, it's alright if I use a normal automotive battery for now, yeah? I'd rather not go out and buy one before I have some idea of what it's going to take to get this thing running.

    Also, just curious as I haven't seen these discussed, but I'm guessing the big black blocks that go between the air cleaner and the carburetors are the oil injectors? They have lines that seem to go down to the oil pump and are oily as hell, so that's all I can figure.


    Edit:
    I just read through the service manual, and noticed that under Crank Indexing, it says "Repetitive plug fouling on one cylinder with no other cause" as well as "Poor top speed". This has me concerned that my issue might be an indexing issue. What do you do if the crank is out of index?

    What is the best way to check indexing to a reasonable degree of accuracy without removing the engine?
    Last edited by bman22; 04-21-2015 at 12:18 AM.

  10. #10
    BlueFishCrisis's Avatar
    Join Date
    Aug 2011
    Location
    Medina, Ohio, United States
    Posts
    4,988
    +1
    140
    Check compression before index.....Redneck crank index check method:

    http://www.greenhulk.net/forums/show...=1#post1502246

    Get the Mikuni Kits. Others who took the path you are thinking about have regretted

  11. +1 by:


Page 1 of 4 1 2 3 ... LastLast

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Detonation project-Pair of '95 750 SLT's
    By mackable in forum Polaris Projects
    Replies: 29
    Last Post: 08-23-2012, 01:24 PM
  2. 1994 Polars 750 SLT Rebuild Project - Piston Wash
    By BlueFishCrisis in forum Polaris Open Discussion
    Replies: 25
    Last Post: 08-20-2012, 06:47 PM
  3. Project Gnadenhutten - 94 750 SLT
    By BlueFishCrisis in forum Polaris Projects
    Replies: 191
    Last Post: 07-30-2012, 11:44 AM
  4. My 94 Polaris SLT 750 Restoration Project
    By policano in forum Polaris Projects
    Replies: 16
    Last Post: 05-30-2012, 08:08 PM
  5. Polaris 750 Triple Project
    By ph2ocraft in forum Polaris PWC Performance
    Replies: 27
    Last Post: 09-27-2006, 02:22 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
  •