ESE's works engine tuner

[wobbly]

The 102mm bore centres on the RD/LC/TZ/RZ cases is a huge impediment to making any serious power - no matter what cylinder you use.
The biggest crank that will go into those engines without trenching an already weak case is 58mm.
But its not that hard to cut up a couple of case sets and widen the bore centres, as was done years ago by Yamaha Europe with the 3 cylinder 350
that simply had another piece of case welded onto one end.
Then the crank is easy to widen in the centre for a big twin with a push fit male/female spacer.
Having gone to all that trouble then its simply a matter of what cylinder to fit.
Calvins Sphynx has the ability to take a powervalve, so depending upon the end use that may be a very good idea.
But of course with wider bores - anything would fit.
The other factor to remember is that big engines need big pipes, and from experience with the 486 Cheetah, that 58/72mm combo is getting into the realm of diminishing
returns due to engine size being offset by having simply no room to fit the needed fat pipes to make more power.
The 486 Cheetah made 102 Hp on petrol and peaked at just over 10,000, the 400 Cheetah made 96 at 11,000 and still had 90 at 12,000, with slightly fatter pipes allowed
due to the shorter length.
Its all a matter of trying to keep a balance - the short stroke allows bigger revs, the bigger pistons are heavyer, so limit the revs.
The high rpms need shorter pipes so they can be fatter, but rule one for making the best power with any engine layout is to try and get as close to square bore/stroke ratio
as you can to keep the available angle area from the cylinder optimised.
If in doubt bore it out - is a very American approach to making power with cubes, but in a 2T it quickly starts to loose effectiveness due to angle area limiting and piston weight.
A certain wanker I was involved with was obsessed with the idea that simply using the hard parts from a Yamaha Ski 1200 tripple would be "easy and cheap" to make the ultimate
road rocket.
Sadly with an upper rpm limit of just over 8,000 rpm getting 3 pipes all of 1200mm long to fit on a bike justly demonstrated the insanity of the idea and the originator.
Same with another short sighted idiot that spent months designing a 1200 twin in EngMod - only to be shown that those pipes would need another couple of wheels on a trailer behind
the bike to support them.

[husaberg]

Its all a matter of trying to keep a balance - the short stroke allows bigger revs, the bigger pistons are heavyer, so limit the revs.
The high rpms need shorter pipes so they can be fatter, but rule one for making the best power with any engine layout is to try and get as close to square bore/stroke ratio
as you can to keep the available angle area from the cylinder optimised.
If in doubt bore it out - is a very American approach to making power with cubes, but in a 2T it quickly starts to loose effectiveness due to angle area limiting and piston weight.
A certain wanker I was involved with was obsessed with the idea that simply using the hard parts from a Yamaha Ski 1200 tripple would be "easy and cheap" to make the ultimate
road rocket.
Sadly with an upper rpm limit of just over 8,000 rpm getting 3 pipes all of 1200mm long to fit on a bike justly demonstrated the insanity of the idea and the originator.
Same with another short sighted idiot that spent months designing a 1200 twin in EngMod - only to be shown that those pipes would need another couple of wheels on a trailer behind
the bike to support them.

Don't worry, not interested in Big cylinders just wide centred crankshafts
I am looking for an off the shelf solution though, but only for crank.
More keen on the idea to make cc's with multiple cylinders.

[peewee]

these guys make most of the billet crankshafts for the banshee which i assume is the same thing as what your looking for. most of the smaller stroke stuff i think is just the standard 102mm spread but since they create everything in house ill bet they would make any thing you requested http://crankworks.com/index.php/atv/...cts/atv-cranks

you say you dont need cases but if you do, these guys make them. the wider spread centers are usually for the longer strokes but again, im sure they would make anything you requested as it should be rather simple for them http://www.mattoonmachine.com/Billet_Cases.html

[TZ350]

Page 990....

Wobbly!

We have talked over how important the blowdown and it's size are, but what about the blowdown's intensity? If the aux exhaust ports are opening later as the main exhaust port, the peak of the pression is smaller, meanwhile the blowdown lasts longer. Of course the STA is always the same. Here is an example 'One Half'

In case of almost every race cylinder the aux exhaust ports are opening later, and this can be observed in systems with or whitout a power valve. In case of a T port the top edge radius is not 0, but pretty much bigger.

