Idle speed rises or motor quits when tilting heli

[CustomPC]

Hi,

I was working on my Spectra this afternoon.

I noticed when i tilted the heli towards it's right (exhaust) side about 30 degrees the idle speed rose by quite a bit.

When I tilted it over to the left (carb) side the motor quits.

I was able to do this several times. What could cause this?

Here are some details that might help the diagnosis.
I'd just put the carb back on after checking the Insulator bolts.
Both needles are at 1 3/8.
I have the Z-RC insulator installed.
It is a brand new NGK Iridium plug
Fuel is regular unleaded with Red Line Racing Two-Stroke oil at 66:1
Tank was about 1/2 full at the time.

[bigrcr]

Are you sure that the fuel line was hooked back up to the carburetor inlet, and not the return line (make sure thy are not crossed)?

Are you running the vent check valve and if so, have you ensured that it is operating properly?

Later,

[CustomPC]

Hi John,

Yep, the fuel lines are plumbed correctly.
I'm not using the one-way valve at the moment. I have length of medium tygon tubing which is looped twice around a frame spacer above the tank and then drops down below the tank level. I was wondering if having such a long vent line could cause such a problem.
The tank is the regular 8oz Nalgene bottle located in front of the motor (position 2 in the manual). The vent is in the center of the tank and was clear of the fuel when i was tilting the heli.

I'm suspecting my clunk line. I'm using the same size id tygon tubing as supplied with the kit but the stuff i have feels a little bit stiffer. I don't think the clunk moves around the tank as freely as it did with the MA supplied clunk line.
How long should it be? At the moment i have it the same length as the one supplied in the kit which is enough to let the clunk lie across the tank at the end of the bottle.

I've checked the insulator gaskets but i'm going to double check it all again this evening. I'll also put back the NGK CMR7H plug i was running before (to eliminate the plug as the problem).

[Toadster25]

Maybe try and see if there is air in the fuel line going to the carb when it dies.

[rbort]

I've seen this before on my heli, last week actually, but today its not there (checked it) after reading your post last night.

A couple of things to note:

a) I am using the z-rc insulator and it happened with it.
b) Last week after this was happening I noticed that my tank stopper was deteriorating. It was black for a dubro tank. I could have sworn I thought it was a gas stopper but I was not 100% sure as I had it in a bag seperately with a small piece of tygon tubing as it came from the manufacturer. Anyway I went down to the hobby shop and bought a gas stopper, but this one was brownnish not black. I put it in and everything is running smoothly now and the problem of a racing idle is gone.

Not sure if the stopper caused this or this problem is a come and go issue. I didn't notice any problems in flight really, just when you lean the heli the idle speed picks up. Didn't do it today so good news I guess, but I don't know what caused it or how I fixed it besides changing the stopper.

Lastly, I have much better luck with the CMR7H plug more so than the iridium plug. I bought one of them ($10) and basically it didn't perform as reliably as the CMR7H. I think it got fowled or something, noticed at full power climbout the engine blubbered. With the CMR7H it runs smooth and strong, and been like that for a good time with no issues. I don't think the iridium plug is worth its weight...

-=>Raja.

[CustomPC]

Hi raja,

Yep, the Dubro gas stopper is brown and the glow stopper is black.

Just for info sake, for sullivan tanks, their glow stopper is white and their gas stopper is black. A few gas boat racing guys have suggested to me that the sullivan gas stopper will deteriorate so they recemmend the dubro stopper in either brand of tank.

When i get home tonight i will check my clunk line for twists and freedom of movement, use some larger tygon tubing on the vent and replace the iridium with the CMR7H. I'll also remove the carb and re-check the gaskets.

Are you using the carbon heat deflector plate? I read Carey Shurley's article in Rotory Magazine and he suggest to use it as it prevents hot air from the cylinder blowing over the carb. I PM'd him about it's use with the Z-RC insulator and he suggests to still use and he was going to try it with the unsulator. Just wondering if other's are using it and what sequence they installed the gaskets and plate. I'm not using it now and i don't think it has any bearing on my current problem. I'm just curious about other opinions.

