No power on low end, new motor

[joshpxj]

Hey guys. Just put a new sbt motor in a 97' xp. All new fuel lines, selecter valve is clear, carbs rebuilt and pop off set at 30psi.
Before I begin, I have not verified compression yet as my buddy has it.
It has no power on the bottom end and he describes it as a bog but once you get it going the mid to top end is strong.
I originally set the carbs to spec and then turned in the low speed 1/8 of a turn,same thing. I'm a little stumped at this point. This is the first time I've had my hands in a 787. Also, I did reuse the rotary valve and it is timed correctly it looked okay to me. Not sure where to start looking.

 

[Dr Honda]

Since it's a new motor... you satart at the beginning.

1) Pull the manifold, and double check the rotary valve.

2) Pull the carbs, and go though them again. Verify EVERYTHING. All the ports are clear... the check valves are good... all the gaskets are good... the jets are right, and not warn... pop-off is good... etc.

3) Check the compression. (probably not the issue)

4) Check the RAVE valves. Make sure they are opening, and closing.


From you description... I'm going to say it's a carb issue. DO you have the factory air box on it?

 

[joshpxj]

It has aftermarket f/a's on it. I did open the low and hi speeds an extra 1/8 turn before it went in the water. I then closed them to spec after he told me it had the bog/low power.
He did provide me with sbt carb kits so I don't that is part of it but I hill recheck it.
Also I thought I would mention we are in Denver so were at 5000 ft elevation. Thanks guys!

 

[Dr Honda]

Opening the low speed screws does nothing, other than cause you to load up in a "No Wake" zone.

With aftermarket filters... you need to drop the pop-off.

 

[joshpxj]

What would you recommend for the pop off?
I see in your other threads you like 25.
I picked 30 because it was on the lower side of the huge spectrum they give you.

 

[joshpxj]

So I've got the cars off so I can drop my pop off. I'm going to drop to 25 since I was set at 30.
The main jet is stock @142.5
The pilot is not stock it's @ 80
Can I compensate for the 80 pilot with needle adjustment or should I change it with a factory 65?
Again we ride at about 5000 feet elevation. Everything else in the carbs looks good.

 

[viper0173]

im having the exact same issue with my 97 gsx. i hope we can find the answer its frustrating!!