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Old 12-19-2008, 01:03 PM   #1
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Default RB c6 l2g tuning troubles...

A couple months ago I purchased an RB concepts c6BB l2g. I heat cycled the motor for break-in and everything went surprisingly well. It has held that tune like a vise for just over 1 gal. I am very careful to check the temp often (never been over about 240, and stays there very nicely) make sure I always have a pretty good stream of smoke, and I do use after run oil to make sure to keep the moisture out.

All of the sudden my motor flames out consistently. Because of the history of this motor being so solid, I checked everything else first. I looked for air leeks in the fuel system including exhaust pack pressure. I checked for faulty glow plugs. I serviced my Fioroni clutch, and then put a brand new one on just in case it was causing problems. I went back to factory settings and retuned from there. Actually I will note that the what seems to be optimum running settings are very very close to the factory defaults (good smoke, good temp, good response). I have had several other racers that are better then me check my tune and they have made minor adjustments but always ended up returning them to where they were. I have checked the pinch when cold, and although it is not as tight as it was new, it certainly has a good pinch. It seems to be most evident after going slower through a technical section then getting on the gas, it flames. Bottom too rich right? Tried that. Too lean? Tried that too. It seems to run great when its up to temp and on the starter box. Stick it on the track, I get problems.

So I leave it to you. Anyone know what I am missing? What I should be trying? I am getting very frustrated, because this once so impressive engine has me stumped.

BTW, try not to flame me, I am just trying to learn =)
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Old 12-19-2008, 01:13 PM   #2
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My suggestion to you is to maybe disassemble the engine and check it out. Check all the carb needle seals for and cracks or abnormal flat spots. Check the fuel system to make sure there is no contamination in the tank of fuel lines. then the fuel tank for a crack and possibly the tank lid seal as well. i run this engine in my RC8T truggy, well the older BB version. hopefully this will help you out in finding the problem. I dont think it's the engine personally. Just my 2 cents


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Old 12-19-2008, 01:22 PM   #3
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If you haven't already take the carb off clean the base and seal it with some sealent and if that does not help It may be time to replace the front bearing. I had the same problem when I first started running 8th four years ago, would run fine for about 2 minutes then it would load up in the infield and clear out on the straight. Check out Boca Bearing's MX Ceramic bearings. I own two C6 BBT7 and they run consistent every time I start them up with no problems. What plug and fuel you running?
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Old 12-19-2008, 01:27 PM   #4
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Yes, I am with you, or was...
I actually just bought a new Xray 808. I built the kit, installed this engine and am having the same problems. I guess this rules out 'not the engine' unfortunately. Unless of course If it is my driving style which, hell, that has caused me many problems before

I might have to disassemble as you suggest and see where we are at. I will wait until I am committed to installing a new engine and then see if I can recoup this one. Thanks for your thoughts.
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Old 12-19-2008, 01:29 PM   #5
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I am running RB turbo medium (#6) plugs.

And no I have not sealed the engine. That could be my problem. If someone has a good tutorial on sealing feel free to post it =) thanks.
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Old 12-19-2008, 01:33 PM   #6
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pull out the high end needle , check for obstructions , clean out with denatured alcohol , lube with synthetic oil and re assemble . you should never need any sealant on a novarossi based engine . if anything replace some o rings . i would definitely suggest a teardown and inspection of the engine if the carb idea doesn't fix the problem .
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i will check it out for free if you want .
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Old 12-19-2008, 01:36 PM   #7
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please also try an odonnell 77t or 97t plug , for some reason the nova based plugs are hit and miss lately . trust me , i have went through all types and have found alot of issues with them this past year .
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Old 12-19-2008, 01:42 PM   #8
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Wow, thanks for your input. I will definitely try the needle idea first and follow up with a plug replacement. In some ways it does 'feel' like a plug problem, however the plugs are always clean and shiny. Sometimes a little too wet, however if I lean it up the problem tends to get worse quickly (and heat becomes an issue). In some ways I hope it is the plug, that would be an easy fix. However I have a lot of those $11.00 things and so I kinda hope that's NOT the problem =). Thanks again.
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Old 12-19-2008, 01:52 PM   #9
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Quote:
Originally Posted by Larks View Post
Wow, thanks for your input. I will definitely try the needle idea first and follow up with a plug replacement. In some ways it does 'feel' like a plug problem, however the plugs are always clean and shiny. Sometimes a little too wet, however if I lean it up the problem tends to get worse quickly (and heat becomes an issue). In some ways I hope it is the plug, that would be an easy fix. However I have a lot of those $11.00 things and so I kinda hope that's NOT the problem =). Thanks again.
i was gonna ask what plug you were running right before i seen you post the plug . trust me i have had this issue over and over , i try to use nova plugs and engines just die for no apparent reason , a little disheartening to me as i really believe in novarossi quality (in case you haven't noticed) . i talk to the powers that be and they tell me they haven't had a problem they know i am very experienced in the engine department yet still dismiss the problem . of course i am not sure what i would do if i had about 5 million $$ worth of bad product either trust me the odonnell plugs will work great !!!!
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Old 12-19-2008, 02:18 PM   #10
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From what you have posted I would look a bit further on air leaks..but When its on the box (wheels off the ground) it runs fine..Have you tried running a 3 shoe clutch set up? hows your bearings..clean, spin free..Just wondering..

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Old 12-19-2008, 02:26 PM   #11
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that is a helpful little diagram you have there
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Old 12-19-2008, 03:00 PM   #12
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I have this same engine but the bbt7 version, engine would always flame out for no reason sometimes after a fuel stop sometimes for no reason, I switched out to a o.s p4 plug and have never had one flame out since. I was also running a #6 RB turbo...

2 other locals run the C6 also with the same flameout issue went to a P4 after I did and have also never had any flameout issues.

but on my s3 lg2 I have had great luck with the rb #6 standard plug? go figure
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Old 12-19-2008, 03:22 PM   #13
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Quote:
Originally Posted by houston View Post
you should never need any sealant on a novarossi based engine . if anything replace some o rings . happy motorin' ,
monty

I have a question for you, what makes a nova rossi based engine any different when it comes down to a air leak? I have seen numerous engines that all they needed was a little more help in preventing a air leak. 10 minute job will save you hours of headaches, try me.
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Old 12-19-2008, 03:41 PM   #14
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perfect fit and finish on all the oring locations and just plain high quality is what makes nova engines different . some manufacturers just have bad fitting and design when it comes to oring seal locations . the only time i ever used air seal on a novarossi(i have had hundreds)engine is when i had a bad oring in the carb seal area (my fault) and it just had a minor mistune at that (slight lean bog). and by the way it was a jp block .
happy motorin' ,
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if for some reason there is a necessity to seal an engine up , do it without taking it apart . go around the neck of the carburetor , both sides of the carb lock , around the outside of the back plate . the newer racers edge stuff is what replaced original air seal .
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Old 12-19-2008, 03:43 PM   #15
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On the issue of not needing to seal a nova based engine. I have never had a problem with air leaks on my RB's. However I have noticed after I seal them which I do generally after a gal or 2 the performance is better. Maybe it's me or maybe theirs a small enough air leak to deplete performance but not make engine flame out. Keep in mind ever air leak is not major causing flame outs but enough to deplete the valuable performance.

p.s. thanks for the diagram and the plug advice. Love people who post with education and solutions in mind.
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