2003 Blaster no power in high RPMs

Discussion in 'Engine' started by 03Blaster, Nov 4, 2019.

  1. 03Blaster

    03Blaster Member

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    Going to start with information on the quad
    2003 Yamaha Blaster
    Been bored 2 times due to piston welding itself to the cylinder
    replaced piston with Wiseco piston and rings and had the cylinder bored and honed
    Cylinder was ported and polished by Angus Kennedy from Kennedy motorsports
    Head squish redesigned or whatever from Angus Kennedy from Kennedy Motorsports
    Vforce 3 reeds
    35mm PWK Keihin carb
    Vito fat bastard exhaust
    Factory seven big air box
    Timing moved 3 degrees (not sure if it does anything been that way since like 09)
    vitos heavy duty clutch
    +4 swing arm
    +3 +1 extended A arms
    stainless steel brake lines
    gearing is up 1 in the front
    400Ex front and rear shocks

    So the back story when this happened was out riding for about an hour and a half and it started to not want to go faster in high RPMs. It still cruised around without issues and started but when you go 3/4 or full throttle and try to get high in the power band it just wouldn't go. It has the low end hit and hits the bottom of the power band but thats it.

    Fast forward to this week. I cleaned the carb 100% except where the pilot jet is because i couldn't get it out. (I have tons of tools and non of my screwdrivers fit there) i pulled the reeds and checked the them and the gaskets and all look good, and didn't see issues on the side of the piston skirt you could see through the intake ports. changed the plugs and the gas with mixture of 32:1 with yamalube 2r and 91 octane gas. Took it out for a spin and same issue. The bike will start, rev, and you can cruise without issues but no high rpm power. Its like it hits a rev limiter 1k RPMs into the power band instead of say 4k RPMs of power band for example

    Tonight i will be pulling the carb again and checking what the main jet size is and post here but i dont remember what it is. I will be checking needle position at the same time as well and reporting back.

    I did a compression test with the motor cold, full throttle and it was 100 PSI of compression so not sure if thats the issue but i dont want to rebuild the top end if its not going to fix my issue.

    I have read a few threads and one said they fixed it by putting the washer on the main jet but all the diagrams i can find the PWK 35mm doesn't have a washer on the main jet. Is that true or it needs one?

    I am trying to sell the bike and would like this fixed as soon as i can.

    ************NOTE: im at 5500 ft of elevation also*******************

    Thank you in advance for the help.
     
    Last edited: Nov 4, 2019
  2. 03Blaster

    03Blaster Member

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    Just pulled the carb and the main jet is 150. Please remember I'm at 5500 ft elevation so sea level stuff doesnt apply
     
  3. Awk08

    Awk08 Administrator Staff Member Technician

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    I'd guess for that elevation to start .....

    42/45 pilot
    DGH or leaner needle (must have)
    #6 slide (must have)
    145-152 mains
     

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