according to everything i've been told, all the Nitrotecs had 17011s

Speaking of Nitrotecs, I heard they started shipping them with the correct head shimming (.80). This is where I get confused... According to the manual, it says that it should already have 2 .30 shims and 2 .10 shims, but according to the settings document, it says to:

Head Shimming: Remove 0.10mm shim, leaving two 0.30mm aluminum, one 0.20mm copper shim.

http://www.losi.com/Products/Support...rodID=LOSR2800

I guess the only way to know for sure is if I remove the head and check. It's running very well after 2 gallons I'm afraid to mess with it.

I wouldn't mess with the shimming until well in to the 3rd gallon then. If its running well don't touch it.

agreed, if it aint broke, dont fix it

I came across a new TOP T421B, I think it's a 2004 model. What can I expect from it?

That's what I thought. Trouble is though, I also have a Roma 25 and it has a shit bearing in it.

The Nitrotec is an older motor, by build date any way, both only have about three to four liters through them, but the cheaper one made in same factory has the superior bearings. I don't want to bag novarossi but does this mean that there quality is going down hill of have I just got it all wrong?

Please advise

I have the same engine about 15 litres %25 Merlin Pro, I'm using 0.7 shimming which is most nova's like it, Manuel says that shimming for %30 Nitrotane fuel , If you are not gonna use %30 ,remove it

not all Novas come with the 17011 anyways. They probably didnt put one in the Roma in an effort to keep the price down a little. Truthfully, the demand for engines larger than a .21 has gone down significantly, even for truggies, so they probably didnt feel it was necessary to put the 17011 in it.

No matter what front bearing is in your engine, no matter what manufacturer, you still will have issues with your first one anyway. The break-in process is tough on front bearings. My bro put a 17011 in his P5XLT before he ever fired it, it only lasted 3gal before he had to replace it, so its not an end-all solution to bearing issues. Personally if i get an engine with a"sub-par" front bearing in it, i just plan on replacing it after a gallon or so.

My buddy just bought a Dynamite Platinum .21XP Euro, which is a rebadged Alpha, he bought TKO ceramics for it, but he did his break-in and ran it to a gallon before he replaced them. The front was pretty much junk at that time, rear was fine, but to me a $15 bearing after a gallon isnt a bad practice if your engine comes with a lower-quality bearing from the factory

Thanks mate. That's a good clear explanation. I have two new 17011's coming so I will replace both either way.

Hi Guys,

Newbie alert. I have a Plus-4 Tuned (my first nitro exprience), with now about 6L through it, and so far it is running very nicely. There is talk through this thread about replacing bearings, rod, and even p/s/r. While I understand the value of engine maintenance and that it extends the life etc, I am trying to understand the value proposition of the various replacements against just buying a new engine.
The 17011 front bearing is ~$30, so no issues with doing that
The 16800 rear bearing is ~$50 (16801, ceramic ~$100, is it worth it?)
The R7 rod is ~$50+

So far up to ~$150. For an engine worth only ~$250, is it worth it? I'm not trying to throw money away, just trying to figure out if the outlay extends the life by enough, with good enough performance to justify it, as opposed to buying a whole fresh engine.

Is it worth just putting a new front bearing in now etc. How do I know when to put these new bits in? Typically how many times do people replace these through the life of an engine?

Sorry for the newbie questions, just trying to learn. And while this thread has lots of talk of these topics I didn't see a post that really answered these questions (apologies if there is one)

Thanks, makes sense, this is my plan for now.

I'm running 30%

6L isnt a lot of fuel through you engine yet, however the first thing that you may need to replace is the front bearing, the 17011 is an excellent choice for that. For Rear bearings, they dont need to be replaced nearly as often, i've gotten upwards to 6 gallons (22L) without needing the rear bearing replaced. In a lot of cases i've bought a new motor before i ever replaced a rear bearing. Buying the Novarossi replacement for the rear isnt necessary IMO. A cheaper Aftermarket one such as a TKO or Protek will do the job just fine and you can get Ceramic for less than the cost of a new Nova steel one.

For the Rod, again wont need replaced for a long time. If you have a set of digital calipers, you can measure the wear on the rod and crank pin to determine if they need replaced. Your crank pin should be no smaller than .192" and your rod should be no larger than .198" and no more that .006 total difference between them. I have over 4 gallons(15L) on my P5XLT and the rod is at .1965 so i would say you can get well over the 6gallon mark on a rod.

So basically, assuming you have no catastrophic failures, lose and air filter, have a runaway, etc. you should be able to get away with just changing a front bearing on it, maybe a rear at some point and keep running it. If you get to a point where you have a ton of fuel through the engine and your piston and sleeve fit becomes too loose, you can sent them out to reputable resize expert such as RayARacing. Ray does an awesome job and IMO is the best in the business. He can recondition your piston and sleeve back to like-new condition(requiring a new break-in and everything) for far less than a brand new set

Im at almost 3 gallons on my plus 4 btt and am showing no signs of premature wear. In fact when cold its still hard to turn over by hand Just use a quality fuel like byrons (i like 30/11) and you will be good to go for a long time. Like stated above the novas will last a long time if taken care of. The 17011 bearing sould be i stalled at about the 2 gal mark.

agreed, the wear on my 4gal old engines is barely measureable, def cant tell by just looking at it. I had a TKO in my P5 from the start, and just replaced it about a half gallon ago. My Toro at 4 gallons still has the original 17011 in it. I dont mind replacing bearings in these things ever so often, the rest of the parts are of such high quality that they simple dont wear out like some manufacturer's parts do.

Thanks Megasaxon, most informative. My plan then will be to replace the front with a new 17011 in ~4L time as a preventative/routine maintenance measure. And I will check the rod for slop and roundness periodically, and replace the rear bearing if it sounds like a rattle. Thanks for helping a newbie out!