KZ Shifter - Cost of ownership

Yeah the difference between good and decent Honda’s was vast, and the consistency from cylinder to cylinder was not great. Castings varied across the years they were produced, and most series initially allowed ‘99-‘02 cylinder designs. The 99’s were quite different, so that added a layer of unnecessary complexity.

The thing is most of us at the club level (here anyway) didn’t care diddly squat if there was a 2% variation or whatever. Jetting and gearing made more difference. If you were serious about wining you ran one of the expensive IAME engines.

At least for me and a few others, it was about getting out and having fun, our version of golfing if you will. “Racing” was just the excuse.

Tons of good dialogue and ideas in this thread. For what it’s worth, I was just pointing out the differences between the running costs and ease of operation from KZ to Stock Honda. Both have their ups and downs obviously but I didn’t intend to turn it into a debate, that has been done enough.

The electric start TM is a great engine. I’d love to see that take off as the replacement class for Stock Honda with a claimer rule, that would keep people from putting a ton of money into a “stock” engine. Think about what has made 206 popular and carry that over to a shifter.

People don’t buy the Rok or TM KZ10ES because they are down on power to an open KZ style engine. People think they are just going to bolt on the best/most expensive KZ engine they can buy and then go win because they have more power. Of course, engine builders tell them this is possible because they want to sell engines. So you are new to the sport, have no mechanical ability but have money. You spend $7k on a new KZ package only to get it out to the track and have problems (carb, fuel pump, poor fuel/oil mixture, etc) then they don’t maintain it and the problems only get worse.

I think shifter karts are one of the coolest things out there but it’s a terrible option for most karters, especially newer ones. Add a KZ engine as the replacement for stock Honda and it gets worse.

Regarding bottom end intervals on the TM, 20 gallons of fuel is straight off the Swedetech website. Not saying that is right or wrong but probably a fair number to start with.

Full disclosure, I like the TM. So much that I used a pair of 10B’s to build a twin superkart. I bought 2 of them for the price of one new R1, I can do 90% of the work on them myself so that really cuts down on the running costs and parts are easy to come by. If you have to send the engine to a builder for maintenance it gets expensive fast and I would say 80% of racers will need to go this route.

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The thing is, higher HP = peakier power curve, which makes that power less user-friendly & more difficult to keep on the pipe, & as I posted previously, keeping a peaky, narrow HP curve motor in the zone on tighter courses is steepening the challenge curve. How many of the majority of drivers would really be able to discern any difference in their times between, say a full on KZ10 R1 vs KZ10ES in tighter courses?

Lower cost was the major selling point with the SM, & at the same time, nobody complained about it being slow; there’s relative parity between the TM-ES & SM engines in terms of both performance & cost. In fact, both motors are still classed together for the SIMA series, though SM entry numbers seem to have plunged up here in the PNW. It was interesting seeing different make motors racing together. Added some fun variety to the field.

Agreed! I think we proved each other’s points.

For the vast majority of karters, a built KZ style engine is a poor choice.

I’ll go back to the 175. I think that’s a killer engine package and wish it would have taken off.

It’s funny, I thought back when it was introduced, that the KZ-ES engines would kind of be more competitive with SM in that market, but TM didn’t have the name presence & “street cred” that Honda does here in the US, at least at that time. SM was the thing. So now the market is transitioning, the TM KZ-ES motors are available, offering relative cost-performance parity to fil that void. Meanwhile, SKUSA cooks up a new class based on the concept of top-level KZ performance minus the maintenance & cost. Enter the bigger bore 175. But the bigger motor doesn’t drive like the KZ, which, I guess, seems to leave people nonplussed about the driving experience. So now KZ seems to hold its own despite costing more. Meanwhile, KZ-ES offers SM like ownership experience without the carburetion & pump issues, being tuned & configured for karting. I have to wonder if SKUSA would ever give it a look, but I think they’re too far down the rabbit hole with the 175 to swing back now.

I’m just an odd duck.

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As a generalization, what percent of racers do you feel are “undertuned” to the potential of their shifter kart?

Odd duck? Yes from the standpoint of how many of these engines are in circulation, but I wish they had more market. It’s a smart platform that very few know about, if TM had a strong distribution and influence with organizations, then I think we would have seen quite a few of these in US. You mentioned the long intervals, couple that with spares that are cheap…you now have a great platform with no supply issues

No clue. Would take a polling effort beyond my capacity. Wouldn’t be surprised if it’s at least half of any local level grid. At least, I don’t think the difference would be notable between the 2 engine variants. But power is a selling feature. For the argument, TM rates the KZ10ES @ 40HP, so there’s that.

Any way, I recall some of the stories I heard about national ICC events back in the 90’s that made shifter racing sound like an exclusive rich man’s game, like competitors with racks of bleeding edge tuned engines (~$25K engine tune jobs weren’t unheard of) & other crazy stuff. The costs to be competitive sounded nose bleed level. I’ve heard of tuned motors that could push a kart to 3-figures on a sprint course. But then you’re tearing it down before the next race, or maybe even next race day. Certainly winning edge performance, but also a class-killer. It was the motivation for developing the SM class here in the US.

