Need some drag racing tips.

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May 11, 2005
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Hi. I'm a newbie to the site, newbie to drag racing this bike.

72 Combat, superblends,
-boyer "red box", stock coils in series
-rear avon super venom with about 15 psi
-drag bars and rear sets from Clubman
-otherwise bone stock.
Sunday was my 2nd attempt at competing on a local "1/8th mile", (I need to confirm but I believe it may only be 500'.)
Best run:
60 ft-2.098, mph-68.08, et-7.617, I barely get into 3rd gear crossing the finish line. The bike doesn't seem to have much of a traction problem as I seem to have to fight a wheelie on every launch. This also seems to keep me from being competitive. What really has me cranked up is that a hopped up Harley "dresser" smoked me twice on Sunday in 2 different classes. What makes matters worse is the "smirk" I got from him at the timing table afterwards. :twisted: (I believe his et is around 7.10)

I guess I'm looking for things I can do without destroying the bike, ie- no cutting or lengthened swingarms. Thanks.
 

Jerry Doe

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Welcome!

Just curious - Where are you?

What size countershaft sprocket are you using?

Welcome to the forum...

Jerry :)
 
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pigpen,

Please don't drag race that Norton; drag racing is not it's strong suit.

I believe the weak link in the Commando power train is the poor little AMC gearbox. You see, it was originally designed for a 500cc motorcycle, like the Matchless. Over the years this same little gearbox was fitted to the 650 Atlas, the 750 Commando and finally the 850 Commando. The power of each engine increased with displacement but the strength of the gearbox did not.

Fortunately, the AMC design is robust.

However, gear spalling and cracked cases are common gearbox complaints from 750 and 850 Commando owners, especially heavy handed ones. So, in my opinion, drag racing a 500cc derived AMC gearbox coupled to a 750cc motor is asking for a catastrophic failure. How about drag racing a Yamaha V-max against that Harley…?

Jason
 
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Re: Welcome!

Jerry Doe said:
Just curious - Where are you?


What size countershaft sprocket are you using?

Welcome to the forum...

Jerry :)


East Coast, 1 hour north of Philadelphia
Countershaft=19
Thanks for the welcome, very informative and friendly site.
Chad
 
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Jason Curtiss said:
pigpen,

Please don't drag race that Norton; drag racing is not it's strong suit.
I believe the weak link in the Commando power train is the poor little AMC gearbox. How about drag racing a Yamaha V-max against that Harley…?

Jason

Hi Jason. I am aware of the historical weakness of the gearbox and thank you for your concern and information. In no way do I wish to offend you in the use of this machine. As an owner of several well maintained or restored vintage bikes, I want to assure you that this is one of 3 presently owned Commandos in which all have been saved from an untimely, sure death. If I truly wanted to be competitive, I'd take the Hayabusa. Surely you might imagine the fun I have seeing a gentleman older than myself walk up up in the pits and giggle about the "one he used to own". As only my 2nd time out, I only want be as competitive as I can be at a local small time track. http://readingmc.com/
I have spent the money and time working on or restoring these bikes and think they deserve to be worked instead of collecting dust on a checkerboard floor. I can tell you this, any one of my Norton's will "blow the doors off" any Triumph or BSA in my garage.
Chad
 
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Mar 19, 2005
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Took a look at the website for your racing...looks interesting. I took part in one drag event about 15 years ago, way back near the Polish border the other side of Prague. A real "rush" to do something like that, although having driven some 600 miles to get there, and having to drive 600 miles to get back home, it made you think about not breaking the bike. These races were run on a normal road, the trees were hay baled off, the road blocked and they brought in a medical helicopter and electronic timing equipment. About noon there were a thousand people standing along the road to watch. All you did was get in line, sign some paper in Czech that you couldn't understand and you got a vest with a number on it to wear. No entry fee, nothing but get in line. People came from all over, Holland, England, Switzerland, Austria...I was the only American, with US on my number plate. They sent me a picture of me on the starting line, as a souvenir, but it is in the attic somewhere, just looked for it, can't find it. Guess who has to clean out the attic. Anyway, have fun, but listen to the others...the tranny isn't as strong as it perhaps should be...send us a picture!
 
