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Thread: 70+ Mph XLL/XLT

  1. #1

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    70+ Mph XLL/XLT

    Ok guys, who has XLL/XLT's that are running 70+ and what mods have you done?


  2. #2
    need4pwr's Avatar
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    Check my signature...also, there are guys that have reached 70mph on a single pipe...

  3. #3

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    Thx Need4Power,

    Doubt I'll go the triple pipe route but all the single pipe mods look in line with what I'm trying to put together. Except I planned to try the '05 pump as well.

  4. #4
    need4pwr's Avatar
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    Well....what are the mods, RPMS and speed that you are getting now? I know Carl @ Island racing built a couple of 70mph single pipers.

    Definately go with 05 pump....

  5. #5
    Moderator RX951's Avatar
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    I beleive JIM1300 (jims performance) knows of one too....

  6. #6

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    Right now RPM's and speed are both 0.000 Ski is apart. All parts for Stage one are in garage with the exception of the plate (somewhere at UPS). Going to probably go the blackjack carb route vs the Island setup.. Does anyone have an opinion on that. All opinions are welcome. And I haven't heard any negative things about the Island set-up. Just less familiar with it.

    I bought the ski for $1200 put a SBT motor (i know i know) in it (blown again). Now i have about $3400 in the ski with the stage one parts. Could trade it in and get something newer faster but then I'd have to fork over another $6000 so I figure for another couple thousand I can go as fast as all my buddies (none have modded skis yet)

  7. #7
    HopatcongGPR's Avatar
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    Quote Originally Posted by Redcrownline
    Right now RPM's and speed are both 0.000 Ski is apart. All parts for Stage one are in garage with the exception of the plate (somewhere at UPS). Going to probably go the blackjack carb route vs the Island setup.. Does anyone have an opinion on that. All opinions are welcome. And I haven't heard any negative things about the Island set-up. Just less familiar with it.

    I bought the ski for $1200 put a SBT motor (i know i know) in it (blown again). Now i have about $3400 in the ski with the stage one parts. Could trade it in and get something newer faster but then I'd have to fork over another $6000 so I figure for another couple thousand I can go as fast as all my buddies (none have modded skis yet)
    imvho, unless you pull those sbt cylinders off and have them ported you will never get that boat to 70.

    i have a 99 xll with sbt cylinders that i cleaned up due to the horrible port alignment. the aluminum portion of the transfers must be matched to the sleeve. some of the smaller transfers near the boost port where probably 20-30% closed off from the misalignment. i spent about 40 minutes per jug with a simple cleanup....now after running the boat, i should have looked more into the port heights and widths in comparison to a stock 1200r cylinder. the exhaust port had to be matched also. to further the sbt "issues", they deck the top of the cylinder to get a fresh gasket surface after the sleeve is installed...so be careful if you use an aftermarket head. with a stock 3 shim head gasket and a stock head my compression was 145 area. to get my squish closer to optimium i went to a single shim increasing my compression to 153-155 and squish in the .040-.042 area. on another boat with sbt cylinders we used a pro tec rec head and obtained 163-165 compression with a stock 3 shim head gasket and .051-.052 squish.

    now with all that said....

    i run a full angle mod island plate
    carbs, choke removed, prok filters, 1.5ns/95g, 110/120 stock airbox with screen removed and extra holes drilled in the box
    stock reeds w/protec stuffers
    153+/- compression, .040-.042 squish
    advent cdi 94 curve
    ho/05 pump (synthetic ATF) non setback, dynafly 14/20 turned down to 11/16, 87mm nozzle
    r & d intake grate
    updated yamaha sponsons
    holes filled in the plate and pump shoe
    pump shoe machined down to mate flush with the intake grate
    pump shoe matched to the intake grate

    and....

    the boat only runs 65.8 best on a full tank of fuel.

    however, it will:

    hole shot a stock 1300r, pull it in the midrange
    give a stage 2 gp1200r and 1300r a very good race from a stand still
    beat most gpr's in the chop
    give most stock rxp's a strong run in the chop and from a stand still
    it will even stay with a xll with triple pipes until about 30-40mph

    i have tried just about everything to get this boat over the 66 mark. i have just come to the conclusion that this particular hull is just a POS OR the SBT port configuartion is that much different then the stock cylinders that it is just killing its ability to pull on top end. i say the later because this boat will only pull a 11/16 to about 7100. most stage 2 xlts that i have heard of with the 05 pump will pull a 12/18 to 7100. the only item that cold be holding this boat back is a set of prok's. however, due to the people that ride my "spare" xll, i dont want FA's on it....but, in my experience i havent seen much on the top end side with FA's unless the displacement is substantially increased. plus, i drilled about ( 8 ) 2" holes on the interior side of the box to increase airflow....so i doubt this could be killing top end. then again, to be honest i never did a back to back test on a modded air box vs prok's.

    in a nutshell i dont care too much because over the winter this baby motor is getting transformed into a monster bus pistoned mill. if the bus pistons cant push this POS over 70...LOL, its time to buy a different hull!

  8. #8
    need4pwr's Avatar
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    Quote Originally Posted by HopatcongGPR
    it will even stay with a xll with triple pipes until about 30-40mph!
    who was that?

    Quote Originally Posted by HopatcongGPR
    in a nutshell i dont care too much because over the winter this baby motor is getting transformed into a monster bus pistoned mill. if the bus pistons cant push this POS over 70...LOL, its time to buy a different hull

  9. #9
    HopatcongGPR's Avatar
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    oh yeah...and for the record, i mispoke alittle above...

    i ran a 11/17 with the 87mm nozzle and tried a 85mm nozzle and had a slightly slower speed. i dropped the prop another degree and the speed remained the same while the rpm was in the 7100 area. i cant come to terms with turning the prop lower then 16.....so it will stay the same until the baby motor is replaced. so is there more speed if i turn down the prop more with the 85mm nozzle? couldnt tell ya....

  10. #10
    HopatcongGPR's Avatar
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    Quote Originally Posted by need4pwr
    who was that?




    golly gee....i wonder who?

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