In that light, it’s ironic now seeing demand going to full-on KZ motors since SM started waning. Seems like the KZ-ES motors would fill in the space left by SM. I mean, the KZ has always been around, so what gives? I’m not getting the demand flip. Either costs aren’t a factor, or else it’s just a case of poor marketing &/or lack of national sanctioning body getting behind it as a concept.

Thank you so much for the documentation and openness with jetting. Can I ask what tool you use to file the ring gap?

Do you have any feedback or experience with some of the KZ jetting apps available such as the one from Jet Lab?

That’s exactly what I have inside the carb as it has
a 9304 tag. Our weather up here is usually drier than California and we are at about 3400 feet above sea level, I will have to go lower in main jet. I have been running Rotax for quite some time, but the KZ is foreign to me and It will be a steep learning curve in both driving and tuning.

Great tips on breaking in the engine and I will take my time as it is brand new and I want to treat it right from the beginning.

Thanks @Andy_DiGiusto for sharing. My son has just gone from X30 to KZ so this is great info to help with the transition. Does anyone know where to get a shop manual for the KZ10C. I’m looking for torque specs and baseline clearances. I can only find the parts list and homologation on TM’s site. Thanks

I’m not aware of any shop manuals from TM, at least not for their kart motors. You can surf general fastener (max) torque specs online, typically based on the material grade of the bolt in question. Your best bet would be to call Italian Motors USA & inquire. They’ve been a N. American TM importer/dealer for years, & have a lot of shifter/KZ racing & tuning experience in particular.

This list is in the KZ10 pages from their site:
5mm - 6 ft-lb 8 nm aluminum
6mm - 12 ft-lb 7 nm aluminum
8mm - 14 ft-lb 18 nm aluminum
12mm - 60 ft-lb 80 nm steel
14mm - 100 ft-lb 135.5 nm steel

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I have a friend that bought a new Titan Red from our builder, Darren Harden at HMG, and this is the jetting that we used for break-in during spring in Indiana (NCMP).

Some additional details that may be helpful for some:

I performed the break-in on track for him, and the motor ran flawlessly both during break-in, and afterwards once we leaned down the main jet for our fuel and weather conditions, which were as follows:

  • March 20th 2022
  • 1,416 Density Altitude
  • 95.9 ADR

Total fuel consumed on this top end was roughly 15 gallons (~56L). It was never jetted overly lean, and there were zero issues throughout the life of this top end.

One word of caution to those new to KZ and the TM-R1 in particular. In my experience the reed life is generally pretty good, but once they begin to fray the reeds can quickly fracture, causing a significant air leak and lean condition. My friend above had this happen on his last day of running on the aforementioned top end. It caused a noticeable rise in EGT, as well as signs of a lean condition upon inspection of the spark plug. There was no failure in this case because he paid attention to the signs, but these are definitely markers that you want to monitor every session, and I would also recommend inspecting the reeds after each day of use (minimum).

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Ring Gap - File for most of the removal then sandpaper for the final part for a nice finish

Jetting Apps - IMO not really needed. Once you have a primary carb setup you can just run up and down main jets depending on temperature. There’s already a setup listed in here for carb but here’s another that we run in our restricted class - safe above 10 - 15 DegC whatever that is in F…

#50 throttle valve
K8 mixture needle
DQ 265 main spray nozzle
CD1 idle diffuser
#50 idle jet
#150 main jet
#300 needle valve

Let’s go in order, as for the technical stuff:
1)For filing the ring, use a small file, then finish with 400/600 grit sandpaper
2)As for manuals, TM never wrote one for any kart engine. A good reference would be to use the IAME screamer manual. Just disregard the specifics, there are sections on how to route fuel lines, maintenance intervals, and an entire chapter on jetting. Again disregard the suggested baselines(those engines are peculiar) but the theory, concepts, how the changes, temperature etc affect the results are all good and usable if you are new to the platform
3)The jetting above with CD1/DQ265/150/K8 is a very unique one, with a big lean spot in the middle and at the end…I see what kind of manipulation is in the works here, but really unusual in my books… @ohasha : you mention you run a restricted class…what does that mean exactly? Are you running something different in terms of engine specs?

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On my Tm 10C I usually run:

DP268
Idle 60
Emulsion 60
K23 needle and using half steps
CD1
12mm float height
Main jet 172-178

Usually only needs to change main jet and clip position when needed, always runs fantastic!

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What is the actual size of the CD1? I don’t have one in my jet kit, so I’m not familiar. How does it measure compared to the other inner pilot jets?

Edit: @KartingIsLife- I should have known better than to hijack Andy’s thread. Maybe you could move this to its own KZ jetting topic?

The CD1 has an inner size of 1mm. So it equals a B100.

B50 equals 0.5mm etc I think :grin:

So what’s the difference between the B100 and CD1?