2003 Trailblazer 400 Lacks Power

[PMitchell08]

Hi guys, this is my first post on the Polaris forums so it's good to meet all of you and thanks in advance for your insight and advice.

I just bought a very clean 2003 Trailblazer 400 (rebadged Scrambler 400). I have previously owned a Trailblazer 250 and a Suzuki LTZ-400. Although I can tell that my new 400 has more power than my old 250, I don't think it quite has as much power as it should. I have read many reviews on the Scram/TB 400 claiming that stock it keeps up with 400ex's and will wheelie until the grab bar scrapes. This is not the case with my Trailblazer. It runs reliably and always starts right up, but does a pretty weak wheelie and won't be winning any drag races. I have run several tests to check some possible issues: cleaned airfilter, replaced fuel filter, removed/inspected/cleaned the silencer, changed sparkplug, did a compression test (115 psi), filled the tank from empty with fresh premium gas. I want to get this quad running its best in stock form, but I might be open to minor aftermarket bolt-ons: air filter, reeds, maybe even a reasonably quiet aftermarket silencer, and jets to match.

So there's my story and my background info. My questions are:

What items should I add to my maintenance checklist to get this 400 running at its peak?

What common problems should I watch out for with this quad?

Does anyone have a recommendation for a good service manual? Anyone have experience with the CD-rom/PDF manuals on ebay?

What is the actual specification for compression on this motor? I have heard that generally 120-130 is good, 110 and under is nearing the need for a rebuild, but I know it varies significantly from one motor to another. Should I be concerned at 115?

Are there any essential minor tweaks or modifications that I should consider?

Any other information you can offer is greatly appreciated!

[Bruce!]

Welcome to the board!

[poposcrammy]

you need to make sure all youre jetting is correct now and you should probably go ahead and do a rebuild mine had about 120 and started running really bad then blew a base gasket and blew up so do a rebuild and look up youre stock jetting and after you do that jet it up a little and some good easy mods are a good airfilter carbon fyber reeds and head pipes and a good silencer idk if this will help but heres a site and if you call them they can help with you with anything you can need and theyre pretty reseanoble on parts and they specialize in the oler polariss https://www.hpd-inc.com/