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Straight Pipe - 1989 HH1 Honda Acty

Discussion in 'Honda Acty' started by MattGiroday, Dec 28, 2014.

  1. MattGiroday

    MattGiroday New Member

    Has anybody straight piped their honda acty? I'n looking to do it just cause, and I was wondering if anybody has previous experience doing so that could share a few tips? Any advice would be very helpful! I have a 1989 HH1 Honda Acty Street! Thanks!
     
  2. shogun

    shogun Active Member

    Derek Niswonger likes this.
  3. shogun

    shogun Active Member

  4. BillyTaran

    BillyTaran New Member

    hi Matt,
    I have a 1991 and I cut the pipe right after the second of the two soft pipes that return (one into the air box and not sure where the other one feeds) essentially removing the muffler. My top end went from 90 km/hour to 120-125 km/hour. I'm thinking of cutting it today about 10" off the header and use a basic pipe to exit out the side of the truck. Do you know why those soft pipes are there and why they would return into the air box?
     
  5. packrat

    packrat Member

    If you mean what I think, you're talking about the hot air pipes that take warmed air from around the muffler to heat intake air when the temps are low. I'm just trying to get a Japanese friend to pick up one of those pipes for me now, but it will be a while before I get it
     
  6. BillyTaran

    BillyTaran New Member

    Hi Matt,
    Thanks for replying. I think you're 100% right about the warm air return. I will reconnect in winter. I went ahead and cut about 10" off the header and wow!!! At first it was loud as hell, I then attached a small $40 bolt on cosmetic tip with small outlet holes and secured it well. The sound instantly improved to a tuned sound and my top end increased by 7-8km / hour . I hit 130 km / hour and that's the fastest so far. Will post a pic for you. I also experiment with fuel mixes if you're interested in chatting about results. I'm on Instagram at: billytaran if you'd like to connect. Thanks again:) image.jpg
     
    Tony Evers likes this.
  7. patricklearns

    patricklearns New Member

    Does anybody know if this would work on the HH4 Acty models? I can't seem to find anyone that has tried to use the "Sports Exhaust" (found on Yokohama Motors - http://yokohamamotors.net/product1037.html) on an HH4 Acty, and for that matter, I can't find any sports exhaust for the HH4 models...At this point I'm wondering if the best option would be to just install an entirely new system with a new CAT...
     
  8. carlosjr56

    carlosjr56 Member

    I am wondering if that yokohama would fit the HA2 but I doubt it...
     
  9. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

  10. carlosjr56

    carlosjr56 Member

  11. rkasc4

    rkasc4 New Member

    Hi @carlosjr56 , did you get round to straight piping your acty and putting a bike back box on? And also, did you get rid of the catalytic converter? Both things I want to do to mine when it arrives from Japan. Cheers!
     
  12. carlosjr56

    carlosjr56 Member

    I haven't :/ its been in storage since salt started hitting the roads here in CT. I'll get to it in spring probably.
     
  13. moonshine

    moonshine New Member

    I have a 95 acty attack that just got delivered at the start of the new year. I ordered the acty sports exhaust from Yokohama. Can’t wait to get it on! I’ll report back and soon as I get it on.
     
  14. rkasc4

    rkasc4 New Member

    Congrats on your new truck, I can't wait to get mine as well. That sounds awesome moonshine! If you can do some pics and maybe a vid that would be a real help for everyone.
     
  15. Arty

    Arty Active Member

    Jigs:
    Damn! I wish you guys would quit putting these ideas into my head. - A Super-trap would be really nice! - but a bit pricy. - - But I'm worth it - right???
     
  16. moonshine

    moonshine New Member

    I wasn’t able to do a video, but I took a few pics along the way. Wow. Rust is horrible. There were a few PIA moments when removing the old muffler. But, once the old muffler is out, it’s super straightforward to install the new one. The new wirus win sports muffler was well worth it!

    My attack has UL, UR, R and is a 4 speed. I maxed out at around 90 before, but now I can easily hit 100 and almost 110. I’ll start a build thread soon and post pics.
     
  17. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    Keep an eye on eBay, they occasionally show up used, and if there is one close to you checkout motorcycle wrecking yards.
     
  18. rkasc4

    rkasc4 New Member

    That's amazing that it's upped your top speed. Did you remove the cat as well? Where did you find your exhaust as I can't find one, guess I'll just straight pipe it and use a bike muffler probably. Keep up the good work mate!
     
  19. Adam C Spry

    Adam C Spry Member Supporting Member

    @moonshine - so did you leave out the warm air return? I don't think I would need it in North Carolina, but i am interested to hear other opinions, @packrat & @BillyTaran...
     
  20. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    Back in the 1980s, I was living in Las Vegas. One of the guys I worked with built a Baja Bug, with a long ram intake, and a Weber 2-bbl carburetor. He didn’t make it to work, at least one day per week, for about six weeks. The cooling caused when the pressure dropped as the air entered the carburetor, was freezing the bit of moisture in the air in his carb. And, the Baja Bug couldn’t run.

    Lesson learned: Sometimes you need to preheat the air before it hits the carburetor or throttle body, if the carb isn’t heated somehow. Even in places like Vegas, which is known for high temperatures, and low humidity. So, you really may need it in North Carolina, if you intend to run the vehicle year round.

    In stock form, the mini trucks have hot water going to the carb, and heated air to the intake. They won’t freeze up, even in very low temperatures.

    When you take out the air heating, and take the hot water off the carb, by either substituting a motor cycle carb, or replacing the choke system with a manual choke and eliminating the heating water, you are increasing the potential for problems when you run the vehicle in cold weather.
     
    Adam C Spry likes this.
  21. Adam C Spry

    Adam C Spry Member Supporting Member

    That's a great explanation. This makes a lot of sense. I understand the physics of pressure reduction and temperature change. I wonder if there is a way to offset with larger intake (lower pressure, higher volume), and/or a way to capture heat from an alternative exhaust set-up. I havent seen any examples of an attempt to d this, but if I come up with any ideas, I will certainly share.
     
  22. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    You can build the heat collector for the exhaust pipe by going up a couple diameters of exhaust pipe welding a tee onto it, and putting it over the new exhaust pipe. If you look at the performance parts places, you can probably get one remade by one of the header companies.

    A quick look on eBay turned up a unit for Volkswagon and Skodas.
     
  23. Adam C Spry

    Adam C Spry Member Supporting Member

  24. fmartin_gila

    fmartin_gila Well-Known Member

    Check out carb heat system & cabin heat system for light general aviation and experimental airplanes. Most all light plane heat systems use an exhaust muff .

    Fred
     
    Adam C Spry likes this.

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