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  1. #1
    ou812's Avatar
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    stage 2 01 GP1200R issue

    My buddy has an 01 gpr thats never ran good after it's rebuild from a reputable local shop. It only saw 65+ once for a few hrs with the mods then it deto'd #1 cyl & got the rebuild & never saw that speed since....1.5 yrs ago. LOL
    Just when we were getting the low 7030 rpms back up to stock 7150ish it back fired & lost power.

    here's the mods:

    fly's & rejet
    stinger2
    water bypass
    free flow
    riva rec heads 145 psi
    protec ride plate & grate
    R&D tabs
    solas 13/19

    It has good hole shot & keeps up with my xpl till top end then I pull him.
    we call it "BOB" 'cause thats what it does in the slightest chop unless you have trimmed all the way down.

    we started off at 7030 rpm in 108 degree heat on glass. cyl 1 & 2 were dark & 3 was light pinkish. He was set at 2 out on hi's on all 3 carbs to start. we ended up 1.5 out on 1 & 2 which were now light/med tan but #3 never changed color no matter where it was set! 2.5 out....pinkish color, 1.5 out...pinkish color. so we left it at 2 out with the 1 & 2 @ 1.5 out & he got 7140 & was keeping up with my xp which runs mid to upper 64's. He decided to leave it at that & while heading back in to load up it back fired @ WOT & lost power. got it on the trailer & saw that the #3 carb & F/A were all wet with oil while the others were dry. So it's obvious it BF'dd through the 3rd carb. Could the reeds in the rear carb be damaged & caused the odd color by letting too much fuel in & then BF'd & destroyed them? He hasn't pulled the carbs yet so I can't tell ya anything about it. I was thinking it was the exhaust hose that blew 'cause he said it sounded like it came from the right of him & sounded like a large plastic bag popped.

    Any advice on this matter would be appreciated mucho!


  2. #2
    Hydrotoys's Avatar
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    The BF more than likely took out the reeds. Could have been any cylinder, but you'll know when you take it apart.

    The rebuild issue could very well be an air leak. 2 strokes are very sensitive to air leaks in the cases.

  3. #3
    ou812's Avatar
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    If the reeds are blown should he just get OEM or replace all 3 sets with aftermarket?

    Which reeds are best for a stage 2 setup?

    Thanx

  4. #4
    subarupartsdude's Avatar
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    If his wallet can afford vf3's,I would go that way.

  5. #5
    Like a chimp with a ball-peen hammer smackwave's Avatar
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    Stock reeds are about $30 per cage, VForce reeds are $500 for the whole set. It's a pricey way to go but the VForce are worth it if you can pull it off. Anyway, I have to think Mark's dead on about the air leak. Pull off the carbs, check the reeds, and pressure check the engine. You'll be chasing gremlins until you're fed up with the whole thing unless you're sure the engine's tight.

  6. #6
    ou812's Avatar
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    So far he found the #2 reeds are F'd! Broken pedal sitting in the cage & burnt. #3 is showing burned pedals too. #1 is perfect...

    What causes them to burn? Lean?

  7. #7
    ou812's Avatar
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    here's a pic. I never saw them in person only in his camera phone.
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  8. #8
    Moderator Insanediego Joe's Avatar
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    The check valves in the #3 carb probably got blown out when it backfired. Might want to check all the check valves in the carbs while its apart.

  9. #9
    Hydrotoys's Avatar
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    Yup, I agree Joe.
    I'd wager at least one of the 6 pump check valves is toast.

    What's that ROUND burn mark? It looks like something molten sat on top of the reed.

  10. #10
    ou812's Avatar
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    Quote Originally Posted by hydrotoys
    Yup, I agree Joe.
    I'd wager at least one of the 6 pump check valves is toast.

    What's that ROUND burn mark? It looks like something molten sat on top of the reed.
    I don't know what the burn marks are. There's a burn on the edge of the end pedal too. Those are the #3 reeds. He said cyl #2 was the one that broke & it has burn marks too but #1 cyl is perfect..

    I'll tell him about the check valves.. Any info links aon the valves here that I can send him?

    Thanx!

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