I have both and to be honest there isn't a big difference between the two on track. My virtus has a little more runtime than the keep-on. The price of the standard virtus and the keep-on /s is around the same.

The front ceramic bearing isn't really needed so if I was choosing between the keep on full ceramic and a standard virtus with a steel front bearing then I'd choose the virtus without doubt. It's a better engine.

noted with thanks
very useful point of view - I'd expect more interest in having full ceramic ...

I think it simply comes down to the cost difference between main only ceramic and full ceramic. There is a benefit of having the main bearing in ceramic but not so with the front bearing IMHO. Especially if not racing at the very highest level.

front ceramic is not reliable compare to steel

Steel or ceramic is maybe noticeable in the hands of a toplevel driver, I am pretty sure 95% of the drivers have no bennefit of ceramics.

Beside that, the Virtus and Keep-on do come with impossible bearings, only ceramic and only available from Novarossi for a special price of 100+ dollar while a TKO ceramic bearing for a 35+ will cost you 30 dollar. The main bearing is one of the things which needs to be replaced periodly......
http://www.murnanmodified.com/produc...f8e9bef77d5680

Maybe something to considder.....

Roelof. I agree that Front ceramics will only be of benefit to the highest level of drivers even then I don't think front ceramic make much difference. Main ceramics definitely do make a difference however.

While it is true that the ceramic main bearing is expensive in the keep on or virtus it's all relative. I've replaced steel bearings multiple times in engines however I have never needed to change a ceramic main bearing and so I don't follow that reasoning. Ceramics outlast comparative steels in my experience so the ultimate cost of ownership isn't vastly different. While the 35 plus 21 is a good engine it is also discontinued.

I have a R4 rod in a B5 JP can i replace it by the R7 rod ????

yes.

Anyone know how to get a broken nova plug out of a nova button and still save the button? I've tried the ez-out method but no prevail. Button 28011 and no where to be found. :cry:

When you say broken do you mean sheared off inside the button? I've never seen or heard of that happening before! You might want to try heating up the button quickly as it should expand quicker than the plug and that may help you release it.

We have seen this before, the plug was that tight the hex part did snap off.

Getting the plug out will be difficult.

http://www.ebay.co.uk/itm/Culatin-Tu...item2c84c0ed77

it happen to me too,i drill it out

Yes hex part of Nova plug sheared off, threaded part of plug stuck in threaded part of button. I tried heating up first , then tried the ez-out. I have never seen this happen before either till to me. :cry: Thanks Roelof for that find.

Hi!

What is good distance for .12 353 or 3st novarossi engine bettwen piston and head at TOP postion?

My 353 factory tuned (purple head, rear ceramic bearing) has already 0.45mm-0.46mm, works great.

Old 3st has 0.5mm.

Or how it compare to plug, driving 6tgf.

Regards
m.

Engine Shim Tuning By Dennis Richey

Experience dictates that just by lowering the head (more compression) you gain more power especially in lower rpm range, idle quality can suffer, but the engine also runs cooler . Also, that a higher head (less compression) will increase top rpm speed on bigger tracks.
A decrease in head shims (an increase in compression ratio) will increase torque because as the compression ratio goes higher, the actual ignition timing occurs sooner. However there is a point of diminishing returns where detonation occurs or engine temps can soar, and if this happens a colder plug can help. A colder plug will also increase torque, except that, in the instance of a colder plug, the ignition is slowed until a greater point of compression build occurs.
When you increase head shims (a decrease in compression), top end is enhanced as the ignition timing is retarded and occurs later. Generally a hotter plug is needed to advance the ignition cycle so that timing does not occur to late in the cycle, but at this point you end up over leaning the engine to get it to rev properly and the engine life will suffer dramatically.

On a .12 engine we would only advise going 0.10mm over or under 0.46mm, so that is 0.36mm or 0.56mm of total head clearance at sea level.
Generally on a .12 engine 0.10mm will change the compression ratio about 3/4 to 1 point..

We should also state that the comments with regards to plugs and head shimming are when both are used together. Used alone a hotter plug will rev harder, giving more top end and a colder plug will make more torque.
One last comment. Never assume that the head shim that is on the engine is the actual head clearance. In many cases you will find that the engine actually has 0.20mm to 0.15mm without any head shim. Novarossi's have 0.20mm without one, and the factory installs a 0.30mm shim, giving the engine 0.50mm stock head clearance. This has not always been the case but 99% of the time it is. When in doubt measure the head button register and the piston to the top of the liner at top dead center and subtract, to determine proper shim. This is the only way to really know.
You can safely use 30% Nitro on the stock head clearance. Using a C8TGF you can go up to 40% Nitro, and If you don’t over lean it, the engine life will not suffer dramatically.
Someone asked about plug fatigue the other day, plug fatigue can occur under high sustained RPM's, and this is where the plug stays shiny and the wire just fractures for no reason. This is why we have always run Novarossi plugs, as they don’t do this. When this happens it is usually not a carb. tuning or head clearance problem. If you see the wire start to pull out of the hole this means that the engine is scavenging really hard and when this occurs the engine is making serious power.

There you have it.

AFM