Stock Honda CR125 and Vortex Rok Shifter Comparison

Just looking for some general feedback from fellow racers. Does anyone have any real life comparisons to running the ROK Shifter engine vs running a Honda for a season?

Any other general thoughts? I often get asked what to buy from those looking to go shifter kart driving and I used to say the Honda to anyone starting, but with the price of the ROK and supposed reliability, I’m wondering how it stacks up.


What;s the rebuild interval on the Rok shifter??

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Hello all… I have a ‘little’ bit of experience with both of these packages :wink:


Haven driven both, coached both, tested and tuned both. We, at ogp, have had extensive use and building of both motors. IMO, the fun factor goes to the rok. Slightly faster than the Honda, with more revs (roughly 13600 vs 12600…standard revs, no over rev) it sings instead of grunts. Not as easy to lug around, it makes up for it by having a bit more top end rush. Stay in the power band and it rewards you with a seemingly stronger pull through the top gears. It does however require one to be more on point with gear selection. The Honda allows a bit more freedom as it does have a little more initial pull. The dry clutch makes launching the rok easy.

The heavy wet clutch requires a bit more finesse to launch, under racing start conditions, on the Honda. Finding neutral is easier on the rok also. The shifting feels lighter as long as you aren’t over revving on the rok. Neither motor has a rev limiter! I just spent the last 4 days doing separate driving schools with new people to the shifter platform. Each one of them over revved the rok to well over 16000rpm, easy to do in miss shifts and false neutrals. Rubens was engine breaking in Orlando and consistently hit 15+…very hard on the reeds and the bottom end. I’ve had plenty of experience with the same in Hondas, engine breaking and excessive down shifting can rev the motor over 15. Actually seen one take out the bottom end, in Vegas, on a Honda. Which brings me to the next point…

The rok will require you to be a bit more on top of things. With a high rpm ceiling and an ‘iron’ bore your piston will need to be paid attention more. The Nicasil (spelling?) Cylinder on the Honda is almost bullet proof. Runs the same piston ‘always’ making the do it yourself guy happy. At a local level you can just slap in a piston/ring and a new head gasket and if you go. No ‘need’ to hone every time, or to size your piston (this is true to a point). Bottom ends are virtually bullet proof on the Honda. The roks is also very strong and very well built, but does require a bit more ‘looking over’. Clutch is stellar on both, but the dry clutch on the rok will also need to be looked at at a higher frequency and cleaned up…

Reeds, well that’s very dependent on how one drives, as does all of the previous comments. If you are a hack with the gear box, neither will hold up. Less so the rok, it is a ‘true’ race engine. If you lack the maintenance schedule, the time, the effort the Honda would be my choice. As a stock engine it was designed for motocross and being in the dirt. It will hold up better if your are not on top of things. The rok will run very well without proper maintenance, and hold up (2 race weekends, 4 newbie days learning to drive one, all on the same engine… 1 top reeds replaced, even with the over revving) the bottom end…? Idk I would have to ask Mario :slight_smile: I wouldn’t advise it though lol…love your engines people!

Is likewise fairly easy on both. Once you have a good baseline, you can pretty much stick to it, as long as you run a ‘tad’ rich. Obviously driving styles and track locations will change things, but it is very easy to work with both. The rok, imo, wins the carb game. With a fixed range to run it makes the average tuner more on point. The fairly open carburation on the Honda requires you need someone to give you a good base.

If you are a once a month weekend warrior, or a do it yourself guy, the Honda wins. If you want a true race engine, bigger smiles and a way better sound, the rok wins hands down…I love my Hondas but the vortex is truly a piece that tugs at a racers heart strings…

Each has it place. The vortex isn’t going anywhere and growing. It is well supported in areas. Has an international series and a world final race (I’ve been multiple times). Imo, more fun to drive. The Honda is a work horse. Parts are cheaper. Requires less to keep running (just not at the front :)). A lazy man’s lugger if you will. Parts are getting a bit more difficult to find, depending on the vintage of your cylinder. Is it dying? Maybe. Will it go away? All things do come to an end… Just when!? Rebuilds on both depend on how they are used and at what level you are racing.

I’m sorry if I rambled, if you have any legit questions you can find me on Facebook or at ocala gran prix.


Welcome @Christopher! Great post! Shows both sides of the coin. Thanks.

Can you give a “range” of the rebuild periods you’ve observed?

Absolutely fantastic review Christopher! Very much appreciated.

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I think a decent argument could be made that KZ provides too much choice for most racers. Before they get started they’ve got to decide what engine to run, do they run their local distributors, but what if it isn’t any good. There have been some stinkers in the KZ market. Add on top of this the ability to tune, and upgrade throughout a season. KZ for the most part is THE professional class now.

