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HomeAircraftHelicopterKyosho Caliber/Quest Neo-Caliber series › Fixin' to join the Nexus club...
06-05-2009 04:32 AM  9 years agoPost 21
ShuRugal

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Killeen, TX

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i fill the tank through carb line with the exhaust line disconnected. have had the muffler off and made sure cylinder drained through exhaust port repeatedly.

could something be causing the engine to flood and lock before it ignites?

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06-05-2009 04:44 AM  9 years agoPost 22
dkshema

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Cedar Rapids, IA

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There's only two ways out of the tank...the main pickup line and the vent. It shouldn't be difficult to see which one is the problem.

Meanwhile, until you get the darn thing adjusted, you might try to keep the tank a bit lower than the carb inlet to prevent siphoning.

Perhaps prop the front of the skids up a bit higher than the rear.

Use a fuel line clamp when the heli is just sitting with fuel in the tank.

Is the muffler exhaust somehow plugged? That would really pressurize the tank in a hurry when trying to start the motor.

I owned three Nexus, never saw the problem you seem to be having.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-05-2009 05:17 AM  9 years agoPost 23
ShuRugal

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Killeen, TX

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muffler seems to be clear, the tank is only about half full.

It it possible that the battery in my glow plug heater was not doing the trick, when i had the plug out to dry it i put the heater on it and it didn;t glow much. Changed the battery and got the whole element glowing. this was right before last start attempt. After changing heater battery, the motor almost caught, but then the shear pin snapped.

Any ideas? the fuel level in the tank is low enough to prevent siphon, the muffler is not clogged, it just wont catch.... breaks my shear pin instead.

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06-05-2009 05:46 AM  9 years agoPost 24
dkshema

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Cedar Rapids, IA

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A few questions...

Is this your first nitro motor?

What starter are you using?

What voltage are you driving the starter with?

What are you using to replace those pins that break?

Is this a ringed version of the OS 32SX-H, or is it an ABC/ABN version (no ring)? The ABC/ABN version can be extremely tight at top dead center, and difficult to turn over.

Before you try to start it again, pull the plug, then spin the motor with your starter. This will blow excess fuel and oil out of the cylinder and clear it well. (Beware, you can get a really good shower if you're standing in front of the glow plug opening when you do this).

I guess the motor is used. Did you peek inside to see if it's in good shape?

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-05-2009 05:57 AM  9 years agoPost 25
ShuRugal

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Killeen, TX

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yes, first nitro

starter is some 12-volt starter i got from local hobby shop, the only one they had, its out in the garage right now or i'd tell you exact model.

running it off a motorcycle battery that is no good to start a full size engine anymore, but runs motor fine.

replacing the pins with HO-scale train axels (my father has tons of them, and they are exactly the right diameter, just trim length)

there does not appear to be a ring on the piston. i can turn it over with my fingers on starter shaft, but with only great effort. looked in the exhaust port, piston looks fine.

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06-05-2009 12:38 PM  9 years agoPost 26
rpat

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Weirton, W. Va.

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shu,
Get yourself a fuel shut off valve. you can get them at any hobby store. As soon as you reinstall you fuel line on the carb after refueling the fuel will want to run into the carb as a natural flow. Keep the fuel shut off valve off until you get ready to start the engine, then release the valve.

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06-05-2009 03:29 PM  9 years agoPost 27
dkshema

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Cedar Rapids, IA

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Those HO train parts might be the right diameter, but most likely not hard enough. Just how hard does an HO train axle need to be?

There's a lot of force being applied to that little pin when you blast away with your starter.

I think I saw a comment further up to find the proper size DRILL BIT and use a Dremel to trim it to length. Short of that, I would imagine some proper (or very close) diameter music wire would do in a pinch.

Great little fuel clamp:

http://www.heliproz.com/prodinfo.asp?number=106455

Don't leave home without it.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-06-2009 03:19 AM  9 years agoPost 28
ShuRugal

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Killeen, TX

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well, i managed to get it started again, ran for about thirty seconds, but then i pulled the glow heater off and it died... i guess a nitro needs a minute or two to warm up eh?

couldn't get it started again though, the shaft i made to replace the original starter shaft sheared off at the pinhole, guess i just need to wait for the proper replacement part i ordered to arrive.

argh... wont be here till at least monday, i wanna get this bird running proper so i can fly it D:

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06-06-2009 03:56 AM  9 years agoPost 29
dkshema

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Cedar Rapids, IA

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NO, nitros don't need "time to warm up". If the needles are properly set (even close to being set) and you have a good glow plug, they start, and they run. There is no need to keep the battery connected for long.

I'll guess that the motor sat for quite a while unused.

I guess we really need to start at the beginning. Have you replaced ALL fuel tubing, is the muffler tight to the crank case?

