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Resurrecting The 1/4 Mile Bike


SlowerThanYou

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Well, points came out today. Not where we wanted to be, but not all bad. It's 12 race series taking your best 9 finishes.

 

Justin sitting in 2nd place.

 

The old man sitting in 9th place out of 64. The Pro Class has the largest amount of racer's at our track usually 55-75.

 

We have a long way to go with only 3 races under the belt. Justin is missing 2 of the races in May.

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Even though the Density Altitude was the shittiest so far today; it will only get worse until Oct, LOL!. We did manage to go quicker with the quad. It liked the gear change, higher shift points & new tires. Today we plan on raising them another 300 rpm. Plus, lowering the shift kill milliseconds from 90 to 60. 

 

Well, we are approaching our quickest runs made at our track by our well sorted out 443 Cub with the 535. This is with about 18 runs & we have plenty of work to do yet.

 

So, what was our improvements for this weekends outings. We were quicker by over a tenth & faster by over 2 mph (almost hit 119). The items that contributed to that was final ratio gear change, millisecond shift kill reduction, raising the shift points, new tires & adding/changing the timing curve. 

 

While everything went in the right direction with the changes except for the 60's. Most of that problem was caused by the 2.05 final gear ratio. While we did loosen the clutch up, we need to loosen the base pressure & less weight on the arm weights before the next race.  

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I got to the clutch inspection today. Everything looks good, just starting to show a little heat in a couple of the steels. We are going to make some clutch changes based off the inspection & a couple things that happened at the track last weekend.

 

We tried some lower rear tire pressures last weekend, but it caused 2 problems. 1st, it pulled the motor to far down in rpm around 15' out & never recovered before the 1-2 shift. The 2nd, was almost a motor killing bog at the drop of the clutch. While we don't blame these issues totally on the tire pressure. I'm sure the change in final gear ratio was contributing also.

 

I'll start with the 1st issue of rpm being pulled down to far around 15', till the 1-2 shift. We are going to lightened the arm weights to correct this. We are removing 28 grams total from all 6 arms. IMO, the boys set it up with way too much arm weight!

 

The 2nd issue was a bog at the drop of the clutch. We kind of figured with the gear ratio change. The tightening of the air gap with a stock pressure plate. Well, the bog cost us in the 2nd round of the second race. I removed 8 lbs. of base pressure & that should get us close.

 

Once we get some baseline runs on the above clutch set-up. We will start looking at raising the launch & shift rpm. Plus, run some more timing, based off the plug readings.

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Just for informational purpose and for the sake of a small discussion that has meaning on this third rate dump of a website Ill toss this out there for some thoughts.

 

I've seen people do some pretty serious tail chasing on the bog situation at the drop of the clutch, I'm assuming that you know the bog is not a lean bog due to the extra load on the motor from the gearing because you have ran these carbs many times over and you are confident in your carb tuneup, or is it an assumption that you would typically make that the bog is clutch related and not tuneup related? I'm sure you have watched people chase carbs, gearing, and tires all day just like I have trying to get the bike to leave and never open up the clutch cover. 

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Just for informational purpose and for the sake of a small discussion that has meaning on this third rate dump of a website Ill toss this out there for some thoughts.

 

I've seen people do some pretty serious tail chasing on the bog situation at the drop of the clutch, I'm assuming that you know the bog is not a lean bog due to the extra load on the motor from the gearing because you have ran these carbs many times over and you are confident in your carb tuneup, or is it an assumption that you would typically make that the bog is clutch related and not tuneup related? I'm sure you have watched people chase carbs, gearing, and tires all day just like I have trying to get the bike to leave and never open up the clutch cover.

 

Yes are carbs are plenty fat & we need to start leaning them out a little. Plus, we need to add some more timing, before leaning them out.

 

As for the clutch, we went out knowing it was a tight clutch. The majority of our problem is with the arm weights. I can here the motor pull down way too much rpm when the clutch arms apply. The base pressure is getting close, but still a tad tight.

 

I understand what you are saying & we don't always fix problems with a clutch adjustment.

 

I can't believe how close this set-up is following the 443 Cub. The basic differences are: of course is a bigger motor, about 400 rpm less thru all aspects of the run, using a standard lock-up & not using the multi-stage. Plus, we haven't switched over to the rat poison race fuel yet. 

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For example I run s smaller motor combo and have about 12 grams on each and I'm sure my base is lower also

  

I don't know about that one, but I will never tell.

 

I'll try & explain this a little better. Sleeper has a smaller/lower powered motor than us. With a lower power motor a low base pressure will keep the motor at higher rpm during the launch.

 

With a higher power motor we are also want the motor at a higher rpm during the launch. But, we are also trying to bleed off some of the power & apply it back at the appropriate time on the track.

 

Not sure if I explained this for Member's to clearly understand. If there are any questions, ask them!

 

 

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