ESE's works engine tuner

[lodgernz]

Re the insert of the Ex duct - make it in ally and give it a real heavy press fit to help the heat transfer path

Thanks again Wobbly.

[speedpro]

No thinning, no lathes. We will have Laser cut new ones. They are the same as Honda RS250, 2mm steels. Ali is an option as well.

I think that is a mistake. Where the plates drive the inner hub will be the same thickness, 2mm. This will accelerate the wear and you will end up with ripples sooner which will inhibit clutch action as the plates will want to stay where they are, with the fingers in the ripple, rather than sliding freely to their disengaged position.

If I was getting some cut I would go for 3mm or maybe even thicker then machine the friction surface down to the required thickness. You end up with 2mm at the friction surface so your stack of plates can include the extra pair and remain at the correct stack height, but you also have the fingers at 3mm which will reduce load and wear where they contact the hub.

I've done something similar on the MB clutches. With standard springs they are good for 27hp and feel just like a standard clutch. Try and avoid big springs. They are hard work and make the clutch feel funny, in my experience anyway. Malcolm has one of mine, and Dave. If you ask nicely I could probably turn your plates down for you, for a fee.

[Sketchy_Racer]

I think that is a mistake. Where the plates drive the inner hub will be the same thickness, 2mm. This will accelerate the wear and you will end up with ripples sooner which will inhibit clutch action as the plates will want to stay where they are, with the fingers in the ripple, rather than sliding freely to their disengaged position.

Well, yeah i would agree normally but it's a little different on the NSR clutch

On the NSR clutches it is the clutch outer which is the problem for "finger wear" Which is where the clutch fibres are engaging, which we are keeping the same thickness on the fibres but increasing the plate count by 20% reducing the load on each plate by the same amount which = less wear. Unfortunately we will be losing 19.3% clutch basket contact area on the steel plates even when fitting an additional plate which is not optimal. But then I go back to two observations on that which is that 1. it is not a street bike so the amount of time that the clutch spends chattering around is much less, and I feel that a lot of the wear would come from clutch chatter as opposed to continuous load. 2. RS250s run 2mm clutch plates in the same configuration and it seems to work just fine for them.


I could also be hopelessly wrong and we'll be filling our clutch baskets after every race haha

[husaberg]

Well, yeah i would agree normally but it's a little different on the NSR clutch

On the NSR clutches it is the clutch outer which is the problem for "finger wear" Which is where the clutch fibres are engaging, which we are keeping the same thickness on the fibres but increasing the plate count by 20% reducing the load on each plate by the same amount which = less wear. Unfortunately we will be losing 19.3% clutch basket contact area on the steel plates even when fitting an additional plate which is not optimal. But then I go back to two observations on that which is that 1. it is not a street bike so the amount of time that the clutch spends chattering around is much less, and I feel that a lot of the wear would come from clutch chatter as opposed to continuous load. 2. RS250s run 2mm clutch plates in the same configuration and it seems to work just fine for them.


I could also be hopelessly wrong and we'll be filling our clutch baskets after every race haha

As I mentioned (a couple of days ago) the stock std steel plate closest to the engine on a std Honda NSR250 with a dry clutch ie se sp. Is 2mm.

[nick gill]

Hello forum gang.
This is my first post, but I've been lurking, absorbing, disseminating, and note taking for a few years now so hopefully I won't be wasting anyone's time.

A question for Wobbly:

I have an Iame small cage reed block in a cylinder-reed application. The engine is now of a much greater bore x stroke than an Iame Sudam for which the reed was designed, but for packaging reasons I cannot use the larger reed version, or any larger reed.
Is there a general rule for altering reed stiffness, that as the flow demands increase you need to stiffen/soften the petals reed thickness? How does this tunability pan out in real life?

Sorry if this was covered 900 pages ago, my memory is only human

[Sketchy_Racer]

As I mentioned (a couple of days ago) the stock std steel plate closest to the engine on a std Honda NSR250 with a dry clutch ie se sp. Is 2mm.

Yep but they are significantly more expensive than 2.58 per plate to get them later cut

[husaberg]

Yep but they are significantly more expensive than 2.58 per plate to get them later cut

Fair enough, I tried to find a parts book for a 87 NF5 but couldn't find one. I did notice though that the later models RS250's seemed to have a fibre plate on the inside.

[lodgernz]

Yep but they are significantly more expensive than 2.58 per plate to get them later cut

Is that $2.58 per plate to get them laser cut? Sounds cheap

[wobbly]

In a word - NO.
The only way to get greater performance from a reed that is essentially too small is to the vary the petal frequency such that it
is resonant within the powerband.
EngMod gives the primary frequency that coincides with a particular rpm.
But then it gets real murky if you start to use soft patals and add revplates and then extra backups.
This cant really be modeled, but all you can do is follow the general advise on how to do this I gave in here ages ago, and test a bunch of
setups on the dyno.
Here is an example where I have done just that, in a SKUSA CR125 where the carb is sitting up high on a manifold bent at 30* to the flow.
All the air was trying to go thru the top,RH petal.
2 days of testing and here are the best few against the stock Honda carbons.

[nick gill]

The only way to get greater performance from a reed that is essentially too small is to the vary the petal frequency such that it
is resonant within the powerband.

Thanks Wobbly for the reply. That has informed the direction I will take. Cheers.

[Sketchy_Racer]

Is that $2.58 per plate to get them laser cut? Sounds cheap

We get quite a lot of laser cutting done through work so we get good prices. My clutch plates accidentally sneaked into one of the orders

[peewee]

frits a couple pages back you showed a pic of 20* radial aux ports. i thought that was a old pic. reason is because didnt jan say eventually he extended the aux window to almost center bore ? there must be a updated pic somewhere

[Frits Overmars]

frits a couple pages back you showed a pic of 20* radial aux ports. i thought that was a old pic. reason is because didnt jan say eventually he extended the aux window to almost center bore ? there must be a updated pic somewhere.

I've been waiting for this question to come up. Those 20° do not indicate the position of the port, but only the difference between its positional radius and its direction.
By the way, I can't remember what Jan did or didn't write, but I do know what he did: he extended the positional trailing angle of the auxiliary exhaust port to 8° past the center of the bore. This, combined with my 20° difference gives a directional trailing flank that exits the cylinder, pointing 12° forward.

The picture below is really a scavenging concept, but it may clarify the above-used expressions positional angle and directional angle.

[Tim Ey]

In a word - NO.
...
But then it gets real murky if you start to use soft patals and add revplates and then extra backups.
This cant really be modeled, but all you can do is follow the general advise on how to do this I gave in here ages ago, and test a bunch of
setups on the dyno.

I modified my daily driver reed with a splitter, as your advice was in #16420, but the 0,25 carbon plate tends to brake right away - so I would be VERY interested what a "revplate" is :-)
(I suggest a second reed petal mounted on top of the first?!)

Just searched my arse off - but I can not find it...
TZ ? :-D

[husaberg]

I modified my daily driver reed with a splitter, as your advice was in #16420, but the 0,25 carbon plate tends to brake right away - so I would be VERY interested what a "revplate" is :-)
(I suggest a second reed petal mounted on top of the first?!)

Just searched my arse off - but I can not find it...
TZ ? :-D

Rev plate is a generic term think what Boyesen used to sell to put in place of the std reed stopper. look under the screws