Page 1 of 2 1 2 LastLast
Results 1 to 10 of 11
  1. #1
    triplekoin's Avatar
    Join Date
    Jun 2012
    Location
    Duluth, MN
    Posts
    26

    SL750 Weak Spark

    Going through a 94 sl750 installed triple mukini pump redid fuel lines with restrictor and noticed Mag piston top was melted but din't have a hole "yet" + was getting a weak spark. Put a new top end kit in and ohmed out the stator to find the exciter coil wasn't ohming correctly to the service manual. Should be 490 ohms and instead I was getting .512!!! Then noticed front crank seal has big leak so I'm think it was leaning mag piston out. So far I've Ordered stator and crank seals....


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Location
    Cleveland OH
    Posts
    17,330
    +1
    31
    512 isn't too bad, but not a bad idea to have a spare stator on hand just in case.

    Bad crank seal is a major issue. Replace that for sure. Since you have to split the cases to install that, make sure to get the rears as well.

    As for the weak spark, have you tried cutting the plug wires back 1/4" yet? Did you check your plug gaps?.

  3. #3
    triplekoin's Avatar
    Join Date
    Jun 2012
    Location
    Duluth, MN
    Posts
    26
    Yes I've cut the wires back 1/4 with same results...as soon as I cracked the crankcase open steel ball bearings spewed all over the place from the front bearings. I ordered a new crankshaft with all new bearings and rods and will send mine back as a core. In my opinion its good to know that you have all new parts on your crank instead of wondering about that questionable rod or bearing while your at wot. Back to this weak spark, the coils seem to be wired in series so they must all spark at the same time.... I'll check over them again to see if they test out ok

    Click image for larger version. 

Name:	test.png 
Views:	55 
Size:	94.2 KB 
ID:	275250

    Click image for larger version. 

Name:	Untitled.jpg 
Views:	59 
Size:	35.9 KB 
ID:	275251

    Click image for larger version. 

Name:	Untitled1.jpg 
Views:	60 
Size:	71.2 KB 
ID:	275252

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,599
    +1
    1,276
    The ignition coils are in series and do all fire together. They do require a solid ground and a good CDI + stator, of course.

  5. #5
    triplekoin's Avatar
    Join Date
    Jun 2012
    Location
    Duluth, MN
    Posts
    26
    Crankshaft still in the shop getting its final touch (Trueing) In the meantime I assuming my little CDI black box must be working cause it was giving a spark just weak. I wonder if that little LR-23 voltage regulator has anything to do with my issue? Is that a common part that gets replaced in these 94 SL750's? Anyone?

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    36,599
    +1
    1,276
    LR module should not affect spark intensity on a Fuji engine.

    Why do you feel that a weak spark could not be caused by the CDI itself?

    CDI needs solid grounding, solid connections to stator and full strength feeds from the stator.

  7. #7
    triplekoin's Avatar
    Join Date
    Jun 2012
    Location
    Duluth, MN
    Posts
    26
    Thanks to everyone who has helped out with my questions. Just recieved my cdi and crankshaft today! I'm going to start on it tonight so I'll keep everyone posted.

  8. #8
    bowsniper's Avatar
    Join Date
    Aug 2008
    Location
    macomb,michigan
    Posts
    5,896
    +1
    6
    If you changed any of the fuel lines to clear or blue, watch for bubbles..

    Are you going pre-mix or oil pump?

    PLUGS>>> NGK BR-8ES. .024"-.028" Gap.

    Make sure you loc-tite the case bolts,crank threads,

    Line up stator line with case seam. add sealer to the grommet for the cdi wires thru the stator cover.

    Seal both the inner and outer stator covers.

    Grease the o-rings on the starter.

    Clean the ground mount on the cradle for the negative cable.

    New base gaskets.

    Grease the carb gaskets.

    Use yamabond or polaris equivilant for the cases and grommet for the cdi wires goig thru the stator cover.

    Grease the gears in the bendix. don't add too much or else the bendix may stick.

    Also grease the bushing hole in the stator cover for the starter.

