Switched from 20% to 30% on .28


Old 05-02-2019, 08:12 AM
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Default Switched from 20% to 30% on .28

have a losi rtr 8ight truggy with the .28 dynamite rtr pullstart. Broke it in on 20% because... well i had no idea they perform better on 30%, the instructions actually say 20% to 30% so i assumed 20% was just fine. Anywho i had it perfectly tuned for 20%. Richened it a hair before switching to 30% to be safe. Ran one tank mostly idling and never going above 50%. Second tank going semi hard and then third getting on it a bit. Probably not necessary but again to be safe. Trying to retune this thing. I got idle to what seems perfect. Bottom end goes, but the biggest issue im having is that it seems when i tune the high speed needle is no matter how much i play with it, even get it to what “sounds” right it seems that its top end is lacking. Like it whines out too fast. And isnt getting to “top speeds” atleast compared to what i had with 20% tuned right. If i richen it, it does what it would normally, sluggish slow too end but im afraid to keep leaning it out as when i do it doesnt seem to go any higher in rpms just temps are higher(still in safe area (no higher than spiked 228F while sitting around 200-205F around the glowplug and the top of the head spit doesnt sizzle for a while, manual says ideal temps are 240-265F but on the top of the cooling heads. Can never get a consistent reading on the heads where they want it to be checked.

Any suggestions? Idk much about bigger nitro engines or 30% nitro for that matter.

also i thought id add that it seems im burning through fuel faster.

Last edited by Dabeardedbro; 05-02-2019 at 08:23 AM.
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Old 05-03-2019, 12:01 AM
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It is all about ignition timing.

With more nitro you shifted the ignition to a sooner moment. That will give more bottom power but indeed affect the top RPM.
You can correct this by using colder plugs or adding an extra 0.1mm head shim with which you shift the ignition to a later moment again.
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Old 05-03-2019, 07:43 PM
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Default 30%

As the previous post said try a colder plug first ,see if that helps then a shim if needed. When you have higher Nitro your tuning window changes as well so just play with it until you find the sweet spot.
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