S&S 124 street/drag build

[johns]

Looking for advice from those who have or are competing actively on the drag strip. I have decided to do more work on my 2003 Dyna FXDX to make it more competitive this season. I am going to leave the motor alone and concentrate on reducing weight and mods that will improve times in the first 100 ft. just for reference the motor is a S&S T124, 640 cams, 1.72 rockers, 12.2/1 compression, ported heads, massaged G carb. In full street trim the motor made 147/152 last time on dyno at DC Vtwin. The trans has a 5 speed gearset from Baker with electric quick shift, taller 1st & 2nd gears , back cut gears, fully blueprinted. I will still be riding this bike on the street between drag meets. I have no intention of making it a full fledged drag bike just a more competitive street/drag bike.

So this is what I have in mind:
First step is to get the bike lowered app 2 inches with both ends level, install a fresh scorpion clutch, wrist kill, shift light, install RB challenger 2/1  2" pipe do some dyno tuning and take the bike to the first drag meet at Bowling Green to base line it. I can also cruise the pits and see what other HD guys are doing.

2nd step is to buy a lighter extended swing arm (how much over??), RC 18 X 1.85 front wheel, RC 18 X 6.25 rear wheel, plus single disc light front disc & caliper to work with stock reworked FXD fork, light weight rear disc & caliper, new light rear sprockets in a selection of at least 3 sizes.

As the bike sits now, stock wheel base, stock wheels & tires, brakes, 2 into 2 mufflers the bike ran a best 1/8 mile of 6.90 at 104 MPH last fall. The best 60 ft. was 1.78.     

[turboprop]

The class will dictate how long the swingarm can be. Bandit makes a bunch of different scorpion clutches, one with some sort of variable pressure plate would be better. One with adjustable weights would be even better. Instead of striping down the fork, or using some sort of lowering kit, look at using shorter fork tubes as they weigh less.

[johns]

The class will dictate how long the swingarm can be. Bandit makes a bunch of different scorpion clutches, one with some sort of variable pressure plate would be better. One with adjustable weights would be even better. Instead of striping down the fork, or using some sort of lowering kit, look at using shorter fork tubes as they weigh less.

Already have the Bandit variable lock up ready to install but we are taking it one step at a time. We had problems with the old bandit clutch which I installed way back in 2004 or 05 last time at the 1/8th mile last fall. We could not slip it the first 60 ft. like we wanted to. The bike would get out about 30 ft. slipping it and suddenly lock up which made getting a good time unpredictable. I found the old basket had very small grooves starting so I am replacing the whole clutch with a complete new Bandit assembly. We are going to start without the lockup just for comparison sake. We will play with the variable lockup later when we know we have the basic assembly working the way we want it too.

As you said the swing arm maximum length will be dictated by the rules. This is where I am undecided as I doubt I am going to go for the maximum allowable as I am still going to street ride this bike. 4 inches is the maximum stretch I will probably want. I do want to retain the stock appearance of the rear of the bike so moving everything back with the added swing arm length will be another job.

The front forks are another problem. This is a FXDX which uses a completely different front fork assembly. These are dual disc fully adjustable forks (compression, rebound & preload), the same as the forks from the sportster sport model back in the 90's. I researched this for a long time and no one makes a fork lowering kit for this fork. We have them completely stripped down and there is no way to simply replace the innards so I am replacing them with OEM HD FXD fork tubes and lowers that are easily modified. 

As I indicated before lowering the bike, getting some more wheel base and above all getting the weight down are my plans to get the 100 ft. times better this season. HP is not a a problem with the set up I have now. How to do that specifically are open for discussion as I don't pretend to have all the answers especially on sourcing parts.       

[turboprop]

The class will dictate how long the swingarm can be. Bandit makes a bunch of different scorpion clutches, one with some sort of variable pressure plate would be better. One with adjustable weights would be even better. Instead of striping down the fork, or using some sort of lowering kit, look at using shorter fork tubes as they weigh less.

