Topic: RE: Found Drag Strip Near my House 750 times

[chewbacca5000]

So happy days I found a drag strip only a couple miles from my house!  Stopped and talked to a guy who had a V65 on a trailer and he said it only cost $35 to complete!  What is even more interesting is that it is $15 next Saturday for test and tune.

Think I would like to see how fast my 750 is, and would like to know what to expect.

[seanbarney41]

get a list of tech and safety equipment requirements before you go...study up on how to drag race, i.e. how the tree works, should you do a burn out, drag racing etiquette, etc.   launching a cb750 is not easy, especially one set up for the street.  Expect high 14's 1/4 mile et's at first for a stocker, and high 13's after some practice at just under 100mph.

My first time at the track was primarily a bike show and party, but the tree and timers were on and racing was cheap...but not that many bike show guys were interested so I made a TON of runs in 2 hours.  I was basically taking a run, ride back down the return road, and right back up to the starting line for two hours straight.  It is unlikely that this will be the case for you.  Nice thing is that the cb750 is a bullet proof lump with good high speed stability, so don't worry about breaking stuff too much.  After two hours of abuse my clutch was petty overheated, but it hung in there just fine.

Try it.  It's fun!

[ekpent]

^What he said-Sean has beat the snot a few times I think on these old critters   

[chewbacca5000]

Thanks Sean,

I will look into cost of protective gear, and give it a go if cost is reasonable.  Guy said Kevlar gloves can be pricey.  Also need leathers and boots.  Things I should have anyway, but don't.

Would love to know how this K1 would go.  It is super fast.  Got a new chain on 16/48 gear combo.  Hope that would be ok, but might switch to 17/48 for fear of the dreaded case break.

It has great acceleration all the way to the red line.  I'd hope that it can do better than a stock bike.  No idea about engine, but has nice 4into1 and 125 mains.

I'd be happy with learning the ropes and a run or two.

[ekpent]

If the engine is that good go with an 18t front, the extra cc's should pull that and speed is what you are after.

[chewbacca5000]

If the engine is that good go with an 18t front, the extra cc's should pull that and speed is what you are after.

Guess I could give 18 a try.

[seanbarney41]

I think most drag strips only require two piece leathers, so you won't need the full road race suit, you can buy separate jacket and pants...double check on this though as rules may have changed since last time I checked

the bulk of a low et happens in the first 60 feet and this is where cb750's that are not set up for drag racing have the most trouble.  That 16 tooth front will help, just don't do too big of a wheelie!

oops, Hi Eric, I feel like the 16 is gonna get off the line better and easier with less rpms and that is where drag races are generally won, but really, I would just use what you are most used to as your reaction times and 60 foots are gonna be pretty miserable the first time out.

[Retro Rocket]

Agree with Sean, 18 tooth front is highway gearing, I have a 52 tooth rear sprocket here, thats what you want, or a smaller front sprocket.... Smaller front/ bigger rear = quicker take off, thats what you want for strip work, bigger front/smaller rear = more top end, this suits highway riding, not so good on the strip...

[Bailgang]

You've got my attention now. My youngest son has been running his mouth about his Subaru WRX and an older brother of mine would like to see if he can shut it up with his modified GT Mustang. It actually should be a close race and traction will be the issue because I feel my brothers Mustang will win IF he has decent traction off the line. On the other hand I figured why should they have all the fun so I've decided to bring my F2 there as well just to see what it can do, I've drag raced before but never on a bike so this should be interesting. I'd be happy with a high 13 but my brother predicts my bike will only do a 14.2 so I'm going to see if I can shut him up. Once my oldest son heard about me taking my bike to the strip he decided to jump in the fun as well and intends on bringing his 73 K3. The date is Aug 15 at US-41 Dragway in Morocco Indiana about an hour from here, I'll let you guys know how it turns out.

[Retro Rocket]

You've got my attention now. My youngest son has been running his mouth about his Subaru WRX and an older brother of mine would like to see if he can shut it up with his modified GT Mustang. It actually should be a close race and traction will be the issue because I feel my brothers Mustang will win IF he has decent traction off the line. On the other hand I figured why should they have all the fun so I've decided to bring my F2 there as well just to see what it can do, I've drag raced before but never on a bike so this should be interesting. I'd be happy with a high 13 but my brother predicts my bike will only do a 14.2 so I'm going to see if I can shut him up. Once my oldest son heard about me taking my bike to the strip he decided to jump in the fun as well and intends on bringing his 73 K3. The date is Aug 15 at US-41 Dragway in Morocco Indiana about an hour from here, I'll let you guys know how it turns out.

