ESE's works engine tuner

[crbbt]

You can bolt anything to anything. Depends on the amount of faffing around you want to do.

whoops! i was meant to say without modification

[jasonu]

whoops! i was meant to say without modification

Then hell no!!!!!!

[Matt@TYGA]

Just thought that I'd share this....
The NSR150 has a rather short exhaust duct according to Wobbly's explanation of what's needed. So I've modeled and adapter up that bolts to the exhaust duct exit to lengthen the duct to 1.5*bore and as and when I have time I'll CNC something up and give it a try.

3D printed out a sample last night for a test fit. Seems ok.

I've done a couple of models of different "effective diameters" @ 1.5*bore, so it'll be interesting to see what happens on the dyno.

Also took the theory of cooling the duct and added a water passage. This'll mean mods to the std cylinder to allow water to get into the adapter. I'm temptered just to add a couple of spigots to it for now and just flow water through it. Saves me a bit of work for first test

I'll also have to adjust the pipe to compensate for the longer duct, but that hopefully shouldn't be a task. But if I just change the header length (minus the additional length of duct), without any other changes, that'll give me a 4 degree included angle header. Any comments on this?

Anyway, here's a couple of pics.

I'll let you know what happens.

Matt.

[Jannem]

My definition of the edge angle is the same as yours, Lodgernz. I assumed that Jannem meant the same with his "15deg from top piston corner to top of the dome".
I can't see what else he could have meant.

No engine I worked on in the past three decades had a 15° edge angle. Most pistons were between 7° and 12°; the highest value I found was 13° (in a Suzuki T500).
To ascertain that we both use the same approach, I took your 53 mm bore, 3,7 mm dome height, 15,8° edge radius and it checked out OK (with a 97 mm dome radius).

As I wrote in my post #28610 to Jannem, the optimum performance of the B-ports does not soleley depend on mass flow.

It's not just that initial reflection; a high piston dome like in the picture below limits the cross flow area much like the axial angle of a transfer roof does.
Attachment 335156

The edge angle of the piston I have is more than 15deg. Would need to check. So, I meant the angle between piston top corner and the tip of the top. Because the shape is rounded the tangent at the piston corner is more. The dome begins ~1mm towards the center from the piston corner.

The raising column speed is definitely something that didn't even cross my mind. As the lower speed translates to higher pressure, I can see how that would be better for less mixing of the fresh charge and exhaust.

I would also think that the higher dome not only shifts the direction of the transfer flow upwards, but also makes the jet flatter forcing it go around the dome and begin the pressure recovery sooner than what would happen with the free jet. How much flow losses this would cause is hard to say, as the directional change does not happen in the duct and more gradual pressure recovery may also be a good thing from the flow perspective, but it probably messes up the designed scavenging pattern. Considering higher surface area of the combustion chamber with the dome and painstakingly designed scavenging for a lower dome piston, it's predictable that the end result has to be worse.

I've struggled to find a good piston with the right compression height for the 44mm bore. Now I have another bottom end, where I could use 5mm longer rod and that would allow using kx60 piston. My cylinder, however, is cast iron and I'm a bit concerned if the ring(s) meant for nikasil would cause me problems. As the piston is such a stressed part and elemental for the performance, I think I need to find a better solution.

The current B-port angle is 15deg before grinding, so I could relatively easily test it with the stock bottom end, then grind and re-test to see the impact with the current piston.

[dutchpower]

Dutchpower - your engine is now Blowdown limited as the second example had higher Transfer STA, but made less power.
Thus the smaller transfer STA of the first example is not limiting the power, but the Blowdown increase is able to make more.
Using the same duration's for both , would then exhibit the power band bias I explained due to the scavenging regime changes.
Neels code cant handle this type of detail, as the scavenging system is a canned input, as would be the case with any 1 dimensional sim.
I have not actually tried it, but maybe the powerband shape would be affected correctly by changing from the RS125 to the RSA125 scavenging input
when using the same durations
Usually the reverse stagger gives greater overall STA as the B ports are way bigger, but this isnt the case with this port set, so you would only see scavenging differences.