BTW, whilst we're on the subject of spark plugs, what effect does excessive gap have on the motor's performance.
I originally set mine based on the Zenoah manual at 0.6mm and couldn't get it to run well on the Australian equivelent to camper fuel (it's called shellite and i believe it is Napha).
I've since done some research and found that most recemmend a 20 thou (0.5mm) gap.
I've set my gap for 20 thou and was wondering if it will make enough of a difference to warrant me trying the camper fuel again. I still have 3/4 gallon here.

[rbort]

I must have had a sullivan stopper then. It was in a bag sealed with a thin piece of tygon tubing that my friend gave me before he moved to Chicago. I think what happened is what your friend told you, as it wasn't like melted or anything like that but chunks of it were in the tank. Weird. Well now I have the dubro one so I should be in good shape.

Honestly I never found the need to play with the gap. I've done alot of work on my cars and every time I bought a spark plug for my car it came gapped right already from the manufacturer. I've kinda come to the conclusion that when you take a plug out of the box the gap is right unless you drop it or something like that. I just take the CMR7H plug out of the box and put it right in. I never check the gap! Not sure what will happen if you open or close the gap, runs great as is so why mess with it?

I don't use the spacer carb plate, not even from day one. Mine is still in the spectra-g box. Hanson told me not to mess with it as that is another place it can leak air. The heat thing is a non-issue for the carb, at least I've never seen any ill effects from not using the plate. I would say don't worry about that one.

-=>Raja.

[Billme]

When you tilt the heli from the very first crank of the day, you are sucking air thru the front bearing, which leans the engine increasing the idle... Sometimes it will kill the engine if to much... This is what got me to running the front seal, but to be honest, after the engine warms up, it should go away as the crank, and bearings exspands..If not, you have the option of putting a seal on it:)
Bill

[CustomPC]

Hi Bill,

Can you please elaborate. Which is the Front bearing? Pull Start side or fan side?

At the time i found this problem the motor was nice and warm. It had been idling for probably 4-5 minutes. Although it probably wasn't up to operating temps.
When i tilt to the right , motor speeds up enough for the clutch to start grabbing. Tilt to the left and the motor slows down and quits.

Motor is mounted in Spectra-G in rearward facing config.

[rbort]

I started mine and tilted it right away today and no problem. I landed after a flight and tried it again later and no problem. But it did happen to me last week, now its gone. I thought it had something to do with the tank stopper, though that doesn't make sense but that is the only thing I changed...

-=>Raja.

[Billme]

Its the fan side which is the front.. I'm sure different condistions can effect when it does it...
What you desribe is probally when you lean to the right, it sucks air, and when you tilt to the left, it seals up , and due to the low needle rich, for that postion of the idle, it dies.. Never adjust the needles for idle...Only hover, and full power...
Zenoah understans this situation, and is called leakage. They allow for it to a certain point.. So long as you can adjust it, or compensate for it with the needles...The reason some engines do it, and some don't is one crank may be undersized a bit...When you tilt, the crank because of gyroscopic action wants to oppose the tilt, and if any slack is there, it will move allowing air to enter...
On the Predator, there is enough room to keep both bearings, and still add a seal... On the Spectra, you'll need to take the front bearing out. and add the marine seal, or find a real sealed bearing to replace the front bearing. I use to think you realy needed both front bearings, but not any more...Even the car engine on the varios machines do fine without the two bearing... The stabalized clutch design of the Spectra takes the side loads very well....
So long as its smooth in a hover, and doing well in other manuvers, you also have the option of not doing anything... There are a lot of machines doing this that most don't even catch this..
Regards,
Bill

[CustomPC]

Thanks Bill,

So basically what you're saying is that it is fairly common and it will have no effect on the flight performance.
I was a little worried that the motor would quit and die if i banked into a turn or went inverted.

[Billme]

It is common, but for us diehards, it bugs us a little just knowing its there, hehe...Enjoy your machine.....
Bill