Thread: GTX 185 Rev limiter off the line
06-23-2009, 10:57 AM #1
- Join Date
- Aug 2007
GTX 185 Rev limiter off the line
I had problems last year with cavatation and hitting the rev limiter on my wife's 04 GTX. It turned out the prop and wear ring were less than desirable so I replaced and had the impeller redone at SBT. Had it out for the 1st time and works so much better and revs right at 7600. From a dead stop it will still bounce off the rev limiter a few times where as my RXT will just pop right out fo the water. If I am half on plane then hit the throtle it is OK. Is there something else I should look at or is it simply just a case where I need more prop on the bottem? Can I change the pitch to a steeper pitch at the beginning and not affect the finish as it rev perfect on top.
06-23-2009, 11:36 AM #2
Check the clearance between the SBT impeller and the new wear ring. There should be no more than .014" clearance. If there is more than .014" clearance, the SBT impeller might have been ground down too much. Most of the better shops weld the tips of the impellers and grind them down to new specs. What speed are you seeing at 7600 rpms?... Ron
06-23-2009, 11:48 AM #3
- Join Date
- Aug 2007
My 100lbs wife saw 65 on the speedo. Me with my son on my 05 rxt could barely go by her on the top end. We had an extra 200 lbs between us. Top end is very respectable but want the bottem to work too.
I just dont think it is loading the motor hard enough off the line. Oh the sputter off the line was with me on it not her. She isn't ready to hit from a dead stop yet. It was her 1st time driving one for any period of time.
06-23-2009, 02:55 PM #4
Well it sounds like the trailing edge is set just right for top end. Knowing that the speedometers usually read high, you're probably hitting 61 or 62 which is pretty good for 185-hp. You might also chech to make sure your ski has the aluminum pump housing. The previous owner may have put in an '03 plastic housing. I would still check the clearance to see where it's at. As I understand, SBT may not return your original impeller, so what you received may not be what you sent.
06-23-2009, 04:24 PM #5
you are cavitating. probably time to repalce the accordion boot, or at least slide it forward a bit to put more pressure on the carbon seal.
try that, if it works, get a new boot and install.
prop spin on low end is not indicative of wrong pitch most times, it is indicative of cavitation.
06-24-2009, 08:19 AM #6
These guys are right...It could be several factors that are causing low end cavitation. Look into the carbon seal issue and contact Erik at Speedfreeks Racing for prop-related issues (pro-pitch, etc.). I think a pro-pitch was $50 or $55, and it may alleviate your low end cavitation AND give you a bit better bite out of the whole. Just something else to consider. --J
06-25-2009, 07:38 AM #7
- Join Date
- Aug 2007
thanks guys. What is the carbon seal and where is it?
06-25-2009, 04:41 PM #8
look deep down in the rear engine copartment.
find the driveshaft coming off the engine. there is a rubber flap over it.
to the rear fo the shaft, where it goes thru the hull to the pump/impeller on the outside, is the carbon seal.
this is your thru hull seal.
it is held on by a rubber accordion boot.
the boot puts pressure on the carbon seal, that pushes against a SS seal.
if you push back on the accordion boot, you can separate teh carbon seal from the SS ring.
problem is when the accordion boot gets old it loses its springy-ness and alows the carbon seal to separate from the SS ring under normal operation. this lets air suck into the impeller/pump or worse, water to flood inside the hull.
new accordion boot will fix the problem. at the same time replace teh carbon seal, and maybe the SS ring. but probably th eSS ring can be reused.
quick test is to loosen the rearward clamp on the accordion boot, slide it towards the engine 1/4 inch, and put a zip tie behind as a spacer to hold it forward.
then retighten the clamp.
this should provide more pressure on the seal. if this cures your cavitation, then you know the boot is worn out, order a new on eand replace at your convenience.
good time to also inspect replace wear ring and impeller.
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