Jetting for 250RR factory hi-comp head

[Gibnut]

Has anyone fitted a hi-comp head to their 250 & if so, any jetting changes to recommend?

I am thinking of trying NOZK 2nd pos, 38p & 168m, 0-900ft asl, 40-95f.

[celler]

Not exactly an answer to your question,

I have found that I can run a little richer jetting with my RB modified head giving me slightly more power in the lower mid VS just the stock jetting with the RB head. I also found I can set my power valve to open sooner. Overall the RB head mod really broadened the power.

[Gibnut]

Thanks, Celler. I will post pics & values when I cc the new part this morning (Australia).

[Bandicoot]

Shouldnt change to much .. maybe just a simple A/S adjustment should surfice !!

[Gibnut]

Well, well - I received an S3 head w/- 3 x inserts! Also, the hi-comp head has now disappeared from Beta USA website?
I also didn't get the o-ring with the kit, so I can't fit it yet.

[Gibnut]

Having ridden the bike twice now with the S3 Stars red insert - I can happily tell you it works.

The motor has a stronger pull off idle & up through 2nd-thru-4th. As far as I can tell, the slight increase in compression has had no impact on the prodigious top end this bike has.

Jetting for SL - 700m ASL, 12c-34c, Australian east coast: 38p, 168m, NEDW #2, a/s 1.5, 98ron/Motorex full syn @ 50/1.

Last weekend we rode some slowish s/t & I reckon the bike runs a smidge hotter, but nowhere near boiling like some orange bikes..

I have been gently ribbed by my brother & a couple other riding buddies for trying to make my 250 a 300 but they are missing the point. The fun the rest of the motor delivers with the added drive on hills (less wheel spin, pulling a taller gear) due to more torque makes this engine set up the BEST I've had in a dirt bike thus far.

[celler]

I have been gently ribbed by my brother & a couple other riding buddies for trying to make my 250 a 300 but they are missing the point. The fun the rest of the motor delivers with the added drive on hills (less wheel spin, pulling a taller gear) due to more torque makes this engine set up the BEST I've had in a dirt bike thus far.[/quote]

I can say this is my experience with good head mods on a 250. Need the compression and clean burn to give that added boost down low but then get the very usable 250 midrange and over rev. After getting my 250 right it I have went back and been working on my 300 GG to get an equally wide usable power. I've made great progress but I just prefer the Beta 250. Part of my enjoyment of dirt bikes is tuning them to get them the best they can be for me. As my wife knows when I get them right it usually means a bike is added and the journey begins with a new one as I keep my best old one as my reference (Now my Beta 250).

[Gibnut]

I rode a stock '16 300RR on Tuesday (+ a '16 X-Trainer..).

I don't think my bike gives much, if anything, away to the 300RR down low jetted & set up as it is.

The 250RR as an all rounder is very underrated in my humble opinion.