Stubborn 1999 indy 500

[monte44]

Working on a 1999 carb fuji indy 500 for friend. Was brought to me for being boggy and no power under load. Does idle nicely but boggs almost to the point of killing the engine under load. Found low compression in clutch side cylinder so after rebuild and new crank seals the sled is acting to same as before the rebuild. Here's a list of what I've tried with no luck from another running indy 500. I'm stumped on this one? HELP!! LOL!

clutches
CDI,Stator
exhaust pipe
fuel pump
carbs
bypassed throttle safety switch
engine has 125 compression
passes leak pressure test
hooked a remote fuel bottle to try
timing is in within "book specs"

 

[MrSled]

Working on a 1999 carb fuji indy 500 for friend. Was brought to me for being boggy and no power under load. Does idle nicely but boggs almost to the point of killing the engine under load. Found low compression in clutch side cylinder so after rebuild and new crank seals the sled is acting to same as before the rebuild. Here's a list of what I've tried with no luck from another running indy 500. I'm stumped on this one? HELP!! LOL!

clutches
CDI,Stator
exhaust pipe
fuel pump
carbs
bypassed throttle safety switch
engine has 125 compression
passes leak pressure test
hooked a remote fuel bottle to try
timing is in within "book specs"

I had a sled that acted like that and was so pissed. I found the choke cable was sticking and not releasing.

 

[monte44]

Any other ideas on this sled? Crankshaft out of phase? I'm two steps from just parting it out.

 

[850Switchback]

Did you put a new needle and seat in the carbs?

 

[monte44]

I have not but have vacuum tested both and they hold pressure. It just acts like stator or cdi but I have ohm tested and taken both off a running sled. Sled will fire right up idle nice. Runs better on a stand but will still bog down. Will barely pull it's weight on the ground and bog so hard it will kill the engine. I've checked belt deflection went threw the the clutches twice and have tried known working ones. I worked at a Polaris dealer a couple years out of tech so I got a decent mechanic ability. Just stuck on this one.

 

[MrSled]

I have not but have vacuum tested both and they hold pressure. It just acts like stator or cdi but I have ohm tested and taken both off a running sled. Sled will fire right up idle nice. Runs better on a stand but will still bog down. Will barely pull it's weight on the ground and bog so hard it will kill the engine. I've checked belt deflection went threw the the clutches twice and have tried known working ones. I worked at a Polaris dealer a couple years out of tech so I got a decent mechanic ability. Just stuck on this one.

Try no air box.

 

[850Switchback]

Everything looked good with the impulse line, not sucking any air there? Carb boots torn?

 

[monte44]

I replaced the impulse hose and clamped it. The boots should be ok because they were on when I pressure tested it. Thanks for all the ideas thus far I'm just stumped. LOL!

 

[monte44]

How anyone even seen a flywheel go bad for some reason?

 

[850Switchback]

Its possible one of the magnets lost charge, I've heard of this happening before especially in old generators that have sat long periods, and having to re-excite them.

 

[monte44]

So I got around to working on this again and did try it without the airbox and could only get it to run good with no airbox and half coke on. then it had great power. Stumped.

 

[MrSled]

So I got around to working on this again and did try it without the airbox and could only get it to run good with no airbox and half coke on. then it had great power. Stumped.

Make sure you air box intake is not being blocked and it sounds to me like your pilots are plugged.