99 gsx limited concord impeller

[Tsef]

I installed a Solas concord st-cd-15/20 impeller in my gsx and now can only pull 6300 rpm. What can I do to regain the rpms that I lost. I put the stock impeller back in and get the right rpms. If anyone is interested the impeller is as new it doesn't have any marks or scratches. With stock impeller it ran 6950 rpm just don't understand why I lost almost 700rpm by putting in aftermarket impeller. Any help would much appreciated. Thanks in advance.

 

[SabrToothSqrl]

Something's not quite right. You should hit 6800-6900 with that prop. What's the top speed with each?

 

[Tsef]

Speedo says with concord 62 and with factory it says 64. I get more rpms out of factory prop. I put the factory impeller back in today just frustrated about to part with the concord. I have to check the throttle cable out to make sure it's opening the carbs all of the way.

 

[Coastiejoe]

The pitch is heavier than the OEM impeller. Thus, the load on the engine is enough that you can not reach max engine RPMs.

How was the top end speed?

How was the out of the hole performance?

How was the mid range performance?

 

[Tsef]

It doesn't seem much different than the stock impeller. It shoots out of the hole faster with the stock, midrange seems about the same and top end was 2mph slower with the concord and only hitting 6300 r's.

 

[SabrToothSqrl]

Is the pump it's self in like new condition? on a 99 you have the bronze pump I assume.

the 15/20 will lose you 100-300 RPM, but your loosing WAY too many.

 

[Tsef]

It has a bronze pump now it had a plastic pump but it exploded. When I changed the pump I put in the Solas. At that time I rebuilt the carbs and got the back in spec. So I'm wondering if maybe I have a cable adjusted wrong or something. I just put the stock impeller back in to see what happens but here in pa the weather has been crap and the Delaware river is chocolate milk with logs floating everywhere so hope to test it out in the next few days. Before changing the pump and redoing the carbs I was getting 6900 r's now that everything is freshened up and carbs are back to spec I lost some. I did everything as per the shop manual so I don't see what could be happening. The ski runs great the compression is 135 per cyl it pulls hard and jump out the hole and seems fast just missing r's at top end. My 96xp feels like it will blow it away though.

 

[SabrToothSqrl]

So you changed two things. Therefor it's impossible to isolate the prop.

if you had 2 pumps, you could take both to the water, same time

 

[Tsef]

I don't see how changing a pump can have that much effect on the rpms. I didn't change any adjustment on the throttle cable just rebuilt the carbs.