Is it important? Why don't we open the ports the widest possible? That way the ports could be positioned lower what would be optimal.

There are two factors in play with the tripple port setup.
You have drawn them correctly with 68% main port width, as this allows greater blowdown area to be gained via the aux ports.
Out at 72% that has proven to be approx the reliable max width, you loose some blowdown, and gain total area. ( not relevant at all ).
The problem is that even at 68% you cannot run a flat port roof with 8mm corner radi, as the ring life will be zero.


Secondly is that it has been proven in many dyno sessions that having all 3 ports open together looses power.
I can only explain this as a function of the fact that the effective duct length from the outer corners of the Aux is alot longer than that from the main port
mid point to the header.
Thus you get a smearing of the initial wave amplitude ( wider but lower intensity ) as it exits the cylinder into the duct during blowdown.
This reduces the effectiveness of the expansion phase, creating less depression around BDC, and less plugging efficiency as the piston closes the port.


It would appear that having a 68% main port opening first gives a good, high amplitude wave action in the pipe, then the Aux STA gets the blowdown pressure dropped as much as is possible prior to the Trans opening.


A few pages back was a drawing I did years ago of a T port with the outer edges higher than the mid point, thinking that this would ameliorate the duct length issue, but later
testing proved it didnt work well at all.
So by inferrence even lifting the Aux higher than the main wont fix this issue either in a 3 port.

On another subject, if you'll bear with me, has anyone experience of porting a Nicasil cylinder?
I need to know what tools to avoid, any important techniques, etc.
The narrow little oval exhaust needs upping to get blowdown.
There is material fatness above the port but not to the sides, so no possibility of auxiliary ex ports or even T shape.

the cylinders i ported the nikisil was removed before hand and replated afterwards. but you shouldnt have much trouble with the right bits. i think diamond impregnated ones should work although i havent actually tried them yet. maybe theres something even better ?

if you have a welder perhaps you can cut a chunk out of the side of the barell and weld the outer side portion of the exh in the water jacket area then weld the cylinder chunk back in. this should allow aux ports to be used. it has been done on other cylinders, maybe it can work for you

You can lift the Ex port on a Nicasil cylinder using a diamond impregnated burr to cut thru the plating and then use RexCut cotton impregnated
rotary "mops " to put a smooth chamfer and radius back on the bore.
But the issue is that the ring , no matter what the port width is, will always bulge out into the port, and the top corner radius is what smoothly pushes it
back into the groove.
The cylinder will last a while like that, but It doesn't take long for the ring to wear thru to alloy around the port top edge, as there is no Nicasil going around the corner
into the duct to support the ring.
Best long term fix is to have the chrome removed, cut the port and re Nicasil it.
But for dyno testing the porting result, doing it the easy way is fine.

A 182MC is the only thing for small bores .

Running the pins each side of the Ex is completely unnecessary and dumb.
Having a ring pinned over the boost means that as the ring bulges out into the Ex port and is symmetrically eased back in by the top radi
then both ends of the ring approach the pin at the same time.
Any time a pin is offset, one end of the ring hits first, causing asymmetric ring movement in the groove, along with the possibility of bashing the pin out sideways.

im not sure how everyone else did it but i did it this way. just with a paper clip to find the roof and floor angle then used a protractor tool to measure the paper clip. i may have a reed cage loaded into engmod from a old dirtbike but im not sure what good it would do you






on your other angles i just used cardboard the size of the bore and used some wire inside the ports to mark the angles like so. be sure to have a line drawn through the center so you can measure all the angles based off that

The radial angles are not actually needed to input the chordal port widths into EngMod ( perpendicular to the direction of the port flow ) but
the axial angle is used to correct the flow area by the cosine of the upward tilt.
There is a worksheet in the code that uses all the angle info to generate the correct widths, but it can just as easily be directly inputed from measurement.

to measure the roof you wont ever need to bend the clip to a full 90* because every transfer port roof ive even seen had atleast some upward angle. just bend the clip on the table corner then put it in the port and see how well it fits. bend it alittle more or use a new clip and bend alittle less, until it fits well then measure the angle. only takes a few minutes

for the floors just bend the clip to the full 90* on the table corner (or as close to 90* as you can), then set it on the table top and bend alittle more past 90*. its rather easy

perhaps theres a better simpler way to measure the port angles but the paper clip was always simple and easy for me

you may have good luck with wire or even solder.

