Elevator pitch on shifter engines

So I’m considering building a shifter kart for next year to run masters/seniors, but wow there are a lot of options. KZ, ROK, Stock Moto, IAME SSE and various engine manufacturers for each.

Does any them stand out as superior, cheapest to run, most power, best support? What’s your 5 minute elevator pitch on the subject? Thanks.

I’d say Rok is a great shifter engine package, easy to tune, decent rebuild intervals and plenty fast. I made my Rok into a KZ these days (needed the HP due to Dad bod :joy:), but still have the bits to make it a Rok again when I want to run Rok events.

Just googled that conversion kit. I like that’s it’s somewhat flexible. Wouldn’t happen overnight but I could switch it up from running the ROK series to SKUSA.

Is there a Honda only series/class near you? If yea, Honda.

If no: Is there a ROK series/class near you? If yes, ROK.

If no: KZ… If KZ, TM KZR1

175 is a hard pass due to hard resale and lack of class support.

There was actually a respectable amount of shifters at the ROK challenge of the Americas this year. There were more shifters than ROK GP master, senior, & junior combined.

1 Like

I actually didn’t do that specific conversion kit. For the rules I run by we have to stay within a homologation sheet for a KZ. The Rok shifter is based off the Vortex RVXX (2010 homologation) so I sourced the cylinder and pipe for the RVXX from Italy. After some fine tuning on the package I now have no issues with power compared to all the R1’s I race against.

The standout engine is the RoK. Reliable, durable, inexpensive, easy to tune, easy to start, competitive with every other engine because it is given an appropriate weight break against the more powerful ones.

Having said that, if you have a point-and-shoot track of long straights and slow corners and hot weather to give good traction and sap power - you need an SSE 175. 51 horsepower is 51 horsepower.

Is the SSE equivalent or count as a KZ? There is some KZ racing around here, but I don’t see much in the way of SSE specific classes.

The primary driver for engine selection is going to be what is run at the tracks/series you plan to take part in.

Unless it’s just for lapping?

I can either run ROK for the Challenge of the Americas and Vegas race. Or KZ for SKUSA/STARS races. Just weighing my options and getting opinions. I’d rather not jump into an engine that is a pain to operate and trying to understand all the different options.

Not really and not really.

TM KZR1 is superior in raceability(?) to the SSE. You may turn close to the same lap times, but the KZ will put race every time with an equivalent driver.

Anyone recommending an SSE is either invested in the program or has one to sell.

Sounds like you can pick your poison KZ vs ROK.

ROK is more budget friendly, but not what I would call majorly.

Well at around $2k in initial purchase price alone it does seem more budget friendly. Jumping from Rotax/X30 I’m sure the ROK is plenty quick.


I have many thoughts on this, but from a high level view I think the Rok is the right choice for you. Fairly cost effective, easy to run, easy to maintain, and solid performance. If you get bored with the power (which you won’t) then you can upgrade to a KZ, which is more disproportionately more expensive relative to the performance gains, but if you have the $$$ and are looking for max performance then the KZ is king.


I’d recommend the RoK based on what you’ve said. Lower initial cost, lower TCO and you don’t have to play brand roulette.

1 Like

SSE is a 175cc engine meant to replace both the stock Honda and the KZ for SKUSA events. It has its issues (just try to start one on a cold day!) but if you have to bore a big hole in hot air it’s the tool for the job. If you’ve got a fast, flowing track the SSE’s Tillotson diaphragm carburetor will drive you up the wall as it is an all-or-nothing device and trying to modulate the throttle will just drain the dinky little cap and leave you out of gas just when you’re trying to get going again. I got lapped at New Castle trying to drive it like a TM.

This…you could run the SSE on a Dellorto setup, but the conversion cost makes it a tough pill to swallow.

You’ll be happy with the Rok. You can still run Rok at Stars if you decide you want to travel to the Midwest.


I’m the 90% of the performance for 50% the cost kind of guy. No need to chase a couple more HP for the extra cost and headaches. Kart will already be a rocketship with ~40hp so that’s fine by me.

I’m not necessarily needing to go fast anyways, this is more of a response that I’ve all but been eliminated from run KA competitively at the new 345 weight. I’d have to cut a leg off to make weight. I still don’t make weight in x30/Rotax at 360 after putting myself and the kart on a diet. This will be a chance to run some regional races in between the regional Rotax races.

I’m really only finding that SKUSA runs SSE as they seem to solely race IAME stuff. Is this correct? Not finding anyone else that runs it.

Some regional and local organizations have lumped the 175 and KZ together, as on track performance is quite similar.

1 Like

What’s the standard service intervals for the ROK? Top end every X hours? Bottom end is good for Y hours? Only need to replace gear oil when you do top end?

Rotax has me feeling lazy. I don’t do anything to it except lube the clutch needle bearing every so often, check it’s got water and go. I did 14-15 hrs on the top end and sent it in as a just because. It was just as fast if not faster from the day I pulled it out of the box.

Really wish DD2 had more of a presence, but I suspect no one wants to buy a dedicated chassis to only run one engine/class.