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Prepping for racing

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  • Prepping for racing

    Hello everyone. I've been really distracted and haven't been around much. With how things have changed in my life, I find myself more and more interested in doing things instead of sitting at a computer. It's nothing personal. That said, one thing I've been spending way too much time on recently is a small pocket bike. It started out as an X-19 with a 110 automatic. I have since tried to get it up to par to just have fun with a friend in parking lots. First was a 125cc with a 4 speed, 4 up pattern (easily switched to gp style shifting with the shifter and linkage I made). Apparently, these things aren't made to ride like mini motogp bikes. After the first outing, I noticed the rear tire was quite diagonal, having slightly twisted the swingarm from the forces of leaning off the bike and cornering so hard. I also had amazing rear chatter. It was more than chatter. It was a pogo-stick suspension. So, I pulled the swingarm, boxed in the frame with my awesome welding skills, cut off the shock mount, cut off the frame shock mount, and fitted a stock shock from a Honda 954rr for real dampening and adjustability. That led to the front being too soft. I cut the springs, drained the oil, and used gear oil to get at least some kind of dampening up front (no real valving, remember, this is a chinese toy bike). So I got it nice and stable for taking through turns. Next problem area was the front brakes. They worked, but were horribly bad by design. The rotor couldn't even contact the whole pad surface. I've since upgraded to the real KTM caliper that the chinese tried to copy, got a larger diameter rotor, and made a bracket to relocate the caliper to fit properly. I've raised the rear, and with the new tires I just put on, the bike is now leveled out again, but with greater clearance for leaning it over. I've gotten to practice with the friend in parking lots a few times during the process, and the little bike is really coming along. I'm still constantly improving it, but now the changes are getting smaller and smaller, and I just need more seat time and practice. My friend though has done some endurance racing with a group that has a racing class that this bike fits in perfectly. The cut off is 120cc vertical engine, 125 cc horizontal engine, or 62cc 2-stroke. We've decided to hit up the next open practice or two to see if I can be competitive on this thing. I still need to do a little safety wiring (minimal) and add two catch cans. One for fuel overflow from the carb, and one for the crankcase vent hose.

    Here is the last time I got to practice. It was the first time I had good front brakes, so it was the first time I could try late braking and entering turns with more speed. I was still getting used to it again in the beginning, and kept getting more and more confident as the day went on. After the video stopped, I eventually started getting confident enough to brake hard enough that the rear would skim the pavement and downshift from 4th to 2nd at one shot and just barely slide the rear out at the beginning of the turn. Had a couple close calls, either caused by dirt/sand or by the cheap chinese tires that I still had on it. Didn't go down, just drifted through a turn and scraped the peg pretty good on it. The more I do to this thing, the more I want to seriously race it. Best parts of this are that the costs of racing this are WAY less than a full size bike, and I can just throw it on a hitch platform and don't need to pull a full trailer. Yehaw! I'll let you know how it goes!

  • #2
    Sounds like a ton of fun. Seen bits and pieces of what you've had going on in the chatterbox, cool to see something that gives a comprehensive picture.
    1998 Katana 750
    1992 Katana 1100
    2006 Ninja 250

    2006 Katana 600 RIP - 130k miles


    • #3
      I think Dan is really serious about winning KR's 2nd annual mini race.
      1992- project katfighter
      2005- GSXR750
      2001- TL1000R

      KATRIDERS RALLY 2014 - cintidude04
      KATRIDERS RALLY 2015 - cintidude04
      KATRIDERS RALLY 2016 - cintidude04


      • #4
        Looks like heaps of fun ... and some great cinematography too.


        • #5
          Look at the New Jersey Mini GP club and Ohio Mini Roadracing League.

          Both clubs meet at PIRC's kart track (5 hours West of where your profile says you're located) for the "Eastern Mini Championship."

          I will be racing my XR100 in the stock 100 class, and Formula 3 (OMRL rules. I think it's called something different by the NJ club's rules). I may use the Katana as a pit bike :P
          **if what I said can be taken two ways, and one of them offends you, I meant it the other way.


          • #6
            It's going to be hard to loose when no one else can find bikes to enter into the contest

            Welcome to! Click here to register
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            • #7
              Common mistake is trying to go fast after you upgrade your bike. Learn the li its of your bike without riding it fast, just try to pt your shoulder to the pavement with minimal speed, learn the limits of the tires and suspension at lower speed before you try the cones.


              • #8
                I admit, I'm not exceptionally good at taking it slow on this thing after the mods. This last Sunday, I went at it again, this time with new tires, a change to the rear shock, and a few other minor improvements. The tires were squirmy as all hell at first. I took my time until they were scrubbed in. I did spend a fair amount of time trying to figure out how to ride a bike that small while staying relaxed as much as possible. I worked on doing the transitions a lot quicker, and smoother, so I could stay seated longer, giving my knees a break between turns instead of setting up way in advance. My friend spent a bit of time just pressuring me, passing me really close, going wide and letting me shoot through on the inside, giving me the experience of being around other people for real racing. That was seriously fun. Those tires just gripped, and were so precise. The ground clearance was definitely the limit this last time around.

