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The Maxair HellCat Carburetor

This beast lies under your tank quiet and unimposing....until challenged !! Then with the flick of your wrist, the chains are off and the chase is on!!!

With the Maxair HellCat Carburetor Kit enjoy OEM  drivability, gas mileage and longevity.  Simply twist the throttle to let this beast out of its cage and hang on!!!
The Maxair HellCat : Mikuni 42 Flat Slide HSR Carburetor - Yamaha Road Star

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    Purchase The Maxair HellCat : Mikuni 42 Flat Slide HSR Carburetor - Yamaha Road Star

    SKU: MAX_HSR_42 The Maxair HellCat : Mikuni 42 Flat Slide HSR Carburetor - Yamaha Road Star

    Rated 5/5 (23 review s)

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    The HellCat is a turnkey solution!

    Our Maxair HellCat Mikuni 42 HSR Flat Slide Carburetor is the difference between a "REAL" carburetor vs. the stock OEM "toy" carburetor. Get the power and throttle response that a flat slide carburetor can offer from people who run them on the Yamaha Road Star every day.

    This carburetor setup provides comparable gas mileage as well as great drive-ability. There is nothing to lose and superior performance & throttle response to gain.

    • Options
      • Standard or Polished Finish (when available)
      • The Maxair HellCat Choke cable (available OEM length or any length -with a polish aluminum knob)
      • Maxair Throttle cables by Barnett: You will also need to swap your cables for the Barnett cables with the appropriate ends for this application.  We even have the Economical Standard Black Vinyl or the Premium Stainless versions.
      • Maxair HellCat 42 Jetting Kit (Max professionally jets the Carb. to your setup- Turnkey !!)
      • TPS MOD Modification to Mount OEM TPS (we need your TPS mailed to us: Video)
      • Shorter non- flexible Idle Speed Knob ( This shorter version will not damage your push-rod tubes)
      • Running OEM Fuel pump:
        • Special float needle valve/seat set- to run stock fuel pump
      • No Pump MOD - Complete kit for Eliminating Your OEM Fuel Pump (click here for more info)

      We install the Jet Kit, TPS Mod. & Choke, adjust the float level and install stainless steel "Allen" (socket head) float bowl screws and set the carb up ready to install. We will also install the Yost PowerTube & Float Needle if  to options are purchased .

    "My Brother and I both run these 42s with the TPS mod. This is like taking off a toy and putting on a real carburetor. Simply one of the best "must have" performance mods. you can do to you can do to your Road Star. We have everything you need to do this upgrade right the first time!!!"



    What Our Customers Are Saying:

    Maxair HellCat 42 Carburetor for the Yamaha Road Star - FAQ

    • What is the Maxair HellCat 42 and why should I purchase it for my Road Star? The Maxair HellCat Mikuni 42 HSR Carburetor is a premium flat slide carb. that allows maximum flow and power gains. This kit has become well known among Road Star aficionados, as the must have for the best power, while retaining real world drivability.

    • Can I just install the basic 42 without anything else? No, but we have provided the Maxair HellCat as a turnkey solution!

    • I have heard about going pump-less vs. using the OEM fuel pump what's the difference? Pump-less is the way to go! When using our No Pump Mod there is no downside and the upside is never having to worry about your fuel pump dying, leaving you stranded on the side of the road! This must be done correctly however, to avoid fuel starvation issues. Our No Pump Mod kit will do the job right! If you decide to run your stock fuel pump, you'll need the optional float needle in the options. We install that for you! 

    • What is the TPS Mod.?  This is a modification we do in house to allow your stock TPS (throttle position sensor) to work with the 42. This greatly improves throttle response performance and gas mileage. We'll need you to send us your TPS for this modification. You can still run your bike during this time without a TPS

    • How will I know what jetting to use? Max professionally jets the Carb. to your setup- Turnkey !! We'll simply ask you what your bikes specs (pipe, air kit, engine mods etc.) are, along with other information such as elevation and make a determination based on that and the data we have. We include a Maxair HellCat 42 Quick Start guide with all the options installed. Most of our customers simply install the carb. and they are done. Some will need minor tweaking.

    • How is the Maxair HellCat 42 different?  The Maxair HellCat 42 is designed to be turnkey with the ability to purchase all options in one automated process. We then include our expertise in setting up the carburetor for your Road Star as well as the in house TPS Mod. Will the 42 choke work with my bike or should I order your custom choke. The 42 choke is too short to reach the stock choke position and is prone to engaging on its own, causing gas mileage problems, so we have design a superior choke for this application. If you have a question about the length let us know and we'll walk you through the measurement process.

    • I have a 42 HSR Carb already, can you work on that? Sorry, as a matter of strict policy we do not take carbs in to work on them. We only work on carbs that we sell. Beware of the multitude of Chinese knock-offs

    • I am worried about the recent Chinese knock-offs of the HSR 42. Do you use authentic Mikuni Carburetors? Yes! We purchase our Mikuni HSR 42s from a USA Authorized Mikuni Distributor. They get them directly from Mikuni USA.


      Maxair HellCat 42 Carburetor for the Yamaha Road Star - Options?

    • Maxair HellCat 42 Jetting Kit ( Max professionally jets the Carb. to your setup- Turnkey!)
    • Modification to Mount OEM TPS (we need your TPS mailed to us? Video)

    • Shorter non- flexible Idle Speed Knob ( This shorter version will not damage your push-rod tubes) Running OEM Fuel pump?