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Dec 5, 2003
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Pigpen

If you insist, here's some tips from the hot riders;
1 Strap the front end down
2 get the stiffest rear shock setting
3 put an electronic ignition (wish they had a tunable one)
4 put on a belt drive (may help the overworked tranny)
5 tune the clutch to give some slip off the line but hook up (may not work on 1/8th mile track)

The rest is motor and rider. Good luck (you may want to get your spare parts thru Jason, he has a hell of a deal with his exchange rate in Texas) :lol:
Scooter
 
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Hi Scooter,

Great riposte to my maligned comment regarding exchange rates!

I hurriedly read your comment and was too quick to respond. I agree, UK parts prices have been going up, owing to the dollar weakening against the pound/Euro.

And Chad, I’m glad to see you’re riding your British bikes; that’s what the were made for.

Jason
 

MichaelB

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You gotta watch out for those sleepy 'Baggers'. I have a friend who has a 106 c.i. Road Glide with a HUGE torgue curve that has all kinds of fun at the stop light drags. He consistently beats big bore rocket runners, GSXR's Ninja etc. through the intersection for about 1/2 block. Then they hit their power it evens out for awhile, until some sanity is restored and someone backs off.
Because of their weight and torgue, the"Baggers" hook up very well. You may very well beat this guy in a 1/4 mile, be warned it will be tough in the 1/8 mile.

What to do. Since you are hooking up and wheeling, my first thought was to raise your gear ratio by increasing the counter shaft by one tooth and trying to launch harder. Maybe, maybe not. This will put even more strain on the mainshaft. (I have pulled a main shaft completely out of the case with this technigue.)

Another thing is the Dunstal 2-1-2 system with velocity stacks should give a nice more controllable mid - upper range hit. I haven't tried this on a Combat, but that was my experience on a 850.

If I were to contemplate any serious drag racing, I would be looking into an outrigger set up for the main shaft. www.stevemaney.com has a nice one.

Best of luck, keep us informed.
 
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Jason
I thought you would get a chuckle from my comment.
Yeah with the x-rate up 30% from last year my resto project is getting ahead of my credit line and there are soooo many expensive tweeks that I can't seem to resist.

Chad; one more thought, take off the silencers and run straight pipes. Even if you don't beat the Hogs you'll be as loud :D

Scooter (single handed supporter of the British economy)
 

MichaelB

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Steve Maney Racing

Since my last post I just had to go on the Steve Maney website. As I salivate over all the goodies I keep remembering the infamous old statement, 'Speed costs money, how fast do you want to go?"
 
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May 11, 2005
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Thanks for the replies. Here is what I got for my list.
1. experiment with the gearing.
2. uncork exhaust, rejet carbs.
3. suspension tuning, tie down front, stiffen up the rear.
4. check out Steve Maney's site
5. experiment with clutch adjustment.
6. drink less, lose some weight.
:wink: Can't do it all at once or I won't know what worked.

I got a video clip of that "bagger" embarrassing me, I'll post it somewhere for the forum's enjoyment.
 

Jerry Doe

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Quaiffe

Hi Chad,

Last year I put a 5 speed close ratio quaiffe box in my commando. That won't help you.

I ordered the strengthened gearbox shell from them too.

The standard gearboxes tend to crack between the layshaft and mainshaft bearings when you boot it!

Well the quaiffe is seriously strengthened there and in other areas. I think I paid about $400 for it. This would help you.

Good luck, let us know how it goes.
 
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Hey Chad,

I'm no drag racer but I thought of a couple things that might help.

First, maybe spend some time practicing your launches? Seems like that's the most important part of such a short run.

And maybe experiment with different (more) tire pressure? Maybe you could find the right balance between excessive wheelspin and excessive wheelying?

Good luck, and let us know when you put that annoying harley guy in his place!

Debby
 
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May 11, 2005
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You are probably correct on both accounts. I could probably gain alot just from a better launch. I have a video clip, I just don't know how to share it.
 
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