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Other Motors in the Hawk Frame

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    Other Motors in the Hawk Frame

    I don't think anyone in the forum would dispute that the engine Honda put in the Hawk is kind of portly. Even after 30 years the running gear is pretty damn good from a weight, stiffness and handling front.

    So the question about other motors...

    I've seen RZ350 mounts (and that motor can be tweaked to insane HP levels if you're willing to deal with a 250 rpm power band...)

    What else is out there? I was seriously considering finding a salvage KTM 690 duke and stuff it in the Hawk frame. Not a trival task, and I'm not even going to comment on anything remotely like "more reliable engine" (there's a reason people say KTM is an Acronym for Keeps Taking Money) but I am interested in if it's a lighter motor with a tad more power and most importantly if will fit in such a way as to not completely mess up the handling of our sublime chassis.

    You may now flame me for my hypocrisy, but remember your well directed & spirited conversation will keep you warm during these cold December nights. (unless you're in the southern hemisphere in which case I apologize for the excessive heat.
    Garth H
    San Jose, CA, USA
    '91 Hawk w/700cc Kit and Africa Twin Cams

    #2
    Here's a Hawk frame with a moderately breathed upon engine from a Honda FT500 that I and a friend put into a Hawk chassis to go Formula Singles racing at Willow Springs. Pics from Buttonwillow.

    Various years 057.jpg
    Buttonwillow Jan 06 004.jpg

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      #3
      I bet I'd find it if I searched, but how much DOES a Hawk motor weigh?
      Garth H
      San Jose, CA, USA
      '91 Hawk w/700cc Kit and Africa Twin Cams

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        #4
        About 150 pounds with carbs. Don’t have an exact number though.
        Flock of Hawks | '13 Tacoma | '69 Falcon (currently getting reassembled!)
        I've spent most of my money on women, beer, cars and motorcycles. The rest of it I just wasted.

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          #5
          love someone to offer up a cr500 - wasn't htere an age old thread about doing that

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            #6
            If your goal was a lighter play bike, another option would be the 511cc RFS (Racing Four Stroke) engine from a 2000-2007 KTM EXC. About 75lbs complete. The pumper carb gives lots of grunt, it is fast revving, six speed, and the chain output is on the left. These are strong and reliable if you keep the valves adjusted. An honest 50 HP in streetable form, but with a light tail section, you could end up with a FrankenHawk that weighed 260 lbs or so. The downside is frequent oil changes, because there is less than two quarts in the system. There are a few on ebay, but not cheap. I had supermoto wheels on my KTM 520 EXC for a while, and it was a blast, but did not have the brakes or handling of a Hawk.

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              #7
              Originally Posted by old_pirelli View Post
              love someone to offer up a cr500 - wasn't htere an age old thread about doing that
              That would be Bad-ass! If you can find a cheap one maybe better going with a CRF 450 but it won't last long.

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                #8
                I always said the yz426f yamaha would be the way to go. It has a 5 speed trans and insane amount of power for a single.
                Don't spend money and buy, spend time and learn.

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                  #9
                  Originally Posted by 69Falcon View Post
                  About 150 pounds with carbs. Don’t have an exact number though.
                  130 or so.Matt Blashfield had a crf450r engine in one for awhile..... Briannut.jpg Briannut's Banshee.....years ago there was a bike called the Yamahawk with a TD850 engine...110 hp and it ate the Hawk cushdrives.Big KTM singles....and the unfinished Mille engine Hawk that Hawkati has.

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                    #10
                    Yeah, IMO the RD/RZ/Banshee engine is the way to go, because all of those bikes were severely limited by their chassis, which is the good part of the Hawk. That line of parallel twin engines is really a work of art.

                    I think bigger, more powerful motors are a poor idea, because the Hawk frame simply wasn't made to take it (stiffness wise). On the other end, big thumpers won't be much fun to ride unless you only ride twisties. The CR500 engine will rattle your fillings out. The equation changes a bit if you are going for a specific racing class - which is how most of the Super-Single bikes came to be.

                    Another suggestion would be any of the old 2T triples (H1, GT380/550) because those were also engaging (if not overly powerful) engines that were held back by their chassis. I would also recommend an SXV450 or 550 engine, but only if you hate yourself.

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                      #11
                      Originally Posted by stpierre View Post

                      That would be Bad-ass! If you can find a cheap one maybe better going with a CRF 450 but it won't last long.
                      This tends to be one of those things that sounds like a way better idea on paper than it ended up being in execution. Vibration has been the main reason the KX and CR500 powered ones weren't very successful but general rideability and unsuitedness of the engine to the job are there too.

                      Matt Blashfield built a CRF Hawk

                      Attached Files

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                        #12
                        Originally Posted by joel View Post

                        This tends to be one of those things that sounds like a way better idea on paper than it ended up being in execution. Vibration has been the main reason the KX and CR500 powered ones weren't very successful but general rideability and unsuitedness of the engine to the job are there too.

                        Matt Blashfield built a CRF Hawk
                        He raced it a few years. said it was like 10k all the time and no fun.I had a 450.....can't see a good hawk not crushing one on the track.

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                          #13
                          And, of course, economics make a difference. As if: you had a Hawk rolling frame sitting in the garage, and a KTM 690 engine just popped up at a good price on local CL. Then you just have to figure out the engine mounts, cooling hoses, and wiring. If the price was right.

                          (Lots of hot rod engine swaps depended on finding an engine in a junkyard. My college buddies put a Lincoln 400 ci engine and transmission in a 1956 Ford econo two door. It bolted up. They kept the original 2.73 differential, slow off the line, but it was good for a very scary 120 MPH. The price was right.)

                          Comment


                            #14
                            A custom 2 stroke exhaust is going to break the bank unless you want it to look like the bike from Full Throttle.

                            If you were looking for a support group you're barking up the wrong tree. This place is fulla enablers dude. - Shooter77us

                            The bitterness of low quality lingers long after the thrill of a low price has gone. - RacerX450

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                              #15
                              Originally Posted by riot View Post
                              I would also recommend an SXV450 or 550 engine, but only if you hate yourself.
                              that's a priceless quote. Both of those were great motors except the part where they tend not to last very long.

                              My thought on the 690 motor was EXACTLY via the junk yard find route. Not like I care about anything except the motor and wiring harness. Sure would be nice to have the spedo/tacho/instrument pod and switch gear, but the wheels, frame, suspension plastic (you know all the stuff insurance companies total bikes for these days) don't really matter.

                              RZ/RD would be preferred, a bit harder to find and oh the bits... so many bits to choose from. Want custom gear ratios for the tranny? No problem, just open your wallet, which seems to be a common refrain from those offering custom solutions to problems we've created.

                              Garth H
                              San Jose, CA, USA
                              '91 Hawk w/700cc Kit and Africa Twin Cams

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