    • Special float needle valve/seat set- to run stock fuel pump

    • The Maxair HellCat Choke cable (available OEM or any length -with a polish aluminum knob)

    • No Pump MOD - Complete kit for Eliminating Your OEM Fuel Pump (click here for more info)


      One of the best add-ons I have done. I do suggest having Maxair jet the carb, install your TPS, and add the short idle screw. The installation was a breeze after that. Maxair helped me to get the correct cables and tech department worked with me to ensure my bike was up and running. It is now flying like a champ, this carb is soooo much better then the stock CV. Should have done this years ago. I will be a Maxair customer for life due to the fantastic customer service. Thanks!!! Customer? Craig Comeaux (Williamsburg, Virginia)


    Customer Reviews

    Review The Maxair HellCat : Mikuni 42 Flat Slide HSR Carburetor - Yamaha Road Star
    5/5 Stars out of 23 Reviews
    Pages 1   2   3
    Verified Buyer
    Couldn't Be Happier!
    Jeremy R Spike (Janesville, WI) | July 24th, 2023
    I purchased the Hellcat setup about a month ago now for my 2006 Road Star and am very happy with the results. Prior to shipment, Max is very thorough in collecting info on the setup of your motorcycle so he can better set up your carburetor. Installation went very smoothly, and all I ended up doing was readjusting the idle speed after I had finished. The bike runs better now than when I purchased it! I definitely recommend using this company if you are looking to upgrade.
    Verified Buyer
    Bike owner
    Richard Townsend (Los Lunas) | February 16th, 2023
    Hellcat 42 carb. Purchased and Max got this to me. Followed detailed instructions on install and in a few hours had my bike running like a champ. Amazing performance improvement. Thanks, well worth the purchase
    Verified Buyer
    Duane Logsdon (Huntington Arkansas) | February 13th, 2023
    The primary reason to purchase was to eliminate the carb puke that Roadstars are known for. Max called me when he received the order to make sure he had all the details of my bike correct. He called me when he shipped the order and again the ordered delivered to make sure everything was received in good shape. I told him I would be installing the hellcat the next day. He called again on the day of installation to see if i had any questions. This man is truly interested in customer satisfaction and is available to answer questions during the installation. My bike runs smoother than ever before and will start cold without having to work the throttle to keep it running. Very pleased with the entire process. And no more carb puke.
    Verified Buyer
    Pumpless, Hellcat Carb 2007 Road Star
    Mark Avera (Atlanta,Ga) | February 12th, 2023
    Wow, I can't believe how much better my bike runs now that I have gone pumpless with the Mikuni Hellcat carb. I was a pleasure working with Max, he made sure I got everything I needed and followed up to make sure I got everything installed and working properly. Thanks, for your help Max
    Verified Buyer
    Titus (Long Beach, CA) | November 16th, 2022
    I have a 2000 Yamaha Roadstar 1600, was having problems with my CV carb for a while, did the rebuild and even took it to the mechanic, at the same time I came across Maxair Engineering online and was checking out the Hellcat. Long story short I pulled the trigger and purchase the Hellcat. Max was in contact with me every step of the way from purchase until installed. My bike runs more efficient with more power and torque. I am very happy that I went with the Hellcat thanks Max for all you do.
    Verified Buyer
    Calvin Dunkin (McComb , OH) | August 21st, 2022
    After continually messing with my stock carburetor and missing out on months of summer riding I finally went searching for a new carb and I am so glad I found Maxair! Max was very thorough making sure my hellcat was tuned just right when I received it. All I had to do was adjust the idle mix screw a quarter turn, set the idle and I was screaming down the road! My Roadstar runs better than it ever has, throttle response is amazing and I still get 48mpg. Best investment you could possibly make to make your Roadstar perform!
    Verified Buyer
    Tobias (Greenwood, IN) | July 19th, 2022
    Good afternoon, I wanted to let you know that it’d take a pretty large pry bar to remove this smile from my face! My bike has never performed this good, it sounds better, it runs better and the throttle response is far better than the factory carb. Thank you for the amazing communication and customer service. I’m 100% satisfied and can’t thank you enough.
    Verified Buyer
    Robert (Lexington, Lafayette) | June 5th, 2022
    Right off the bat don't hesitate just buy it!! From the moment I clicked purchase max has made purchasing this carburetor a awesome experience. The results of the product completely speak for themselves. No second thoughts about it will definitely be looking forward to returning as a customer
    Verified Buyer
    Bill Anderson (Spring, TX) | September 5th, 2021
    After rebuilding my 2004 stock Roadstar carb for the second time and never really being able to get it tuned right I really had no confidence in rebuilding it again. Then I stumbled on Maxair on YouTube. After speaking with Max on a Saturday I was sold and had my TPS off to him on Monday. Everything was received back just as promised and I was kept informed the whole way. I installed the no pump mod, cables and carb all within about 2 -3 hours following clear and concise instructions. First time start up was just as i was told to expect and with some minor adjustments the bike was idling better than it has in a long time. I love the simplicity of this carb. It gets better though. The bike runs smooth as glass through the range of gears but when you twist the grip you'd better hold on...regardless of what gear you are in. Even with the incredible performance there is no spitting or popping on decel. This bike was meant to run this carburetor. The stock carb holds the bike back like a ball and chain. The Hellcat turns it loose. Thanks Max for making my motorcycle fun to ride again.
    Verified Buyer
    Tom (San Diego, CA) | February 27th, 2020
    After continual rebuilding and fighting with my stock carb, I finally threw in the towel, and fortunately stumbled upon Maxair Engineering. The Hellcat carb specific for my 2000 Roadstar is a top notch piece of engineering. Paired with the tech support that you get with Max, you cannot go wrong! Max was right there for my every question, and he gave me answers within minutes! I am blown away by the way my bike now starts, idles, and rips through full range of gears like never before. The 1600 Roadstar really is handcuffed if you’re still running the OEM carburetor. Buy a Hellcat!!! Thanks Again Max!

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