1996 GSX topping out at 54 MPH @ 6500 rpms WOT.

[Joel_CA]

Engine compression is at 150 PSI. Rebuilt the carburetors with Mikuni parts with the needles at factory settings (pop off pressure at roughly 30psi), new Denso plugs, new coil, rebuilt Rave exhaust valves (adjustment knob level to the cap) and rebuilt Rave waterbox valve. Everything else is stock. Is there anything I can do to squeeze out the extra 500 RPM at the top end? I've read that the waterbox Rave can affect performance, but there's not much information regarding what the original settings are and how to properly set it thereafter. She runs great otherwise and will run at 6500 RPMs for long stretches without any hiccups.

 

[Paul Bretz]

What impeller do you have in it?

 

[Joel_CA]

It's the stock impeller.

 

[Paul Bretz]

Are you going off of factory tach for rpm? My 97 gsx only turns about 6700ish. You maybe searching for a ghost. If it were mine, i would lower the pop off pressure and run it. I only say that because ive seen high pop off readings that are still in spec to cause bogging issues.

 

[Joel_CA]

Are you going off of factory tach for rpm? My 97 gsx only turns about 6700ish. You maybe searching for a ghost. If it were mine, i would lower the pop off pressure and run it. I only say that because ive seen high pop off readings that are still in spec to cause bogging issues.

I hadn't considered the tach being incorrect. I bring home my inductive clamp for my DVOM and recheck actual RPM with my meter. Other than that- no bogging issues here. Thanks for the input.

 

[Paul Bretz]

Do a plug chop and check and adjust accordingly

 

[Joel_CA]

Do a plug chop and check and adjust accordingly

Never heard of a plug chop.. pls tell me more

 

[Paul Bretz]

Never heard of a plug chop.. pls tell me more

Put in new spark plugs. Id recommend ngk br8es. Run wide open throttle for atleast 30 seconds. Do not let off throttle but pull lanyard to kill engine. Pull plugs and see what they look like. Whether rich or lean. Of course do in a safe environment.

 

[amcreativ]

Engine compression is at 150 PSI. Rebuilt the carburetors with Mikuni parts with the needles at factory settings (pop off pressure at roughly 30psi), new Denso plugs, new coil, rebuilt Rave exhaust valves (adjustment knob level to the cap) and rebuilt Rave waterbox valve. Everything else is stock. Is there anything I can do to squeeze out the extra 500 RPM at the top end? I've read that the waterbox Rave can affect performance, but there's not much information regarding what the original settings are and how to properly set it thereafter. She runs great otherwise and will run at 6500 RPMs for long stretches without any hiccups.

On my 951, I adjusted the water valve cap to about 3mm above the cap, power valves one click from all the way down and gained about 400 RPM on the top. I was cruising at about 6600 to 6650, then after adjusting the water valve, I was cruising at around 7050. I also hit about 62 mph on my 1998 GTX Limited on a calm day with air temps in the low 70's and water around 69 to 70.

 

[Joel_CA]

On my 951, I adjusted the water valve cap to about 3mm above the cap, power valves one click from all the way down and gained about 400 RPM on the top. I was cruising at about 6600 to 6650, then after adjusting the water valve, I was cruising at around 7050. I also hit about 62 mph on my 1998 GTX Limited on a calm day with air temps in the low 70's and water around 69 to 70.

Excellent information. I did read somewhere that adjusting the water valve Rave will have an effect on engine performance, but there was no further discussion after that. Hopefully, I can get out there a few more times before seasons end.
My 01 GTX DI can hit 7000 all a day and although I rebuilt the exhaust Raves and the water valve Rave, there was a steel cap over the water valve adjustment and I don't think it has ever been touched (I'm the 2nd owner). The GSX on the other hand, has been molested by untrained hands or someone that really didn't want to put any money into it.

 

[Paul Bretz]

Adjusting the rave valves on engine and on waterbox only changes when they open or close. Its not like they will open more because you adjusted them.

 

[POPPS]

Check that your carb butterflies are fully opened,,,and that the choke is fully open. Are the rav valves totally released?

 

[mikidymac]

The waterbox valve can cost you top rpm. Make sure it’s not leaking.