Question on DRX90 throttle response

[rinaldi]

I ended up picking up my son the 90cc DRX2 and got it home to take it for its first test run. Keep in mind I have not owned a 2 cycle since a snowmobile back in the mid 80's. It seems to not want to move from a stand still unless it is fully throttled? And then it starts off slow and then builds up speed. Is this normal? My concern is if he is riding at the local atv park he will not be able to pull himself out of ruts, etc since it shows very little low end.

[Hemi636]

That thing should rip.

Check under the gas tank for the CDI box. It will have two screws on it. loosen the two screws, and then the little metal jumper clip will fall out. After you get the jumper out, it'll run like a raped ape.
I read some of your posts where you posted that your kids aren't real aggressive riders. You'll know when you get this thing running the way it should, because you'll probably have second thoughts about putting your kids on this machine. They are very impressive little machines.

[TeamNeilson]

Check the clutching as well, depending on various factors, you may need to adjust the roller weight. What is the weight of the rider with gear?

Were any other modifications done to the machine?


Hemi is right, the machine should be quick.


I've never owned a new DRR (always used), maybe someone else can pipe in if there are other limiters on the bike (similar to eton), one in the carb, one in the exhaust.

[bulldogfallon]

A couple of things on the 90 depending on the parts that are on the unit.

Some units came with a combined mix of high speed gears and the newer lightened clutch, which will cause a very soft launch and lots of CVT slippage.

We usually end up shipping 1,000 rpm clutch shoe springs to new 90 riders, which makes the engagement a lot more user friendly.

If the stall of the clutch is too high then the belt starts to drop into the rear pulley so you lose a lot of your low gear giving you a sluggish start.


The units also come jetted way rich will also make the unit sluggish..

We run 42 pilot, needle #2 slot, 118 MJ with Uni mounted to carb.

Feel free to call anytime to help trouble shoot your unit

It is usually a quicker learning curve than readin post after post

[rinaldi]

Thank you. I will do just that. I let it idle for a bit in the garage last night. It is running rich I believe. THe exhaust opening has oil around it-pushed up against it to move it and had an oil circle on my let. In addition, it seems to spit out a bit of oil through the exaust-I saw little dots of oil behind the can. Also a small oil spot under the motor (about the size of a push pin head).

[rmuscle]

ah the famous oil circle , get used to that one. lol. hey gary if u read this , i am running the red shoe springs in my 70 with the mk cylinder and snyder pipe, def feel like i have a bit of a soft launch , should i go back to stock ones.

[bulldogfallon]

What rpm is your clutch engaging?

What is your torque spring and roller set up?

[rmuscle]

ill put an rpm gauge on it tonight and see . running overrange with yellow mallossi and 4.7 or 5 rollers

[rinaldi]

Backed out the throttle screw and it seems to be much more responsive. Not used to the 2 cycle lag off the start.

[bulldogfallon]

Shouldn't be any lag...unless you cvt is not tuned or jetting is off

[rinaldi]

Just seems that with this 2 cycle it takes about 1/2 throttle to start going and then she will ripp. Is this abnormal? Anything I can do to check if this is proper?

[TeamNeilson]

Ya. It should hook up right away.

Perhaps your rollers / torsion spring or shoe springs are bad, or even your belt is worn.

I'd go over the whole setup and make sure.. I know the springs don't last forever.

[bulldogfallon]

Don't change anything.....before you know what your quad is doing....

What could be the issues:

Check the adjustment in the throttle cable to make sure you don't have excess play in it.

The DRX90 with the lighter clutch will engage at around 6,500 rpm, so if you had an RPM gauge it would be most helpful to determine your engagement. (this is something I get asked about a lot)

You could also be engaging your belt on the rear pulley before the clutch engages giving in a soft and slippy take off...and allowing it to over rev some before taking off

If this is thge case then you could change to a lower rpm set of clutch shoe springs and you will be just fine. ($7 to $8 at most shops on this forum).