Topic: CB750F private test session results.Video added

[dragracer]

We were able to make it to a private, limited occupancy  test and tune session at Rockingham Dragway yesterday.  The temperatures were in the lower to mid nineties but the air density was horrible as far as being perfect quick ETs. My wife made a good pass on her dragbike. She ran 5.69 in the 1/8th mile and a 9.24 quarter mile pass. The 1/4 ET and mph tells me she probably rolled out of the throttle before the stripe. I'd venture to say it would have been a 9.10 pass if she stayed in it. I was next to go out on the new F model.  I wanted to see how hard i could leave on the bike before it would lift the front wheel.  I had the rpms  up pretty good and dumped the clutch when the light dropped.  To my surprise the rear tire lite  up off the hit and spun throughout the 60', fish tailing like I was on the street. It hooked and went on down the track. It felt very stable making the full quarter mile. My time slip showed it only had a 1.70 sixty foot but still ran a 10.84 inspite of the horrible spinning off the line. One of my fellow racers suggested to line up outside of the groove on the next pass. Now normally I would never do anything like this because you always want to make the pass where the most rubber is layed down. This is typically where the best traction can be found.  I lined up outside the groove as suggested.  Mind you,  my thoughts didn't allow me to feel comfortable in this spot so I lowered my launch rpm much more than the previous pass. I figured it would definitely blow the tire away in this bare groove.  As I threw the clutch away, the bike immediately bogged down but pulled out without choking off. Oddly enough the bike had a 1.56 sixty foot time. It only ran an 11.05 at 118 mph. The issue was the bike didn't shift properly a few times. I went  back to the pits and pulled the shifter button out to check connections.  I found nothing wrong but flipped the shift around in the mount. On my next, and final pass of the day I decided to line up in the groove again. I did bring the rpms up but not quite as much as the first pass.ight came down and I threw the clutch away and locked throttle.  The bike left the line strong,  shifted perfectly every time and ran great down track. The time slip showed a 1.45 sixty foot, ran a 6.45 in the 1/8th and crossed the stripe to a 10.35 ET at 123 mph. Yeap, after 6 total passes on the bike its a low 10 second Honda. No, i didn't get close to the 9s, but I'm fine for only a hand full of passes on the new build. I'm still trying to figure out what the bike likes, working on my comfort level on the bike and it still has to be fine tuned suspension and engine wise. Will we ever see an all motor 9 second pass?? At this moment I don't feel we'll ever make it with the current engine platform but I see 10.20s and possibly 10 teens if all things are perfectly aligned. I haven't decided when I'm going to put the nitrous bottle in the bike yet and dial in a tuneup. I want to get the very best  all motor ET before I juice it up. Stay tuned. We're getting there.

[Old Scrambler]

You're the man

No one will want to line-up next to you

[dragracer]

Here you see the 3 time slips from yesterday.  I do have a gopro video of the first pass. I'll try to figure out how best to post it so forum members can view it. I am have to link my YouTube video channel to allow easier access for everyone.

Obviously the virus situation has limited everyone's activities.  Although we all practiced social distancing at a private, limited occupancy test session , i will admit i was apprehensive at first.  Fortunately we had folk there that respected each other's space. I'll probably go back to the next session in a few weeks. There are already tracks opening up for regular events but I'm not comfortable with exposing my wife, or myself at this point. I'm thinking maybe mid July for our first organized event.

[dragracer]

I was able to upload a video of one of my passes from saturday on youtube. I hope you can view it okay from the link below. Let me know please.

[PeWe]

Looks and sounds great!  Nice throttle response!
Felt like like riding myself in the sofa while working from home 

[dragracer]

Thanks for the feedback. Glad you were able to view and enjoy the video. I tried to set the camera angle so you could see down track instead of any part of the front of the bike.  Next time I do a video  I will aim the camera more at the hand controls and shift light so a viewer can see exactly what I'm doing to get the bike from point a to b.

Looks and sounds great!  Nice throttle response!
Felt like like riding myself in the sofa while working from home 

[gschuld]

Great video Frankie

Glad to see you getting more track time👍

George

[johno]

Looks like a Honda.
Sounds like a Honda.
Go's like a cut snake. 

