This new engine just run 4 hours, the piston melted as photos attached.
Could someone identify what could be the cause?
I am so new on shifter, has very limited knowledge …
Tks guys in advance.
This new engine just run 4 hours, the piston melted as photos attached.
What fuel, oil, and mix ratio?
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Signs of piston hitting head judging by the ring around the entire piston.
Consider:
Insufficient head to piston clearance (Commonly called squish)
Or
Failed components in the bottom end allowing the piston to make contact with the read.
Signs of detonation too which is often caused by jetting that’s too lean. It could also be caused by insufficient head to piston clearance.
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Looks like detonation.
-check jetting, looks lean
-check the squish gap
-check timing
Looking at it you where lucky, always check the piston top when finding the correct jet. I use a small stick light through the exhaust port and looks down sparkplug Hole.
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fuel is 98, 4% of mix ratio
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fuel is 98 4%, main jet is 160, is it too lean?
The EGT only reach 600C, which I was told 650 is optimal ?
May I ask with is optimal squish gap?
Could this caused by over revo too often, like 16K?
Seems like you have detonated a lot. Could be caused by tight squish, aggressive ignition, poor fuel or lean conditions
Tons of detonation, and on the intake side which is kinda weird… I’d guess the squish is set really tight and the 98 octane is not enough. Could be that the engine was setup for 112 race gas?
To me it looks like you’re set up way too aggressive for whatever fuel you’re on, and that’s causing the detonation. Which specific fuel are you using?
A safe squish measurement is typically around 1mm when measured one side at a time, parallel to the wrist pin. You’ll also want to verify ignition timing as others have mentioned.
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I would stay around 1mm that should be on the safe side.
Between 0.90 and 1.00 is optimal, less you need special fuel/head insert, increase risk of detonation/sensitivity to jetting and lose top rpms in favor of (less usable) power.
The piston above looks grossly detonated, you said 160 main but what tube/needle were you running? What EGT reading were you seeing?
Overrevving certainly won’t help.
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Hi, I wish I could answer your question on type of tube/needle on it, but the fact I have no idea. I unboxed, installed it and run. This is brand new TM R2 Total Black I bought from Italy with its stock setting.(maybe?)
EGT is 600C
May I ask for squish, what would the difference could that gap make ?
Also for the timing ? how will I know it is the optimal angel?
The term “Detonation” mean “Knocking”, pre-ignite before piston rise to its top ?
Sorry for question, if sounds stupid
Feul is 98,
By saying aggressive set up, do I need to use lager jetting from 160 to 165 or 170 ? What would be recommned me to do?
There are a number of factors. Ignition timing, squish (distance between piston and combustion chamber outer rim), are the primary ones altered for tuning. More advance and tighter squish need more octane or more fuel to cool the piston.
Also, jetting requirements change with atmospheric conditions.
My guy please share your carburator setup so we can help. If you don’t know what is inside, remove the three 4mm bolts at the bottom of the carb and take a picture of all the components you see. Remove the needle from the slide with a 9mm long socket.
Please also share atmospheric temperatures.
EGT temperatures don’t mean much when you are leaned beyond any reasonable operational parameters.
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Needle is K98
atomizer is DP268
Main jet 160
Atmospheric temperatures was 25C
Hope these would help.
Tks.
The squish is 1.02mm
Oh, well, thats plenty of squish.