I can ride three quarter throttle all day long if I go full throttle it will run fine for about two minutes than acts like it's running running it of gas it almost does it will cough and spit for awhile then start idling fine than be ok. Rebuilt carb recently used the jets that were already in the carb cleaned them well because I knew the ones in rebuild kit were stock.Not sure what size jets they were because I figured a rebuild would do the fix. Real weak on power. I have a friend seeing the valves this weekend. Backfiring also hard to start

 

You just answered your own question, if it runs right up to 3/4 throttle then acts like it's running out of fuel, your main jet needs more fuel flow to match the air flow. These bikes have a hard time starting when valves tighten up, which is just the opposite of old four stroke technology where they loosened up. Normally pipes and better filters just need the main jet rejetted. You will even notice you will hit the rev limiter on the top of each gear, fixed with a Dynatek cdi rev box. Have your friend check the main jet while checking valves you could be mistaking lack of fuel for factory rev limit cutting you out before you get full use of the pipe. Let us know!

 

Yea but the part that didn't make sense is being able able to go full throttle for a couple min. Then start doing it. I knew about the rev limiter. Will go to bigger main now that I know about what size too put inget valves set and let you know how it runs thank you guys for the help

 

You might want to verify your float height/setting while your in there....it could be a tad low.

 

Was going to have him check that too. I pulled the gas line from the tank to make sure their were no restrictions had good flow. My buddy and I rebuilt carb not too long ago not sure if he checked the float setting. This is a great site will let all of you know the outcome

 

While checking valves may check timing marks on cams and crank thru inspection bolt. I adjusted my valves on my ltr 450 marked chain and cams to line back up to find that last valve adjustment someone was off one tooth on exhaust cam since I've owned the bike, it ran good but after 20 riding hours it would act like running out of gas or clogged idle jet letting off throttle for deccelaration once bike was rode about 10 min. Thought valves were gone to find out was off a tooth exhaust cam and valves still a little too tight, thankfully I have an honest mechanic when I need his services. Easily could have got took for valve job and valve replacement which with my titanium valves runs about $600 to 700 for the Job.

 

The pilot was an 80 main was 155 adjusted the float and can go full throttle all day long now. That problem is fixed. Still low on power and is missing when climbing to full rpm once I've reached top speed it doesn't miss anymore. Getting valves set now hopefully this solves the problem thank you guys for all the info will let you know final outcome

 

Your stock pilot is a 22. 5 or a 25. The jet you may be reffering ( 80 and maybe a 60 as mentioned by LTgrandad, sometimes not easy to read ) to is the "starter" jet. If you were missing at WOT going up a hill, in a higher gear, then your main jet may be too fat ( large ). Have a look.
2003 Suzuki QuadSport (LT-Z400) CARBURETOR | CarolinaCycle
I will look at your mods again and I will edit my responce as required and try to help you. Ok, your lid is off but...
- Whats the exhaust your running? As mentioned, is it a slip on, or full FMF exhaust?
- Do you have the lid?