Author Topic: Street 750 looking for drag strip advise (Read 4549 times)

scottly · « **Reply #25 on:** July 27, 2021, 09:21:11 PM »

16/48 is even better than 17/48, at least for the 1/4 mile. I don't recommend it for cruising at sustained speeds of over 70 MPH, as I found out on the first relay.

dragracer · « **Reply #26 on:** July 28, 2021, 10:41:32 AM »

I think I'm 17/50 with my F3. Stock valve, ported 410 head @1030cc.

Don R · « **Reply #27 on:** July 28, 2021, 10:45:34 AM »

I hate to admit this but the front sprocket has no retainer bolts. I'm glad I looked. I wonder how far from a disaster this motor, bike (and me) were? The oiler and retainer were still in place. Loctite and a thorough nut and bolt check seem like a prudent plan. I'm the yearly nut and bolt check proponent but if you don't remove the cover,,,,,,
I checked the sprocket thread and my usual sources, most suppliers have 17 or 18 front and 48 rear and that's about all.

Old Scrambler · « **Reply #28 on:** July 28, 2021, 12:04:34 PM »

Rebel Gear will make any sprocket needed

I have sourced HONDA sprockets from Parts Unlimited..........have a 43 and a 37 in original packaging to fit CB750s. Front 16-19 on ebay almost every day.

sohc boy · « **Reply #29 on:** July 28, 2021, 11:52:15 PM »

ran same as Scottly 16-48 drag race only 836 engine

dragracer · « **Reply #30 on:** July 29, 2021, 08:21:58 AM »

16/48 works out to be a 3.00 gear ratio, same as my 17/51 on the new bike I built.

Don R · « **Reply #31 on:** July 29, 2021, 10:02:22 AM »

I found 16T for dohc but not SOHC. I'll run it as is.
At any rate my helmet arrived, after several measurements the numbers said L but experience with Bell and Simpson said XL. I got an XL and it fits snug. Feels like it could come down lower, most need to be worn to fit properly. I went with the XL G Force. SA2020, it's not SM but it will be allowed in my race car and has a fireproof liner. I just need to remember not to drag my head excessively on pavement.
It's made in china just like our way more expensive 2015 Simpson. The face shield has a tight appearing seal and I'm expecting greatly reduced wind noise and lift over the old Bell.
It's raining now so I'll have to wait to test it.

Don R · « **Reply #32 on:** July 29, 2021, 10:15:55 AM »

The old drag bike I have sat around a shop for years and was heavily parted out. I have no idea what the ratios were when it was raced but with the welded stroker crank, I'd doubt it was revved to the moon.

dragracer · « **Reply #33 on:** July 29, 2021, 01:49:37 PM »

I was 16/48 on my street K8. Good for all around riding and 2 up on a stock engine. The speed limit is only 70mph on the highway so why worry about top speed anyway.

754 · « **Reply #34 on:** July 29, 2021, 05:27:11 PM »

I have run 17/54 a lot.. similar to 15/48 but far easier on chain.
At times, like going to Sturgis I would run 19/54 for there and back.... and switch to 17 for the week of racing around town...
FWIW... i slip the clutch a lot.. highrevs feed it out as fast as you can without bogging i keep my fingers on it fir mayge 60 feet or more.. if you bog and dont have your fingers ready in the clutch., you have usually lost...

Don R · « **Reply #35 on:** July 29, 2021, 11:11:25 PM »

With an 836 with a Kenny Harmon F cam, APE springs and retainers, mildly ported head and a little compression what would be a prudent launch/shift point?
It seems safe on the jetting so I may drop in my K&N air filter, pull the baffles and make a few test runs near home with the air/fuel meter on it. The Koni's I have under the bed are a bit shorter too, I'll swap them on and drop the fork tubes an inch.
With me riding I'd like to think it can run stock bike numbers at least. MPH will tell me about the bike, the ET will tell me if I can ride worth a dang. There is a track rental at Cordova late in the year, would be a good day to get some laps.

Don R · « **Reply #36 on:** July 31, 2021, 01:37:45 PM »

Well I got it out, not sure of the speedo accuracy and it has a part throttle (cruise) miss with the baffles out. It sounds awesome, I may never put them back in. I'm not sure the gas is any good so it will go in the lawn tractor. At 85 indicated I'm having sensory overload, the corn is too close to the road I was on.
The 4-1 sandcast repro shocks are like struts, so off they will come for now, I'm not sure if they are that stiff or they bottomed out.
All in all, I need to do some work to be ready to run in two weeks and with the low Daytona seat I can't seem to get into a good tuck, my legs are too long or something related to being 68. I want rear sets on the drag bike, The po shifted with his left hand, I'm not seeing that happen.
I'm heading out for some of the 90 octane no alky gas nearby and will report back

Don R · « **Reply #37 on:** July 31, 2021, 03:36:52 PM »

Part 2, I pumped out the gas, filled it with 91 octane no alky. The plugs aren't new, look good but the porcelain was already black.
The 4-1 repro shocks apparently bottomed out, it's a low spot followed by a bump.
I made it to 105 twice on a better road with more visibility, the speedo cable must be dry, it's bouncing a little it's a NOS speedometer showing a just couple hundred miles. I hit my shift points at redline, now I need to practice launching it.
The G force helmet is miles ahead of the old Bell, no lifting at 105, no wind noise when it's closed, a little whistle when wide open.
Wide open throttle sounds good but part throttle cruise it talks to me a little, like 4,000 and 5,000 I wonder if the lack of baffles created a lean situation that raising the needles a notch might cure?

