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Old 05-31-2010, 11:14 AM   #1
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Default had a runaway, now what?

When I was racing yesterday my Novarossi N21BF I bought used (but only 1 gal on it) ran away with me due to Rx loss of power (dead battery). I was up on the stand and I had to run down and get it to shut it off (on its lid). My concern is it sat there high revving on its lid while I ran down the steps and went to get it. Maybe around 10 sec max! I did manage to shut it off by plugging the exhaust.

My problem is now its being a pain to keep running. It would crank right up but then when you drive it about 20ft it would flame out. Then it would fire right back up and do the same. Even sitting on starter box running it didnt want to idle. Now this was my first time running this motor and my run away happened not long after installing the motor, so I can't say that the motor was in perfect tune from the get-go, but I can tell you it was at least going around the track. Do you think my tune got way off when I had the run away? Or is there something else I need to do/check?

I can't do to much now as I have to get another throttle servo (probably blown due to runaway stress) and a new Rx pack.

Also, one last question on run-aways, so obviously I dont want this to happen again, how can I prevent it? I fellow racer gave me a spring ("fail-safe") to put on the throttle side connected back to the HSN to keep the carb 'closed' if my battery dies again. Also note my radio is a spektrum DX3S

Thanks for the help in adv.
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Old 05-31-2010, 11:19 AM   #2
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I used to use an old manifoldspring. It was strong enough to move the servo when the battery was dead, but on the other hand its alot of stress on the servo and its gonna drain the battery faster. How much I dont know but still.
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Old 05-31-2010, 11:19 AM   #3
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Yes make sure to charge your pack and not run it for too long. As far as the spring use it! I use a rubber band but the springs work good too. this way when you look power it shuts the carb and no more run aways.
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Old 05-31-2010, 11:30 AM   #4
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Originally Posted by jeff_ellis_9 View Post
When I was racing yesterday my Novarossi N21BF I bought used (but only 1 gal on it) ran away with me due to Rx loss of power (dead battery). I was up on the stand and I had to run down and get it to shut it off (on its lid). My concern is it sat there high revving on its lid while I ran down the steps and went to get it. Maybe around 10 sec max! I did manage to shut it off by plugging the exhaust.

My problem is now its being a pain to keep running. It would crank right up but then when you drive it about 20ft it would flame out. Then it would fire right back up and do the same. Even sitting on starter box running it didnt want to idle. Now this was my first time running this motor and my run away happened not long after installing the motor, so I can't say that the motor was in perfect tune from the get-go, but I can tell you it was at least going around the track. Do you think my tune got way off when I had the run away? Or is there something else I need to do/check?

I can't do to much now as I have to get another throttle servo (probably blown due to runaway stress) and a new Rx pack.

Also, one last question on run-aways, so obviously I dont want this to happen again, how can I prevent it? I fellow racer gave me a spring ("fail-safe") to put on the throttle side connected back to the HSN to keep the carb 'closed' if my battery dies again. Also note my radio is a spektrum DX3S

Thanks for the help in adv.
Engine sounds like it's toast.


You never want runaways, always make sure your reciever pack is charged and don't run more then 45 min on a good fresh pack. Sitting tinkering also kills the pack too.

Get gmk bands or little rubberbands and make a return spring on the carb. this way when the pack dies it should return. May not always... but most of the time it should. I never had a run away on one of my race cars.

Check if you radio has fail safes when you bind it. set throttle to neautral in fail safe mode.
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Old 05-31-2010, 11:52 AM   #5
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throttle return bands to me are much more important the a fail safe. I use both but the return bands have actually saved me twice.
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Old 05-31-2010, 11:55 AM   #6
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throttle return bands to me are much more important the a fail safe. I use both but the return bands have actually saved me twice.
Yea failsafe is for the TX failing. Bands for the reciever pack.
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Old 05-31-2010, 12:19 PM   #7
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how can I check if engine is toast?

this motor is not old at all. just 1 gal
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Old 05-31-2010, 12:21 PM   #8
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Originally Posted by jeff_ellis_9 View Post
how can I check if engine is toast?

this motor is not old at all. just 1 gal
It doesn't matter how old it is, it matters that it was ran Wide open throttle for an extended period of time. It sounds like it's lost its compression.
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Old 05-31-2010, 12:53 PM   #9
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Default Maybe not.

Quote:
Originally Posted by jeff_ellis_9 View Post
how can I check if engine is toast?

this motor is not old at all. just 1 gal
yeah it sounds not too good. Did you replace a glowplug?
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Old 05-31-2010, 01:22 PM   #10
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Try replacing the con rod in the engine, extended high revs can stretch the rod and cause the problems your describing.
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Old 05-31-2010, 01:43 PM   #11
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Try replacing the con rod in the engine, extended high revs can stretch the rod and cause the problems your describing.
Yep what He said 100% Right. You need a new Rod and it should be Ok.
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Old 05-31-2010, 01:45 PM   #12
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any links please? for the con rod. Thanks
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Old 05-31-2010, 02:25 PM   #13
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any links please? for the con rod. Thanks
I really doubt if its you connecting rod. Thats a easy check, if it has little or no play its fine. More than likly that motor had a lot more than a gallon of fuel through it. Did you buy it from somebody you know, or was it just word of mouth? My guess is the sleeve is gone. Have it resized and you should be good to go for a few more gallons.
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Old 05-31-2010, 02:31 PM   #14
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put a new glow plug in it, i have had a run away and it did the same thing and it was just a glow plug, i ran it for another 6 gallons after that.
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Old 05-31-2010, 02:37 PM   #15
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^ I bought it from the guy that just replied, Jmaxey. But it ran fine when I first got it going. And I can tell by looking at the motor that it hasn't been used much.

But, keep in mind guys, I haven't had the motor running long at all to really get the temps up and get the tune exactly right. Im just telling you the problems I encountered after my run-away, BUT, could have just timed right that my tune was off.

Also, I forgot to mention, the fuel I was using I have had since about Sept last year.

hdcruzer, how can I check the play you are talking about?

oh and tried new plug
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