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No low end power

12607 Views 12 Replies 4 Participants Last post by  dwhst9
A couple years ago,I purchased a 2001 trailblazer 250 that had recently had a new top end bored to .040. I have since installed a new 38mm(400cc) carb and a FMF fatty gold exhaust . I have also installed a EPI performance clutch kit. The trailblazer had both lower and upper power to spare for about a year. Have lots of hills that I climb, and over the last several months I have noticed a very definite decline in low end power. Barely able to make it up hills, but starts on a dime and has plenty of high end power. I checked compression;was 115 psi, after putting a little oil in, it came up to 120 psi. My service manual indicates 115 psi is spec. Again, starts on a dime, idles like a champ, just bogs somewhat on low end, just doesn't have the same take-off power, can't climb a hill for squat like it once had. Installed a new Ricks CDI box, as well as repacked and cleaned silencer,did not help. Is jetting the carb what I'm missing? I have never changed jets. Is compression too low? new rings in order? Can anyone help, I'm at a loss.


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Worn secondary clutch buttons?
You have to disassemble the secondary clutch to replace the buttons, which you wouldn't do when you buy a clutch kit. Worn clutch buttons will prevent the secondary clutch from back-shifting correctly and you won't have any low-end power.
Thanks for advice, I will look into that possibility. Is the 115 psi compression ok?
A stock 250 should have around 120 psi, so you are good at 115.
Thanks for all the helpful advise. I did a complete secondary clutch rebuilt, and installed 42 tooth sprocket. The quad has never had so much low end. I believe the buttons were the main cause, but wow. AWESOME! Thanks again everyone!
Glad you found the problem. Time to give 'er hell!!! :)
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