754 · « **Reply #38 on:** July 31, 2021, 05:27:08 PM »

Run your feet on the rear pegs , move your foot to shift...

Medyo Bastos · « **Reply #39 on:** July 31, 2021, 05:31:00 PM »

Or just run rearsets

Sent from my iPhone using Tapatalk

Don R · « **Reply #40 on:** July 31, 2021, 10:16:55 PM »

The next bike might get rear set controls, this is just me learning if I really want to rebuild that bike. Frank, it got through the gears pretty quick, I'll probably stay on the front peg until I'm done shifting. I also rebuilt the rear pegs so I know where they are. (Less floppy now).

Don R · « **Reply #41 on:** August 15, 2021, 09:59:27 PM »

We raced this weekend, I just took the car, the bike in the nose of the trailer is too much weight on the front. I didn't get the bike mount moved back to the middle, I realized the slicks won't go past the angle bracket I made if I put it behind the tires with the car in backwards. If I load the car forwards the golf cart has to load first and then it won't go past the mount.
There was a newer Honda there today, I think I got something for that bike. I'll shoot for September.

cbr954 · « **Reply #42 on:** August 22, 2021, 07:40:12 PM »

Quote from: 754 on July 29, 2021, 05:27:11 PM

I have run 17/54 a lot.. similar to 15/48 but far easier on chain.
At times, like going to Sturgis I would run 19/54 for there and back.... and switch to 17 for the week of racing around town...
FWIW... i slip the clutch a lot.. highrevs feed it out as fast as you can without bogging i keep my fingers on it fir mayge 60 feet or more.. if you bog and dont have your fingers ready in the clutch., you have usually lost...

You race around sturgis now days and you go to jail, do not pass go do not collect $200 lol

754 · « **Reply #43 on:** August 23, 2021, 12:30:58 AM »

We started going there before the drag strip was open.

Don R · « **Reply #44 on:** August 23, 2021, 09:53:37 AM »

I was at Sturgis for the 75th, Talked to a tow truck driver. He bought several bike trailers to aid in cleaning up all of the wrecks in a more timely fashion. I rode a 78 gl1000 it got a lot of nice comments. I was careful where I took it.

cbr954 · « **Reply #45 on:** August 23, 2021, 08:35:07 PM »

I live 10 minutes or so from Sturgis, gone since I was about 5yrs old, went to school in Sturgis. Not like it used to be. The cops are getting to were you cant do anything anymore. Honestly accidents are very few considering the amount of people. More breakdowns than anything else.

Don R · « **Reply #46 on:** August 24, 2021, 08:39:42 PM »

I can see how people watch the scenery too long and ride off the edge of the road.

cbr954 · « **Reply #47 on:** August 25, 2021, 07:32:02 PM »

Quote from: Don R on August 24, 2021, 08:39:42 PM

I can see how people watch the scenery too long and ride off the edge of the road.

Thats what happens most of the time with the accidents during the rally.

Don R · « **Reply #48 on:** August 27, 2021, 11:43:12 AM »

I was remembering a car drag race in 1989, We towed from Galesburg Illinois to Memphis to a race, got runner up in the fast bracket class and was awarded a princely sum of $15. The club that sponsored the event insisted on $50, we waited an hour to get it but hey, that was a tank of gas back then.

Don R · « **Reply #49 on:** September 24, 2021, 10:38:35 AM »

We're going to Byron this weekend, if we go rounds in the dragster it may get busy but I'm hoping to make a pass or three. I did some test launches and feel pretty good about it.
I made a K0 seat latch for the Daytona seat so I don't slide off the back and it might pass tech. It's crazy, I had one in my box of seat parts, it needed the bends reversed and then it fit on the first try.
If I let the clutch out with a couple fingers and keep a couple around the grip I feel pretty secure launching it. They are picking corn and deer are moving so didn't make any top end runs. I did practice getting tucked in on the rear pegs but was still in fourth. My friend had his pegs on the swingarm and shifted by hand. I was tempted to try it but thought better.
I used my old boots and didn't notice I had them on so they are better than my new ones.
3 sets of denso plugs are due on ups today so maybe I can get a good read on them.

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Author Topic: Street 750 looking for drag strip advise (Read 4549 times)