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About TC33

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  1. TC33

    YZ426 FMF Q4 Exhaust Diameter!

    1.782 inches. The sleeves reduce the diameter for smaller header pipes. Of course this is a Q4 for a 09 450, I just noticed you specified a 426, sorry!
  2. TC33

    YZ426 FMF Q4 Exhaust Diameter!

    I can measure mine if you want, but my Q4 came with 2-3 sleeves that I didn't need for the stock 09 header. I was a little concerned at first as the place where the pipes join doesn't use a clamp, but I slobbed it up with copper stuff (as the directions recommend) squeezed it together and waited till the next day to run it and it has been fine. It was a very tight fit over the stock header and the copper gasket stuff sealed it well, I have no backfiring. Hope this helps!
  3. I would keep the Q4 and use it. I needed to buy a spark arrester for riding in the forest and just could not live with the endcap version for the stock exhaust. Also like to keep my bike as quiet as possible without sacrificing much power. With the Q4 I have way more midrange, bike revs clean with a strong hit on top. Whats not to like? If the Q4 will run stronger than stock thru the whole rpm range and sound good, why would you go back to stock?
  4. TC33

    high altitude jetting HELP needed!

    When I put the pipe on and took it for a ride I was very surprised how well it ran. The only problem I had was a hanging idle, which was cured with a half turn on the fuel screw. At 10,000ft+ it has way more mid range and a little more bottom than stock, no bog at all. Top end still has a pretty good hit, but is smoothed out a bit with the more mid-range, if that makes any sense. I figured I would ride it for a while and make some changes when I had problems, but have to say I am happy with it the way it is. My bike has never backfired, not even once since I got it. I read here that some backfiring is normal, so my bike may still be a little rich. I am still running the stock header pipe. Hope this helps!
  5. TC33

    high altitude jetting HELP needed!

    I ride at 9-11,000 ft, 09 450 with FMF Q4 exhaust. Pipe must have leaned out the jetting, cause it runs great on the stock settings. Opps, except fuel screw is 2 turns. It starts cold with 5-7 kicks, warm is 1-2. I was very suprised, I expected to be making some changes but it runs great, no bogging and pulls well thru the rpm range. Stock main on the 09 is the 160. Hope this helps!
  6. I just got a new 09 yz450 and have the fmf q4 spark arrester on its way. I want to ride this weekend and was wondering if anybody had run the stock bike with the fmf q4 at 10k and what main jet they liked?