I thought I would post my recommendations for the stock carb.
These suggestions are only a guideline that has worked for me.
Different altitudes and temperatures will require jetting adjustments.

Step 1 - AIR - LID ON
The snorkels running under the gas tank cover is a major restriction.
Go to the local hardware store and buy some sump pump hose.
Some sell it bunk in 6’ sections or a box of 24 feet.
If you have to buy 24’, you will have enough to do 4 quads.
At around $10 this is $2.50 per set. Cheap mod.
Even though tubing is same size as stock, adapter end is .100 larger.
OD of adapter end is around 1.700, with end of tubing to first ring measuring just under 1 5/8.
Pull out your stock snorkels from airbox.
Remove clamps and pull out tubing from adapter.
Install new tubing into the large end of airbox adapter. Little WD will help.
This is a snug fit and no clamps are needed. End of tubing will fit into adapter groove.
From the groove in airbox adapter to end of tubing should measure 12”. About 34 rings on mine.
Run new snorkels along side snorkel to carb, where old tubing ran, and install small end into the airbox.

Benefits:
1- More air because tubing is shorter(minus 9”), not under cover(hood) and less restriction thru adapter.
2- Tubing has larger ribbing which reduces the shock waves from reversion.
Reversion refers to reversed air flow, or in simpler terms, it’s when air in the intake runner reverses
direction for a split second. The condition is caused when a burst of pressure escapes into the
intake runner from the cylinder during valve overlap. Reversion creates resonance shock waves
which exit the open end of the tube at various rates depending on engine speed. To help maintain
inertia in the airbox and resonance, thus increase air flow
.

Step 2 – Throttle Slide Spring
You need to cut your spring to an overall length of 3 1/8".
Older DS's had to be cut 3-5 coils to come to this length.
The new springs are 3 1/8 from the factory.
Do not go shorter, static height is 2 7/8, you need alittle load so slide does not bounce/flutter.
If you do not like to cut your spring, than order a 05 spring. They are inexpensive.

Note: More spring information-10/28/05
All factory springs appear to be made out of .032 spring wire.
2000/2001 had a pitch of .140P and were 26/27 coils. Length 3 5/8”
New 2005 has a pitch of .120P and are 26/27 coils. Length 3 1/8”
When we cut the old springs 3-4 coils, we had a length of 3 to 3 1/16”
When you tests the force of the cut old spring to the 05 spring you get
very similar gram forces throughout compression.
Summary:
If you check your spring and it is 3 1/8” with 26/27 coils, this is OK.
If you check your spring and it is 3 1/8” with 24 or less coils,
order the new 05 spring.
If your spring is over 3 1/8” long and has 26/27 coils, cut to 3 1/16” to 3 1/8”.

Step 3 – Throttle Slide
This is where I have gone and a few of you will get nervous.
On the bottom of the slide are 2 vacuum ports.
Freez has spent many hours on the dyno and comparing the Raptor slide to the DS, he has drilled extra vacuum ports. He is at 4000’ elevation so size had to be determined.
I drilled 2 extra vacuum ports. Starting with a small size and testing.
The size I ended up with was .125 for all 4 vacuum ports.
At this size I could get the slide to rise all the way up, even with the lid off.
You need to measure and drill the extra ports in the same relationship as the first 2, just
on the other side.
The surface is not flat so use a sharp pick to have a pilot. Drill first a 1/16 hole.
Turn slide over and look for best location. If hole is not centered between ribbing, you can install 1/16
drill and side cut to best position. Then final drill with .125. Stock ports just need to be redrilled.


Step 4 – General Jetting
I prefer to use the Dynojet Kit.(Moose is the same)
The needle is up to .011 thinner in mid range. All around riding gives better throttle response.
For drag only applications the stock needle is very adequate.
Stock CDI:
Needle clip in 2nd groove from top.
3rd groove if exhaust system is over rev design. Testing required.

CDI with noted aggressive timing. I have a new Big Gun and works fine.
Needle in the 3rd groove from top.
4th groove if through testing works.

Main Jet:
Start with the Dynojet 175 and tests.
Note – If you can run with the needle higher, you may have to jet smaller.
These needles are very tapered and it is better to start leaner(main jet) and then get larger.
Try to get needle height set first before finalizing main jet.

Step 5 - Breather Tube/Balance Tube
The clear hose that runs from the carb to the beginning of carb snorkel no longer has a purpose when
slide control has been altered. I have disconnected the hose at the airbox end and installed a unifilter.
The barb going into the snorkel has been covered with a soft plastic cap and clamped with original hose clamp. Too much negative pressure is being generated below the slide bladder causing the slide to rise too slow. Conflicting pressures on both sides of the bladder not good.

If anyone needs additional advice, I will try to help.