When I do not have my own equipment at hand I use solder. Works fine.

It's not crossing the line at all but at the moment it's asking for the impossible because I haven't got them with me and I have no pictures or drawings, apart from my bent feeler gauge with which I measure port heights.
I use a 1 mm gauge, bent at 45°, that I pinch between the piston edge and the port edge in such a way that the bent end is vertical (parallel to the cylinder bore).



Then I measure from cylinder top deck to piston edge and subtract 1,41 mm from the measured value. It works for every port as long as its axial angle is not steeper than 45°, even when both the piston edge and the port edge are chamfered or radiused.

There's more to this than meets the eye. The piston is playing a double role: it pressurizes the cylinder and at the same time depressurizes the crankcase.

But even if the piston didn't move at all, there will be flow reversal if the transfers do not close at the right moment. It's a Helmholtz thing: gas flows from one vessel to another, the pressure difference will change sign, and the flow will slow down and reverse.

This is even more striking in the inlet system. The inlet port pops open, the inlet flow will fill the crankcase and at low revs it may reverse direction while the piston is still moving upward!

All 2Ts have some flow reversal when the transfers open, as the residual blowdown pressure is greater than the pressure in the case.

Bulk flow doesnt occur till closer to BDC if the pipe is correctly designed, and the diffuser depression holds the Ex port below atmospheric long enough to promote a differential across the open transfers.

I discovered the flow reversal, and the idea that the port to open first/flows last when I first Beta tested the Dynamation 2T code done by Kurt Leaverton of HotRods fame.

You can see the pressure rise in the transfers, when they crack open, in the running screen of EngMod - see the sample screendump where the green transfer line jumps up at EPO.

Perfectly correct, Jan Thiels setup in the Aprilia engines does exactly that - open the B first.

The B is wider than the A as well, and the lower A port helps to reduce the direct short circuiting upwards into the Aux Ex ports. This layout maximises the available transfer port STA and is great for peak power at high rpm levels.

The usual reverse stagger as seen in Honda T port engines, with the A port the highest, works better in the 3 port layout when you are looking for wider power bandwidth.
Best example would be the KZ2 kart engines, as with no power valve, and the need to be able to pull hard from around 9000 to 14000 + this layout gives better bottom end and overev power, at the expense of outright peak.

I have dyno tested high B port KZ2 engines, and been just over 50 Hp at the sprocket, but no matter what I tried with pipe length and ignition advance I could never generate
enough power down at 9000.

So although the cylinder was very fast in outright terminal speed, it lost too much off every slower corner, fine as a qualifying engine but no good diving under someone entering
a corner - as it simply would not pull out hard enough when on the "wrong " line.

[Drew]

The 102mm bore centres on the RD/LC/TZ/RZ cases is a huge impediment to making any serious power - no matter what cylinder you use.
The biggest crank that will go into those engines without trenching an already weak case is 58mm.
But its not that hard to cut up a couple of case sets and widen the bore centres, as was done years ago by Yamaha Europe with the 3 cylinder 350
that simply had another piece of case welded onto one end.
Then the crank is easy to widen in the centre for a big twin with a push fit male/female spacer.
Having gone to all that trouble then its simply a matter of what cylinder to fit.
Calvins Sphynx has the ability to take a powervalve, so depending upon the end use that may be a very good idea.
But of course with wider bores - anything would fit.
The other factor to remember is that big engines need big pipes, and from experience with the 486 Cheetah, that 58/72mm combo is getting into the realm of diminishing
returns due to engine size being offset by having simply no room to fit the needed fat pipes to make more power.
The 486 Cheetah made 102 Hp on petrol and peaked at just over 10,000, the 400 Cheetah made 96 at 11,000 and still had 90 at 12,000, with slightly fatter pipes allowed
due to the shorter length.
Its all a matter of trying to keep a balance - the short stroke allows bigger revs, the bigger pistons are heavyer, so limit the revs.
The high rpms need shorter pipes so they can be fatter, but rule one for making the best power with any engine layout is to try and get as close to square bore/stroke ratio
as you can to keep the available angle area from the cylinder optimised.
If in doubt bore it out - is a very American approach to making power with cubes, but in a 2T it quickly starts to loose effectiveness due to angle area limiting and piston weight.
A certain wanker I was involved with was obsessed with the idea that simply using the hard parts from a Yamaha Ski 1200 tripple would be "easy and cheap" to make the ultimate
road rocket.
Sadly with an upper rpm limit of just over 8,000 rpm getting 3 pipes all of 1200mm long to fit on a bike justly demonstrated the insanity of the idea and the originator.
Same with another short sighted idiot that spent months designing a 1200 twin in EngMod - only to be shown that those pipes would need another couple of wheels on a trailer behind
the bike to support them.

