Page 1 of 2 1 2 LastLast
Results 1 to 10 of 13
  1. #1
    Myself's Avatar
    Join Date
    May 2007
    Location
    North Central Arkansas
    Posts
    2,772
    +1
    129

    Some SL650 fuji triple questions

    So I ended up with a basketcase '92 SL650. It actually looks pretty decent but had been sucking in water and broke a couple piston skirts and wiped out a thrust washer. So after sourcing another one for parts I'm now in the process of re-assembling the engine. First question....What's with the huge caverness recess in the heads? This thing is gonna have like .150" squish! I'm used to seeing a lot less than this. I also found some port info and noticed the 780 porting is a little lower. So that got me thinking......why don't I just put all the cylinders back on with 1211 only and no base gaskets like I do on various other mod builds. This isn't really getting modded but surely it would have to help with a slight bump up in the compression right? Also do I need to update/reroute cooling lines or leave them as stock? If I were keeping this thing I would surely break out the carbides and attack the upper case, I don't even know how the fuel mix finds it's way up into the cylinders, I see so much room for improvement.


  2. #2
    Myself's Avatar
    Join Date
    May 2007
    Location
    North Central Arkansas
    Posts
    2,772
    +1
    129
    Well, I went ahead and re-assembled today with NO BASE GASKETS. 1211 sealant only. Still have about .130 squish. Leakdown test went just fine so I hooked up a battery and cranked her over. Fresh hone with freshly scuffed ring edges on used rings netted 120# cranking compression. It has been my experience after a bit of run-in it will come up. I'm expecting it to be 125-130psi. I know this would be just fine for a Yamaha or Kawi triple but how about this little Fuji?

    Pic of all the worst parts, and the assembled engine.
    Click image for larger version. 

Name:	polaris fuji 006.jpg 
Views:	65 
Size:	161.9 KB 
ID:	324757Click image for larger version. 

Name:	polaris fuji 007.jpg 
Views:	66 
Size:	163.5 KB 
ID:	324758

  3. #3
    BlueFishCrisis's Avatar
    Join Date
    Aug 2011
    Location
    Medina, Ohio, United States
    Posts
    4,988
    +1
    140
    120 is good for the Fuji. Don't be surprised if it doesn't come up.....

  4. #4
    Banned User
    Join Date
    Jun 2010
    Location
    Milwaukee WI
    Posts
    16,708
    +1
    1,324
    No base gasket may affect port timing. It may run with less power. Could possibly be a little better on the bottom end but possibly lose some up top I would think.

  5. #5
    Myself's Avatar
    Join Date
    May 2007
    Location
    North Central Arkansas
    Posts
    2,772
    +1
    129
    Which would be just fine for this little 650 I'm sure. It's not exactly a rocket out of the hole.

  6. #6
    Myself's Avatar
    Join Date
    May 2007
    Location
    North Central Arkansas
    Posts
    2,772
    +1
    129
    Test rode last weekend. It feels very powerful from a start to midrange. Does not feel at all like a little 650. And the top speed feels real good too.I'll do another compression check and see if it came up any. This thing has power trim that still works too! Here's a pic.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	polaris sl650.jpg 
Views:	50 
Size:	50.1 KB 
ID:	327562  

  7. #7
    Myself's Avatar
    Join Date
    May 2007
    Location
    North Central Arkansas
    Posts
    2,772
    +1
    129
    Ended up keeping this instead of selling. My son really likes it. Compression after some break in time is at 127/125/125. GPS readings are 43-43.4 consistently. Low to midrange is VERY good for a 650. Just cut the center bars out of the grate and the plugs show rich so maybe we can get 45 out of it?? Flame arrestor is stock with a K&N on the end of the housing. Maybe I should try taking the k&n off to lean it out a bit.

  8. #8

    Join Date
    Aug 2014
    Location
    Richardson, Tx
    Posts
    246
    +1
    20
    Easiest and most reliable way to build more power in that Fuji engine would be just make it bigger. 750 cylinders, pistons and heads will drop right on that engine, could be run with existing ignition and carbs (rejetted of course), will make a lot more power and could be found probably basically free. You could also explore a better pump setup, if you are still running the original '92 pump.

  9. #9
    Myself's Avatar
    Join Date
    May 2007
    Location
    North Central Arkansas
    Posts
    2,772
    +1
    129
    Yep, still the original pump.

  10. #10
    BlueFishCrisis's Avatar
    Join Date
    Aug 2011
    Location
    Medina, Ohio, United States
    Posts
    4,988
    +1
    140
    Quote Originally Posted by Myself View Post
    Ended up keeping this instead of selling. My son really likes it. Compression after some break in time is at 127/125/125. GPS readings are 43-43.4 consistently. Low to midrange is VERY good for a 650. Just cut the center bars out of the grate and the plugs show rich so maybe we can get 45 out of it?? Flame arrestor is stock with a K&N on the end of the housing. Maybe I should try taking the k&n off to lean it out a bit.
    Just double check to be sure that the FA screen wasn't removed when the K&N was installed or you will obviously loose that functionality.

    If the bottom end and midrange are good, I personally would be happy with low to mid 40's on a 650!

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. want to do some mods but have questions
    By jusloungin in forum Yamaha PWC Performance (4-stroke)
    Replies: 50
    Last Post: 06-11-2010, 05:09 PM
  2. old school triple questions
    By krispaintballz in forum Yamaha Old School Skis
    Replies: 12
    Last Post: 05-20-2009, 01:50 PM
  3. I got some dirty valves!...and question
    By jeepinwi in forum 2-Stroke Performance
    Replies: 16
    Last Post: 02-26-2009, 01:11 PM
  4. Fuji triples! almost new?
    By ZMANN in forum Polaris Classifieds
    Replies: 8
    Last Post: 09-05-2008, 10:09 PM
  5. Fuji crank question
    By xlint89 in forum Polaris Open Discussion
    Replies: 6
    Last Post: 04-28-2007, 03:28 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
  •