My b5 bailed me out today. It was the first race of the mountian rc pro series and all friday during practices my B7 in my buggy and B5 in my truggy ran great. Then saturday came and both went to heck. Couldnt get any bottem end pwer out of them By the end of the day the B5 was working pretty good but the B7 couldnt find the tune. So for the final i ran the B5 in both truggy and buggy. It sure got its work out this weekend .

how did you get 11 mins out of it?? my engine ran awesome today but I was only getting about 8 mins out of it coming off around 235..
what fuel? plug? how lean is it?

Hey guys need some help on this one.

My sons B-5 has less than 2 gallons on it. Could not get a tune on it yesterday. Everything was fine except for 2 things.

One was as he went full throttle to clear jumps the engine would make a screaming noise in the air. Half throttle and this wouldnt happen. Cant figure out why. It was only doing this on the track when their was a load.

He kept flaming out as well which very rear does that happen.

We ended up pulling the carb and sealing the neck just in case their was an air leak. It didnt help any thing. We were running a p-3 plug.

Any thoughts on why this is happening. By the way I had two very experienced racers look at and tune it.

Idle was dead on power was there smoke was perfect

my cousin's b5 was having flame out problems and no matter what always had to mess with the tune this weekend.this is his 2nd b5.the first one was awsome never had a flameout problem and never had tuning issues. it could be his tuning? the carb on this new b5 seems rough compared to his older one,what could be the problem? this was at the ACS yesterday.

dishsoap,you may of heard his name at the nitro pit,nathan wagner int.buggy.

Yes I have heard the name. We were at the ACS as well to finish up the last race of the series. I might put a nova carb on to see how it works out.

Dishsoap, unde load engines run leaner than without load. The engine screaming when at full throttle over jumps is a classic sign of being to lean, it's commonly refered to as running on. If you are seeing good smoke in the infield and a normal operating temperature then this would tell me that you are running a rich bottom and are too lean on top. Please go back and tune via my tuning guide and most importantly pay atention tonsetting the air gap first and then adjusting the idle with the LS. If you do this then it is impossible to have a rich or lean bottom.

You sealed the carb neck (which is not needed as we run 2 o ring on our carb) but this virtualy eliminates and chance of an air leak. So the only way a novarossi carb will make a difference is if you are way out of wack on this one and you are not when you put on the novarossi one initialy.

went to the rebel open this weekend, made the final after some rough qualifyers, anyway, engine ran perfect all weekend....unfortunatly I sucked some dirt in it from all the fine dust (and alot of it) at the track, But Alan Burton from the speedshop was there to give me a fine pinch and away I went to the 45 minute final, after once again a horrible start and dropping to last I made my way to 5 gaining on fourth due to being the only one who could triple double a section of the track, only to break a rear pivot 20 minutes in.. anyway had a top 3 or 4 car for sure and the engine performed better than I could ever hope for.. Adam Drake took the win by .8 over (TQ)Weatherholt but it was a great time, and thanks for these awesome engines Ron
MO

Hey ron or anyone with experience

My b5 lost compression after a gallon of fuel but it was my fault. I was running the motor below 200 degrees to tame it. When you run a motor cold the sleeve doesn't expand, the piston or sleeve just wears, correct? I was wondering if a pinch could restore it or should I just get another p/s. If I wore my piston down then it's probably best to replace the set. I'll probably just let Ray A decide what's best.

Ship it today USPS priority, and you should have it back by weekend, return shipping same method

RayAracing

A lot of folks run below 200, and you will from time to time, but as long as you're not trying to race an entire gallon in race conditions at like 110F, you shouldn't be going through pistons/sleeves because of it. Perhaps your air filter was letting fine dust in? How was break-in? Perhaps your needles were fighting -- if you have one needle over rich and one over lean, you can hide a lack of lubrication at times because your temps will seem normal due to the cooling effect of the over rich side of things.

