All

BBR makes a badass swingarm that comes with a shock too for 1500 bucks.

If you're gonna do it, do it right https://diamondminis.co.uk/collections/crf-125f/products/crf125-diamond…

My understanding is that going much richer on premix than 50:1 creates issues with the power valve operation. This is second hand info as we are still running a fiddy. Gearing I’m sure will be highly rider and track contingent.

We run stock grearing. Running av gas at 32:1 with amsoil.

Pump gas, amsoil dominator 45 ish : 1, stock gearing.

nihilo jetting kit for the bike. you can buy the parts yourself but it pulls the guesswork out. the new needle is what you are mostly seeing the results from, that alone will have it run much better. stock is too rich on bottom and too lean on top for most kids. https://nihiloconcepts.com/products/ktm-husqvarna-gasgas-65-jet-kit?_pos=5&_sid=67c1dc4b4&_ss=r t2 is really good but $$$. if not that i'd run the best pump i could find, and a good oil like amsoil @ 60/1, thats what the manual calls for. 50:1 is as much oil as i'd mix with pump gas. i was so scared of...

Stock gearing 14/48 and we run either VP C12 50/50 Pump at 50:1 or U4.4 at same ratio's. U4.4 is great but you have to be careful when it gets hot and humid as the fuel will vapor lock and make the bikes hard starting.

I run stock gearing and 93 with dominator 60/1 and the Nihilo jet kit. I don’t see a need for race gas with these bikes and my kid doesn’t have trouble running up front locally.

Whatever you do just make sure the actual jetting is spot on. These little bikes like to "blow up" if they are run too lean and are ridden hard. Especially the little Kawisakis. I think the little Austrian bikes are a million times more reliable than a KX, but I still would argue jetting is much more critical on the little bikes because they live in the high RPM range with fast kids. I always try to run my kids bikes just a tiny hair on the rich side and then keep the air filters really clean. Will help you...

Nihilo jet kit and 91pump 60/1 with stock gearing

Pretty much what everyone else stated. Stock gearing, 93 pump gas mixed 50/50 with avgas and dominator 55:1. Tusk makes a jet kit that is the same as the Nihilo kit but cheaper. https://www.rockymountainatvmc.com/parts/tusk-ktm-65sx-jet-kit-p?v=16662

Stock gearing, VP VPR mixed with Motorex Cross Power 2T at 60:1.

Stock gearing and T2 with fmf pipe/silencer. I put in the nihilo carb baffle and their jet kit. With their recommended settings it was pretty rich. I had to lower the needle clip to the lowest spot. It was good here at sea level. Went to a lectron carb. Seems to run a little cleaner, and plugs always look great.

Yeah.....cuz no mini dad has ever had to work on a 50 clutch or top end

And be sure to get a 10 pack of clutches to go with it....and a good supply of ear plugs to protect yourself from the most annoying sound in motocross.