Great Vid Thanks bro

[Jerry Rxman Griffin aka MuthaF'er]

Great to ride with you. It sounds RIGHT!!! How's that time compare to your record?

[dragracer]

Great to ride with you. It sounds RIGHT!!! How's that time compare to your record?

10.48 is the official super eliminator record Jerry.

[Sam Green Racing]

Great Frank, inside the record on shakedown runs with a lot more to come, good luck my friend.

Sam.

[dragracer]

Great Frank, inside the record on shakedown runs with a lot more to come, good luck my friend.

Sam.

Yes Sam, this bike has already  shown it will run a quicker ET than the current record in the Super Eliminator, CB/SS class. The beauty is i never installed the lockup clutch so i can still enter it in the CB/SS class. The potential is there to lower the record even more than the 10.48 record i've set with my other bike.  I feel the bike would have been quicker on saturday but the air density varied between 1729-2300 feet. It was a horrible air day and not ideal for low ETs. I still need to figure something about replacing the throttle. Its not a 1/4 turn throttle and i feel i'm not going full throttle at all on every pass. Nevertheless, i'm satisfied thus far with the bikes performance and ease of rideability. Its much smoother off the launch than the F3. I'll be working on lower my sixty foot times when we go out again.

[scottly]

Does anyone else hear some odd sounds, starting at about 4:00?

[Don R]

 Thanks for the ride-along. That was fun. 
  I'm getting our trailer and Dragster out of storage this week, hoping we feel safe enough to race, not sure. My driver has a 1 year old baby now and asking her how she feels about racing is like asking my wife where she wants to go for dinner. I don't care,  "I'll go if you want to".  The three of them think they had the virus already.  I'd prefer, hell yeah or not really. Either way I'm putting the engine and trans back in.

[754]

 Man you must be well prepped, and have a formula that you use.
 My thoughts  are its first time out, and you should be able to bring it down a bit with more testing........and three tenths or more does not seem out of reach.. .. quick bike, góod job.,

[dragracer]

Does anyone else hear some odd sounds, starting at about 4:00?

Funny you mentioned that sound. I noticed it right after I downloaded the video. I watched it a few times and concluded it must be wind noise from the camera. At the end of the run when I'm slowing down is where it seems to be appear first.

[PeWe]

I remember that I also heard "wind noise" when watching the video.

[dragracer]

Man you must be well prepped, and have a formula that you use.
 My thoughts  are its first time out, and you should be able to bring it down a bit with more testing........and three tenths or more does not seem out of reach.. .. quick bike, góod job.,

Frank. I suppose i do have a basic formula for building a 10 second SOHC. Its not as difficult as you think.  I'm not a trained mechanic, machinist or engine or chassis builder. I've just figured out what works best and try to follow my road map. I concentrate on the chassis first to make it suit my goal. Without a good platform to put the power to the ground,  you'll spend a lot of time fighting the motorcycle instead of riding it. I then build an engine within a reasonable budget knowing full well an SOHC is antiquated by today's standards. Its senseless to throw tons of money at one to still be the slowest bike at the track.  I try to spend money on the important things that will make the package work to its full potential.  Sure, a nice head would be great, a stroker crank and custom pistons would make the bike quicker,  but in the end, no one cares at the dragstrip that you own the quickest Honda 750. Its all about turning on the win light, round after round. Hopefully this bike will eventually prove to be as reliable, and even more consistent than the F3. Otherwise,  I've wasted a lot of time and $$.

[scottly]

I just watched/listened a few more times; from about 4:16 to 4:26, it sounds a bit like a squeak, and then stops. Make sure the top end is getting oil!

[dragracer]

I just watched/listened a few more times; from about 4:16 to 4:26, it sounds a bit like a squeak, and then stops. Make sure the top end is getting oil!

Will do. Thanks for your attention to details in the video. I definitely heard a noise as well when I first downloaded the video.  I attributed it to wind noise after listening a few times. New builds always concern me because you never know when a problem can arise out of the blue.

[PeWe]

Front brake pad gently touch as a " positive" alternative.