This is the difference Wobbly

[teriks]

Return to Rygerised engine again, this time with almost isolated A, B transfers, just small parts left to do. But first decide to try this on std. engine, if this scheme works.

Today tested NS 250 engine with isolated A and B transfer channels, connected directly to carb through boyssens and isolated from crankcase (like in sketch) and special piston with pockets on sides (add pic), its like imitation Ryger on std. engine. Only C transfer work like normal.
First trying without reeds, but impossible to start from kick and impossible to push bike because winter outside.
With reeds, started easily and revs to 14200 rpm. and then na-na-na-na, feels like rev counter (honda rs 250 ignition 1986) I don't know.
And very interesting thing, when trying std. piston with very low transfers intake timing ( when piston is at TDC, transfers open just at they height) it revs to 12500 rpm. I cant believe. Before test I wish that engine with std. piston revs no more than 7000 rpm.
Can't say anything about power now, but want to try adjustable reed valve block, to understand if this scheme work without reeds at higher revs.

And one similarities with Rygerised engine is that it revs imeadeatly very cleanly without bubbling when engine is cold.

I don't know about Ryger real working principle, but if its in this way, maybe very short con rod on Ryger engine, generated stronger suction signal and faster accelerate fresh mix from carb, through transfer channels when piston close up to TDC.

You need to get studded tyres or a dyno, really interested hearing how this goes.

[SwePatrick]

Just thought that I'd share this....


I'll let you know what happens.

Matt.

Yes please, I have about the same idea, to weld a waterjacket at the first 10-15cm of the header on the pipe.

If you´re project is showing promising results i can´t resist build it =)

Rgds.

[husaberg]

whoops! i was meant to say without modification

http://www.tz250.com/forums/showthre...A-kit-cylinder

There was a major cylinder change at 1997 I think and the stud spacing will not allow newer cylinders on the older 1995-1997 bikes (I think).

but it can be made to fit rather easily it seems. see link above.
But you might be far better off with a 04 PV CR125 cylinder.

All the CR ignitions from about 2002 onward are 12v to drive DC ignitions and powerjets ,TPS and powervalves ( 04 ) so these will bolt

straight onto earlier models.
The later RS125 kit engines with PV and the short ( 800mm ) pipe with 200* Ex are easily replicated using the 04 CR cylinder as it had a cable
PV as standard - the only model that did.
It has reverse transfer stagger like an Aprilia, a really nice small oval Exhaust duct exit, and could easily be ported to make well over 50 Hp.
And with the PV in place it would jet past any bog RS125 out of every turn, due to the gearing enabled by the great overev.Here is a dyno sheet ( rear wheel Hp ) of a well tuned customer Honda, a B kit, and Azuma's A kit with PV - I know what I would be trying to replicate.

Yep, it would be impossible to compete against an engine that had the same power at 13800 as a well tuned stocker has at 12200.

As i say, the CR cylinder is well capable of being tuned to even above this level, is cheap and available.
Add a long 110 rod from say Samarin with a plate and you have what won the last 250GP championship.
Slap on an Ignitech, a modern fat pipe, a VF2 and you are well into the 50Hp zone cheaply with ease..

Are you able to comment on the CR125 cranks and how they'd take the abuse in a road racer vs MX bike Wob? The service interval on the NX4 crank is 2,000 kms, how would they compare.

It'd be a fun exercise to build a NX4 into a superlite/F3 class beating 2 stroke with an engine you described Wobbly!

Is the famous Kiwi ingenuity is dead then? In superkarts here in Australia a friend of mine pioneered several things that are now

de rigueur

in superkarts. All on a humble old NF4 engine that ended up nudging 45hp. All done with off the shelf parts, no expensive " A/B/C/D kit" parts most of them we got off ebay. That engine ran rings around karts that someone spent $5000 on a NX4

rebuild

. We even tested a $18 conrod from Thailand that worked a charm.
A recent race meeting on a tight track a very good rider with a CR85 engine in a NF4 frame won races outright against a NX4. Point is the humble NF4(like a RSW 125) is still a very capable bike in the right hands.