If its a proper WRX, my money's on that, it'll leave the mustang for dead up too and over 100MPH and it'll all be over by then......, You can't beat 4wd for traction..

[Jerry Rxman Griffin aka MuthaF'er]

A proper rider on a proper F2 should break into the 12's.

[seanbarney41]

A pro rider on a prepared for drag racing F2 might break into the 12's.

ftfy

[Head]

Sound's like a good family thing and a good time.

[Bailgang]

A proper rider on a proper F2 should break into the 12's.

As far as me the rider is concerned I've have yet to seriously launch the bike from a start so how much balls I have when I do will be the key to a decent ET  and it hasn't been until recently that the bike has really woken up. I had it on a dyno to track down carb issues last year and the HP was dismal, only 47 however during the dyno run it show my carbs were way too fat at WOT and way too lean at part throttle. The stock mains went back in and raised the needles 1 notch and it woke up and then earlier this year I replaced the ignition with a boyer bransden untit and it woke up even more. I thought my HP was dismal but the dyno operator was actually impressed, he said my bike put out the most power of all the vintage bikes he's ran on his dyno. Now that it is running MUCH better now I'm sure that HP number climbed as well but haven't been able to get it back on a dyno to find out how much.

As far as the Mustang/WRX challenge the Mustang GT is an early 2000 sumtin with the 3 valve engine that my bro has played with quite a bit, different cams, ring and pinion, suspension mods, exhaust and engine management programming. It's been a few years since I've seen it make a pass but it was turning consistent 13.2 ET's at that time. My kid has messed with his WRX a bit as well and the last run he made with it was I think a 13.4 but he destroyed his clutch in the process. He's got a good clutch in it now and has made some other changes as well including engine management reprogramming and it runs much stronger than before too. Traction is key because the WRX has the AWD and my bro's Mustang wastes a lot of time spinning the tires even with sticky street tires so if the Mustang has any chance of catching the WRX depends on how well he can get it to hook up. He's also seen how well the WRX runs and has had time to do something about it so who knows what ace he may have up his sleeve to insure a win ...... no nitrous allowed though. It will be a good race.

[BobbyR]

Since the strip is very close to your home you have a unique opportunity. If I had that situation I would just tune what you have and see what she does and have a baseline. You can practice your launch and get some feel for it. You can then use then so some tinkering and see if the ET goes up or down.

Shifting is always the finer point on the track and can make a lot of difference. I spent some time with some racers and they laugh at what they call elbow flapping on the throttle. The trick is to preload the shifter with your toe and all you need is a twitch of the toe and quick pull to get her into the next gear without letting off and losing rpm. I would perfect this on the street at less than full power to get your rhythm. Good luck and keep us posted.

[Jerry Rxman Griffin aka MuthaF'er]

I like the way Bobby thinks about this BUT if you do powershift better get you a rev limiter in case you miss one of those shifts without letting off the throttle  . I know the sorrow.

Get that baseline too and practice your hole shots where ever. 

[BobbyR]

I like the way Bobby thinks about this BUT if you do powershift better get you a rev limiter in case you miss one of those shifts without letting off the throttle  . I know the sorrow.

Get that baseline too and practice your hole shots where ever.

Ditto. Practice a lot at lower rpms. A Rev limiter can save you bucks.

[cb650]

I wish there was a cheap local track here.  Usuallty a 2 piece isnt need untill over a certain MPH 120 I think.  But tracks and sanctioning bodies differ.

[Bailgang]

How aggressively/confidently I can launch the bike combined with how well I shift is definitely key. I had the cases apart over this past winter to address some transmission issues and the trans shifts MUCH better now than before however not quite good enough to where I'd trust it speed shifting. If I ever split the cases again on this engine then back cut gears will be going in, I wanted to do it that way when it was apart but finances at that time forced me to use what I had.

As far as safety gear at the track so far for my bike all that is required is helmet, long pants, closed toed shoes, gloves and leather jacket. Both my oldest son and I have riding jackets with body armor but they're not leather and so far it seems the track rules are very particular that it be leather regardless if my current jacket has body armor or not. No problem there because my youngest son has a leather jacket with armor that I and my oldest son can use, it's just that me and my sons K3 wont be able to make a pass together because we'll be swapping the leather jacket between runs if the track doesn't allow us to use our own jackets.

