• Welcome to RCTalk! 🚀

    Join the #1 RC community where hobbyists connect, share, and get expert advice on RC cars, trucks, boats, drones, and more!

    • ✓ Friendly & passionate RC enthusiasts
    • ✓ RC tips & troubleshooting
    • ✓ Buy, sell & trade RC gear
    • ✓ Share builds & upgrades

engine problem

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
M

miami fanatic

RCTalk Qualifier
Messages
174
Reaction score
0
Points
0
RC Driving Style
I just purchased a novarossi 421b. I broke it in carefully.I used the bess method of heat cycling. The problem is after i broke it in i tuned it at the track.I ran one week of racing the motor ran between 270-275. Then i lost the compression. When i took the air filter off there was a little dirt on top of the carb. I was just wondering if this could be the reason i lost compression or could i maybe have a cracked fuel tank because it leans out on the bottom half of the tank. :shrug:
 
are you sure the headbolts are on snug? the carb as well? If not you may want to check the piston and sleeve for any marring or scratches.

The leaning out on the bottom half of the tank is almost the norm for most mills. If you add more fuel to the tank that should go away. Never tune with a half tank. you get incoorrect tuning. If you do have a cracked tank, disconnect both lines to the engine and the pipe and blow into the Back pressure line while pinching the other line. If you can blow threw continously and not feel any resistance then you may have a crack.

good luck

Jon
 
my 421b is a top. i had a similar problem with mine. not even a gallon and there is no pinch left and the rod even has some play in it. i have been accused of not breaking it in properly and running it too lean during break-in or thereafter. jim hottinger at fusion motorsports told me i would have to mail the motor to him so he could look at it. I'm not too happy about doing that because there have been several complaints on these motors. i was told that we are all using the same clutch we use on our p5's and that the 421b needs an aluminum shoe with 1.1 springs minimum. using anything else will cause you to have to lean out the lsn too much therefore causing serious damage to the motor. to me thats like telling me i dont know how to tune a freakin motor. mine has never been too hot and always had some blubber throughout the rpm range. my main problem with it is the fact that it likes to flame-out for no apparent reason. i dont know if I'm going to send this motor off or just call it a lesson learned, but what i do know is that I'm switching to picco and i won't buy another nova based motor for a long time.
 
When you say you lost compression, does that mean then when you stopped the engine and you could easily turn over the flywheel by hand? Well, there's really only a couple of things that can cause that, and it's all at the top of the motor. Either your button/head is loose and/or damaged thus not sealing properly, or the piston/sleeve is shot. If the latter is the case, no amount of sealing or tightening will help you. You may be able to get the sleeve pinched, but I'd be concerned about the root cause of the problem.

But I'd probably replace the shims and glowplug and see what happens.

My engine isn't a "Novarossi" engine, it's a Medial Pro, but it's a basically just a Novarossi mill that's JP modified. It's got over a gallon through it now and it's got even more punch then it did when I first got it. You can not turn over the flywheel by hand. Most folks agree that Novarossi makes some of the best engines you can get, so this is very unusual. Perhaps they had a lapse in Quality Control or something.
 
all of my past nova based motors were good mills. all it takes is one "oh poop" to wipe out a hundred "'ata boys". I'm concerned about their recent quality control. way too many complaints lately for me to trust them.

i can honestly say that none of my p5's ever flamed out for any unknown reason. i hope this m2k holds up better than my 421b. i have a big race this weekend and can't afford to take any chances so I'm gonna bite the bullit and run my old paris picco. it has more power than any novarossi motor I've ever had and i can't see any sense in saving it forever.
 
flash said:
all it takes is one "oh poop" to wipe out a hundred "'ata boys". I'm concerned about their recent quality control. way too many complaints lately for me to trust them
Click to expand...

I suppose so.. Although I have not personally heard much in the way of complaints about Novarossi engines, or the 421b in particular, if they have a problem with this engine it's too bad.

But I dunno, I mean, I've had good luck with Sony equipment, and I've also had bad luck with a few of their things too. But I'll still buy Sony in the future. I won't rule out an entire brand just because I had one bum DVD Player or Speaker.

As far as I've observed, all of these R/C companies have their fair share of problems in their products, including the real expensive ones like the Kyosho Kanai buggies.

Good luck with the Picco. I've never seen the Paris engines but I'm sure they're good because they put the word "Pro" on 'em.
 
i dunno. i may switch back soon. its hard to hold a grudge for very long. like i said- all of my other novarossi motors have been great. thanks for that last sentence...that made me laugh. too many times the word "pro" is misused. not the case with paris motors. they are good.
 
It was brand new so everything was tight when i took it apart the only thing i saw was there is alittle bit of dirt on top of the carb when i pulled the air cleaner off i never put oil on my air cleaners could that be my problem but i clean them after each week of racing
 
Hmmm,,, after looking at your first post, then looking at your second post, it sounds like you might have some issues with the way you install / maintenaince your airfilters, I know everyone likes to make a bigger deal than it really is,, but I'd bet a dollar on the air filter,,, ...
If you already have some fluctuations in the temps you're seeing on your motor.. you might want to have a hobby shop or a knowledgable racer help you with dissassembly of the motor and making sure the entire interior of it is clean, just by READING your first post (come on guys who are talking about non-helpful stuff here) it sounds like you have some amount of dirt inside your engine(micro or otherwise),, when that happens, that play in the rod/crank-pin is what you'll get, since the dirt likes to settle there. After reading your second post, that's almost certainly a place you'll want to start with....
The 421 is a ripper of a motor, but it is an AAC motor not an ABC motor so it seems to be more sensitive to heat and to any outside grubbery... (dirt)
if you're getting stalls or flame outs, run a hotter plug (lower number) , since the temps seem to fluctuate, you might want to make sure you're using the recommended Nova6 or 7 plug in it,, ...

Again no one above seemed to respond to you seeing dirt on top of the carb AFTER you took the air filter off, that's a major red light,, MAJOR RED LIGHT.... so before you go through anything else,, start at the base of the problem and work your way forward,,, dirt is the number one killer of engines,, lean screws is right after that....

k have to go ,, paint,, i know this is only partially explained,, but post again,, when i get a chance i'll try to help more,, or send me an email and pictures of the interior of the motor,,, [email protected] , ill try to help as much as possible...

Lates!!
-Will-
www.WilzWerx.com
 
Ohh get off your high horse man, if you got something to say then say it, but don't bash the rest of us because it's not what you would have said. We're not paid to be here, we're here for fun.
 
cbreaker said:
Ohh get off your high horse man, if you got something to say then say it, but don't bash the rest of us because it's not what you would have said. We're not paid to be here, we're here for fun.
Click to expand...

Who are you talking about?
 
I think he's talking about Hirez.
But you know what? He's right.
Cbreaker, He didn't say that you were wrong, he just said that know one responded to the dirt.
Don't be so critical of peoples advise.
 
so is the dirt the whole problem do i need to oil it i just clean really well with soap and water let dry and go race. It worked well with my ready to run cars last year
 

RC Builds

Back
Top