Let me give you a little background before we get started on the technical crap.
I bought my 04 DS used without knowing the owner. I purchased it from a dealer who had reposed it so I have little to go on with regard to what was done to it with regards to modifications. I do know that the exhaust was changed to a FMF Titanium-4 and some non-mechanical bolt on pieces we added such as bumpers and a grab bar.

However this has little to do with the questions I have so lets get started. Keep in mind I have little experience with the DS or any quad for that matter so some of the questions may be elementary. First, last night I completed the oil and filter change and started it up. Yes the red light went out thank God……As I was warming the bike up I noticed it having a difficult time staying running ( popping ) nevertheless when I gave a twist to the throttle it jumped into action. In addition to the popping I noticed that the exhaust pipe down where it exits the cylinder was turning red! [img]i/expressions/face-icon-small-shocked.gif[/img]

Now I’ve been around Harley’s for years and I have never seen an exhaust turn red as it sits at idle but maybe the quads are different. My first tendency is to think the AFR is incorrect in that it’s running too lean. So, is it normal for the exhaust pipe to turn red near the cylinder? And if not would you suspect the AFR is not correctly set? and lastly what are the optimal settings for a base line adjustment for the air fuel mixture screws?

Sorry for being so winded.....still learning...[img]i/expressions/face-icon-small-cool.gif[/img]

 

as long as your a 2500' or below you should be at 172.5 to 175 main, needle clip on the 3rd to 5th slot from top . 2-1/2 turns out on the air screw apx. and a 45 pilot. this will put you really close. Ive heard the glowing pipe thing being from a lean cond. and others told me its from unburnt gasses coming out the head igniting in the pipe. so may be a pro can clear this up my money is on the second.
hope this helps
Sam

 

Two things will cause this.
#1. A lean mixture.
#2. A late ign. timming.
A slow burning fuel will cause the same symptoms as #2.
See where your jetting is at and jack it up as needed to correct the problem.

 

So far what has been said is true. since it is a 04 i doubt the motor has been opened up unless you have done it. i had the same problem after replacing the rings before i went with a hi-comp piston. turns out my timing was off and the pipes lit up real quick. i doubt that is your prob. make sure the main jet is big enough for the aftermarket pipe. then screw in the air/fuel screw all the way and back it out 2.5 to 3 turns and start from there. after that it is fine tuning. somebody correct me if i am wrong about the number of turns. also run 93 octane if ya can this will prevent any pre-detonation with the stock piston.

 

The best octane I can get in Calif. is 91......

Being that it is the stock carb I shouild be able to pick up jets at the local motorcycle dealer?

 

A lean condition and way retarded timing will cause this...when you crack the throttle does the red go away?
I had some DynoJet jets(dj170 dj180 dj190) laying around from a 1998 Dyna CV carb that I had Dyno Jet kitted...bingo same jets. So yes you may even get the jets you need from your local Harley dealer...keep in mind that the main jet does not come into play until 1/4 throllte or more. Idle is the pilot jet and mixture screw. part throttle is the slide needle and a very little mixture screw and pilot. I would richen the idle with the mixture screw first....

 

To get more air screw it out or in?

 

I'm a newbie to DSs but am not new to modern 4 strokes i.e. motocross bikes. If you've ever been on a starting line at night or watching a race at light every single YZF and CRF head pipes will be glowing red. The glowing pipes (at night) are not out of the norm for newer engines. What is out of the norm is the popping you describe, that's a lean condition but the two symptoms would not be connected (as in a problem) in the Japenese bikes. These long time DS guys can weigh in but I wouldn't be concerned about the nighttime pipe thing.

 

Scoundrel, does the popping go away after it warms up? Mine did the same thing when throttle was applied before it was fully warmed, right after I put a pipe on. The pilot they sent me was wrong for the carb so I used the stock pilot (too small). It was a lean idle condition, corrected by turning the airscrew in. It was bad enough it blew the carb out of the boot.

 

OK here's the scoop on the carb. I took it apart last night and this is what I found.
The Main jet is #180 and the pilot is #45. This combination seems to be within the ballpark so it shouldn't be running lean.
The only thing I need to understand is adjusting the air fuel mixture by way of the pilot screw. Where the hell is it! [img]i/expressions/face-icon-small-blush.gif[/img]
We are not talking about the screw on the end of the black hose are we? I thought that was nothing more then an idle adjustment...... [img]i/expressions/face-icon-small-confused.gif[/img]