ESE's works engine tuner

[teriks]

I assume they just run plain bronze bushed big and little ends, is that right?

On the big end yes, the small end run directly in the aluminium rod, no bushing.

[Frits Overmars]

I assume they just run plain bronze bushed big and little ends, is that right?

Yep. There have been attempts to make caged big end bearings, but no joy there yet. On the other hand, the main bearings are hybrid.
Cages and outer races from conventional ball bearings are being used, the inner bearing races are ground directly on the crankshaft, and ceramic balls are fitted.
Expensive? Nea. The nine balls cost one Euro a piece and these bearings have eternal life.

[lohring]

Jim Allen has experimented with rod big end bearings in high rpm model engines. The rod big end is the weak link in all high power engines. My article on the subject is Big End Blues. Below are some pictures of Jim's bearing. It uses a very high strength cage with two rollers per slot.

Lohring Miller

[/URL]

[husaberg]

On the big end yes, the small end run directly in the aluminium rod, no bushing.

Yep. There have been attempts to make caged big end bearings, but no joy there yet. On the other hand, the main bearings are hybrid.
Cages and outer races from conventional ball bearings are being used, the inner bearing races are ground directly on the crankshaft, and ceramic balls are fitted.
Expensive? Nea. The nine balls cost one Euro a piece and these bearings have eternal life.

cheers

Jim Allen has experimented with rod big end bearings in high rpm model engines. The rod big end is the weak link in all high power engines. My article on the subject is Big End Blues. Below are some pictures of Jim's bearing. It uses a very high strength cage with two rollers per slot.

Lohring Miller
L]

Nice

[andreas]

70 bore 64.7 stroke 7mm squish width. What clearence will I want in standard MX form, and does it change with a higher bmep and rpm?

[TZ350]

What clearence will I want in standard MX form

You might have to dig through it to find what you want. I used the Google "site:" search term to find a whole lot of references to bore and squish on the ESE thread.

Bore Squish site:https://www.kiwibiker.co.nz/forums/s...s-engine-tuner

[andreas]

Thanks TZ. p1805 seems to cover it.

[marsheng]

70 bore 64.7 stroke 7mm squish width. What clearence will I want in standard MX form, and does it change with a higher bmep and rpm?

I think the general rule is 1% of the stroke. This would be .65 to .7 mm. I run 0.8 on my Maico 250 with a 70 mm stroke. Added a bit for safety. If the piston is clean around the squish area, then its roughly right.

[Michael Moore]

On GrabCAD I found a model of an Aprilia RSA cylinder

https://grabcad.com/library/cilindro-aprilia-rsa-1

It seems very detailed, to a point where I suspect the modeler had a cylinder on hand to work with, rather than just making something that looked reasonably close to photos. Has anyone else looked at this model and been able to check it for validity/accuracy?

There's also an assembly with crankshaft/cylinder head/piston and exhaust that can be downloaded with the cylinder model.

cheers,
Michael

[monkeyfumi]

Unless it has been updated, there is an error in that model, the aux ex ducts break through.

(Edit: having a closer look, that may have been fixed)

[Michael Moore]

The ex ports seem pretty contiguous surfaces to me other than what I presume is the hole for the power valve in the main port.

[Frits Overmars]

On GrabCAD I found a model of an Aprilia RSA cylinder
https://grabcad.com/library/cilindro-aprilia-rsa-1
It seems very detailed, to a point where I suspect the modeler had a cylinder on hand to work with

Never mind the details Michael, it's not an Aprilia RSA cylinder at all, no matter what it says on that site.
It's an RSW cylinder (left), very different from an RSA cylinder (right, by GighenZz Marco).

[Frits Overmars]

The ex ports seem pretty contiguous surfaces to me other than what I presume is the hole for the power valve in the main port.

Some more GighenZz Marco-pictures:

[Michael Moore]

Frits, is it known how accurate the RSW cylinder model is? If it is only a "looks sorta like this" cosmetic model then I won't put a lot of time into trying to glean any information from it.

[Frits Overmars]

Frits, is it known how accurate the RSW cylinder model is? If it is only a "looks sorta like this" cosmetic model then I won't put a lot of time into trying to glean any information from it.

I haven't got a clue Michael. I don't know who made it and I would have to "put a lot of time into trying to glean any information from it", as you describe so aptly, before I could say anything about it.