The front forks are another problem. This is a FXDX which uses a completely different front fork assembly. These are dual disc fully adjustable forks (compression, rebound & preload), the same as the forks from the sportster sport model back in the 90's. I researched this for a long time and no one makes a fork lowering kit for this fork. We have them completely stripped down and there is no way to simply replace the innards so I am replacing them with OEM HD FXD fork tubes and lowers that are easily modified. 
     

Yea, get rid of that DX fork. Its guts are too heavy and the tubes are too long. Narrow glide fork stuff is dirt cheap. 39mm tubes can be had in just about any length. No need to tie yourself to FXD or any other model fork. Think in terms of length of the tube.

[Hossamania]

A lithium battery will shed a few pounds. Carbon fiber wheels will also shed pounds, but they are certainly not cheap.
I figure that these have been explored, just throwing it out there, because I like to think I help make people go faster.

[pwmorris]

The class will dictate how long the swingarm can be. Bandit makes a bunch of different scorpion clutches, one with some sort of variable pressure plate would be better. One with adjustable weights would be even better. Instead of striping down the fork, or using some sort of lowering kit, look at using shorter fork tubes as they weigh less.

The front forks are another problem. This is a FXDX which uses a completely different front fork assembly. These are dual disc fully adjustable forks (compression, rebound & preload), the same as the forks from the sportster sport model back in the 90's. I researched this for a long time and no one makes a fork lowering kit for this fork. We have them completely stripped down and there is no way to simply replace the innards so I am replacing them with OEM HD FXD fork tubes and lowers that are easily modified. 
     

Yea, get rid of that DX fork. Its guts are too heavy and the tubes are too long. Narrow glide fork stuff is dirt cheap. 39mm tubes can be had in just about any length. No need to tie yourself to FXD or any other model fork. Think in terms of length of the tube.

This^^^^^^^^^^^^^
OP, Your front end is a whale, difficult to lower and not in your future. Get rid of it.
Also, I am not a big fan of the RB pipe, so just curious why you are going there. Did Derek at DC recommend it for your build?
As far as the swing arm, I have an FXR, and I went 6" over and it is still is fine as a street bike but not a canyon carver by any means.
Did you get the low profile Scorpion LU with adjustable weights as Turboprop mentioned?
Your 60' times need work as you know.
Are you running a 2 step?
What rear tire and what rpm do you launch at?
How much time have you spent at the track to really see what kind of rider you are?

[pwmorris]

Also, can you go to a 17" wheel? Lots more stickier tires available.
How much do you weigh?
How about the bike....have you weighed it?
1.
HP
2.
Weight
3.
Set up of bike as a whole
4.
Clutch (huge)
5.
Rider skill
6.
Budget, as you might have to work on these one at a time.

Determination can and will overcome a lot (including $$$),  but most nowadays talk big-but quit before they get anywhere near their potential.
When you look in the mirror.....what do you see?

From what you have said -I see big time potential.

[johns]

A lithium battery will shed a few pounds. Carbon fiber wheels will also shed pounds, but they are certainly not cheap.

Already have a lithium battery

Also, can you go to a 17” wheel? Lots more stickier tires available.
Yes I can, I have not bought the RC wheels yet and will not until after at least the 1st BG spring meet

How much do you weigh?
165 to 170 dressed

How about the bike....have you weighed it?
The bike weighs 635 stock. I am still waiting on the FXD front forks & will weigh it with the new exhaust. To answer your question about why my choice of the RB exhaust. I have had it for over 2 years, never installed them, got it for $400 from another guy who wrecked his bike and never got to install them so they are brand new. No it was not a recommendation of DC V twin as I am sure you already know. It is very light and I expect it at least performs as well as the heavy 2/2 muffled pipes currently on the bike for the drag strip. I will be doing dyno testing and tuning with the RB pipe so if it at least equals the HP of the current heavy muffled 2/2 pipes and makes acceptable TQ and cuts weight I will start out with it this spring. I need to use as much of what I already have initially in order to buy the RC wheels, new tires, brakes and a swingarm later this season.

