First nitro car, high revs

[mrkennie]

Hi guys, my first post and apologies for being long.

I got my son an ACME Condor Pro for Christmas. Initial running up seemed to go well, after we figured out firing the beast up, it seemed real easy to start. The problems started on the end of the second tank when the engine just went to full revs causing the car to crash into a fence. Initially we thought it was due to interference from our phones but the throttle was at the lowest position. The tank was empty so we put it down to more air than fuel as it run out.

We refuelled and started it up and before we could do anything it shot off at high revs (we had no control at all) and crashed again breaking a front shock. We caught up with it but by that time it made a loudish puff sound and the engine stopped. The clutch bell housing was smashed to pieces and the clutch shoes were not in a good shape at all, lol.

All the spare parts arrived today and we replaced the clutch and shoes. Now it seems really hard to start, often resulting in a saturated engine. When we did manage to get it started it ran sort of fine for about 20 seconds but suddenly go into a fit and run at really high revs. Pulling the throttle back or forward made no difference whatsoever. Fortunately the pinion gears have been removed so it can't launch itself again.

I'm really not sure what could have caused this. Also, why adjusting the throttle makes no difference at all? Could this be a faulty engine? Or have I done something wrong?

 

[REVO-5309]

does the carb open and close when u use the transmitter. or is it stuck open??

 

[mrkennie]

I've taken the filter off and I can see that it opens and it does indeed open and close with the transmitter. I forgot to mention that the rocker arm also got snapped which I've also replaced. One theory I had was that this was the cause of the sudden high revs. I thought perhaps I broke or weakened it while holding the car down during starting and it got stuck full on? The results I've been having today seems to disprove that theory however. The throttle was at its lowest position with the trim on the transmitter turned right down.

 

[hamz9561]

The first thing that you should do is seal the engine with a good quality RTV silicon and let it dry at least overnight. You can get this at any auto parts store. Make sure that it is the sensor safe type.

 

[mrkennie]

I wish I found this forum before Christmas! Thanks for the advice. I was about to say "but it's RTR!!" and then I read and watched the videos in the stickies. =) Most excellent!

It does make perfect sense as fuel does leak out the back of the engine where the pull start is and it's actually taking the colour out of the pull cord. I've not seen RTV silicon before, at least not in the form seen in the video, can you point me to some links please?

Finally, those pesky hex screws and grub screws found on the pull start cover and various other locations. I can't seem to find a set of tools that fits these perfectly. For instance, I'm trying to dismantle the spur and pinion gear assembly and I need to loosen a grub screw to slide the gears off but it's impossible, just seems too tight and the allen keys end up burring off, even reasonable quality ones. Also, I tried to remove the back cover to give it a clean because of all the fuel but I just can't get a fit. What do you suggest here?

Tried metric and imperial sizes BTW.

 

[FrostByte25]

I've never sealed an engine but heres a few links to some diffrent sealents i have read of people using...
http://tkocompetitiondev.com/index.php?cPath=38_114 <---Lucky 7 Sealent
http://www.amainhobbies.com/product...237/n/Racers-Edge-Air-Seal-Carburetor-Sealant <---Racers Edge Sealent
Also I've found that using a Torx bit works better than a hex wrench on some screws..
FrostY

 

[mrkennie]

I've never sealed an engine but heres a few links to some diffrent sealents i have read of people using...
http://tkocompetitiondev.com/index.php?cPath=38_114 <---Lucky 7 Sealent
http://www.amainhobbies.com/product...237/n/Racers-Edge-Air-Seal-Carburetor-Sealant <---Racers Edge Sealent
Also I've found that using a Torx bit works better than a hex wrench on some screws..
FrostY

Thanks for the links. I know exactly what to look for now. I'll try some torx bits, I'll try and find a set that includes both hex and torx.

I'm guessing the tightness could be due to thread lock? Is it safe to apply some heat to help loosen these off?

 

[FrostByte25]

Glad i could be of help

Thanks for the links. I know exactly what to look for now. I'll try some torx bits, I'll try and find a set that includes both hex and torx.

I'm guessing the tightness could be due to thread lock? Is it safe to apply some heat to help loosen these off?

Heat might help loosen things up a bit...just dont get crazy with a heat gun and melt your surrounding plastic parts... I prefer to use my trusty hairdryer..

And you might want to recheck your idle speed needle...I've backed mine out to far before and got the rotatry part of the carb jacked up. Remove your air filter and see if indeed the carb gap changes while turning your idle speed needle...and maybe richen your lsn might help i think

FrostY

 

[mrkennie]

And you might want to recheck your idle speed needle...I've backed mine out to far before and got the rotatry part of the carb jacked up. Remove your air filter and see if indeed the carb gap changes while turning your idle speed needle...and maybe richen your lsn might help i think

FrostY

Is this the screw on the side where the rocker arm is? I can see the needle which moves in and out when adjusting the screw and when moving the throttle back and forth.

 

[mrkennie]

I've finally got the engine sealed up and it is much easier to start now. I'm just struggling to tune it, I try to restore to factory settings and work from there but nothing seems to work. I can get it "ticking over" nicely but when I pull the throttle it chokes with fuel spluttering out the exhaust. Somehow I feel it is running way too rich but trying to find the right balance seems impossible. Its not running anywhere near like it was when it was new. Not sure if it helps but often I have to leave the glow plug heater on for a while after it starts otherwise it just stalls as soon as it's taken off (or maybe this is what you shoul do? I just don't recall doing it before).

I'm close to giving up on this, selling it as it stands and going electric instead. Maybe I just chose the wrong car to begin with.

 

[hamz9561]

Let's start at the beginning here. With the receiver on remove the air filter and neck from the carb. The gap on the inlet should be about 1mm or the width of a credit card. Now start the car and see if the idle is solid. Since I'm guessing that this is a new car, that the engine isn't broken in yet. The engine is running rich. Follow this thread to do your engine break in: https://www.rcnitrotalk.com/forum/showthread.php?t=42716

Once your engine is broken in then go ahead and start slowly leaning out the LSN an hour at a time until it takes off without stalling.

 

[mrkennie]

Having read that thread, some perseverance and some borrowed patience I've finally managed to get it working much more smoothly. Fuel consumption is much better now and the throttle is definitely more responsive. I'm still fighting with the grub screw to change the pinion and spur gears so I can't road test it yet. Looks like I'm going to have to drill it out.

I'll keep you posted with how we get on and thanks again!