GTR lost top speed

[hockeymd]

My 2017 GTR 230 lost 20mph off the top speed from last year. I purchased the 2017 GTR 230 used last year. Ran great in the Summer and hit 65mph before I put it on the trailer last Fall. I had the local dealer winterize it. I removed and stored the battery inside the house (I don't like to store batteries in unheated storage during our cold winters). I had to replace the battery right away this Spring anyway as it just couldn't hold a charge. Has fresh 91 octane (non-ethanol) fuel.

This Summer my GTR top speed is suddenly down from 65mph to 48mph. With the learner/trainer key its even slower. Starts and runs smooth. Doesn't sound like it's hitting a rev limiter or cavitating. I can pull up an adult male slalom skier so it isn't particularly weak but may have slightly less acceleration by my seat-of-the pants measure.

I've visually inspected the exterior of the intake and the nozzle output and don't see any obvious obstruction or damage.

I'm looking for possible causes of the drop in top speed with a priority on 'most likely' and 'easiest to check/fix'. After some research I've found the following possibilities. I'd appreciate your advice.

(1) throttle cable needs adjustment
(2) bad spark plugs
(3) wear ring damage/wear
(4) SuperCharger failure
(5) electronic limiting from some problem with the DESS key fob programming
(6) something wrong in the output Venturi nozzle causing water to be ejected elsewhere (I read about someone had a bolt come off?)

Thanks

Mark

 

[skiasylum]

Spark plugs are always first.

 

[MacSeaDoo]

Here is the thing..

When a machine doesn't reach top speed it is one of 2 things; It is not making the rated HP or it is but is unable to put the HP into the force required to achieve that top speed.

A often simple check on helping to figure out which one it is, is the relationship between speed and RPM. When you are hitting 48 MPH, where are you with RPM's? Where were you when you could hit 65 Mph?

My thoughts of what you posted:

(1) throttle cable needs adjustment

Possible but unlikely. The throttle body in you 230 is electronic so there is not simple visual way to confirm this without software like Candoo.

(2) bad spark plugs

Absolutely, this is where I would start as it is cheap. I replace the plugs each season. Pay close attention to the ones you are pulling out as well because sometimes they can tell you have a problem and in what cyl.

(3) wear ring damage/wear

Next to plugs, I would look here as well. A slightly damaged impeller can have a huge effect on the performance. If you want, try to crawl under the machine with a light and camera and take some photos of the impeller from up through the intake grate. Share them here and we can comment.

(4) SuperCharger failure

Totally possible that the clutch (washers) are slipping. Hard to check here without pulling the unit out but you can pull the hose and attempt to spin the compressor. It should not turn without considerable force. (Watch out because the blades can be sharp)

(5) electronic limiting from some problem with the DESS key fob programming

Unless you are using a learning key, this is not likely. When you put the key on the DESS is should say normal or learning on the display. If it says normal, it is a standard key with no limitations.

(6) something wrong in the output Venturi nozzle causing water to be ejected elsewhere (I read about someone had a bolt come off?)

Have never really heard of this. I pull the cone each season though to check to make sure there is not water in the housing and that the grease is clean. I do this because I am very mechanical and it allows me to fully to inspect and confirm my impeller and condition of the pump.

One thing I would check would be the clamps for all of your intake hoses. If you have a loose clamp, you will be loosing boost which would reduce HP.

 

[hockeymd]

Thanks for your help!

I started simple and changed the plugs. Went right up to 67mph indicated so appears that was the problem.

I had one very brief stutter about as long as a hiccup when I was doing a full-speed run, but didn't recur.

Is there a fuel filter that's easy to access and clean/replace or is it down in the tank?

Mark

 

[POPPS]

Bottom of tank,,,new plugs solved it?,,,amazing,,,lucky you.