Geez Chewbacca I'm sorry for hijacking your thread like this but maybe we can inspire others here to takes their CB's to the track at least once.

[Lostboy Steve]

Chewie, it seems as though the 550 that is in literally pieces in my garage is going to be a "track bike".  A bunch of my friends run modern gsxrs and such. I live about 5 miles from Englishtown Raceway Park. Even though (ironically) the track is littered with blowing up Honda Automobiles which leads to a poor track condition, I feel like I'm missing out. So, I am going to build a bike as light as possible (given what I have to work with) and will eventually try to do some bracket racing with the fellas. Why a 550? because I have an extra one. lol. Anyway, from what i understand and my past history with cars, its not so much the 1/4 times, but the consistency. Because our bikes are "slower" the safety requirements are minimal. In NJ at least anything over 11:00 is considered low risk. Good luck in your endeavors and I await to see what you and your 750 can do.

[chewbacca5000]

Thanks for all the tips!  I am especially encouraged that they consider our older bikes low risk.  Sweet!  My thought process is that this could be a fun inexpensive way to tune my cb750s with the added bonus of no jail time. 

Seems to me this is just as relevant as dyno runs?  Now how would I translate a time into HP?  Is there a chart or formula that I can go by. 

Would be fun a heck to see a bunch of forum members get together and have a SOHC shootout sometime.  Seems like there are a few of us with tracks near by.

Maybe have to give the newbies a handicap or something to be fair.  From what I read the launch is a big deal.

[Bailgang]

  Is there a chart or formula that I can go by. 

There is but I'd have to look it up. I don't know if it's dead accurate but it is in the ball park.

[chewbacca5000]

  Is there a chart or formula that I can go by. 

There is but I'd have to look it up. I don't know if it's dead accurate but it is in the ball park.

I'd appreciate it.  Ballpark is good enough for me.

[Bailgang]

I know there is a formula where you figure the weight of the vehicle with you on it, it's 1/4 ET and it's mph through the 1/4 which will give you an estimated HP but I can't seem to find it just yet but here's a site that does the calculating for you. Again I don't know how accurate it is. http://www.wallaceracing.com/et-hp-mph.php

[Bailgang]

I played around with the calculator on the site I linked and I have a hunch it's estimating HP right off the crank rather than at the tire.

[seanbarney41]

I played around with the calculator on the site I linked and I have a hunch it's estimating HP right off the crank rather than at the tire.

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

Honda's horsepower figures were supposedly at the crank, and were all over the map, over the years for the cb750.  I personally think, Honda was playing the numbers game with the buying public, the EPA, and Insurance companies  and that the difference in Honda's rated horsepower between say, a K1 and a K6, is largely due to insignificant tuning changes, such as timing, exhaust, and jetting.  By the time these old bikes get to us in the here and now, these tuning anomalies have all been changed, resulting in all year/model 750's being right in the ballpark of 65hp at the crank and 50hp at the rear wheel.

[Bailgang]

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

I sure hope not, by just estimating the bikes weight with me on it with an HP of 50 pretty much means I'm doomed to 14's.
I know what you mean by HP readings being all over the map, every web site I've gone to pretty much gives a different HP for my bike. I've never had mine on a scale to confirm it but it seems mine weighs around 558 lbs with gas and oil, add at least another 200 for me with riding gear on. Oh well we'll find out in a couple of weeks.

[seanbarney41]

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

I sure hope not, by just estimating the bikes weight with me on it with an HP of 50 pretty much means I'm doomed to 14's.

yup...the drag strip trip can really bring you back to reality after all the magazine articles, inflated factory hp figures, tall tales, and butt dynos

[Powderman]

I think any formula will only get you in the ballpark. There are too many variables that can change on each pass to give reliable results.
Wow, I just punched in some numbers to try it. My bike weighs 360lbs, if I weigh 170lbs that's 530lbs and if I make 100hp (I think it should at least), then my 1/4 mile time should be a 10.16 @133mph. The Sputhe Sportster featured on the cover of the July'80 CycleWorld ran the 1/4 mile in 10.55 @133mph with similar motor.

