Hello. I recently upgraded my 2004 DSX with a QRS slip on muffler from HMF. I also have a UNI filter.
I run with the lid on. I started jetting with 175 main, but it didnt like it (too rich), went down to 170 and it felt right.
The problem is, after this mods, my quad cant beat a stock z400 on a 300ft race. It stays preety much with it until the very last moment. We switched quads with same results. Is this right? Or do I have a problem
I have 22 Razr with stock gearing.
I dont do drags, I do mostly desert racing and some motocross, but am concerned that I am not getting the maximum from this mods.
Any suggestions?

BTW, the QRS is a very quiet pipe, which HMF states it only looses 10% ovarall compared to the sport series.

Thanks

 

What is the weight difference between you and the other rider? I am 330 on a DS and my friend is maybe 200 on a Z400, and I can get him by a couple lengths in 300 feet. I run the HMF sport, and can't comment on the QRS, but it seems to me that you should be able to take your friend easily. I wish I had an answer, but maybe try checking your plugs to really know if your jetting is on. Good luck.

 

Hey DSlider,

I know what you mean... I did a bunch of mods to my bike and I was just able to keep things neck and neck on a race with a YFZ450 as I my DS was way out of tune.
I caved in and had the bike Dyno tuned and gaind like 6 horse to the rear wheels you could see the power was dropping where it should have been strong then pick back up again ....
Now I am ready to RUN with the Big Dogs...
Proper tuning makes all the difference in the world ... enought to pay for it I guesssssss
[img]i/expressions/face-icon-small-smile.gif[/img]

 

With 22 inch rears try gearing down to a 14 tooth front sprocket, it will help considerably.

 

ILivSD, how was your jetting after the dyno tune? Did you mod the carb (vacuum holes?). Are you running with the air lid on?
I weight 200lb, and my friend 150lb. But the thing is, when we switched quads, the result was the same.
I feel the engine takes too long to rev. I does get there, and feels strong, but it takes a while to hit the rev limiter.

 

I had the same probem and it ended up being the carb slide.

look here

 

You must have some sort of problem. My neighbor has a Z400 and i usually take him by around 3 to 5 lenghts by the time i shift to 5th. He weighs around 180 and im around 300.

 

order a 14t and 15t front sprockets from RMATV, cheap, like 15 a pop, and try them both to see which you like better, right now your gearing is too tall

 

As others have mentioned you should gear down to compensate for the 22's however even with stock gearing you should be mopping up the Z. I would say you have a tuning problem of some sort. Where is your needle set?

 

Here are my specs:

Needle in 4th position
Main Jet 170
Air lid, on
Uni Filter
Muffler: HMF QRS
Everything else stock

Alltitude: 3000ft
Temp: 90F

Also, just read Oldman's stock carb reccomendations, and am doing them tonight.

Thanks