If the motor sat for quite awhile, there could be numerous things wrong. Glop in the needle valve spray bar, bad O-ring seals for the needles and carb body to crankcase junction, bearings doing weird things.

Try a new glow plug.

Is your fuel good? Fresh, and had been kept tightly sealed?

This is not going to be an easy thing to fix long-distance if you're not familiar with motor tuning.

My usual procedure with a stubborn motor would be to tear it down, clean it out, inspect it for wear or damage, then carefully reassemble, setting the needles to factory recommended settings.

These things are pretty straightforward to set up and adjust.

Is there anyone local who can help you?

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If it quit when you removed the battery it could be an indication of a too rich setting, or bad glow plug.

While it was running, were you getting a lot of fuel and oil out of the exhaust?

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-06-2009 04:29 AM  9 years agoPost 30
ShuRugal

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Killeen, TX

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there is a local hobby shop that does a lot of RC stuff, the guys there seem to know their stuff. seller said he ran the motor before listing and it started fine for him. i had it running for several minutes twice on wedensday before the starter cup was just too loose to continue.

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06-06-2009 08:27 PM  9 years agoPost 31
ShuRugal

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Killeen, TX

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Ok, i got the motor started again today, ran it for about 10 minutes, but unable to start again. Same problem: motor turn and turns and turns but wont catch, when it does it dies almost immediately or as soon as i remove the plug heater. Went to hobby shop and bought a new glow plug, but my current starter shaft has just had too much abuse and broke off at the shear pin (pin didn't break, shaft broke at hole).

i suppose that's what i get for making my own shaft. I suppose i could make a new one, still have about two feet of steel rod, but i think i'll just wait until the replacement part arrives.

hopefully the new shaft will be sturdy enough to get the motor started.

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06-07-2009 12:57 AM  9 years agoPost 32
Quickster

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Victoria, Australia

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I had a Nexus for my first bird and i never once broke the start shaft or the little pin at the bottom! The only thing i did shear off was the clutch shoe bolts! But that was only when the clutch and engine were badly aligned. Are you sure your not too rich on the mixtures? That would cause it to die when removing the glow warmer! Especially the low end. Also did check the clunk line in the tank? It coould be perished or have a hole in it. I would replace all fuel lines just to eliminate that as a cause.

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06-07-2009 01:00 AM  9 years agoPost 33
Quickster

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Victoria, Australia

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Just another thought! You may have a hair line crack in the crankcase that is opening up as the engine warms up and causing it to quit. This would be hard to see if the engine was cold however!

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06-07-2009 01:34 AM  9 years agoPost 34
dkshema

rrMaster

Cedar Rapids, IA

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If you can't get it running and there's no good local help, you could send me the motor, I'll take a look at it, fire it up, and see what's up with it.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-07-2009 01:48 AM  9 years agoPost 35
Quickster

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Victoria, Australia

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There you go! Thats the sort of help that makes this forum such a great resource! Good on ya dkshema.

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06-07-2009 01:50 AM  9 years agoPost 36
ShuRugal

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Killeen, TX

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i think i am just trying to start it too rich, and am compensating with too much throttle, which is just flooding the cylinder with enough fuel to extinguish the glow plug. for the ten minutes i was able to run it i checked control input response and blade tracking (both are great) and after i brought it back down to an idle it died. i then noticed the grass in line with exhaust port was soaked. i think i just need to set my mix needles in some more and try again.

any suggestions on what i should try for settings? i have been using factory settings for both (1.5 turns out on the needle, the screw turned to shoulder is flush to throttle body wall as shown in picture). I am probably gonna set each in half a turn and try from there.

hehe, hell, i know i', starting it too rich. Just remembered that on one start i forgot to reconnect fuel line after fiddling wiith other stuff, and the motor started up almost instantly, then revved up and died in the space of three seconds. When i put the fuel line back on, it didn't wanna start again.

The reason i keep breaking shafts, i think, is that the replacement i made is made of too soft steel, and the abuse of spinning it ten seconds at a time repeatedly for several minutes is taking a toll on the softer metal.

i think if i get the correct shaft and find the correct mix range i should do OK... though i may tear the motor down completely and make sure nothing appears damaged.

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06-07-2009 08:13 PM  9 years agoPost 37
ShuRugal

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Killeen, TX

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Ok, i think i have it done up more or less proper. Made a new shaft, this time used the drill bit i used to drill the shear pin hole as the shear pin. hopefully no more slop in that fitting means i'll quit breaking the shaft.