    Smear a little grease on the inside stator cover plate. it will collect "junk" that accumulates.. and it will....lol

    Slide the big pipe back n forth to get the manifold bolts in!

    Buy a stubby wrench for the carb nuts! ugh!!!!!!

    Red-Loc-tite the stator screws !!

    Blue-loctie the crank snout. Red Loc-tite the threads.

    Use a monkey wrench on the coupler and torque the crank nut on the flywheel. that will hold everything still for ya.

    Driveshaft should be aligned with an alignment tool. wrap tape around the end of the shaft to prevent the splines from hurting the seals in the bearing carrier(actually, its a bushing carrier!)...lol they are brass they are no bearings in there. Anyways...

    Battery disconnected of course.

    Check the grounds in the e box for being tight. especially the one ground stud in the cdi box.

    Might as well check the wear ring for clearance and the prop condition along with cleaning up any nicks on the stator blades. dont sharpen it, just smooth it out.

    If the motor got hot, it may have warped the water rail just a tad. watch for leaks at each opening on the rail. Mine was warped and sprayed water right at the carb openings! I fixed it by doubling up the gaskets. works fine now.

    Did you ditch the auto cock?

    Did you follow Beerdarts fuel routing diagram? jus asking...

    You can even check the fuel selector switch and replace that gasket if you see bubbles in the line from that area.

    Check the driveshaft splines for being flat not pointy. check the coupler too but be careful, it could be sharp from wear.

    Do not forget the driveshaft bumpers on both sides of the driveshaft.

    Keep all shims on the cradle exactly where you had them before. that aligns the motor.

    Do you have a alum fuel sender or 2 lines with screens and weights on them? if the ladder.....make sure the lines arent curling up in there. there are weighted screens that go on them. the shorter line is your main. the other is your reserve. if you mix them up, you won't have any reserve when you need it.

    A good AGM battery is the snit on these fugis..about 85.00 well worth it.

    Fuel filters going the correct direction? new?

    Check the screen on the big pipe if you can get it out without snapping it off!...lol

    These are just things I remember when I was doing mine. I hope this helps.

    Clean the intake screen in the exit nozzle!

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Location
    Cleveland OH
    Posts
    17,330
    +1
    31
    Quote Originally Posted by bowsniper View Post

    PLUGS>>> NGK BR-8ES. .024"-.028" Gap.

    Red-Loc-tite the stator screws !!

    Blue-loctie the crank snout. Red Loc-tite the threads.

    Use a monkey wrench on the coupler and torque the crank nut on the flywheel. that will hold everything still for ya.
    Wrong.......

    Are we going to go through this again????????

    That last one can cause MAJOR crank damage if followed.

  10. #10
    triplekoin's Avatar
    Join Date
    Jun 2012
    Location
    Duluth, MN
    Posts
    26
    Well I got everything back together (after taking apart the crank twice because of a leaky front crank seal) and its running nice and cool!!! I did the rope trick on the pto to tighten the driveshaft to the crankshaft. Ran it to make sure it was aligned...I used a plumbers wrench to tighten it up. Left the shims on the engine mounts. Used red locktight on the case bolts per service manual. I'm using NGK BR-7ES plugs without any troubles. I assume my oil pump is working but I mixed the gas 50:1 just in case which I wouldn't think will hurt anything.

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. 94 sl750 weak spark
    By wright-performance in forum Polaris Open Discussion
    Replies: 18
    Last Post: 06-19-2012, 04:20 PM
  2. 1993 sl750 weak spark
    By damo300 in forum Polaris Open Discussion
    Replies: 29
    Last Post: 10-25-2008, 12:30 PM
  3. what's a weak spark
    By web in forum Polaris How To & FAQs
    Replies: 1
    Last Post: 08-29-2007, 09:37 PM
  4. 95' SL750: No spark!
    By SeaBee63 in forum Polaris Open Discussion
    Replies: 19
    Last Post: 07-18-2007, 12:06 AM
  5. SL750 No Spark
    By KKubacki in forum Polaris Open Discussion
    Replies: 18
    Last Post: 06-01-2007, 02:34 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
  •