Thread: STX-R - low on power
06-26-2009, 02:45 AM #1
STX-R - low on power
Can anyone point me in the right direction to possibly explain this problem (or what to look for).
The STX-R has higher compression (130PSI on my guage), V-Force Reeds (about a year old) and some carb tune (other stuff is handling and prop).
Everything was running fine, then all of a sudden it lost power (like a spark plug went). I changed the plugs, and made sure each cylinder had spark, and they did. Put it back on the water and it's doing the same thing.
I notice it bogs down when you take off, almost like it's flooded, and then goes ok (but down on power). If it's cold, it's almost impossible to start.
I'm almost thinking a broken reed, but it's probably only done 20 hours on the reeds so I'm not sure. Could it be something simple like a fuel filter and it's running lean rather than rich?
What else should I check?
06-26-2009, 08:00 AM #2
You can take the f/a off and rev the motor a few times, if you notice its spitting back through one of the carbs then that is a sign of a broken reed. Have you rechecked compression since it started acting up?
06-26-2009, 07:47 PM #3
Yep, compression is still 130 on all cylinders.
Great suggestion on removing the FA, here I was about to dismantle the whole intake
06-26-2009, 07:57 PM #4
I have put more than my fair share of reed petals through my ultra motor. I know the signs well.
06-26-2009, 10:40 PM #5
Reeds...!! They just dont hold up...compared to stock. The reeds would actually last a long time if the ski stayed in the water all the time but it's when the ski cmes out and bangs the rev limit is where the reeds are stressed and damage can happen or weaken them. But ski's come out of the water all the time and it's just a matter of time. Another thing if using the D2's is the screws can somtimes come loose just a little and thats enough the loose the tight grip and let the reed vibrate more causing premature failure. Morris I would check yours even more so since your changing reeds alot and this is what wears the cages.
I would put stock back in and never think about it. Unless your racing the gain is very minimal.
06-27-2009, 03:42 AM #6
Well it's looking like broken reeds for me. After removing the F/A I started it up and held a piece of cardboard just over the top of each carb inlet. I'm getting the cardboard blow back a bit from one of them (and spots of fuel)... I guess that's the one with the broken reed.
I'll remove the carb tomorrow and let you know. If it's a broken reed, yes, the stock ones are going back in (as I've heard aftermarket ones do break often). Thanks.
06-27-2009, 07:08 AM #7
aren't aftermaket reeds too expensive if they just go all the time? seems like it wouldn't be worth it.
06-27-2009, 09:27 AM #8
I ran d2s in my level 1 with no problems other than I did have a screw fall out. That screw wound up embeded in the top of a piston and scarring a cylinder. It would still run 71 mph like that I did start using loctite on them. When I started having more trouble is with the ported level 2. The cases have been ported and I belive that creates more turbulance and wear on the reads. I have found that there has been a design change to the d2 cage. The later design has the reed tip slightly recessed to help protect it. The later design hheld up to my level2 with tripples. Now im running the v3 reeds. They are holding up ok with 10 hours on them so far. Both give a more crisp throttle response and mabe a little more top end. I havent really tested them to see. I do agree with johnny though comming unhooked alot can be a reed killer. Your motor can see spikes over 8k even though the stock limiter is 7400. The d2s are going to go in my 00 project, then mabe I can get some real #s
06-27-2009, 09:44 PM #9
Well, looks like I'm going back to stock reeds. I can't believe this has happened after only about 20 hours on an almost stock ski. All of the petals are chipped on the ends too.
These are the stock ones, with about 80 hours on them. They look perfect!
Do you guys recommend picking up some new petals for the stock ones before I put them back in, or leave it the way it is?
06-27-2009, 10:31 PM #10
That pic doesnt look like a v force reed, if it is its not for a kawi 1200. Those stockers will be fine no need to replace them. This first pic is of a d2 reed the second is the v3.
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