Any thoughts on the wear and blow-by staining below the ring?
TM R1 piston with 2.5 hours. Last race it overheated to about 160 on water temp (darn driver) but no noticeable loss in power. Location of staining looks to coincide with the exhaust port bridges which is where I would expect the cylinder to lose its circularity first when hot.
Definitely not ideal but is this typical for the amount of time regardless of the temp or is it a replace without question due to my lack of attention?
Replace without a question, what did you set the ring gap to?
TM has been offering reduced maintenance KZ engines since the K9ES debuted back around '07, & continues with the KZ10ES:
Rebuild intervals (based on fuel consumption):
Top end @ 100-140 L (26-37 gal)
Crank bearing @ 400-440 L (105-116 gal)
Also has a starter.
As for the piston above I agree replace for sure, but this is not normal, you need to understand what happened. It would help to know ring gap, why it overheated (e.g. forgot the curtain up or out of coolant? jetted too lean?) Look at my piston up above after 6 hours, barely any blowby visible. You also have a fair amount of wear on the skirt for 2.5L.
For the KZ10ES, that’s a lot of run time, basically double the interval! @WheelSpin : do you know how it compares to the 10C/R1 power wise? I know it’s de-tuned but not by much
Don’t know how all the metrics compare (although they have the same published HP ratings), but on a technical course, like I’ve often seen at the SIMA facility, the difference is academic, & more about the driver (no surprise).
Got distracted after a restart and forgot to pull the curtain down. Motor was as delivered (stocker-not factory prep) so initial ring gap was unknown. Also still need to check squish and timing FWIW.
Jetting was pretty conservative but road racing does spend a lot of time at high load so I assume that also contributed.
Overall I’m impressed that I didn’t have more problems. Temp came down once I caught it and was still pulling the same MPH at the end of the straight.
Oh yeah, that’ll do it. Yes change piston and needle bearing and you’ll be ok then. Inspect the cylinder wall for marks, but it should be ok.
Going forward, you can use your mychron to help…I’m using a blue light in the left for cold, goes away when engine is in temp range. Then I use the other one on the right, red when getting hot, blinking when over the max, at that point if I can’t get the temp down quickly, I stop
Had a light set up and I still missed it…
Guess I was having too much fun. Can’t fix that
I think we’ve all been there! Glad it’s not bad!
I use a red solid light for overheat and a magenta flashing light for EGT over limit. The only other red light I have on my display is the last “ok, you’ve gone way too far” shift light so the overheat light is the only solid red on there.
not to derail thread, but yeah I absolutely love my 80, i just find they require a bit more attention than stock honda or restricted ROK, and new piston every 3.5 hours (albet piston is $65 and you can do them in 15-20 minutes) but yeah the cr80 package is still a ton of fun and blast to race on hard tires.
4h on piston and 0.35mm ring gap. Barely any wear at all, runs on aspen 98 with 4% motul 2t oil!
Vertex piston, 53.93
Looks super clean! Have you had to tweak anything with the Aspen fuel in terms of jetting, advance or other parameters?
It is almost the same as normal pump gas. It has lower density so slightly more fuel is needed. But when running too rich it could pop sometimes, but the quality is excellent so zero problems. Ran it the whole 2022 season as it became mandatory 
Never leaves residue and I didn’t need to change timing. Running 1.1mm squish, 4 degree piston
I’m assuming F here,160 is nowhere near overheating. It’s not optimal, but definitely not overheating.
I’d sometimes see temps around 150/160 in road racing too. It’s not a cause for concern, but if you can get to 130 that’s not a bad thing.
160F. Running a big radiator, keeping it at 120 has not been an issue. (other than driver forgetting curtain). Usually have more of an issue getting up to operating temp, especially if it’s cold out.
I’m going to add in some of my experience based on running my first full year of KZ (TM KZ-R1) this year. Keep in mind, I was competing at the national level in KZ Masters, and was racing against others with highly-prepped engines from top builders in the country (SRP, Swedetech, Carblos). Point being, I optimized for performance at all times.
Top End:
I’m on my 4th piston of the season, and it will last me through any remaining club races and practice days for the remainder of the year. I have used predominantly aftermarket (Meteor) pistons based on availability, and these have proven to wear nearly twice as quickly as the OEM pistons (Vertex). I log my engine hours based on on-track time from my mychron that I enter into a spreadsheet, so I don’t account for warmup time on the stand. Not saying this should be the way everyone does it, it just works for me. That said, I’ve been replacing the Meteor pistons roughly every 3 hours. Some of this is because I want to go into a race weekend with a new piston, but also the pistons have about 0.03mm of wear at that time (same as Andy’s original post with 6hr run time on the Vertex piston). I have a Vertex piston that I sometimes use for practice, and it has less wear at 3.5hrs run time, so I’ll continue using that a bit longer.
Bottom End:
I started the year on a brand new rod kit, so new lower rod bearing as well, and haven’t touched it all season. I’m at around 11.5 hrs and ~110L of fuel consumed, so I’ll be right around 12+ hours and 120L once I finish my “season”. I use MS98L and Elf oil mixed at 5.3% (series spec), and the bottom end seems to always be getting plenty of oil. It looks great whenever I have the cylinder removed and am inspecting the engine.
I’ve had zero mechanical issues this year aside from a top side reed that was fraying slightly. At one point I was jetted slightly over the edge of lean, and had a very small amount of detonation on the center of the piston crown. I richened jetting for the next session and it was perfectly fine from there forward. I change my gear oil on similar intervals to what Andy suggested. I’ve installed new gaskets here and there over the season, but those amount to literally a few dollars in total.
Overall I’ve been very impressed with the quality of the TM R1, and it’s an absolute joy to drive. You’re going to replace parts more frequently than a Rok Shifter, but to me it’s easily worth the trade-up.
Great to hear! Since then, I actually sold my R1 to a former Honda racer who just switched platform, and he is reporting the same observations. In his case, went in with some fears (somehow, many people think these engines are ready to grenade in the blink of an eye) but he is now enjoying it a lot.
I’m actually surprised by what you’ve seen with the Meteor, those are high quality pistons (brand-wise) but I guess there is a lot that goes into a piston (shape, materials, process etc) that ultimately determines its longevity. Thanks for sharing!
The Meteor pistons definitely seem to be good quality, but they must have a slightly different alloy to the Vertex piston, or something of that sort. They’re lighter weight, and feel wise they seem to be lighter in the crown area, tough that’s just a guess. They work well when they’re new, but the quicker wear seems to cause a quicker drop in performance.
I have the exact same experience on the Meteor pistons, likewise performance when brand new compared to Vertex. But the drop off is more noticeable, Vertex keeps performing twice as long😁
The price isn’t that difference, so in the end it is pretty much cheaper to run Vertex cost/hours
