Is she toast?

[aMawds]

So I was running an OS .30VG in an Ofna X1 Truggy. I've been going to the track locally and learning the race line, learning how to tune engines, suspension etc. Basically, I'm a noob to nitro and land racing. I'm learning fast, and giving some of the other guys a run for their money with an old rig design and a less than optimal engine. However, the engine was running sweet and was working fine for me. I planned to drop a .21 in it very very soon but wanted to get some reasonable life out of this motor and keep it as a spare motor just in case, since it held such a great tune and ran circles around the more expensive rigs in the technical parts of the track as long as I kept my finger out of the throttle in the turns

Pretty much out of nowhere, the engine stopped idling properly. Flame outs every time I tried to allow it to idle longer than a second. I assumed clutch bearings and a weather based tune issue. Clutch bearings didn't seem terrible, and after just tearing into it today the front bearing is notchy but I don't think it was bad enough to cause such idling issues. Could be very wrong. I had a guy help me tune it and he ended up going way leaner on the low end and richer on the top. From there it ran like crap. I tuned it myself and it was back to blowing a healthy amount of smoke and running like a stripped ape, but still refuses to idle. I tried leaning the hell out of the low end again and could get nothing but a high idle or no idle at all. Just when I'd think it was idling alright, I'd run the track twice and it would flame out off throttle.

Now keeping in mind this is the moronic design by OS that is an ABL p/s rather than ABC which causes much faster wear, and this engine having almost 3 gallons through it, what do you guys think? I'm not spending money on it. It has much less pinch than when I got it (used, with the truggy, gallon through it already) but seems to run too damn well around the track to be out of life already. Then again I'm inexperienced so I'm just sort of stumped on the subject. Now if it's toast, I plan on putting a Werks B5 with a new clutch assembly on the truggy, but I literally just bought a new motor for my buggy and I'm not made of $$$. Clutch bell has grooves from me running the clutch all the way down to the springs. Noob mistake. Oops.

What do you guys think? Anything else I should check? Or are these mills so useless anyway that 3 gallons sounds about right anyway.

 

[Nitro Nerd]

Pretty much out of nowhere, the engine stopped idling properly. Flame outs every time I tried to allow it to idle longer than a second. Could be very wrong. I had a guy help me tune it and he ended up going way leaner on the low end and richer on the top. From there it ran like crap. I tuned it myself and it was back to blowing a healthy amount of smoke and running like a stripped ape, but still refuses to idle.

Okay no one has responded so I'll see if I can help. I am confused though. How do you know the guy who helped you tune went too lean/rich, etc. if you needed his help? Please take that with all due respect I'm just a little confused.

I've found tuning it is ALL about LSN/Idle gap. My 11-year old daughter can tune a HSN..."okay it's getting RPMs, now what?" ;-) Often I see people with lean HSN and fat LSN as it can be very deceiving. Sounds to me like the guy at your track was going in the right direction. You also have to define "sounded like crap". Were the balistic RPMs running on? You state you can't idle more than a second (BIG problem)....could you idle more than a second after he helped? To really set your race tune you'll need to listen to what it does after WOT so if you can't idle longer than a second perhaps open your carb gap so you can at least begin the tune? Either that or I'm seriously missing something (always a strong possibility). If you have it solved great, if you still need help I'll do what I can based on what I've learned.

 

[aMawds]

I'm not sure he went "too" rich or lean, but he did bench tune it and it did run like crap and high idle very badly after it warmed back up, flaming out often. It also got hot, quick. An update to this thread, I ended up buying two motors at once. A Werks B2 for the truggy in question, and a hyper .21 for my buggy to replace the toast RTR motor. So in a way, yes the problem is "solved."

When pulling the flywheel on the motor in question, the flywheel nut was finger tight, if that. There is obvious marking on the flywheel collet and the crank itself showing that the flywheel was occasionally spinning on the shaft. After plenty of research I see that the crank can then back into the casing, letting air past the bearing. I had PLENTY of unburnt fuel making it's way through the bearing. The bearing itself is very smooth with the crank removed, and with the crank installed and pushed fully back into the housing, I cannot blow any air through the bearing. Yes I wrapped my mouth around the front of my motor haha. There were also small markings on the backplate where the con rod had very lightly touched the back plate. Completely assembled, compression is great, but there is close to no pinch at all with the plug removed. I understand now that this is the point where the motor typically drops its nuts, and because it still has compression and the tiniest of physical pinch, the motor itself should be completely fine. I don't have a spare flywheel and clutch assembly to test this theory. As such, it's packed with ARO and sitting on a shelf all cleaned up and sealed. I need to repair or replace one of my tuned pipes and buy a couple packs of header seals before I worry about it again, and since it can't be reasonably run competitively I'm not too sure what to do with it anyway.