1994 XP - engine rebuild - barely runs

[seadoark]

I bought a 94 xp that had a blown motor but was otherwise in pristine condition. I rebuilt the carbs, replaced every fuel line, fuel selector and bought a SBT motor. I timed the rotary valve and it was perfectly aligned. Went to the lake today. Good news is it started. It idles rough, if I have the fuel selector set all the way to 'on' or reserve then it dies. If I turn the fuel selector to almost off then it will idle and also let me rev to about 3k RPM but it bogs then dies if I try to give more throttle. I thought I was meticulous in my carb rebuild, used Mikuni kits, replaced needle valves, etc. Any suggestions or help will be much appreciated.

 

[etemplet]

I would suggest replacing the fuel selector with a new OEM. Also check the water seperator gasket (fuel filter) If the system can draw in any air it will overwhelm the ability of the fuel pump to pull enough fuel to the engine. Look realy hard at the feed system. I usually block off the fuel lines near the baffle with a clamp and pressure the system to 10psi. Any leaks and it is a no go. Good Luck

 

[seadoark]

I made huge improvement. I went to Harbor Freight, purchased a digital pressure regulator and added male fittings and made a pop-off pressure tester. It's crazy accurate. One carb was within specification and the other carb was way off, I also found that I had left a hose clamp off the pulse line from engine to carb which I think was leaking. I just got back from lake and was able to do the first two rounds of engine break-in. I believe I still need to adjust low speed needle because it seems a little slow on take off, it doesn't bog down but just doesn't seem snappy. I have a 94 spi and it jumps out of the hole compared to this so not sure what I need to adjust.

 

[etemplet]

Yes that pulse line can't tolerate any leaks. When I want to test the pump, not often thankfully I bet a clear hose put it in fuel connect it to the carb.... then I get another clear clean hose and connect it to the pulse fitting on the carb. Yup... let my mouth be the pulse line. If fuel flows up the clear line and doesn't bleed off.... I'm good. One day I'm gonna rig something else up. Ha ha. It's weird. Glad you found a problem... keep looking though.... they are sneaky.