Thread: 99 xp limited mod ideas???
06-07-2011, 02:52 PM #1
99 xp limited mod ideas???
im a huge car guy and built several decent horsepower drag cars in the past, but for some reason i never got to the water. i just picked up a very clean and nice 99 seadoo xp limited and i want to modify it had to settle for this instead of an RXP but owell. i did the normal google searches and i kinda came up blank.. i really dont know jack about skis other than the general stuff. any ideas or places to get parts from. looking for exhaust, ride plate, etccc just normal bolt ons... anyone have one??? whats the realistic speed she reaches?? whatshould i change first
06-07-2011, 06:08 PM #2
Welcome to GH. Water toys are a different story. the Doo motors are already tuned up to haul azz. by adding gofast parts your going to be tuning more than riding. you can how ever do mods that let you have some speed and throttle response but trying to get to 70 is unrealistic. you should be seeing about 62-3ish on a stock 951 XPL. you can do things like flame arrestors, rejet kits, high compression head, prop and nozzles to get some added performance. the big HP pipe (Factory Pipe Spec II) will eat pistons if not tuned properly and tuned again. If you can find a Coffmans pipe it will help you but the HP is not all there. carbs can be added but are temperamental to humidity and temperature. there are a few lurking around here that have shops and have the go fast parts you are looking for. Just get your post count up with some contributory posts (20 I think) and you can post a WTB add in the classifieds
06-08-2011, 04:06 AM #3
thanks man ....huge help mega pumped!!!!!
so what basically leave the engine alone.. and find a coffamn pipe thats all?? im not touching the carbs, or engine thats for sure. is there BMX style bars for my old fossil ?
06-08-2011, 05:08 AM #4
yea leave the engine be. you can port and polish the cylinder jugs also but out side of that there isnt much you can do the engine thats worth it for rec riding. you can also Look up Group K for kits also. Ive been the route of trying to build a rocket and it just sucks unless your racing. Rec riding, stick to what I listed and if your that set on a pipe id get the Coffmans if you can find one....
06-08-2011, 07:47 AM #5
The 951s dont need alot of compression to run well as they produce great torque when set up properly from their displacement size. I do alot of surf riding and usually go offshore several kilometres to get to our spots so reliability is a factor .
More compression will only get you low/mid range torque and will not get you any more revs, so instead of running higher numbers I have done this instead ,I run Rinnaldi reeds with 10mm spacers,aluminum flywheel and the pto reduced in size and weight down to the coupler diameter,I run the ignition with a higher timing curve and raised to 7300 rpm limit similar to Franco's.The pumps have been removed from the carbys and rejetted with prok filters.I run the 97.5 pipe and manifold . We usually scollop the back of the impeller blades out just a little which gives good drive in rough conditions and relieves pump pressure at low/mid range speed .The impeller is enlarged on the outer blade areas and then machined back to the diameter of the OEM wear ring which gives you zero cavitation. My cylinder bores are offset to the crankshaft centre line by 3 degrees (bored on an angle) which then gives you considerable more torque because power is directed to the side of the crank in the direction of the rotating crank instead of dead centre.
These things done together give me good torque and good reliability as my engine isn't banging away with higher comp reducing its life cycle
Lots of guys go the aftermarket pipe route but with a large displacement 2 stroke like the 951s it reduces longevity and enhances wear and tear on the top end bearings and front and rear mains.Don't be mistaken the pipes make power but there is another way of getting that power.
06-08-2011, 08:33 AM #6
- Join Date
- Apr 2009
Can vouch for trevors ski/mods.... Have had a short blast in encounter bay, goes like a shower of shit!
06-10-2011, 09:47 AM #7
SURFnTURF your running a pipe. The 97 wasnt made for that engine... "I run the ignition with a higher timing curve and raised to 7300 rpm limit" you mean REV limit. Raising (advancing) the timing can be a killer with some years of XPL especially if the compression was raised. Using the 97 pipe would be raising compression but only in the range the pipe is tunned for. so say the lower rpm were the pipe is not on higher compression would help or water injection but with higher compression it would be too high when the pipe came on.... Maybe injection tunning is the way to go ?? or you could retard the advance in the range were the pipe peeks pressure... ..LOL just thinking out loud. How about you just start with a level 1 from PPG or Group K
Check this out http://www.revlimiters.com/html/99-02_curves-m.html
The 99 has more advance advance in a bunch of ranges that would effect lots of stuff
06-10-2011, 09:50 AM #8
Not to be a total arse but weight reduction works better than HP I dont know your size but 125lb girl will wack a 190lb guy every day
06-11-2011, 01:44 AM #9
The 97.5 GSXL pipe gives an instant 100-150rpm due to its larger displacement and a better flowing design. These pipes will run at 7400 rpm and the engine just sings.Those pipes work trick @ 7400 !!! but I don't set my rec skis up at that rpm anymore as it shortens top end life. My compression is 135 with a higher timing curve (similar to franco's)with a raised rev limit to 7300rpm .I run a Reflashed MPEM with a higher timing curve similar to the Franco one ,not a FPP one as they are pretty gay (RXX).
From one of these .
If you ask nicely they will program any curve you want!
Everybody runs aftermarket pipes and high compression with these ignition curves but run one of these pipes with low compression and higher curves and see what happens.
My cylinders are from Les Cooke over here and he bores them on a 3 degree offset away from the crank center line (no one has done this to my knowledge,Even Bill O'Neil ,Harry and Perry haven't heard of this as I spoke to all of them about it. I'm not after a high revving point to point race engine cause it just kills the cash flow from tearing down all the time ,so I opted for a lower revving version with a good spread of power that is reliable for the surf. Oh and the raves can have a bearing on the lean carby signal .
06-12-2011, 10:42 AM #10
I used to ride surf but after a stroke in 02 or 03 I gave it up. Now I ride more sedate and mostly flat water. Sad but thats what happens. I cant list all the injuries that at 59 make me afraid to ride surf again. Maybe its why I took up sailing.. LOL
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