As an example of needle fighting, the first time I had the b5 out, I had the low end set too rich and the high speed set too lean. I was used to tuning an OS motor and the LSN of the b5 has a larger range of rpm between normal off throttle idle speed and the fully loaded up idle speed, so I had artificially set the low end mixture rich and the high speed lean (to get desired acceleration). The motor seemed fine for the short bursts on the street, but when I got to the track, something wasn't right and on the box that two bursts of high speed made the second burst (where it was already cleaned out) cut out from being too lean when you got on the throttle. This let me know there was needle fighting going on. I quickly re-tuned the HSN from boggy rich without letting it idle much, then re-adjusted LSN and idle speed -- I ended up a good quarter turn or more richer on the HSN with the same performance and temps, just without the patchy lean condition. When the patchy lean condition hit, the motor was starved for lube, but the low end was rich enough that it kept the temps in check. If I hadn't caught it, I would have probably ended up with no compression after a while as it was raping the piston once the motor cleaned out on top.

Food for thought.

Are you sure that you are not confusing loss of metal pinch with loss of compression? The reason I ask is that even running a little rich it is highly unusual for a piston/sleeve to wear out in a gallon of fuel... If the compression is indeed shot I'd take a look at some other things like how you are breaking it in, possibly the fuel that you are using, make sure that you have not sucked any dirt and also double check your tune to make sure that you are not just running super lean on the bottom and fat on the top (which will wear out a p/s but still keep the overall temps low so it looks like you are running rich). Out of all of these I would lean towards the last as the more likely culprit. In any case, send it down to Ray and have him put a pinch on it. Once you get it back follow my tuning guide and you should be good to go. You should be getting 6+ gallons out of a p/s on a properly tuned engine.

Regards,

Ron

Just a suggestion on going with raya -- you may want to ask for the firm pinch instead of the default medium pinch if you're only a gallon in and exposed it to something that trashed the p/s. It will take you longer to break in, and you'll need a heat gun to start the motor like new again, but I think it is worth it incase there's some decent damage to the p/s that a good break-in might seal up. I got the medium pinch from raya on my vspec and it's still running good, and it is my backup motor, but the motor didn't keep as much compression/kick over as I would have liked after a while -- it *never* flames out and it still runs strong, but I would have rather broken in longer and had the re-pinch last longer given the terrible abuse the motor received before the re-pinch (I had a fuel nipple air leak that made the tune go wildly rich/lean and I pulled the motor off the track at 306F once).

As long as the rest of the b5 is in good shape, I'll be shipping my p/s to raya when it needs a refresh.

Thanks guys I'll get it out to Ray for a tight pinch. Then I'll study the advice so I can tune it properly. Ron i can push the piston to the top of the sleeve fairly easily. I'm running byrons 30 fuel 11 oil. I broke it in with factory settings around 15 tanks, figure eights in a parking lot. I just never got over 200 degrees.

Thanks for the response, Byrons is a solid fuel so that was not the cause. You might want to take a look at your break in procedure though. I've mentioned this several times on the thread but so called "factory settings" on carburetors are not "break in" settings. There are way too many variables that will not allow a guy in Italy (or Japan or China depending on where your brand of engine is made) to pick a needle setting to put on the carburetor before it leaves the factory that will guarantee a rich setting for you running your specific type of plug, fuel, pipe, length of fuel line and atmospheric conditions. These engines have to be tuned after being installed by you to a rich setting. Running "factory settings" for break in is like playing Russian Roulette, sometimes you will be fine and sometimes things will go wrong. But why take the chance? Try following my break in procedure that I posted in the thread if you do not have a system that you normally use or are unsure no how to do this. If you have any specific questions or need more help please do not hesitate to ask!

Regards,

Ron

Just wanted to thank Ron for putting such a great engine on the market at an incredible price! This last weekend at the track with the B5 equipped Losi was the most fun I've had in this hobby so far. My last vehicle started as nitro and I ended up converting it to brushless because of all the nitro related problems I had. I decided this year to take a risk and give nitro another try. The B5 has been great and I'm really glad I decided to go the route I did. Can't wait for our racing season to start!