Victoria! Zeke's CB175 Build
- Thread starter Texasstar
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Texasstar
Can't is a four letter dirty word
Teazer is right we have some dialing in to do. We need to change the shifter it is what cost us the ton...it wasn't quite long enough for the Bostrom's to reach cleanly. You can hear Ben miss a shift. The Bostrom's spent an invaluable hour one on one with us teaching us about chassis tuning and all the things that were scrubbing speed. The biggest besides the shifter is we needed more mounts for he Dustbin. The wind was pushing the bike across the track. We only ran the T4 fuel because we were sharing the track time with Revival Cycle. Amazing day we learned a lot. They were very impressed with the front brake and gave us words of encouragement. The best part was the constructive criticism.
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Texasstar
Can't is a four letter dirty word
Let's start with what didn't work starting with the front of the bike. Dustbins are dangerous. The men that raced dustbins defied danger. We had a 6mph cross wind coming out of the northeast and we were running east to west. You could see the wind pushing the bike as the speed rose. I got to ride Victoria to the back of turn 12 but had no wind and a big goofy smile and took her up to 12k 4th gear on the back straight. Both the Bostrom's BOTH said after their first runs "I think that was the fastest 100mph I have ever run" We are running a vintage ribbed tire on the front. Ben thought that the ribs, like a wet motogp tire on dry pavement, were pulling. Also the little rubber tits on the tire weren't scrubbed off. The fairing was also chattering because we didn't have it reinforced from the front. We did reinforce it like the original fairings but the original were way more rigid than fiberglass. The chattering was also because the front suspension was too soft and the rear too stiff so as Victoria ran over a bump the greatest shocks in the world couldn't compensate for poor set up and 40 year front suspension. I do believe the Öhlins saved my life when I lost the brake stay a few weeks back.teazer said:
What worked on the front? The mighty cb450 brake and cb77 hub. Eric said he was very impressed with the front brake and had a blast bringing Victoria back to the paddock. We still need to arc the pads in and we will have the race compound you suggested coming later. The Bostrom's said we need better cable pull for both the front brake and clutch. The short levers didn't help the 40 year old mechanism to operate better than the original design. Just plain physics. They want better feel. Ben had air shifters on his Ducati Sport Bike because the other shifter kept them from being competitive.
Ben said every stock frame when he raced Harley's had to be placed in a jig, measured with lasers, torqued and twisted true. His Japanese bikes had race ready true frames from the factory. Would you think a stamped out 40 year old cb175 frame would be true and rigid enough? I don't think so. He also told us some great "secret stories" on stealing speed...it was the same thing you have preached to us from the beginning. Making sure everything is true and that nothing is scrubbing off your speed.
We hit 428 degrees on the temp gage. The Bostrom's said we should think about better cooling and an oil cooler. I think we will back the advance back a tad first. You were right Sonreir.
Moving to the bottom of the engine...the gp shifter cost us the ton. Eric showed Zeke the perfect position for the shifter.
We need to set the bike up neutral. They both told us to lightly grab the front brake and bounce the bike just behind the tank on the seat and the front and rear suspension should travel in concert with each other about an inch.
Btw the run length of the back straight for our runs was reduced to just over a half of mile because of the topography of the track.
What worked? Every little post from DTT. All your collective wisdom and encouragement. We thank you from the bottom of our hearts.
What is next? We have a honey do list that has been neglected so we need to take care of Mom. My wife has made the greatest sacrifice. She gave up our 25th anniversary trip to fund this project and we are very grateful to her.
We go to Barber in two weeks.
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Texasstar said:
With a long tank you will probably want to do that push test on the rear of the tank , but what they said is correct. You are pushing down more or less at the center of gravity and you want it to go down evenly at both ends and come back at the same rate at both ends. That way you have spring rates and damping balanced. It's an easy check to do..
>400 degrees is too high and may be air flow (lack thereof) or too much advance for the fuel. More air usually helps and if it's lean at the top end that will heat soak at the track and get too hot. If it was still pulling hard at teh top end it was probably not too much ignition. How much advance does it have at the top?
Control position is very important to make the the bike easy to operate. That applies to bar angles and lever angles and shifter and peg positions too. It's all about making the controls light and easy and natural to use. GP shift pattern is a good approach on teh track but the trick is getting the lever in the right place in relation to the peg. If the lever is too long, it has to rotate too far to operate, so in that situation use a shift linkage and play with leverage to take out the slack and may the action short and crisp.
Dustbins: there's a reason they were banned in 1957 or somewhere around there and you worked out why.
Front forks: I don't remember what you used but a set of Gold valves and new springs should sharpen that end up a lot. Stock suspension tends to have a lot of stiction and tends to be mushy and still lacking in damping. Thick oil doesn't make much of an improvement which is where those Gold Valve Emulators come in
BTW 99 is more than many race bikes based on that motor are achieving. Congrats to the whole family.
crazypj
Split personality, I fake being smart
To echo what Teazer said, you need to 'push down' around the middle of bike so it will be on tank not seat.
You found out why dustbin fairings were banned
You will probably need much higher front tyre pressure if you continue using it plus much heavier fork springs, the air pressure over 80mph is probably loading the front? (do you have any video to compare ride height at speed?)
Do you have any ducting inside fairing to supply air to motor? Just having the openings isn't going to work
You found out why dustbin fairings were banned
You will probably need much higher front tyre pressure if you continue using it plus much heavier fork springs, the air pressure over 80mph is probably loading the front? (do you have any video to compare ride height at speed?)
Do you have any ducting inside fairing to supply air to motor? Just having the openings isn't going to work
