MCX180 over-rev from dead start

[Dimebag]

Hi,

Last season i had troubles not getting enough rpms on my 180 MCX Nytro.
Also the sled was bad on belts. They would only last 500 kms or so.

This summer I installed a 39 degree helix and a stiffer spring to hopefully solve these problems.

Now rpms are great, boost level is spot on and the sled works awesome.

The only "problem" is that sometimes (pretty often) it hits the rev limiter when i pin the throttle. Especially from a dead start.

It hits the limiter once or twice and then settles at about 8600 rpms.

It never hits the limiter while climbing, only from a dead start or from slow speeds when i pin it.

Is this something to worry about, or am I good?

Thanks

 

[180 nytro]

Isn't a 39 degree helix stock?

I have a 45 degree helix and it made a huge difference ! Pulls a lot harder and shifts up faster.

I would try that.

 

[Dimebag]

My RTX has a 43 degrees helix stock. In europe the MTX has the 39 degree, thats the one im using now. It works so much better on my sled than the old one.

 

[mrtwostroke]

Get a Dalton 45-39 helix or there R-helix with similer angels.

 

[rxrider]

IMO you need more weight in the primary to keep it off the limiter. Add weight to the inner hole first, if it's not enough add in the outer hole.

What kind of weights do you run?

I recommend a set of supertips weights, you'll get all the adjustability you need. A set of 55 gram Supertips would work nicely.

 

[Dimebag]

I'm running the mcx weights that came with the turbo kit. No rivets.

Other than that i have the mtx stock secondary setup with the 39 degree helix and the pink spring wrapped at 90 degrees.

What will be the result if I run the oem RTX spring (which is not as stiff as the pink one) with the mtx helix ?

Or the stiffer spring, with the 43 degree helix?

I am wondering about this since these are the only changes I've made since last season. (Except for the exhaust leak, that may or may not have made my rpms drop).

 

[TBird]

This summer I installed a 39 degree helix and a stiffer spring to hopefully solve these problems.

When putting in a more shallow helix AND a stiffer spring you changed the balance between the clutches!
If your shift rpm is perfect you can solve it two diffrent ways, one right way and one wrong way .
- Wrong way, you can put in an helix with an initially steeper angle to keep it of rpm limiter from dead start, this can work, most problably you will keep it from rpm limiter, but you get slippage in the clutch, the reason you put in a more shallow helix in the first place.
- Right way, add more force initially in primary, this by adding softer spring @ engagement = lower engagement, maybe not for you. or more weight in heel, this demands adjustable weights for ex. Heavy Hitters or Supertips!

 

[Dimebag]

Does the rivets from the stock weights fit into the mcx weights?

In that case I'll have to check out which weights are in each holes of the stock weights.

How much weight do you suggest that i put in, and are we talking about the hole that is closest to the rollers, or the third one (far away from the rollers.) ?

 

[TBird]

If you add weight the shift rpm will be lower, but you can try it.
Heel is closest to the pin.