11/02/05
DS Float Maintenance and Pilot Cleaning

1- If you have inconsistent main jet setting, float height adjustment may be the problem. If you find your jetting always rich, that is, after a trail ride the plug
looks gas soaked, and black is the color on end of plug and porcelain is dark brown; adjustment to the float is required.
I feel that the factory spec is a little on the rich side. The spec is 10mm(.394).
Trying to bend the tab and hit this dimension is like hitting a moving target.
I have found more consistent results using this procedure:
With float bowl cover removed, turn carb upside down.
Note that the floats are formed with a crowned end surface. How can you take a measurement off a surface that is not flat - You can’t.
But there is a edge just below this crown that is straight.
I take a first measurement to this edge, at the pinned end. Write down reading
I take a second reading to this edge, at the unpinned end. Write down reading.
Subtract second reading from first reading.
My Spec: 0 to 3/32(.090) That is - The second reading should be equal to first reading or lower to as much as 3/32(.09).
I have used this spec for 3 years and have not had inconsistent readings or plugs fouling out.
If you are doing power testing runs and find that top end is inconsistent. That is, sometimes strong and sometimes flat. Float height is the issue.


2- Pilot Cleaning
If your motor starts hard or not at all. Pilot circuit is dirty or clogged.
Remove pilot screw, be careful not to loose small spring and washer.
With a air compressor, that has a rubber tipped nozzle, blow air into the
orifice that the pilot screw was removed from. Spray alittle carb cleaner
into orifice and blowout again. Gas has a tendency to dry-up and leave deposits
around the pilot air/fuel passage. Try to clean twice a year or when having starting problems.

1/04/06
Needle Assembly Into Slide:
The injection molding of the vacuum slide sometimes had a slight mismatch in its production.
With the needle and washers removed from slide, look down with good light and where the washer will rest, does your bottom look round or can you see a slight flat lip that is raised and thus looks like like the bottom is D shaped. Many slides seem to have a D shaped bottom.
If you have a D bottom:
Take the thick metal washer and grind a flat. Usually about half the width to the inner hole is find.
Install the thick washer first to align in the D.
Then install thick nylon washer.
Then needle with clip in 4th or 5th(stock needle) or 2nd or 3rd(DJ needle) from top groove, and thinner washer on top of clip.
Press in plunger with small spring attached.
When assembled and you turn the slide over and look at the needle going into the slide, you will notice that the needle is positioned in the middle and has equal space around the needle. This is important otherwise the needle will be dragging in jet needle and wear out of round. Also the better it is positioned, the better fuel will be drawn up the jet needle and the fuel will atomize better.
Final Check:
Push needle lightly up into slide body. There should be a slight movement. Spring will return needle when released. If running in the 5th(Stock) or 5th/6th(DJ), you may find that there is no movement.
Warning: If no movement, the assembly may come apart while riding.
Fix: Grind 1/32-1/16 off top of needle and re-assemble. Check again for movement.
I have found that the slide length varies. Excess shinkage is the issue.

 

Is there anywhere on the net that you know of that has a schematic of this carb?

I am not clear as to where you are drilling the vacuum ports. Is it in the bottom of the slide?

Why not just remove the snorkles all togather? Are the air box and snorkles part of a "tuned" air intake system? Or are they just a way to keep dirt/sand/water from getting to the air filter?

 

http://www.nightrider.com/biketech/hd_cv_mods.htm


To show where the vacuum ports are located.

 

The snorkels and airbox are a tuned system.
I will admit that with the lid off, low and midrange are great.
I just can't get upper mid and top to rev as good as with lid on.
I am working on a modified emulsion tube that adds power everywhere,
but has not helped the lag with lid off.
You have a full exhaust system with over rev design.
With end cap or HMF slip ons I have not been successful with lid off.
Yesterday I installed a slip on with a over rev design. Hope to test
to see if that will bridge the gap.

 

Excellent info Oldmanracing, thanks for taking the time to post!!!
J

 

With all the problems I see posted for poor carb response and low dyno readings,
that is why I posted these guidelines.
There appears to be alot of lookers but very few jumping in and making any other recommendations.

All I wanted out of this posting was a few thanks, Freakneh, thanks for giving an oldman a pat on the back.

 

Oldmanracing,
Thanks a bunch for the post. I talked to the guys up at Little Sahara Sand Sports today. They told me thay had been on the phone with DynoJet all morning going through all the calibrations. Everything apeared to working properly. I guess there reading must be correct. I will study the Mods HARD and perform them EXACTLY as they are stated. I can't wait to see the "new" dyno numbers. You may be correct about the slide, if you are sounds like the mods will solv this.
I will post my results after the next run.

 

Thank you Professor O ! I have the Dynojet kit ,and i'm always looking for a little more HP. Beats buying a new 450r carb.

 

OPPS The absent minded professor forgot Step 5
Please review original post. I have added Step 5.

 

CLSHORTT,

Are you running the stock CDI?
If stock and after you have your machine running better, I would recommend the new Big Gun CDI.
It is aggressive in mid range and would enhance performance.
I am looking forward to your next dyno runs.
Success stories are good for all forum memebers.