1. HP--147 with the current 2/2 muffled pipes
2. weight--It was 635 stock but don't know with new FXD forks, Lithium battery, RB 2/1, Will weigh soon
3. Set up of bike as a whole--Lowered 2 inches, stock wheel base, chain drive, stock spoked wheels
4. Clutch--New Barnett Scorpion lock up including new scorpion basket
5. Rider skill--Good but no experience on HD's. Not me, health issues make track riding not wise anymore
6. Budget--For this season $4000.00 which does not include money already spent on clutch, forks, shift light, wrist kill, shocks. This money will be for new RC wheels & sprockets, tires, brakes, swing arm, misc.

My initial goals for this spring are to get my feet wet initially with the bike lowered 2 inches , stock wheelbase, tires, wheels, brakes & current S&S 124 motor with RB pipe. Once we get the clutch setup right & some rider experience this spring I will order the light wheels, tires, swingarm, brakes and work on other weight reduction. Again as previously stated for this season this is a street/race bike which will be used for both and mods made in steps through the season. I really want to talk to other guys at the BG spring meet to see what others are doing & look for sourcing for wheels, tires, swingarm, brakes before making those final decisions. After this season I will look for another pipe, do you have a suggestion??

When you look in the mirror.....what do you see?--A guy determined (that's me) to get as much as possible from my $4000 budget. From my friend the rider someone who shares my goal. We both look forward to having a good time this season and learning a lot.

From what you have said -I see big time potential.

[johns]

PW Morris I am sure you are going to ask and I forgot to give you the name of the current 2/2 exhaust system that the bike had when dyno tuned by DC VTwin. These pipes are AR100's that came from Zippers back in 2005. They have non removable built in baffles and Zippers cut 3/4" off the end of the tapered mufflers to increase their capacity. At the time I bought them Zippers said they were good for 140 HP. I was surprised to see 147 HP from these pipes on the DC VTwin dyno. The 5 speed transmission with Baker innards was built by R&D Performance in Florida. R&D blueprinted and assembled the 5 speed, good people.

[turboprop]

PW Morris I am sure you are going to ask and I forgot to give you the name of the current 2/2 exhaust system that the bike had when dyno tuned by DC VTwin. These pipes are AR100's that came from Zippers back in 2005. They have non removable built in baffles and Zippers cut 3/4" off the end of the tapered mufflers to increase their capacity. At the time I bought them Zippers said they were good for 140 HP. I was surprised to see 147 HP from these pipes on the DC VTwin dyno. The 5 speed transmission with Baker innards was built by R&D Performance in Florida. R&D blueprinted and assembled the 5 speed, good people.

While 2-1 pipes are very trendy right now, everyone that has run a few big blocks on the dyne knows that those 2" 2-2 pipes with tapered mufflers are very hard to beat.

[johns]

While 2-1 pipes are very trendy right now, everyone that has run a few big blocks on the dyne knows that those 2" 2-2 pipes with tapered mufflers are very hard to beat.
[/quote]


Yes I know, but this is also about weight reduction. I tried a Boarzilla last year. What a colossal waste of money, didn't gain anything but more weight than my tapered 2/2 AR-100 pipes. The RB pipe is significantly lighter than the AR-100's. I have it laying around gathering dust so I might as well try it for the strip. Will probably go back to the AR-100's for street use between races. Still waiting on the new FXD forks.

[johns]

Finally got the new FXD forks. One each from two dealers with no others shown in stock at any US HD dealer and no date shown for replacements from HD. 1st stage of this project is finally coming together. Would like to give credit to John Sachs for his work on the heads and G carb. Not bad results for a S&S crate motor with a minimum of aftermarket attention. 