But as a side point we get 41.5 Hp at the sprocket from a 2002 CR125 dead stock except for the reeds and the pipe for SKUSA racing, throw on a 2004 cylinder with cable PV,do some porting
and your RS125 will get blown away easy.
A complete SKUSA engine parts kit is still available from HRC for under 2000 USD,and I bought a siezed 2004 cylinder,to fit on an old NSR250 MC21, here in NZ
the other day for $200, they are available new on line for around 400USD complete.
The CR125 may be wet clutch, but fit Hinson alloy/kevlar plates and you would never know, and they last forever.
Cheap as chips the whole thing.

The CR125 crank parts are same same as RS125 quality wise and last forever over 12,000 rpm in a SKUSA engine.

I think Lozza has looked at putting a HotRods CR125 crank into the RS as it has higher inertia, and revs on better ?

[katinas]

Where do you place the reed valve?

Testing on original cylinder in simplest way, just add profiled sleeve on cylinder to isolate crankcase , blocked intake windows and increased boyesens. A and B sum area equal to 31 mm dia.
Much better, would be made straight transfer ducts on both sides of cylinder with two carb, but cutting, welding and so on need more time.
And eventually, maybe its just revs without power.

[katinas]

Thank you Husa for this RS/CR collection

[Flettner]

Testing on original cylinder in simplest way, just add profiled sleeve on cylinder to isolate crankcase , blocked intake windows and increased boyesens. A and B sum area equal to 31 mm dia.
Much better, would be made straight transfer ducts on both sides of cylinder with two carb, but cutting, welding and so on need more time.
And eventually, maybe its just revs without power.

we will all be watching,, keen to see how this pans out
I have a similar cylinder on the bench, but uses injection.

[crbbt]

Thanks Husa

always on the hunt for a cheap 04 125. ended up getting a 05 250 instead

be interesting to see if anything lines up on the nx5 cylinder. lucky I have some scrap cases to play with

[husaberg]

Thanks Husa

always on the hunt for a cheap 04 125. ended up getting a 05 250 instead

be interesting to see if anything lines up on the nx5 cylinder. lucky I have some scrap cases to play with

If you want to beat NX4 with a NF4 try a 2004 cr125 cylinder with a PV. If you get out of the corners quicker you will beat them around the track.
Jerry Burgess and Doohan then Rossi did this for years.
Pray on the weak points of a NX4 rather tha try to replicate one.
Get yourself a decent carb
if moneys tight.A Keihin PWK38S (short body w/Power Jet)

of a KX250 the electric solenoid and tps arround 2001.

throw in a decent pipe and a VF3 Reed valve and a short intake
Spend the rest of some decent suspension.

https://www.tapatalk.com/groups/nsr2...rels-t414.html

Ask Wobbly about the rest he has given out the details on how to mod the mx carb.

[katinas]

we will all be watching,, keen to see how this pans out
I have a similar cylinder on the bench, but uses injection.

Interesting how wind is blowing in A B C tunnels with this scheme.
When piston moves up, is more or less clear. But what happening on down stroke. Maybe at low and mid revs some gas return to A B tunnels and build up pressure and when windows open, pressure help for scavenging. At high revs, maybe wind blows in one way with help from exhaust diffuser and what's happening in C.
Maybe, with isolated bottom, piston not cooled well and for big end needed additional oil. But fresh gas is less contact with hot parts.
Interesting how transfer duration and size influence this type engine performance and what kind exhaust is needed ( Tested without exhaust, just with ex header, and revs easily, but can't say how much, because very strange, Koso tachometer not working with this huge sound in closed area, can't understand ).

Will try to film outside.

[katinas]

In 2002 or 2003 Honda on Cr 125 use biggest reed cage with smallest 28 mm insert, but carb is 38 mm.
2004 they return to std. smaller six reed cage type and normal insert. Maybe with big reed cage they lost speed in midrange and try compensate with smaller insert.
Very interesting, maybe someone know about this and had experience with that time Honda Cr 125 engine