To get the motor started i set the both mix screws a little less than half a turn back from factory (that makes it richer than factory, yes?) and it started on seconds try. first try i had them half a turn in and it wouldn't start, so i turned back to factory and it started, let it run for a few minutes, it seemed too hot, so turned half a turn back and started it again (was able to start it in about 2.5 seconds with starter motor on it).

idle no longer goes down when heater is removed. got the throttle hold setting so it idles well (set to 18%) and set idle-up switch to 70% throttle (just so i have a second option while fiddling around, i dont plan on trying anything fancy yet).

I had throttle curve set to default, and pitch curve set pretty low (54% on high end and 19& on low) to get the pitches reccomended by manual, but was still unable to lift off like this.

So i flipped into idle-up and was able to lift off. my yard is decently sized, but not anywhere close to level, so i didn't get more than a few inches up at a time. i noticed that the cyclic controls are a bit funny, instead of pitching forwards with forward cyclic, it want to pitch forwards and a bit to the left. instead of back, back and right, etc etc... Is this normal for this model? do i need to set up mixing to counter?

had one bit of a bad spot though, when i satisfied myself as to the functionality of the bird and turned i'dle up off, the idle didn't come down. So i hit throttle hold, nothing. zero stick, throttle cut, nothing and nothing. Looked at the side of the bird and saw the throttle servo-arm resting against the skid with part of the throttle lever still attached, the lever on the carburetor had broken off at the bend... so i set negative pitch, got a long stick (well, two wooden arroes zip-tied together) and wielding my jacket (good hearty denim) as a shield, plugged the muffler and the engine died.

when hobby shop opens tomorrow, i am buying the stiffest most heavy-duty part they have to replace it, i do -not- want to have to do that again...

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06-07-2009 11:50 PM  9 years agoPost 38
dkshema

rrMaster

Cedar Rapids, IA

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With the 32 -- once you get it running, use your THROTTLE TRIM tab on the TX to keep the darn thing idling.

Then, increase throttle up to the hovering point. Adjust the low-speed needle to give you a good, solid transition from idle up to hoverig. NO blubbering, spitting, coughing, or just flat out dying.

When you achieve decent hover power AND a good, solid transition, you need to go up to full throttle to adjust the high speed needle. Adjust for good, solid power -- Full collective should allow the heli to go vertically without sagging or bogging down from overheating.

Recheck and adjust the low speed needle, and your idle setting, and check the top end a couple more times.

The low speed needle is effective up to perhaps 75-80% full throttle. It interacts to a large extent with the high speed setting, so you need to re-check both needles when you get close to the correct setting.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-09-2009 02:21 AM  9 years agoPost 39
ShuRugal

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Killeen, TX

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Got the throttle control arm replaced. local hobby shop doesn't carry that sort of part, so i fabricated one out of heavy-gauge brass, taking pains to apply heat while bending it so as not to make it brittle. I am satisfied with the integrity of this new part, i applied pressure to it in numerous direction with my hands, and was not able to flex it with my bare fingers.

Started it up again to continue tuning the mix (started with only half a second of starter motor application!) and discovered a massive exhaust leak. took a closer look at fuel line and it is bubbly... which would explain why i have been needing to run rich...

So i took the muffler/manifold off, put RTV silicon on the manifold and bolted it back to the motor to cure. however i cannot get the muffler to come loose from the manifold, and i think that may be where most of the leak is... turned the pinchbolt as tight as i could get it, hopefully that will take care of it. I guess i'll find out after the RTV cures.

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06-09-2009 03:51 AM  9 years agoPost 40
dkshema

rrMaster

Cedar Rapids, IA

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took a closer look at fuel line and it is bubbly
Would that be the fuel line between the carb and the tank?

Even with an exhaust leak, that line should not be full of air bubbles, and an exhaust leak will not cause bubbles like that in the main line between the tank and the carb.

There would be two causes of air in the main line to between the carb and the tank:

1. Somewhere between the klunk(that weight inside the tank that is on the end of the pickup line inside the tank) and the carburetor nipple is one or more holes. Replace ALL fuel tubing, inside and outside the tank. Fuel line doesn't last forever, it rots and does all sorts of nasty things as it deteriorates.

2. You have some serious vibration caused by an unbalanced clutch, clutch bell, flywheel, and/or fan. Possibly the whole thing mounted to the end of the crankshaft is not centered well. Check and balance the stuff that spins that's tied to the motor and clutch assembly.

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A header tank attached to the heli -- between the main tank and carb will filter out any bubbles and keep the flow of fuel to the carb going as it should.

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There is supposed to be an O-ring on the muffler header that plugs into the muffler body. If you loosen the pinch bolt and GENTLY spread the pinched area, you should be able to twist the manifold and pull it out of the muffler.

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Good luck, it sounds as if you're getting there, just very frustratingly slowly.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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HomeAircraftHelicopterKyosho Caliber/Quest Neo-Caliber series › Fixin' to join the Nexus club...
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