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Discussion Starter #1
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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Discussion Starter #3
Thought that a possibility as well, installed a new clutch kit already, seems it is engine related, thank you though.
 

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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.
 

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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.
 

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Discussion Starter #7
Thanks so much for the advice, I will try what you suggested, the buttons gotta have some good wear on 'em.
 

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I agree, look at the clutch. Give it a GOOD cleaning and service the sheaves. Look close at the belt.. it should NOT be shiny.

If your convinced its the motor, have you cleaned the carb? Do you run anything to keep it clean?

CW
 

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Discussion Starter #11
I agree, look at the clutch. Give it a GOOD cleaning and service the sheaves. Look close at the belt.. it should NOT be shiny.

If your convinced its the motor, have you cleaned the carb? Do you run anything to keep it clean?

CW
Buttons are slightly worn, belt has a little sheen on it. Going for a secondary clutch rebuild, new belt as well. What do you recommend to maintain carb?
 

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Discussion Starter #12
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!
 

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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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