[Powderman]

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

I sure hope not, by just estimating the bikes weight with me on it with an HP of 50 pretty much means I'm doomed to 14's.

yup...the drag strip trip can really bring you back to reality after all the magazine articles, inflated factory hp figures, tall tales, and butt dynos

I had a 1978 Plymouth Volare' Super Coupe with a Police Option 360 package. Ran blistering 16.80's with it. Ya, what you thought was fast goes away real quick when you are around real race stuff.

[Bailgang]

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

I sure hope not, by just estimating the bikes weight with me on it with an HP of 50 pretty much means I'm doomed to 14's.

yup...the drag strip trip can really bring you back to reality after all the magazine articles, inflated factory hp figures, tall tales, and butt dynos

I had a 1978 Plymouth Volare' Super Coupe with a Police Option 360 package. Ran blistering 16.80's with it. Ya, what you thought was fast goes away real quick when you are around real race stuff.

I hear you on that, I thought my 78 Trans Am that I had many moons ago was a missile until the first time I took it to the strip, low 15's if I remember correctly. Dyno's can be a reality check as well, I knew my 750 wasn't in optimal form at the time but the 47 HP that showed on the dyno last year had me bummed. Maybe the dyno operator was trying to cheer me up when he told me mine put out the most power of any vintage bike he had on the dyno but the first though that came to my mind was "geez, you must get a lot of clunkers in here then". That shop charged $40 for a dyno pull with exhaust analyzer, the problem is since then they've sold their dyno and the only other nearby shop with a dyno wants $100 to do the same. The drag strip will tell the tale this time around.

[seanbarney41]

If you can go there on a slow night, the strip is the best place to do tuning/plug chops...

[Bailgang]

Well today is the big day and the excuses may already be starting. My youngest son showed up yesterday with his WRX and immediately popped the hood, apparently its loosing boost pressure and getting 16.5 lbs of boost when it should be around 18.5  and he's loosing it at the rubber coupling where the intercooler connects to the intake. He thought he took care of it last night but I guess it's loosing it again, I told him he better think of something because NO EXCUSES will be allowed if his Uncle's Mustang beats him. Unfortunately on the other hand my oldest son wasn't able to bring his 73 750 because he couldn't find a trailer to haul it here, it's too long of a story to explain right now why he couldn't have just ridden it here but he will be there at the track with us anyhow. On the other hand a nephew of mine in Illinois decided he wasn't going to just set back and hear about his Uncles and cousin having all the fun and has instead decided to join the fun with us and bringing his front engine small block chevy powered 67 Corvair to tangle with us. I've got my 750 all set to go, my only fear is that I hope I don't tear it up too bad because it's clutch will be taking a beating. I'll start another thread with the results so I don't hijack this thread any further.

[Restoration Fan]

Good luck today.  Go whip the pants off the "car boys".  Oh yeah...my money's on the Corvair.....to come in last. 

[Bailgang]

The Corvair turns a high 12 but that's with the help of a 70 hp shot of nitrous, low to mid 13's without it. Not too shabby but I think it should be in the 12's without the bottle.

[chewbacca5000]

Sounds like fun bailgang,  Better represent!

[Powderman]

Like to see pics of the Corvair conversion, don't see too many with front engine. I inherited a 65 Corvair with a Toronado V8 in the back this year. I imagine all it's good for is drag racing and wheelies with all that weight hanging off the back.

[Bailgang]

Like to see pics of the Corsair conversion, don't see too many with front engine. I inherited a 65 Corvair with a Toronado V8 in the back this year. I imagine all it's good for is drag racing and wheelies with all that weight hanging off the back.

I'll have to dig around later for pics of the Corvair but here's a link describing yesterdays event. http://forums.sohc4.net/index.php/topic,150642.0.html#msg1719270 I haven't uploaded any vids yet from my camera either just yet but I will later on in that new thread.

[Powderman]

Like to see pics of the Corsair conversion, don't see too many with front engine. I inherited a 65 Corvair with a Toronado V8 in the back this year. I imagine all it's good for is drag racing and wheelies with all that weight hanging off the back.

I'll have to dig around later for pics of the Corvair but here's a link describing yesterdays event. http://forums.sohc4.net/index.php/topic,150642.0.html#msg1719270 I haven't uploaded any vids yet from my camera either just yet but I will later on in that new thread.

Please do, I'm seriously interested in seeing them.