[pwmorris]

PW Morris I am sure you are going to ask and I forgot to give you the name of the current 2/2 exhaust system that the bike had when dyno tuned by DC VTwin. These pipes are AR100's that came from Zippers back in 2005. They have non removable built in baffles and Zippers cut 3/4" off the end of the tapered mufflers to increase their capacity. At the time I bought them Zippers said they were good for 140 HP. I was surprised to see 147 HP from these pipes on the DC VTwin dyno. The 5 speed transmission with Baker innards was built by R&D Performance in Florida. R&D blueprinted and assembled the 5 speed, good people.

For sure you have a solid HP start and R&D is a stout trans build, but.......
147 HP on a big twin Dyna, with the heavy weight of rider and bike (how much weight have you shed?), and average 60' time,  and no air or electric shift, not ideal rear tire (do you know your ideal tire pressure?), with average rider, and a clutch that is not ideally set up, with pump gas on a true street build,
-is low 11's to mid to high 10's....based on 1.60-1.70 60 ft times and the track and conditions you make a pass. For a reference, on a mostly stock, no shift assist FXR with a 124" at 142 HP, I ran a 10.88 at 122 mph, with a 1.60's 60 ft at 2,200 ft elevation, with almost no knowledge of what the hell I was doing-but I was relentless to push forward no matter how much I failed and broke stuff.
The RB straight head pipe, no step, small diameter head pipe overall design was a loser for me, straight up no games, head to head, against my pipe...and like I've said for years, if it was the best, I'd run it. Period.
2-2 duals set up right can make big time HP. Big time.
You have other fish to fry, and try not to get caught up in HP per say, as you have a lot of other issues to deal with.
Re-read the questions I asked you earlier.....(you don't have to answer them on this Forum), as this is a process, that takes guts, determination, smarts, cash, and a relentless pursuit of you and your bike being the best it can be.
Is that you? If so, the sky is the limit to make you and your bike a bad ass combo-feared by some, and respected by all.

[johns]

PW go back up this thread, I did answer all your questions and I appreciate all of them. I am not ego driven and I appreciate all your input. This is why I posted these questions here hoping guys like you who do race would chime in.
1.  I hear you concerning more HP. We have no intention of doing anything more in that dept. this season.
2.  We do have a electric shifter on the bike, set up by R&D.
3.  Our initial goal with the bike lowered is to get more experience, work on 60 ft. times, and talk to other HD racers at the BG meet this month. Then we will make choices on taking weight off the bike.

This race season will be a learning experience for me. 

[pwmorris]

Sounds like a great year coming up-the learning part to me is always ongoing, but the initial learning is usually the most fun-as you see things in big moments and faster times that you never understood before.
They key is to keep at it, and keep at it, and keep at it, and don't let setbacks get you off your goals.
4 grand is a really small budget, so understand that going forward.
Since you are not the rider, You need his weight with leathers (if he weighs 160 you can usually add 15-20 lbs for full leathers, helmet, gloves, boots, etc. and you need the weight of the bike when you start with the basics like the battery, front end, etc. you are not going to have the swing arm this year so weigh it without. Go to your local truck scales with your pilot, and weigh each separately and then together.
You are gonna be shocked at what you see......
Pull every junk chrome cover off the bike, including coil cover, any strut covers, everything.
Too bad you didn't go full PMFR front end....

http://www.pmfr.com/products.html?sortBy=default&tagIds=13333&minPrice=&maxPrice=&action=Filter
Weight is such a huge advantage I can't stress enough.

Get a two step or make one from your clutch perch and work on solid 1.50's 60' at a good sticky track. It makes launching so much more consistent.
That's why I want you to go 17" tire...all the sticky Shinkos are available to you from there.

Best of luck, and excited about your future, as you sound like a determined SOB-
Hopefully, you will still be determined when you have multiple failures, setbacks, slower times than before when testing, broken parts, setting aside a whole weekend for the track only to have it rain out or be too windy and have to go home, and many other issues.
It's not linear gains, but like the stock market, zig zags up and down, up and down, but hopefully your stock has good staying power and value, and you find dividends in the long run.

[johns]

Thanks Paul I appreciate the reply's.