ESE's works engine tuner

[katinas]

I think Katinas might be onto it with the cooking model rather than full monty 500.
The never released the Fireblade for 2 years as they were worried about lawsuits.
Another reason might be how much trouble the MVX250 gave and how much the NS500 and RS500 vibrated.
i am not really sure how the NS400 is balanced i don't think its like the MVX with the heavy piston and rod in the upper center.
either way Making it a 400 meant it never had to directly compete with the full 500's

On NS400 all three crankpins is in one line, so vertical piston work alone, after 90 degrees two horizontal cylinders fired. Just center cylinder crank webs heavier.
Engine is on the rubber, stroke 50.6mm, angle V90, so I think this help eliminate vibrations. Both NS 250 and 400 didnt have any troubles with this.

NS500 and RS500 racers V 112 angle engine, separately 120 degrees firing, 54mm stroke and no silent blocks, so maybe more difficult eliminate vibrations . And double power output.

DRM guys made 500 kits for NS, with two EX ports and dry clutch
https://page.auctions.yahoo.co.jp/jp/auction/g298854497

[husaberg]

On NS400 all three crankpins is in one line, so vertical piston work alone, after 90 degrees two horizontal cylinders fired.
Engine is on the rubber, stroke 50.6mm, angle V90, so I think this help eliminate vibrations. Both NS 250 and 400 no troubles with vibration.

NS500 and RS500 racers V 112 angle engine, separately 120 degrees firing, 54mm stroke and no silent blocks. And double power output.

DRM guys made 500 kits for NS, with two EX ports and dry clutch
https://page.auctions.yahoo.co.jp/jp/auction/g298854497

The MVX250 is also 90 degree two down one up. but the top gudgeon is real big and solid to equal the weight of the other two lower cylinders.
The NS500 also had a balance shaft. With it firing at 120 ntervals it had uneven spacing because of the bigger V i posted some stuff on the RS500 and RS500 eons ago.
The NSR25, NS250, MVX250 and NS400 are all big bang then.

[katinas]

Very interesting about MVX balance
Thanks

[husaberg]

Very interesting about MVX balance
Thanks

it wasnt without it problems ut when it ran it was smooth but i are not entirely sure some of the issues they had with reliability were not related to its very odd set up. not all 250s were thrashed so the rliability issues might be overstated
But it had if i rember right iron cylinders not just the liners

i will find the links

The story goes early ones had a 13mm or so solid pin that was later replaved by a 17mm hollow one or similar.
Some here
https://www.kiwibiker.co.nz/forums/a...p?albumid=5017

https://www.kiwibiker.co.nz/forums/a...p?albumid=4861

[husaberg]

Wouldn't fit

[katinas]

it wasnt without it problems it was smooth but i are not entierely sure some of the issues they had were not related to its very odd set up.

i will find the links


Some here
https://www.kiwibiker.co.nz/forums/a...p?albumid=5017

WOW....
Yes I know that this is bad thing, but always interesting how factories trying to resolve some problems.

Maybe not in theme, but I still thinking why Suzuki on second generation RGV 250 VJ22 used sooo heavy steel lover triple clamp and heavy front brake disc steel inner part. First idea that this is cheaper (or opposite), but maybe they want more loads on front, or eliminate some high frequency frame vibrations that emerged after all work was done.

[Matt@TYGA]

Matt from Tyger can correct the stuff i got wrong

I'll see if I can add a little....

I have on my knee an NSR250 MC21 and NSR150SP cylinder.

The NSR150SP coolant enters the cylinder under the exhuast duct and flows around to the top of the exhaust duct, then back over the transfers. The head gasket will allow coolant into the head on it's journey, with the biggest passages through the gasket being at the rear of the cylinder. The coolant then exits at the front side of the head.

The 250 cylinder is very similar, however, the coolant enters under the exhaust duct and then flows up and over the transfers. There is a small area above the exhaust duct, but it looks like it'll cool the recess for the exhaust valve, rather than any relevant cooling of the duct. Similar story to the 150SP regarding the head gasket and flow inside the head.

Extra cooling of the exhaust duct would be somewhat easier on the 150SP, as the cooling channels are already there, just needs a little work. Looks to me like something could be done by coming in from the end of the duct (where the manifold would bolt on). Maybe drill some holes, or mill some slots, allowing the coolant to flow right to the end of the duct. The manifold could then be used with some sealant, to keep things from leaking.

Not quite so simple on the 250 cylinder, as there's no meat on top of the duct. But I guess one could weld a plate over this, closing it in, and then using this for cooling. Worth a thought perhaps.

Cheers,

Matt.

[Frits Overmars]

I have one cylinder from RS 125 that differs from others. Seller said that this cylinder was used in WGP race, but I didnt know anything more. All ports looks best that I ever see, but one thing is very interesting. Looks like they added some material to normal production cylinder from C side for bigger B ports. But I cant understand how they do that, additional casting form or welding on.

Early Honda RS125 cylinders had a tendency of cracking at the stud mounts, so the first Honda A-kits contained sand-cast cylinders with higher ears.
Several standard NF4 cylinders were modified in the same way by welding, but it is quite possible that your pictures show a genuine early A-kit cylinder.
Later A-kit cylinders were recognizable by their exhaust power valve, something that the standard RS125 never had.

