GT750 Drag Bike

[water cooled]

Thanks Dave....I love the smell of two stroke in the morning. Hope the neighbors dont mind if I fire the bike up to clear the motor before I leave. That should piss a few of them off.

[Suzukidave]

Kevin .. ya ever see the movie " Worlds fastest Indian " LOL

[water cooled]

One of my favorite movies... I think Burt still holds the record for his subclass. The movie inspired me! I know the scene your talking about though. I probably wont bring myself to do it....but the thought puts a smile on my face!

[tz375]

Kevin,
Martin is next weekend or this one?

U4.4 sounds interesting. We used U4.2 in teh past and that stuff smells like race gas. Nasty stuff. Q16 sounds like it could be an even better option but you need DF to try it and see what timing and jetting it needs.

[water cooled]

R, Martin is next week - Sept 22-24th. But Im leaving this week for a family vacation. I remember the day it when it struck me that I had to have the bike and trailer ready a week early.

The U4.4 wasn't my first choice. I wanted to stick with C12 but all the sources around here have dried up. No one is carrying it right now. The U4 was the best option and I needed fuel in case DF was going to test the bike.

U4.4 is the new version of 4.2 and is supposed to be less volatile but still powerful as an oxygenated fuel....as a result, we need to jet up 2 or 3 sizes on the MJ and PJs.

[tz375]

Kevin's summer vacation - not like Chevy Chase I hope....

[water cooled]

This video is a clip of Gary Seeley on his Triple Obsession H2 vs. my GT750. I still need to work on launching better and body position. You can see he wins the race right off the starting line.

http://www.youtube.com/watch?v=UOP7jxbbc38

[tz375]

That was eye opening. Gary has it nailed - so clean off the start. That comes down to technique and that will come with practice and experience. By the next time you meet at 131 you'll nail him to the wall metaphorically speaking of course.

[water cooled]

Yep! Gary Seeley is one smooth racer. I watched several slo-motion videos of him from last Octobers race. There is NO wasted motion when he launches. Except for lifting his toes up, he barely moves at all so there's no weight transfer to the bike. Its incredible watching him.

Here is a cool video clip during Test N Tune on Friday where I raced an HD. I backed out of the 2nd staging light and thought I could re-enter but found out you cant do that. As a result, there was no time shown for the pass but I felt it was one of the better ones I made that weekend and you can see that I was able to close on him. It was also the pass where my rear wheel yanked forward and the slack chain did some damage. At the very end of the race, you can see a glimmer from my chain guard that got ripped off and bounced around sideways between my rear wheel and battery box. I was able to hit 5th before the shift solenoid and tubing got thrashed. Dave Derrick and Doug made and collected parts for the wheel that night and the next morning and one of the other racers gave me the pneumatic fittings that I needed to get it all working again. If it wasnt for their effort and generosity, I wouldnt have been able to make any Qualifying Passes.

http://www.youtube.com/watch?v=zjV6Zf8y8eU

[tz375]

That's a good video but the hand free run was crazy. The bar just yanks out of your hand.

What sort of clutch do the fast H2 boys use? is it a set of weights that are forced out by centrifugal force to keep the plates clamped shut at speed or is does it allow the clutch to progressively take up drive after they drop the hammer. It's hard to tell from video exactly what the technique is or what technology they use.

[tz375]

Kevin, I just watched the videos again a few times to try to see what happens in that initial fraction of a second.

The start is clearly crucial both in terms of timing and technique. Watching the fast boys it's hard to see their technique but they are smooth and clean off the line. It's a sort of fluid motion - fast but no jerks, bumps, etc. Is that all technique with the left hand or are they using different clutch technology? Do their clutches take up the drive more progressively of is it all in their technique?

In the video titled Bad Launch, your bike lurches at the moment the clutch is dropped and you can see the whole chassis jerk and whip around which is how it yanked the bars out of your hands. It's possible to see a wave motion move down the bike and then back to the front as it distorts. The tire distorts but I can't see how much the frame or swingarm are also twisting or bending at launch point.

A new, stiffer swingarm would help to transmit power to the wheel, but there is something happening at the point of clutch take up that appears to need to be smoothed out and make it more progressive.

I watched a couple of other videos in slo-mo and some riders appear to almost dump the clutch but without such a violent reaction.

[water cooled]

R, most of the H2's have a slider clutch like you described in your post. MTC and Hayes makes them. They operate on RPM and squeeze a hat section down onto the plate stack during the run. There is no clutch handle....they activate at a predetermined RPM and stay locked up above that level.

I studied the one-hander video and slowed it down even more. It appears the rear tire bit and squatted down...the wheelie bars hit the ground and everything came back up. The front end responded by doing the opposite which is what caused the wave action. At the time, my hand was opened from releasing the clutch lever. The bars bucked up and when I went to grab it, it bounced down and I just missed the handle. Dave Derrick showed me a better way to grip the bar when working a clutch lever. It didnt happen again after that but it did leave a lasting impression on me....

[tz375]

Is your slider clutch conversion on order and on the way yet? Sounds like it might reduce or eliminate one issue, potentially.

[water cooled]

MTC helped me quite a bit this past winter. GS1100 and 1150 baskets are too big. My primary gears are not straight cut which is another issue but we could work around that. MTC found a Kawasaki basket that was nearly identical in diameter and could be shortened slightly...then riveted onto my existing gear. Its all do-able but we both ran out of time going into this season. It would be an investment....

[tz375]

MTC slipper clutch sounds like just the item for Santa to bring this year. It's interesting how steep the investment curve is as you move forward. It seems to be like an exponential curve that rises steeper with every step.

First second, $1000
Next half second $1000
Next quarter second $1000
Next 1/8 second $1000

Except that those numbers also grow as you head toward the front of the field. And those numbers were for road racing. I'd guess that drag racing has a similar cost curve. What does it cost to compete at the Spiderman level????