                NJminiGP is where I'm going to give it a shot. The first two open practice sessions I can make it to are at NJMP, 2 different track configurations. I'm excited about this.


                • #9
                  The NJ folks are a good group. I need to make a trip out to run a round with them some time.
                  **if what I said can be taken two ways, and one of them offends you, I meant it the other way.


                  • #10
                    Alright, so I've taken the time to over the past few weeks to keep improving the bike. I've ended up making my own exhaust, testing it out, wrapping it with header wrap I had left over from when I did the Mustang's headers years ago, put in a CDI with advanced timing and no rev limiter, a better coil, tuned it better and did some other carb mods. I've learned a few tricks that I may even try applying to the Kat's carbs.

                    It's going faster than ever, and pulling the front up when shifting hard into 2nd and sometimes 3rd. It's been tricky getting used to the gp-style shifting. It's difficult for me to downshift 2 gears quick going into a corner, and I've made some mis-shifts in the opposite direction as well. This motor/trans seems really strong, and even with as much as that should upset the bike, it remains quite stable. I'm confident in the suspension and tires.

                    Eventually, I'll need to raise the rear just a tad, and or modify where the rearsets attach to make those adjustable and higher for better ground clearance. It's almost ridiculous that this thing can lean over far enough to grind the pegs and still be so stable, but it can.

                    The front brakes, while adequate, still weren't great. My friend convinced me that brakes that take less effort will help me go faster just by making me more relaxed, even if they can't stop the bike any faster because of weight transfer on such a small chassis. So for that, I've modified and fitted a caliper from a full size scooter. It takes a little less effort, and almost feels like it's trying to rip my face off keeping the rear tire an inch above the ground. I haven't tested that out in track like conditions yet though.

                    I'm headed to the track tomorrow for the first open practice session that I can make it to. I've watched videos on youtube of one of the races from last year on the same track configuration, and know they were hitting lap times in the 43-44 second range, so I know what I need to shoot for.

                    This is my friend doing some testing with the new exhaust. It was a tad rich on the bottom end, but it wasn't as bad down low as the video makes it seem. Also wasn't quite as loud as it seems. It was reflecting off the building a lot.



                    • #11
                      Progress update

                      Thought I'd give a little update on this endeavor. I've made a few more improvements after finding some issues. The swingarm was cracking and there was interference with the shock spring when compressing fully, so I made some extra room, fixed the cracking, and made the swingarm even stronger. I also modified the frame where the rear sets attach so I could move them higher for better ground clearance. I can now lean the bike over to the point that the tires will start sliding without hitting any hard parts.

                      My schedule has not worked out to make it to a spring race with this thing yet. I've kept practicing most Sundays. I did make it to a 4 hour endurance race as part of a 3 man team on my friend's CRF150F. That was amazing fun. I was putting in some really good lap times, especially once I started getting comfortable. I did go down once when someone tried to hit me cause I was making a pass. I found that my weakness isn't my willingness to carry speed through the turns, but with my ability to make a pass on an unwilling person that's swerving across the track to stop me. We only had one bike, so we lost time on fueling, and we had 3 extra pit stops, 2 of which were to air up the rear tire cause it started losing air. I slid off track once and had to get back up and restart the bike. We still ended up 5th out of 7. Out goal was to not be last.

                      This last weekend, practicing on the pocket bike, I ended up trying to work on body positioning. That ended up just goofing around exaggerating the body positioning just to see if I could drag my elbow, which I did! It was pointless, but I did learn a lot about tire traction, and feathering the throttle because that was at that tipping point between having the traction for the turn or not, and no extra left for throttle or brake. It was fun and a learning experience, even if it was a bit stupid.


                      • #12
                        Exaggerated body positioning is one of the easiest thing to do to improve your bike handling skills.
                        Most people think leaning the bike is more important to get through corners quickly..

                        On a small pocket bike is difficult to get a feel how much pressure you can put on your (outside) knee to save your upper body strength and help with body positioning; but the concept is there and just apply it to endurance racing when your body really get tired after few hours on the bike.


                        • #13
                          cool man
                          2015 BMW S1000R


                          • #14
                            Originally posted by "K" View Post
                            Exaggerated body positioning is one of the easiest thing to do to improve your bike handling skills.
                            Most people think leaning the bike is more important to get through corners quickly..

                            On a small pocket bike is difficult to get a feel how much pressure you can put on your (outside) knee to save your upper body strength and help with body positioning; but the concept is there and just apply it to endurance racing when your body really get tired after few hours on the bike.
                            Yeah, you're right about the body positioning helping get through turns quicker. When I first tried to lean that far off and down, I had to almost immediately stop turning because it turned so quick compared to what I was used to. It's pretty amazing what a bike like that can do. I'll admit though, I weigh around 50 pounds more than the bike, so me leaning so far helps it a LOT. I was basically trying to put my body in a position as if I was trying to drag my shoulder.