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  1. #1
    Just say NO to "Stock" TechSLX's Avatar
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    1996 SLX Compression prob, 90psi at mag, hmmm?!?!

    Hey guys/gals,

    Listen, bike ran real weak today on the ride in after some strange behavior. Carbs are GOOD TO GO but bike would not go over like 3100rpms, hesitating, stalling, etc. Could not even get the bike up onto the trailer, had to crank it up. When I got home ran a compression test to all 3 heads. PTO and Center held 122 and the mag(front) only 90psi. Thoughts? Hole in piston? Or would not register that(90psi) if so, etc, etc?!?!?

    Bike seems to crank up full RPMz outta the water, while flushing, etc. Is a little boggy during rev up but will hit high R's outta water, wierd...

    Just do not know what to start ripping apart, anyone got any ideas re: this 1996 SLX 780?

    Thx, in advance...
    Last edited by TechSLX; 08-31-2008 at 03:23 PM.


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    I doubt a holed piston would create any psi. More than likely ring or cylinder wear.

    Time to remove the head and have a look see.

  3. #3
    Just say NO to "Stock" TechSLX's Avatar
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    Pulled the MAG head and there it was, about a full silver dollar divot outta the top of the piston. So, Piston is trashed, sure the rings are not any better, cylinder wall, etc, culprit has been found. I know I need a new Piston/Ring/cylinder/head etc setup for the Mag, but should I do all 3 as a full overhaul? I know I could do the cheap easy fix, get a clean used head/cylinder/piston rings/clips/bearing etc and get it running in an hour, but maybe anyone have any suggestions as far as hop ups while I have to do it anyway? Port and Polishing maybe?!?!? Hmmm...

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    How much do you want to spend?

    You know the cheap and easy fix...

    Fresh rebuild would run for many years to come. Expensive

    Reeds and porting would be a nice upgrade, but will be very costly.

    Need to figure out what caused the piston meltdown and fix that before you do anything.

  5. #5
    Just say NO to "Stock" TechSLX's Avatar
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    Yeah, know the problem, mag and pto carbs were outta sync, and set WAY too lean from previous owner. Got the OEM specs for the carbs outta the factory manual, reset to factory and will tune once piston is repaired. What do you think the porting will run for this bike? I am in the process of doing the easy cheap fix to last the rest of the season, but am considering a project for the winter while I have it stowed in the Gee-rage.

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    PM Santa Cruz as he just had his done this winter.

    I think it's in the $400-500 range for triple cyl porting.

  7. #7
    Just say NO to "Stock" TechSLX's Avatar
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    Thx Meng, will do...

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