bbr F2 thrust exhaust - I like it, but it is LAF

Discussion in 'Intake & Exhaust' started by el Diablo Guapo, Oct 4, 2017.

  1. el Diablo Guapo

    Joined:
    Nov 27, 2013
    Messages:
    136
    Likes Received:
    1
    So after a loooong time with my bent 1/2 inch conduit exhaust i got a "real" exhaust.

    I started riding to work because i got a new job that is only about 3 miles from my house.

    Because I was riding a lot more i was able to notice that not only was my conduit noisy, it seemed to be creating a lean condition due to being long and narrow, and my mileage seemed kind of poor. I also have clearance issues because i build really low bikes, many available pipes protrude beneath my already low frame...

    My first change was to jam the cut off "leftover" stock muffler on the end of the pipe. Surprisingly this did seem improve the mileage and was a lot quieter, but the bike did not seem to pull as hard.

    I was reading up on expansion chambers, discovering that the exhaust can really make a difference on 2 stroke engines. I considered making one, but ultimately decided to try the BBR F2 Thrust. It was only about $40 - although i will point out that is how much my frame cost on Craigslist- and it is chrome, so it matched my bike.

    I really like this thing! the bike pulls hard across the band and it has made a real difference in the mileage - WAY better! I guess my old narrow pipe just vacuumed the fuel through the cylinder. In fact i appear to still be running rich, in spite of adjusting the needle a few times. I ordered a set of jets and will be dialing this in.

    oh yeah, this pipe is LAF (Loud As #%ck), perhaps louder that the old straight pipe, certainly more pronounced, but i like it, in spite of being an alarm clock for transients down in the industrial area i ride through in the early morning. I get a lot of thumbs ups on my commute, so i guess there are not too many hard feelings...

    and I like how it looks

    el

    2017-09-19 18.49.23.jpg

    2017-09-19 18.48.42.jpg
    2017-09-19 19.06.31.jpg
     
  2. doomedgame

    doomedgame Member

    Joined:
    Jan 26, 2017
    Messages:
    65
    Likes Received:
    3
    I have the same pipe I put a cheap glass pack on it without power loss
     
  3. el Diablo Guapo

    Joined:
    Nov 27, 2013
    Messages:
    136
    Likes Received:
    1
    After checking my plug, and listening to to my engine "load up" and measuring low temperature i felt confident that i was running rich, in spite of moving my needle valve to the top notch.

    I got a jet kit with jets from #60 - #80.

    I I re-jetted today with a #67, and it really smoothed out the performance and my temperature was up a bit.

    I have not done a spark plug "snap shot" but i will tomorrow. I think i may need to go down another size or two, and perhaps re-adjust the needle, but I can really tell the difference- less bap-bap-bap and more response.
     
  4. el Diablo Guapo

    Joined:
    Nov 27, 2013
    Messages:
    136
    Likes Received:
    1
    went to #65 last night, great test ride, even better on the way to work this morning.
    It has been somewhat surprising to me how the combination really affects performance.

    I will throw in at this point I am doing this at an elevation of about 4200 feet
     
  5. el Diablo Guapo

    Joined:
    Nov 27, 2013
    Messages:
    136
    Likes Received:
    1
    More torque for sure!
    And while I was riding at lunch I noticed the engine itself seemed to be visibly vibrating more than normal, but i seemed to be feeling it less.
    Then on the way home i gave it a little gas and threw the drive chain.

    Put it back together on the sidewalk, but it would not quite tighten up. hmmm...

    Limped home and upon closer inspection i discovered my front motor mount had cracked along the edge of where i welded it to the frame.
    I cleaned it up, welded it back on, ran some more welding on the other side and other mount.

    Tough week! Planning on riding tomorrow though!
     
    #5 el Diablo Guapo, Oct 12, 2017
    Last edited: Oct 12, 2017
  6. Tony01

    Tony01 Member

    Joined:
    Nov 28, 2012
    Messages:
    924
    Likes Received:
    17
    sacks cruck! gusset it up!
     
  7. el Diablo Guapo

    Joined:
    Nov 27, 2013
    Messages:
    136
    Likes Received:
    1
    seems good for now.
    I just need it to hold a little while longer till the weather turns bad for the winter, then I'm gonna take it further apart and really complete a few things for spring!

    riding daily has really shown the weak spots
     
  8. el Diablo Guapo

    Joined:
    Nov 27, 2013
    Messages:
    136
    Likes Received:
    1
    Went down to a #63 jet, seems like it is getting close to being correct. Nice power, smooth with no "loading up" on my test and on the way in to work. I actually have to put the choke on to get it to start cold.

    Plug checks have all still seemed to indicate running a little rich up till now, and the choke would seem indicate the same.

    Seems like the engine actually gets warm now too. Anyone know the "correct operating temperature for these engines?
     

Share This Page