Thread: Issues with XPL
09-27-2009, 11:46 AM #1
Issues with XPL
Hey guys, i just finished up my XPL project. Basically i bought a 98 XPL for $900 with a new trailer. had a burned piston, rock jammed in the impellor. I rebuilt the entire machine, new crank,bored 1.50mm over, fresh top end, rebuilt and milled down RAVES, new fuel lines, jetted the carbs to : 167 mains, 95 lows, 2.3 needle/seat, removed acc pump,installed primer kit, prok fa's, solas 15/20, and a brand new wear ring. I broke the motor in properly and have put about 10 or so hours on the boat. i did a top speed run and could only click off a 58.1 mph pass. Plugs look great. did a compression test when i first put the motor together and i had 135 in both, its still the same compression. i do not feel one bit of hesitation or bogging while accelerating. my lows are 1 1/2 turn and my highs are closed. Whats is going on here? i thought i would be in the 63mph range.
09-27-2009, 12:11 PM #2
- Join Date
- Jul 2005
we need your TOP speed/WOT rpms.
But I think you need to get an OEM prop and test with that. the solas can be too tall of a prop.
09-27-2009, 01:55 PM #3
IMO, you do not have anywhere near the compression (or a tight enough squish-if stock-ish, which is likely) for that Concord.
Why such a big bore?
The prop may be the whole problem but I was able to turn 7000 with the exact same jetting with the HS screws at .5 turns out so I wonder if you might not have enough fuel on top. That was with a stock prop and it was GPSing at 62-ish ('99XPL). I do have more compression and the squish is a bit tighter than stock, but not by much.
09-27-2009, 08:02 PM #4
With no accel pump you should be at 162.5 highs. I'm there with .5 out hsa and plugs are mint. I just rebuilt mine last winter, have the same mods as you with stock prop pulling 60.2 gps. Just got my prop back from impros and pulled 61.2 gps.
Your compression will go up once the rings are seated more. Mine did. Had 135 like you and now I have 148 after riding most of the summer. If you read the 951 mods link, he uses 15/20 but is also going to more mods later. I think its too tall myself, some will disagree though.
Did you get your timing corrected at all with the new motor? I have still yet to and was told I should be about 63 with my set up. I am going to do it, just haven't had time yet.
Definitely drop your mains, too high on top. You want a nice tan color. Don't be afraid to drop down, your making up for it with the low speed. Its 10 higher than a carb with accel pump and a 167.5 main. Some people even run 160 with closed and no burn up pistons.
What are your max rpm?
09-27-2009, 08:10 PM #5
yes definately need to know your max rpms. That prop is tooooo tall for your ski. You need a high comp head to turn that prop. RQ has a trick for the stock prop but I will let him tell you if he wants to, and its just as fast as the concord.
09-28-2009, 08:42 AM #6
not sure on rpms cause my tach shit the bed. the reason i did the high prop cause i planned on running a high comp head but the deal fell through. i will be running a head next spring, so should i keep the prop?
09-28-2009, 08:57 AM #7
I know there are some piptch differences on props, but I have that exact setup in mine only 170 mains (I was afraid of burning down) 15/20 Solas Concord new wear ring not bored quite as big ProK filters the only thing I have that I didnt see in yours was I have a R&D head on mine... I am GPSing 64.3 MPH and I am 290 Lbs I turn 7050 exaclty. I really think it is eomthing else. Try taking the springs out of your raves it will kill your low end but on top they will be open already and will tell you if they are stuck closed. My GSXL is turning low RPMS and running about the same top speed I pulled the Solas out and gained .5 MPH with a stock prop. Try to find the issue before taking the time to pull the prop, alot of people are running them and it may in fact be to tall, but I dont think its going to hold you back that much.
09-28-2009, 09:44 AM #8
i work at a performance machine shop, and i was wondering what is involved to modify my stock head to bring up compression?
09-28-2009, 10:18 AM #9
The differnce in the engine loading can be significant. It is easy to tell if the prop is too much for the engine because it will slag the rear cylinder. It is not just the pitch of the prop but the profile of the prop itself.
Since you do not know what your RPMs are on top it is possible that the RAVEs are not opening. Did you check that Check Valve to the RAVE solonoid when you did the build? Those can get clogged up and the RAVEs will not open.
09-28-2009, 12:46 PM #10
Well Krunch I have to admit I didnt do a squish test I bought it with 47cc domes and was afraid that would be to much so I ran it with the O rings and a single layer from my head gasket. The compression is only 145 PSI in both cylinders and I have run it for 2 years now flat out up the river for miles at a time with no issues (well except electrical I think I los tthe MPEM last ride this year) I bet I have gone 6-8 miles at WOT at times coming back up the river to beat a storm. THe one thing I dont know is if the MPEM had the timing advanced or not.
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