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  1. #1

    Join Date
    Mar 2008
    Perth wester Australia

    Help tuning my XPL 98 with mods

    Hi all

    I have finally got my XPL back on the water... and are having some issues with it..

    Its got 48cc head (ada racing) 165psi comp, 65thou squish, carbon reeds, power plenum (r&d), 13/19 dynafly and R&D intake grille.

    It is running really lean and is really down on power in the top end. it pings a little in the top, and plugs come out bone dry and a beigh colour. I though the carbs may have stock jets and need jetting. I thought in the meanwhile ill try give the jets some turns to compensate. I ended up going 2 full turns on the high, and 2 turns on the low and it didnt really seam to make a difference.. still lean and dry plugs.

    I got it home and pulled the carbs off, and it has 170 high jet in one carb, and 165 in the other. I thought that is rather large? shouldnt be lean at all. The carbs are pretty bad inside, diaphrams are old n tacky, and got stock 2.0 needle and seats.

    I am thinkin now that it probably either has a leak in the engine and is drawing air somewhere, or the carbs are not working right and not supplying enough feul. Maybe the needle and seat it too small to let enough feul, or there is a crank case leak which is lowering engine pulse and therefore less fuel pressure..

    Has anyone had any experience with this? I think i am going to order some new 170 high jets and 2.3 ml needle n seats and full carby rebuild kit anyway, but i have a feeling this may not solve the issue.

    Any help would be greatly appreciated.

  2. #2

    Join Date
    Mar 2008
    Perth wester Australia
    Also.. if someone can give me pointers as to what jets to use..

    I will haev 2 combos..

    All combos will yse 165PSI heads, carbon reeds 13/19 dynafly

    One combo stock pipe.. one combo Coffmans..

    I am thinkin probably for stock pipe 90 lows and 16 highs...and for coffmans 100 lows and 190 highs..

    I am also looking at the mikuni high volume pump and fuel rail.... should this be neccesary

    Again help would be appreciated.. I am going to order the stuff from the states to Oz... so i need to get it right.. takes agess
    Last edited by peachypete82; 03-29-2008 at 05:02 AM.

  3. #3
    Brian Thomas's Avatar
    Join Date
    Apr 2007
    East TN

    I would rebuild the carbs with new mikuni kits and new 2.0 N/S. Make sure you replace all the clear plastic check valves in the fuel pumps. Your jetting is good. Stock pipe, 165-170 mains, with 90-95 lows works great for me.

    Next check the timing. Is there any modification done to the timing or MPEM?

    Your compression and squish are also fine for pump fuel. As long as it is equivilant to our US 93 octane fuel.

    good luck, -BT

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