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Old 11-30-2014, 07:49 AM   #31
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Too wide at 1mm. Told you its a small engine and cant be treated like a .12,
.15 or .21. My adjustment, .05mm or smaller. Got to idle like a Harley. You can not hear it running 5' away. All of my engines run that way. It takes time!! But possible. Its better to have a radio that has EPA and Servo speed, makes it a lot easier. Photos attached. Note: How far the LSN turned out!! It possible! Sorry its so dusty, its on my shelve since '06. I would think between Turnigy and Xray Clutch parts could be interchangeable b/n 1/16 and 1/18 models. Xray has three different clutch bells, and aluminum clutch Shoes and springs. Find them online through Stormers Hobbies, or where you can find them.
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Old 11-30-2014, 11:07 AM   #32
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If I get the idle anywhere near as low as what you're talking about, the engine just shuts off after each speed run.

The gear pitch on your clutch bell looks to be finer than the gear pitch on mine.
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Old 11-30-2014, 01:29 PM   #33
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Gear pitch all universal on small models And 10th -8th scale. It take time and patience to get it idle that way, its possible!!! 1/4 turns on it you should adjust by a hair at a time or 100ths of a turn. took me 3 days.
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Old 11-30-2014, 03:51 PM   #34
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That level of precision may be possible, but it's impractical given the wide temperature swings I see on a daily basis where I live. Yesterday it didn't get out of the high 30's, and today it was 67F. For the sake of not having to retune the engine every single time I want to run it, I err a bit on the side of caution with everything except the HSN, which is easy to adjust mid-run when necessary. Among other things that means setting the engine to idle a little higher than ideal.

Shaving the clutch shoes to reduce their surface area, and replacing the clutch springs just in case they were starting to get soft, seems to have made the difference I was looking for. The clutch now engages just above the bottom of the engine's powerband, instead of just below the bottom of the powerband, and because the shoes are a bit lighter now, they aren't dragging on the clutch bell even a tiny bit, so I was able to tune the idle down a bit without risking stalling after a speed run.
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Old 11-30-2014, 04:37 PM   #35
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67deg ambient temp was here also. I run a hotter GP lower then 72. What temperature after a long run, and at idle. do you run at track or a basher. I live in Vegas, what's your location.
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Old 11-30-2014, 06:08 PM   #36
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I run an O'Donnell hot glowplug year-round, because the engine is so small and loses heat so easily. I aim for 250F peak temperature, sometimes I get up to 265F by accident, but after yesterday's rebuild the engine is running happily at 230F. When I leaned it out to get a higher temperature it stopped idling-down after speed runs, so I enriched it again and left it alone.

I just bash my vehicles, there are no tracks within an hour of where I live. I live in northern Virginia, where the ambient temperatures would be warm and humid all the time, except for cold wind from the Midwest and hot wind from the south. The only time the weather is the same two days in a row is when it's way too cold or way too hot to go outside for very long.
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Old 11-30-2014, 09:27 PM   #37
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Been in the hobby since '82. Traveled to Ct, FL, Tx, Ca, and Thailand to race. Run every weather you can imagine. Run O'Donnel fuel, strictly RB engines. And all Serpent Models.

Racing engine experience Champion Auto Race Teams(CART) '95-'98 season. Or Jimmy Vasser, Alex Zenardi and Juan Montoya. NHRA with Super Shop '91-'93 Team Eddie Hill. Was a mechanic from '77-'84 specializing on Porsche's, Speedster, 356, 911 carburetors. So carburetors I know about.

Carb adjust to easy for me to do. Local tracks, when someone knows me, experienced or rookies, they come and ask question. If you understand Vacuum, Fuel flow, Metering rod(HSN), idle circuit(LSN), Some nitro engine has Mid-Range Needle(MRN), And know how to use them. Its easy. This is too easy for me.
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Old 11-30-2014, 10:52 PM   #38
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I'm not doubting your expertise, I'm doubting whether it's actually possible to improve on the performance I currently have, given the age, small size, and high-stress of this particular engine in this particular application. I've been working on it for about a year now, and I've had a much easier time tuning larger engines.

I never did understand how mid-range needles work. I know what they're supposed to do, but I can't imagine the physical arrangement of parts that enables it to work as intended.

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Old 12-01-2014, 08:19 AM   #39
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MRN is part of the LSN. LSN is taper at the end. LSN fits inside the MR. And where is the high vacuum occurs? At the end of the venturi(airgap). Flat spot when accelerating occurs cuz there a lean condition abruptly. remedy you want the LSN rich the a split second or blue smoke. All nitro RC engine has a high point in rpm's. As you say power curb. and always constant. Like the HSN,LSN is always constant when set. Depending on your ambient temp you not adjust more then a 1/4-1/2 turn. Technical from saying richening it up, that's the way engineers talk and they understand what your speaking about.

Can I ask, what radio are you using?? Toshiba or Airtronics?
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Old 12-01-2014, 11:47 AM   #40
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Ah, so that's how the MSN works. Thanks for the explanation, that makes a lot of sense.

All my vehicles are using Spektrum radios.
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Old 12-01-2014, 01:38 PM   #41
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Spektrum TX. Play with TH Travel(EPA), to where the slide on carb clear the venturi. Anything more than that, a waste. Then play with your Servo Speed TH. You'll find the engine responds better and quicker.
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Old 12-01-2014, 03:43 PM   #42
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I set the throttle linkage by loosening the retaining clamp, pulling the throttle trigger all the way, opening the throttle all the way by hand, and re-tightening the retaining clamp. That way the throttle servo opens the throttle all the way and no further, with no need for a spring to keep the throttle servo from pulling too hard and damaging the linkage.

Servo speed is set at 100% and can't go higher; the power supply is already 6V, and any higher would burn-out the servos.
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Old 12-01-2014, 03:50 PM   #43
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*facepalm*

I just realized why the engine was running cooler after the rebuild. When I reinstalled the heatsink, I applied a tiny amount of Arctic Silver 5 thermal-transfer compound to the area where the heatsink touches the cylinder-head, and then I smooshed it around a bit, removed the heatsink, and carefully cleaned off the excess before reinstalling the heatsink. It was running cooler because heat was escaping from the cylinder head more effectively.
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Old 12-01-2014, 06:13 PM   #44
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Go lower than 100%. You'll find in slow speed the accel is smoother, Try 80% and see the differance. Years agoI stop adjust linkage the physical way. With Toshiba, Airtronics and Spektrum TX's easier to adjust electronically. And more accurate and it stays on memory in modals you have.
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Old 12-02-2014, 11:37 AM   #45
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You're saying to turn *down* the throttle servo speed? Interesting, I never thought of doing that, it would certainly eliminate temporary leaning when accelerating hard, but it would also slow down brake response, and I'm not sure I'd like that. My little TNB uses Hitec HS-5055MG servos, which are equally tiny, and they probably take half a second to move across their entire range of operation. Would turning down the throttle speed further actually do anything useful?
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