First time on the dragstrip!

[Guest]

I took my first passes last night at Portland International Raceway on the GS drag bike. Good stuff!

Biggest problem was that I couldn't get the air shifter to work. It's probably something simple, am going to do some troubleshooting and/or bench testing this week. So I had to swing my foot up ~2' from the rearset to the shifter every time I wanted to shift.

Made good progress jetting the new "cone" carbs. Started off with 150 mains, bike ran so-so. Tried 160s, it ran worse, then 145s, and it ran much better. I'm guessing mains in the ~140 range will do the trick. Ordering them tonight.

Had a good crew come out to help with setup, tuning, etc. Looking forward to the next time out!

 

[Guest]

Brass hunt ... Mikuni cone carbs had Keihin hex mains when I got them. Most of my mains are Mikunis, I need to get a new jet box for Keihins!

 

[Guest]

Replacing the main jet drain plugs on the carbs by touch. That's pure concentration!

 

[steve murdoch]

Way to go, Patrino.
Great having a couple friends at the track to bounce ideas or offer encouragement.

Changing jets blind is indeed "fiddling".

 

[dorkburger]

Nice. Glad it went relatively well.

 

[Guest]

Also, found the timeslips ... best one was 11.695 @ 120.48 mph.

Plenty of room for improvement!

 

[Baatfam]

Also, found the timeslips ... best one was 11.695 @ 120.48 mph.

Plenty of room for improvement!

Cool...

Reaction time? 60ft time? 1/8 mile time? Or perhaps just a scan of the timeslip?

 

[Guest]

Best run:

R/T: 0.739
60': 2.002
1/8: 7.672 @ 96.17
1/4: 11.695 @ 120.48

second best:

R/T: 0.222
60': 2.208
1/8: 7.725 @ 97.97
1/4: 11.76 @119.31

 

[rphillips]

I'm confused, but it's been a long time since I's on a drag strip. Your best run was when you left, right at, 3/4 sec. late? Dang, You'd have been down in the 10's if you left on time.

 

[Guest]

@rphillips, like I said, room for improvement!

And on the bike side, the better jets are on order, and I'm diving into the air shifter this week.

 

[Baatfam]

I'm confused, but it's been a long time since I's on a drag strip. Your best run was when you left, right at, 3/4 sec. late? Dang, You'd have been down in the 10's if you left on time.

Reaction time has nothing to do with ET. He could have sat there for 10 seconds, and still run under 12.

 

[rphillips]

Like I said it's been a long time. I thought the ET was from the time the green came on till the finish came on. It must be from the time the green goes off till the finish comes on. Not a biggie, Ya'll all know this ain't the first time I's wrong

 

[headsbikesmopars]

Reaction time is independent of the elapsed time clocks. As Baatfam says, the ET does not start until you move out of the staging beams , starting the ET clocks .

 

[Guest]

Good info everyone, I had not understood that ET timing starts on physically leaving the line, not the green light.

Heading to the shop tonight with my to-do list from Friday night:
* bench-test air shifter / identify cause of problem
* find spare shift shaft
* extend pegs
* change low-speed rpm pill
* test operation of high/low ignition switch, on clutch
* install 140 mains
* bush shift shaft hole, in sprocket cover?
* find extension cord splitter
* inspect plugs
* change oil
* install carb float bowl drain lines (to make rejetting easier and less messy)
* move Keihin jets into their own box

 

[Guest]

OK! Air shifter is nearly working now. I'm not 100% certain, but it looks like the problem is either with the pushbutton switch on the handlebar, or the wiring between the button and the solenoid for the shifter. I cut the solenoid activation wires back by the sidecover, then connected one to positive, the other to ground - the cylinder fired just like it should.

Disassembling the switch for inspection I noted one of the three leads had separated from the switch housing. I'm not sure if that's the cause of the problem, but will dig a bit deeper later this week. Rather than try to fix that particular switch I'll probably just grab a universal pushbutton kill switch out of my spares boxes and wire it up. I'm sure I can find a replacement microswitch for the Pingel button assembly, but that'll take some sleuthing.

Regardless, we're one step closer!

 

[Rob S.]

I had not understood that ET timing starts on physically leaving the line, not the green light.

Me neither. Doesn't that render the reaction time irrelevant? Even the green light irrelevant? If the clock doesn't start till you move, why even pay attention to the green? Why would you be disqualified for leaving early (red lighting)? At what point would you be flagged for "delay of game"?

Rapidray, could you clarify?

 

[Baatfam]

Me neither. Doesn't that render the reaction time irrelevant? Even the green light irrelevant? If the clock doesn't start till you move, why even pay attention to the green? Why would you be disqualified for leaving early (red lighting)? At what point would you be flagged for "delay of game"?

Rapidray, could you clarify?

Remember, the strip is designed for racing, not just how fast you go. First to the finish line wins.

When the light turns green, that's when the race officially starts. The one who starts first, (better reaction time), gets a head start. An advantage. But leave too soon, and lose. Red light. (I am leaving out human and vehicle reaction time. You really need to go before the green to get a good RT. That's what the yellow lights are for, to tell you when the green is coming.)

ET starts when you leave the staging beam and ends when you break the beam at the finish line.

With a faster reaction time (Green to leave) you could win with a slower ET.

Let me know when you are ready to discuss bracket racing, because that's where it gits fun.

And of course Mr. Google is still open:

https://www.us131msp.com/drag-racing-101/

https://www.onallcylinders.com/2012/06/22/bracket-racing-101-learn-basics-then-get-out-race/

https://www.youtube.com/results?search_query=bracket+racing+explained

 

[Guest]

It will change you Et and reaction time depending on where you stage in the beams. Shallow staging will slow your reaction time but quicken your Et. Deep staging will quicken your reaction time but increase your Et. I personally prefer to deep stage. Most shallow stage. I use a delay box so it really doesn?’t matter where I stage. But for me Deep staging helps me be more consistent on my reaction time. Deep staging does tend to irritate some racers.
I use a 2-step launch limiter with a crossover delay box and a slider clutch with the auto shifter.
I am thinking about naming my pro Et bike “ Flicker” because I can make the top bulb flicker on and off

 

[Guest]

OK! Air shifter is nearly working now. I'm not 100% certain, but it looks like the problem is either with the pushbutton switch on the handlebar, or the wiring between the button and the solenoid for the shifter. I cut the solenoid activation wires back by the sidecover, then connected one to positive, the other to ground - the cylinder fired just like it should.

Disassembling the switch for inspection I noted one of the three leads had separated from the switch housing. I'm not sure if that's the cause of the problem, but will dig a bit deeper later this week. Rather than try to fix that particular switch I'll probably just grab a universal pushbutton kill switch out of my spares boxes and wire it up. I'm sure I can find a replacement microswitch for the Pingel button assembly, but that'll take some sleuthing.

Regardless, we're one step closer!

how are you testing your shifter? You need to disconnect your shift lever to test it.
I have lost quite a few races using cheep switches. A lot of racers use these. https://www.mpsracing.com/products/MPS/Probutton.asp

This is the the switch I use.
https://grothusdragbikes.com/collections/frontpage/products/dominator-button-bracket

 

[Guest]

Good advice, stetracer, thank you!

Yes, I disconnected the cylinder from the shift shaft prior to testing, no sense beating up the shift forks & transmission internals. I talked to the folks at Pingel yesterday (great customer service, by the way!) and they assured me the cylinder could be fired without any resistance.

Here's the switch I'm running, but bear in mind it's probably 25+ years old: http://www.pingelonline.com/handleb...uge-and-electric-button-handlebar-control.asp. Thank you for the recommendation and options.