97 xp dies when powerband kicks in

[masta2000]

i just rebuilt my 97 xp after i blew the engine on the water. did whole top end rebuild with professional porting and oversize. then i installed the microtouch rev limiter while keeping standard settings. then removed all grey lines and replaced with nice black ones. i installed everything when i did rebuild. when finished, tested the machine outside of water. we had to run it for 2-3 hours on idle to do correct break-in. machine runs perfect outside of water. once in the water, the machine idles fine but when i kick it into powerband, machine "runs out of fuel" feels like starving and dies down. it starts back up no problem and can do the same thing again. running oversize carbs and type 2 exhaust pipe. carbs have been cleaned and lines are new. i removed elbows right after fuel sender under the seat, is it possible i have kink in lines? i looked and looks fine. maybe microtouch system? the other day i reved machine and it overreved on its own even after removing key, few seconds then died: weird? why does machine cut out? everything is new.
please help!!!

 

[kustomkarl]

With the over sized porting did you re-jet the carbs to keep them from starving the engine? Did you check the pop off pressure? is the timing advanced slightly? There is more to doing mods than just making thing bigger and new.

Karl

 

[timmyboy76]

:agree:, from reading numerous threads/post, when "goin bigger", something about manifold pressure, you need to compensate then, with n/s(needle and seat) assy (pop-off).
Might check specs on equipment you installed, for what you need to do to compensate for it.
Also, if I read right, did you "break in" your motor, 2-3hrs outside of water?

 

[kustomkarl]

I saw that too Timmyboy...That's not the way to do it unless you want to rebuild it again. It not only isn't good for the engine, but it causes undue heat to the Jet Pump assy, bearings and seals. The seadoo needs to be in the water to properly cool the jet assy, and Varied rpm's for proper break in with temperature change.

Karl

 

[PWCdoc]

You stated: "the other day i reved machine and it overreved on its own even after removing key, few seconds then died"

Did it rev very high over and above what you would expect as its limit? If so, you have an air leak somewhere or it's jetted way too small for the needs of the motor. You need to run a pressure test to see if the motor is leaking or not.

 

[masta2000]

i didnt rejet the carbs yet because i thought i needed to test the machine first. what would be the common modifications i would have to make? i read someone posted about the needle and seat. sorry to sound like a newb but i am not sure how to adjust it. do i need a pressure monitor? does anyone think something may be wrong with my fuel line system, i personnally replaced eveything and cleaned filters and petcock. would a wrong pressure cause the machine to die so suddenly like that? if i am guessing right i would definately have to jet bigger; i did first oversize so jetting 10-20 more? somehow i have to create less pressure or more pressure in intake? sorry for all the questions, i would consider myself pretty knowledgeable in 2-stroke tuning since i've rebuilt and tuned my banshee, but this seems a little more complicated.

 

[masta2000]

also do i advance the timing? i have the microtouch controler. and to answer the last question: i revved up the machine outside of water one shot and the revs climbed hardcore for no reason even after letting go of throttle, so i pulled key and was still going so i panicked and removed spark plug wire and still turning. very weird, the whole thing lasted 5 seconds or so but i'm worried might happen again. as far as i know there is no air leak in intake as well as manifold. engine also has tons of compression, just tested with thumb on spark plug hole. the machine is currently under a foot of snow here in montreal, getting a head start on the season

 

[PWCdoc]

You have an air leak somewhere or it's jetted way too small for the needs of the motor. You need to run a pressure test to see if the motor is leaking or not.

Do not run it again until you pressure test the motor and get the correct jets for the carbs.

 

[timmyboy76]

i didnt rejet the carbs yet because i thought i needed to test the machine first. what would be the common modifications i would have to make? i read someone posted about the needle and seat. sorry to sound like a newb but i am not sure how to adjust it. do i need a pressure monitor? does anyone think something may be wrong with my fuel line system, i personnally replaced eveything and cleaned filters and petcock. would a wrong pressure cause the machine to die so suddenly like that? if i am guessing right i would definately have to jet bigger; i did first oversize so jetting 10-20 more? somehow i have to create less pressure or more pressure in intake? sorry for all the questions, i would consider myself pretty knowledgeable in 2-stroke tuning since i've rebuilt and tuned my banshee, but this seems a little more complicated.

Banshee, huh....had one of those, no other quad like it, brother. Ur right, these rotax aint noth'n like the banshee,...throw a set of k/n pods on intake, and bump up the main 100, banshee tuned along with, pods off, and twist throttle, make sure "slides" pull'n same, there, carbs sunk....with these(ski carbs), think/somewhat sure, the difficulty lies, with the n/s(needle and seat). Has thrown me in a twist a few times....:cheers:

 

[masta2000]

ya, the banshee is quite the machine. i also have a ds650; used to swear by the 4 stroke. not anymore, i bought banshee for 1000$ with a blown engine off my buddy, transplanted race engine for another 1000$ and bam!, cant believe how fast and light the machine is. will never go back and its a 94!.now i am putting the ds up for sale and keeping the bansh. as for the seadoo i will rejet for sure and read up on this needle and seat stuff.
Thanks for all your help, this is the best forum around for professional help.
and one last question: the machine dies down and even stalls sometimes, is this a common issue with jetting too small? or is it more commonly a pressure issue? thank again guys for the help, much appreciated.

 

[timmyboy76]

Carb tuning...

Hey dog, check this out..:cheers:
http://www.factorypipe.com/t_carbtuning.php