[Pavel Myslik]

In my story I'm more garelli rider
For that reason I was calculating all possible final ratios ,36 of them, then pick sprocket which would be universal for the rear wheel as it is much harder to change. My question is, (and partly answered by Frits some years ago on this thread) to choose between acceleration from corners AND acceleration to max speed and where max speed point should be .
In some cases you need crucial intermediate gear (let's say between 3rd and 4th) and to adjust that you have to change your final ratio in expense not using final gear 5th or 6th at all.
In your case Pavel I would go for huge 100cc kart overrev

Yes, I always go for the overrev and change the sprockets all the time. I have modified the sprocket mounting system to change them easier.
I don't know which gearbox you use but usually the difference in ratios is smaller with higher gears so maybe you should try using all gears, then if you have to compensate for the "intermediate gear" the trade off will be smaller. Or try to change your line on the track.
I have been told always have the engine overreved at or slightly before the fastest point of the track. It is also more benevolent to rider's error than gearing faster.
But if you are really good, capable of slipstreaming and then passing on the brakes...
If you are interested here is one of my races and if you are not then pardon my narcissism. : https://www.youtube.com/watch?v=bk7glKx236c&t=43s
Skip to 12:20, the last laps were interesting.

[wobbly]

Anyone got a TZR250 2MA cylinder - reedblock - manifold I could have a look at.

[Pursang]

Plenty of work has already been done on this with no good results.
Firstly Jan filled in under the Ex duct to reduce the coolant flow - result deto city.
Secondly, I ceramic coated the duct inside surface , result lost power - deto city.
Third,Franco at TM tried the air gap shell idea, result - deto city.
Fourth,TM originally designed the KZ10 with all the coolant flow entering the cylinder under the duct.
This heats up ALL the water ,including that flowing over the transfer tops.
They later plugged the holes and directed all the water into the cylinder , from the side over the top of the duct.
This gave better power.
Lastly I bored a hole into the water jacket above the boost port , so all the cold water flowed over the transfers first.
Then added two 3mm holes thru the plugs under the Ex duct to help cool this area separately.
Result just over 1 Hp in 48 , with alot less deto level when under full power.
But the CIK and NZ techo guys would not allow this " additional " water circuit.
Moral of the ( long ) story is that cooling the duct first is bad , as is not cooling it at all , as you must keep the retained
mixture in front of the piston as cool as is possible to prevent the returning stuffing wave from pushing hot gas back into the cylinder.

Here is a highly efficient insulation that does not retain heat in its body or on the surface.



Not sure how long it would last in an exhaust duct, might need to fit a new one for each 'heat'.

cheers, Daryl.

[F5 Dave]

Anyone got a TZR250 2MA cylinder - reedblock - manifold I could have a look at.

I should have the reed and manifold but no cylinder of 1KT which should be the same as 2MA (but totally different to 3MA). UK and probably Europe got 2MA, Japs and us got 1KT

[yatasaki]

Pavel, you have pretty tight ratios for three speed moped, I thought it would be much wider. That green rider's bike is slowing down from lap to lap but he has much less mistakes than you..
Glad to see good moped race.
This is how Slovenians prepare 60cc tomos six speed engne, my friends bike,just love to hear this bike singing from time to time
https://youtu.be/XrjUK2431pk

[katinas]

Early Honda RS125 cylinders had a tendency of cracking at the stud mounts, so the first Honda A-kits contained sand-cast cylinders with higher ears.
Several standard NF4 cylinders were modified in the same way by welding, but it is quite possible that your pictures show a genuine early A-kit cylinder.
Later A-kit cylinders were recognizable by their exhaust power valve, something that the standard RS125 never had.
[ATTACH=CONFIG]34Thank yo0684[/ATTACH]

Thank you Frits, very helpful and interesting how they do things.

I will try to follow with what I have about RS cylinders studs location location at C, with some guess.

First crankcase reed RS 125/250 NF4/5 stud ears height at C side was just 15.5mm, at EX side 20.5mm.
Dimension between studs at EX side 96mm, at C side 80mm ( like on the first NSR500 1984 and 1985 86 with vertical reed block position, maybe because all cylinders exhaust arranged same side and wider studs location at C would be in the way of rear cylinders exhaust manifolds )
Between Ex and C side studs pairs 81mm and looks that this is not changed until the end..

When NX series appears 1995, Honda widened studs location at C on 1998 or 2000 (not sure) 125 NX4 from 80mm to 94mm for more more open space between horizontal reed block and transfers ports ( like on the 1987 NSR 500 new 112 degree engine where exhaust pairs on different sides and left more room for horizontal reed block position with wider studs location and more open directly to transfers ports). Stud ears height at C was rised from 15.5mm to 20.5mm ( like on new NX 250 ) like at EX side.

First RS 250 NX5 appears in 1993, but as both exhaust on the same side, new V 75 angle and cylinders close to each other, no space for wider studs location at C, because of exhaust, so studs position they left unchanged 80mm. But vertical reed block position had no conflict with this. And this configuration left until last 250 season. Just Daijiro special engine, with exhaust on different sides and horizontal reed blocks position, must used special cylinders with wider studs location at C maybe from 500.

I have std RS 125 NX cylinder from 1996 engine and one interesting thing. The B port wall shape near C, changed gradually from lower to upper corner lines. Add drawing. Cylinder not ported.
And add another interesting cylinder, maybe like you write, for NX 125 with power valve, modified (welding everywhere with wider 94mm stud location at C) from nx 250 , I think from All Japan Championship.

[2T Institute]

NF4 never had water under the exhaust, from the factory (had right angled press in inlet) . The cases can be modified to send the water up under the exhaust duct.