175SSE vs Modena vs TM KZ10c for “open” racing

There are some shifter drivers at my local kart track that go out on Sundays, separate to the regularly scheduled saturday races, and its really just meant to be fun racing. They don’t check to be sure were the same weight or any of that.

With that in mind, I’ve been in contact with a seller that has a 175SSE, TM KZ10c, and a Modena shifter motor for sale. All are in good shape. Disregarding initial purchase price, which would be the overall best motor?

Looking to compare in terms of ease of use, maintenance costs, overall speed, etc. I’ve read that the Modena’s have the best gearbox, the KZ10c pulls hard at the top, but don’t know a ton about the SSE. I think it’s a little more powerful and supposedly more reliable because of lower RPM limit?

Also, if you know of anything to look out for when purchasing any of these motors, let me know.

Your help is appreciated!

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I have now 3 KZ engines. How I ended up with 3 engines in my non prefered class is a mystery.
It’s been recommended to me, to change the piston every 4 hours on a KZ.
I read an article by Billy Musgrave on the EKN website https://ekartingnews.com/2020/01/06/taming-the-beast-iame-sse-175cc-shifterkart/ about the 175 SSE saying that he was getting 15+ hours out of a piston and 30+ out of the bottom end. That’s KA100 territory in terms of longevity.
I would trade all the KZs for 1 SSE.
Having never driven one, take that as you will.
However the biggest selling point for me with the 175 is the diaphragm carburetor, and not having to carry a box of emulsion tubes, needles and jets to every race sounds great.

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I looked hard at the SSE, but I went with the KZ10ES instead. A critical aspect concerning engines local support, & since I’m in the land of Italian Motors USA, which is all about TM engines in their service & track club class structure. This thing has an equivalent rebuild schedule to the CR moto engines or the SSE, primarily due to the ignition rev limiter.

Since I already have its ancestor, the K9ES, there was a familiarity aspect, & the ES version of the TM KZ engines kind of sold themselves to me back when I saw a prototype in 2006. I really like the battery + starter over push/stand spin starting, & the higher durability/lower maintenance schedule was just the ticket. The Euro SS has that, but sticks with the float carb. The SSE is still old school push/spin start, which is part of what kept me leaning towards the TM. But the SS/SSE do have the lower maintenance demands.

So, IMHumbleO, reliability is important. Just be sure to factor in local engine support.

This is pretty convincing. Thank you!

Electric start is nice. My local builder would support either really, so not so concerned there.

I wonder if the 175SSE could be converted to electric start with some doing.

I can’t say from personal experience, but to my knowledge from people that run the national scene the 175 hasn’t been great for reliability. Especially on longer tracks they wreck the bottom end or so I’m told.

I believe an electric start was considered initially for the SSE. It’s base product, the X30 Super Shifter comes with an electric start. You might be able to bring some starter parts from that? I can’t comment on compatibility.

All that said, if it’s just for fun, why not grab an inexpensive moto and see if you can outdrive the others?

The 175 issues I’ve heard of were both at the outset. Reeds cracking (resolved with a thicker petal) and some carb things that had to be worked out with the pumper-style carb.

I can’t say whether you are correct or not, however the article I linked admits issues were had with the Tillotson being assembled with the high and low needles the wrong way around.
Perhaps unreliability you have heard of comes from that time and the issue is now resolved?

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The issues I heard of were more recent, and the track was a lot of wide open throttle. The bottom end is the same as a 125 so the thought was the extra reciprocating mass due to the larger piston was killing the bottom end. Like I said, no personal experience but I know some people getting rid of 175s and getting KZs. That said, the Modena is a rocket and isn’t known for awesome reliability in its own right.

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There are differences. SSE runs a 22mm crankpin whereas the Screamer for KZ runs a 20mm.

I did not know that, but you are correct.

TM KZ10 series has a 22mm bottom end bearing. They originally started putting it in K9ES as part of the goal to up durability, then carried it to the rest of the line with the KZ10.

Honestly, the ES is a great engine. Slightly less output than a full on KZ, though it’s plenty sufficient for the club & maybe even regional level events. I doubt it would be a noticeable disadvantage vs full KZ, especially on more technical circuits. The return is a rebuild schedule on par with CR moto engines. Based on consumed fuel volume, top ends get a refresh at 100-140 L (26-37 gal), & bottom ends at 400-440 L (105-116 gal).

I hadn’t heard about the bottom end issues with the SSE. Maybe a 24-25mm bearing would have been the ticket.

Tm kz all day.

The modenas are great but stink for reliability. My buddy blew his bottom end, and was having non stop issues for a year. They are fast but can be a headache.

I have a cr125 and it’s fun but it’s hard to keep up to my buddies modena even though im a better driver. Takes a bit for me to make a pass on him.

175 is pretty well rock solid now. All the reliability issues were at the start of the program and have been solved.

A good KZ and 175 are on par with each other. When I say a good KZ, I mean a GOOD KZ. IE Expensive. More maintenance than a 175 as well.

Downside, not everywhere runs or allows the 175… Yet…

CR125 is gonna be out to lunch in a good field.

TM KZR1 is where I would be looking.

Thanks for the info, ill have to look into this. As far as why I’m not getting a moto, I have a seller that can make a complete shifter package with a used Modena, TM, or IAME 175. I am deciding between those three.

Do you have an approximate date that the reliability issues were fixed? This is helpful. I’ll look into this, but if you know off-hand that would be helpful.

I had only heard about issues relating to carburation, specifically throttle response, not the crank issue. Definitely want to make sure the bottom end is solid.

It didn’t take them long to figure out what was going on. It wasn’t even an issue with the engine internals. Tillitson was putting out carbs with swapped needles at the very beginning. People were using too thin reeds as well. They caught on and corrected. Any good engine guy will put you on a solid engine.

What about the crank bearing? Was it an issue, & was it addressed?

We have had TM-10C, R1, and now are on to Modena KK2. Honestly all engines are fairly similar and i think you would be happy with all. The R1 didn’t like to rev like the 10-C did, but had more bottom end grunt. The Modena’s seem to have the least bottom end but keep pulling up high. Never had any reliability issues with any of the three, and we road race and sprint. Lastly, don’t let the carb set up be scary. I saw someone say you need a case of emulsion tubes and needles, while yes we do have them, the only thing we ever change once it was set up is the main jets. No experience with the 175 however I’m not a fan of bringing in more engines and more classes.