I had vibrations causing irritating noise (high pitch like oil starving bearing can sound in my mind and soon starving wallet) around 5000 rpm that convinced me about a cam without oil.
I checked behind tappets cover, oil everyhere. Even with engine running, especially everywhere

Googled about vibrations between 4800-5100 rpm something and got a hit on a  motorcycle forum ( I think Kawasaki) where this was up 
"This is the typical resonance frequency of an inline 4 and can be things that sit a little bit loose, like exhausts"

I checked my exhaust pipes and found one ex spigot sitting loose, thread failed. Helicoil and fixed it.  OK after that.

I was stressed before finding it, reading here about oil issues to cam.
I have heard it again after that and re-tightened my other exhaust in need of more when copper gaskets had softened after initial assembly.

This vibration comes very abrupt just before 5000, ends after + 5100 rpm.

I have had a similar sound before when speedometer gear in speedo was in need of oil. Failing speedo or tacho wires sounds different. I had this in mind too when this happened.

[bwaller]

That's a good birds eye view Frank, great vid.

I appreciate your statement "still trying to figure out what the bike likes". This is often overlooked or not even considered, but shows experience on your part. I feel the same and it takes time to work these little nuances out. A good rider is one who has the instincts to translate this into solid tuning either chassis or engine.

It took me a while to realize front chatter in a corner was an "off throttle" issue. In a little slower and on the throttle sooner eliminated the problem. No amount of 35mm fork tuning would ever solve it.

Good luck getting the ET's down further.

[dragracer]

I'm not certain if anyone paid attention,  but when the bike launched off the line you might notice a little bobbling around going on.  Then the video straighten s up the rest of the run. The bobbling around coincides with the increase in engine rpms that sounds like the clutch slipping. In reality,  the rear tire is spinning and the bike was fishtailing.  Unfortunately the gopro could only record the riders body movements or you could see the motions made by the tail end.

[dragracer]

........and three tenths or more does not seem out of reach.. .. quick bike, góod job.,

3 tenths might be a stretch. I see 10.20s as being a strong possibility right now. Truth is this bike is no where being properly tuned in anyway. I rejetted it based on my other bike but its doubtful I'm on target. I need to install an AFR data logger to get real time numbers. I'm  not even sure my ignition timing is optimal since I actually adapted a different pick up plate and rotor from a GS on the bike. Yes I did use a degree wheel to set and mark a timing notch. Yes, the cam was degreed per RC specs but us it where the engine makes the most power- i don't know for certain. Is the suspension set up properly for the bike? Its close but I may be leaving a tenth or so on the table. Have I geared it correctly? I think its right for an all motor pass but I will have to lower the ratio for a full blown nitrous pass. Am I shifting at the right rpm or could I be going beyond the maximum power band?? Once again,  its probably okay but I may need to lower , or raise the shift point to find out in the absence of a dyno session.  Was i hoping for a 10.0 something or maybe a 9.99 pass? While I was hopeful to see a 9.99, I realize my engine package is probably not capable of running those numbers. Yes, the chassis is definitely set up for 9 second passes. The chassis is not the limiting factor at this point. I'll test that assessment when I put the blue bottle in the bike and program a soft nitrous tune up.

I know there were some that doubted this project would produce the numbers and thats alright. In the end,  all I could do is show you. I haven't done anything unique. Anyone can do the very same thing, if not better, with greater resources. We've still got some tweaking to do that could lead to better numbers. I just don't know until it comes together.

I do want to thank some folk for helping in  various capacities along the way. George,  Bill, Kenny at Cyclex,  Mike, Jerry and Wilbur. Also a few forum members that sold me small parts to complete the package- the names i don't recall at this time. I'm thankful for this forum. Its been a wealth of information and it has been instrumental in bringing about a lot of friendship over the Years.

[gschuld]

Frankie,

You are, or at least should be, an inspiration to everyone here.  Your success in cost conscious yet high quality reliable race engines should be a good example for anyone to consider. It’s hard not to appreciate your knowledge on chassis mods(maybe looking past some of the welds😄), wiring, nitrous systems, carb systems, chassis tuning, etc

You’ve shown that you can make respectable big bore power levels, make them reliable, and do it without needing to sell a kidney.  I’m glad to help wherever I can.😉

George