Excellent option still.

There will be all sorts of opinions with header/pipe, but I don't think you can go wrong with the 9901/41021 combo.

Does anyone have more info on the new Novarossi 41031 manifold?

http://www.amain.com/Novarossi-41031...nifold/p360742

I've driven it on several different engines. It made all of them noticeably more powerful compared to the 41021. It drinks more fuel though.

I have two P5 's on my Workbench taking apart. one crankpin measures 4.9 mm the other 4.8 My question is 4.8 to much worn. only 2 gallons on both.

Frank... Those engines are toast. Give them to me. I will take off your hands

For real though, 4.8 is not that bad. I measured mine brand spankin new Clio ( newer version of the P5) and it was at 4.95, So I think you should be fine.

If it still running right then good to go unless it wont. If only 2 gallon then during break in period, not enuff heat generated to run the motor. It stress the conrod n the pin...

Whats up fellow Novarossi fanatics Does anyone have a factory setting for the idle screw? How many turns out or in for a good start point. Thank you

Depending on how accurately it is being measured. If it is truly 4.8 that is worn .006" or more and is way too much. I am assuming you are using a caliper, a micrometer is more accurate. With the crank worn that bad the rod will also have wear and you could have .010" total slop which will not last long. I consider .003" total slop or worse a back up engine.

Rex

4.8 is very bad.
You are right that at new they are 4.95, I get the same measurement on mine.
However, my engines when worn to the point that they have so little compression that they don't run right, generally tend to measure around 4.88-4.91.

Now this is where it gets interesting, engines that have been re-pinched and then ran a whole lot, end up measuring at 4.82-4.86.

My friend recently had his con rod come out through the crank case on an engine that had been re-pinched and ran at least 5-6 gallons after that.
The last time I measured the crank pin it was 4.81-82 and I warned him that this could cause a catastrophic failure. Sure enough, boom, rod through the crankcase.

So no, 4.8 isn't fine, 4.88 might be fine for a while, but 4.82 definately is not fine.

Thanks for the info. How much less was your run time per tank?

Im glad to see someone say why someone else is wrong. To many times on line, you get that "you are wrong" and that's it.

Keying into what I was and wasn't saying, not "that bad" but yes bad none the less. Problem is when you measure something that small and precise and leave such a big open ended number ( 4.8mm) when it should have at least 2 or 3 numbers after the decimal. And Frank didn't really specify where he should have.

question about your buddys motor? Did the rod break or did the crank pin sheer? I really don't see a worn crank pin could snap a rod and shove it thru the case. But that's just me. Harmonics? Vibrations?

If Im wrong, enlighten me some more. Im a knowledge whore!

Due to the cost, imo wen it stil running right, y change it. We all know Novarossi parts are costly.

I'm getting about 30 seconds less per tank in truggy.

.

The Efra 2032 (not approved anymore) with a Novarossi 41001 header is a living beast with better mileage than 9901/41001.
My pinched, rebuild BTT out-ran any other engine at a race this summer... and it was fitted with a 6mm mizer venturi. Very impressed