NitroVein

Well those numbers are more in the norm, though the first two is timed for onroad, more or less. But if they are worn they can easily differ some.

30Tooth

iTrader: (1)

The REDS is brand new from EBIS, I was surprised with the numbers pulled from the P5 sleeve.

NitroVein

Which Reds modell is it? It's the very opposite of what I've seen from them before, seems Very strange.

Yes, the P5 seems very strange as well, never seen such high numbers on any of those... Maybe one of the Nova gurus can shim in.

That's why I like to measure myself, some have trouble getting it right.

30Tooth

iTrader: (1)

WR7 Diamond, same Elliott Boots run. About the P5, can be Go internals on NR crankcase.

Roelof

Novarossi transfer ports are always 65 or lower, only some modifiers will use 66 or even 67 (works good with onroad)

70 and 91 on the ports looks like a higher placed sleeve or maybe a domed piston in the sleeve made for a flat piston. Go is basically a copy of a Novarossi so I would expect no differences, but who knows...

NitroVein

Okay, then it might just be so, things do tend to evolve over the years. And it says that it's a high rpm engine on the website, so it does add up.
The single exhaust also makes a slight differens.

That might just be the case, I don't have the thickness of the collar written down, but it makes sens.

30Tooth

iTrader: (1)

I have one idea. How about making the oil rings wider now that they are worn? If the blade is strong enough to push the metal to the sides, like ploughing.

The P5 is already shot so why not try this? For science.

NitroVein

I do carefully clean the groove if there is a lot of buildup in them, but other then that, I would leave it alone.

Roelof

They do something but w/o it is not the end of the world. I have seen many .12 competition engine w/o the rings.

RCTecher12

iTrader: (1)

One thing I haven't seen discussed much in this thread is in regard to the crank - namely the size of the bore of the crank. I've had discussions with a couple guys on his subject - the common consensus is the same between them. Curious what others have to say about it? How thin can the wall of the crank be to stay in one piece? Or rather - is there a correlation of the size of the crank to the size of the carb? Some have said that changes to the crankshaft are half to three-quarters of what improves an engine.. Thoughts?

I have some books on the list to buy since the library cannot get them, but some of these details I doubt would be contained in a book. :yup:

stanleyw808

Hello NitroVein and Friends,

This might not be relevant with the Engine Timing Subject.

I just want to share my knowledge about basic mathematic calculation sequence.

30Tooth mention that,

360-89x2 = 182
360-144x2 = 72

As far as I know, 30Tooth calculation is correct because multiplication and division will calculated first before addition and deduction.

Cheers..

30Tooth

iTrader: (1)

Think of it like redoing the groove in the hopes the displaced material is sculpted outward and upwards of the groove.

See above reply.

Speed of mixture, how fast it travels through the vacuum created by the piston

Yeah, while the calcs were correct the timings not!

RCTecher12

iTrader: (1)

I haven't seen anything posted or published in regard to what the crankcase pressure levels are in a small two-stroke glow engine are. I have an engine that has a pressure tap installed in the backplate that I can connect a gauge to. I'd be curious to know how crankcase pressure is affected (if it even is affected) by boring the crankshaft to allow better breathing and also altering the rotary valve timing.

It's too bad most of the books I've found online dealing with two-stroke engines don't deal with rotary valve engines like our tiny toy engines. All dealt with motorcycle and go-kart engines.

NitroVein

I see... That might very well be true... I'm sorry if I wasted some of yours time!
Most of my math is adapted for calculating in my head instead of on paper, my teachers might had a good point in that you should do as the rest.

Roelof

I believe it is one of the standard mods of Murnan to drill up the bore of the crankshaft. The larger bore creates the mixture more like a ball giving a more equal filling in the lower crankcase but sadly the larger bore does give a larger volume as well giving a lower bottom power.

With good materials a huge bore is possible. We have played with 9.5mm on a 12mm crankshaft. Novarossi went from 14 tot 14.5mm because of the larger bore (10.5~ 11mm) and less hussle with expensive materials and hardening.