have you guys ever switched riders?

 

Give this guy an E-mail His name is Eric. He is one of the best people to tune on a stock DS! He will tell you what the jetting should be and what to do with the airbox.

I will tell you to put clamps around the intake hose for it will collapse when revved real high.

DuneDevil

 

Nothing contreversial here. My 400 is nothing special, and has seen many a DS and Raptor from behind while eating roost, which is exactly my point. For what it is and the money I have in it, my 400 runs great. It is competitive with a stock Rap or DS, it takes a mistake on the other guy's part for me to beat a piped one (poor holeshot, missed gear, or shifting way too soon or late). But, this DS should be wasting me, as others with similar mods would and have in the past. But.. this particular DS is not. My buddy is down about it, especially after the a$$ chewing he received from his wife for spending all the money on parts. I am out of answers as to what could be wrong with it, which is why I came here. However, all I mainly got is a bunch of little girls with their panties in a wad (although there were a couple of honest and helpful replies, which I appreciate - thanks).

So... it's time to head upstairs and hang out with the missus. I definitely didn't mean to get anyone's feathers ruffled. If you can think of something I may have missed that could be causing this, I would love to hear your input.

Thanks again,

Matt
P.S. - We'll be at Little Sahara, OK for our summer dune trip (mainly night riding) on 8-22 thru 8-25 if you would like to witness this amazing spectacle.

 

I would have agree that it is probably the rider. I would consider myself an average rider on my bone stock 2001 DS, and I smoke my buddy , who is an excellent rider on his 400EX, by atleast 10 bike lengths in a 200 yard uphill sand drag. It would be more, but I spend the first 50 yards spinning my too small paddles. If your freinds bike was that far down on power, there should be something fairly obvious to find.

 

I to beat most other quads[img]i/expressions/face-icon-small-happy.gif[/img]

 

Maybe the cam timming is off??? You say compression is what it should be, which is???
You should'nt need to mix race gas with the 93 pump if the piston is 11:1.
Did you put a jet kit in the carb(Slide spring, needle, etc), or just re-jet the stk carb? I know some have cut 3-4 coils off the stk carb spring and had a VERY NOTICABLE acceleration gains!
Does he have an aftermarket CDI unit? He'll need one if he has cams and slip-on, BIG TIME! STK rev limit kicks in WAY too early, even for a stocker.

 

i would try running just premium pump gas without the high octane mix and see what happens.i have a raptor with 11:1 compression and i was mixing with 110 octane and i was losing a considerable amount of power.when i first got my raptor built i had smaller jets in it and i ran with the lid on and the 110 octane actually helped then but now with the much larger jetting the 110 robs power especially on the top end.i know what i have said may not make sense but i actually gained a couple of quad lengths in a sand drag race up a 300 foot hill so it made quite a difference.why would the 110 octane increase performance with the smaller main jets and decrease performance with the larger mains?so has anyone else experienced this?HRBART- sorry to ask a question about my experience on your thread but maybe while we are on the subject of performance someone may be able to answer my question also.what i have suggested could really help,i hope your friend at least gives it a try .i am just running 92 octane premium pump gas now which is what made such an improvement for me.i hope this information helps but of course it may be something else like maybe jetting.proper jetting can be hard to achieve if you are trying to go by reading the plug because as you probably know todays gasoline can have a lot of additives that can make a plug reading seem like something that is is not. i can see why your friend is getting disgusted with his quad because i ride almost every weekend at the dunes here in oregon and i see a lot of quads race and he should be beating you with little effort.if he gets his quad dialed in you will see why the ds is so well liked by those who own them.

 

I would agree with birdoprey, chk the CDI unit, it seems like you've installed quite a few mods on it, but no mention of an after market ignition. Once that stock ignition hits it's limit, and you've run out of gears thats it.

 

K&N with no lid? Remove the rubber gasket from around the top of the box. With the seat on and him sitting on it, it is like having the lid on. Are the 2 big tubes still connected to the air box? My brothers needed those tubes connected when he was at that stage for it to run better. Don't know why. As another has asked, have you switched riders? Maybe it is just the rider. With the 11;1 and cams, properly jetted as you say and you and the Raptor just being piped, the DS should be several bikes in front of the Raptor and you shouldn't even be a concern. You can check the cam timing but if a reputable shop put it together it should be ok but the possibility is there. Tell him to put the 22" tires back on. For dirt flat drags use stock gearing 16/40?? for sand hills 15/40.

 

I agree the cam timing needs to be checked.