ESE's works engine tuner

[ceci]

With 76mm x 61mm and rod (from your previous pic, add, looks like 25mm smaller dia /46mm bigger dia), pumping volume reduction is just 30cc, so from 276cc to 246cc it would be minimal influence.
Its similar to Rotax 503 engine.

In the Ryger the pumping volume reduction is 58cc, 50%.
As in this other engine

https://www.youtube.com/watch?v=TB9PGPnSEtA

[AndreasL]

If you insist on using both that con rod and that piston, I'd reluctantly go for a hardened sleeve. The other option, a cageless crowded needle small end bearing has been used with success by a feller named Jan Thiel in his world championship-winning 50cc Bultaco racer (below, still the nicest 50cc bike I've ever seen).
Attachment 343580

Very nice Frits.
Monocoque chassis.
Do you have any further information about the (frame)design or know where to look?
The shifter mechanism looks really interesting to.

[Zrt1200]

If you insist on using both that con rod and that piston, I'd reluctantly go for a hardened sleeve. The other option, a cageless crowded needle small end bearing, has been used by Jan Thiel in his world championship-winning 50cc Bultaco racer, still the prettiest 50cc bike I've ever seen.
Attachment 343580
In your case it is paramount that you take the slack out from between the needles, or they will skew, skid and overheat. It can be done with one smaller-diameter needle that fills the gap.
A needle with a diameter of 3,0838 mm would completely fill it, but you need to use a somewhat smaller diameter, because the filler needle must not be allowed to carry any weight, otherwise it would be wedged between its neighbours, jamming all needle rotation.

The clearance will also allow for lubricant between the needles that are all rubbing against each other with a relative surface speed of double their circumference velocity. Reducing this rubbing is the main reason for using caged bearings.
In a small end bearing, with its limited rotation speed and swaying angle, you may get away with a cageless bearing. But in a big end bearing,
with its additional orbiting g-force flinging the needles against each other, you might just as well bin the crankshaft right-away.

The red filler needle in my drawing below is kept in place by its blue neighbours. If its diameter were less than 2,63 mm, it could radially move in- and outward through the gap between the blue needles. A diameter of 2,8 mm should be about right for this layout.
Attachment 343579

Thank you Frits. For some reason I did not see your post yesterday. At this point I am still trying to decide on what I should do. I know what is the right thing to do is. Change rods or crankshafts but I hate selling a new crankshaft that has never been run. If I did decide to go with a hardened sleeve. How much Press fit do you think i could get away with?? I had another thought on this today. If I used a 18 X 22mm hardened sleeve and had a ring fit or very light press fit on the wrist pin then I could use the stock 22 X 27mm needle bearing.

[F5 Dave]

How much would you prefer a ventilated crankcase? And it puts you down pretty quick let me tell you.

The earth is big heavy object when someone throws it at you.

[speedpro]

I can confirm that

[TZ350]

Well, we got Pinky to the Two Hour endurance race but Pinky refused to play nice and did not make it to the start line.
A bit much I suppose to expect an un tried bike finished the night before to behave perfectly. We need a few shake down meetings to get things right.




So Blair Lambarth and Nathaniel Diprose rode the number two GP-NSR110 and finished in third place. The only two stroke in the race.

This bike is basically a bog standard re plated Honda NSR250 cylinder on a Suzuki GP100 bottom end with a de stroked crank for 110cc's.
No porting or serious tuning work what so ever and they were able to run at the front for two hours with the big, bad boy 4 strokes.

The nosiest 4S was measured at 102db, the Team ESE 2S 95db and the quietest 4S's were at 92db.

[F5 Dave]

Where was that held Rob?

[mr bucketracer]

at tokaroa 2 hour

[F5 Dave]

Of course, there's the crazy hairpin. Ran over Pumba there. Fence looked familiar but couldn't place it.

[Frits Overmars]

Trying to shake that transponder to pieces? We've seen so many malfunctioning transponders that we added a line in the rulebook:

The transponder must be positioned at least 300 mm away from all ignition components and must be mounted in a vertical position as much as possible (manufacturer's prescription). The transponder may not be mounted on unsprung parts such as the lower legs of the front forks.

[yatasaki]

I'm wrong again

[mr bucketracer]

Trying to shake that transponder to pieces? We've seen so many malfunctioning transponders that we added a line in the rulebook:

and up side down

[guyhockley]

The nosiest 4S was measured at 102db, the Team ESE 2S 95db and the quietest 4S's were at 92db.

I was talking to a bloke who has a son who races 2 stroke Motocross and he claimed that in the UK we've lost many more tracks to noise complaints since 4 strokes took over.

[Frits Overmars]

I was talking to a bloke who has a son who races 2 stroke Motocross and he claimed that in the UK we've lost many more tracks to noise complaints since 4 strokes took over.

Same here. A screaming two-stroke may get on some people's nerves (not mine) but when it's round the corner, you don't hear it anymore.
But you can still hear four-stroke when it's three forests away.

[JanBros]

yep, probably the main reason for the decline of Belgium as a top nation in MX. think we're down to 4 permanent MX tracks in the entire country . if you can't ride/train, ...