ROK seems to offer that inbetween where you can feel like a KZ Pro without having to get a works drive or shell out a years wages. Racers care about that, if they (we) can feel special without spending all their money then they are in. People seem to respond better to high revving sound then they do to lower rpm grunt, not sure why but I do know I didn’t watch one honda race at supernats, they just sound blah.

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I mostly club race with a few regionals thrown in. I had a built moto for a while then switched to an ICC (Maxter). I learned that the maxter in particular had strict rebuild intervals needed to be adhered to. I dont have nearly the experience of others on this site, but for me running those motors ended up costing alot more money just to keep up with the maintenance. When I tried to stretch the interval my Maxter suffered catastrophic failure. I was out of karting for a few years and when I returned I went with a stock moto. More important then the longer rebuild interval is the significant reduction in parts cost.
It is probably worth noting that I am not 22 years old and 125 lbs either Im north of 40 and pushing 200. I find that due to my total lack of driving ability and pretty much being a no talent hack that the honda is more forgiving to drive because of the torque it produces. When I muffed up a turn with the maxter and fell out of the power band I paid in the 10ths it took to grab a gear when others didnt have to.
Anyway just my $.02, Love this site!!

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Great post Chris thank you

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This turned into a great thread! Thanks for all those who have contributed!

I was really looking for a direct comparison of Moto/Honda to ROK and this thread definitely delivered. I have a bit too much invested in my Honda to make the jump to ROK right now, as I’m sure many of us do, but I do think it is a high possibility in the future.

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I saw a ROK set up in an Energy Kart at the track today. I guess they are going to do some testing. Im looking foreword to seeing a lap time comparison.

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Should be a few in the F-Series results. Just need to find out who was on Roks.


As a side note, the rok is faster, everywhere (compared to a stock motto)! Also, with an external water pump, it must be warmed on the stand… One of the classes I have given, the gentleman raced a Honda previously. He had the biggest shit eating grin after getting out of the rok package. Said it just feels faster! More work= more reward…

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It’s vortex, what I would say is one of the most stable, consistent platforms there is. The tt hasn’t changed since its inception for tag back in the day…what series iame are we on now? The rules here in America haven’t changed in over 4 years, that I’m aware of (in America, Europe allows for open carb tuning as their fuel is Crap! Lol). in all my years of this vortex/otk has been the best at keeping with what works. Why change a solid platform. There isn’t any wiring harness to mess with or starter bs. The only change in the engine itself has been a reed cage change last year (which all come with now), and the addition to a new top reed for reliability this year. Both minor changes at a very small cost, but nothing to denote a performance change (with a little proper jetting adjustment).

Kz comparison? Why… The rok is a fixed engine. No you can’t cut the head, piston or reed block. No you can’t polish the exhaust, cut/polish/treat the transmission or run any reed you want. You can’t stuff the bottom or run variations of a polished/lightened rod… Etc. If you want a performance difference, compare it to a stock moto vs a mod moto. No, they won’t run together competitively.

The problem with kz is the parity amongst engines and the true rebuild time/costs of them. If you truly want to race them at any level (besides local) they are expensive. Having a fixed set of rules and a consistent set of parts makes it easier and cheaper to run the rok. It’s how Honda has managed to stay alive so long…

I loved my tm’s, but the time it took to keep it an honest winning package is at least double what it does for a rok. The rok clutch holds up for many many races (some of our packages have years on them). The top ends are competitive for more than just a few weekends. The only weak link in a rok is a shift piece that is easily replaced by removing the side cover by the splined shift linkage (rare but an issue for ‘hard shifters’ and no lift shifting people).

Bottom ends last seasons. I can’t give you an honest time frame (for a club racer) on any of it because of the level at which we race. It depends on the driving technique and skill of the racer. When Rubens B is running in the front, as with all of our drivers, at a national level race you do what it takes to stay there. But I do know we have won with a motor that ran two full winter tour races on it, with just oil changes.

There really isn’t any debates left, just choices. Spec motors are in. They are easier, more reliable and cheaper to run over all. It incorporates a larger populace the chance to be competitive. If one can afford to play with the kzs, I say have at it. It is the pinnacle of karting. It Just hasn’t a place in actually growing the sport here in America.

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Took the most helpful posts from the original topic to make this one…
Thanks again for the input folks.

I’m making a comparison table to make it easier for folks to compare the two packages at a glance. What items should be included? Now I realize these things are somewhat fluid at times, but we can still capture some reasonable assumptions.

Here’s what I have for fields so far


Initial purchase cost
Typical top end cost and frequency
Typical bottom end cost and frequency
Approx TCO for first season based on 10 races and gluing a piston to the cylinder once.

Tech Specs
Peak RPM
Clutch type

What else (That’s at least somewhat quantifiable) would be helpful to compare the two?

If/when an IAME shifter becomes a thing in the US, I’ll add that too.