If someone goes to all that trouble, the room for pipes is easy to overcome by making one slug reverse port, no?

[F5 Dave]

theres alot of various combinations of cylinders. what is the bore and stroke on the 496 ? i wanted to give the 68x68 cub a go but i dont think that 68mm stroke crankshaft will fit in stock banshee cases. from what i hear, 64mm stroke is about the largest you can use in banshee cases and even then requires quit a bit of trenching and such to make it work. the billet cases for longer strokes above 64 are very expensive and out of my price range. i may have to settle on a 68x64 which should be possible on stock cases from what i hear. unfortunatly i dont think calvin made a 64mm cylinder intended for a 64mm stroke, which seems strange as that seems like it would be a good combo.

The 496 is 61x72. Typical cranks are 54 std. +4 / +7 /+ 10 /+ 14. But you get the 4 in std cases, the 7 & 10 with trenching which isn't that hard really and bore the cases to take the bigger sleeves. I got the local re conditioner to do it they set up those sort of jobs all day. Anything bigger is a liability and billet cases.

For or sure they are a serious compromise but a twin knocking on 100hp with better midrange and less weight than a tuned 4cylinder sounds attractive. And easy for a garage dweller to bolt together. Now I don't have the time or money to rego and ride two road bikes.

i wasted too much time on a porous barrel that wouldn't tune with water injection to some level.

[wobbly]

You try to get a 1200mm long pipe and THEN a muffler to fit onto the Exhaust port face and NOT stick out past the rear wheel.
I did this on a NS400 tripple and even with it tuned to 11000 and a length of 880, it barely fitted even with a big S bend under the seat.
The 500VDue had to use a U bend and face the muffler forward again - sorry I dont do ugly as shit.

[lodgernz]

On another subject, if you'll bear with me, has anyone experience of porting a Nicasil cylinder?
I need to know what tools to avoid, any important techniques, etc.
The narrow little oval exhaust needs upping to get blowdown.
There is material fatness above the port but not to the sides, so no possibility of auxiliary ex ports or even T shape.

[peewee]

the cylinders i ported the nikisil was removed before hand and replated afterwards. but you shouldnt have much trouble with the right bits. i think diamond impregnated ones should work although i havent actually tried them yet. maybe theres something even better ?

if you have a welder perhaps you can cut a chunk out of the side of the barell and weld the outer side portion of the exh in the water jacket area then weld the cylinder chunk back in. this should allow aux ports to be used. it has been done on other cylinders, maybe it can work for you

[F5 Dave]

On a 50 there is so little room it's hard to see how you would complete the weld. Microbots. That's what we need.

[peewee]

what 90* grinder is you guys using on them smaller cylinders ? ive got just the standard size like the ccspecialty 1MC. mostly i work on larger bore stuff above 80mm and it does ok but for smaller bores i think it would be much bulkier than i would like

[wobbly]

You can lift the Ex port on a Nicasil cylinder using a diamond impregnated burr to cut thru the plating and then use RexCut cotton impregnated
rotary "mops " to put a smooth chamfer and radius back on the bore.
But the issue is that the ring , no matter what the port width is, will always bulge out into the port, and the top corner radius is what smoothly pushes it
back into the groove.
The cylinder will last a while like that, but It doesn't take long for the ring to wear thru to alloy around the port top edge, as there is no Nicasil going around the corner
into the duct to support the ring.
Best long term fix is to have the chrome removed, cut the port and re Nicasil it.
But for dyno testing the porting result, doing it the easy way is fine.

[wobbly]

A 182MC is the only thing for small bores .

[Sketchy_Racer]

Hi guys,

sorry if this has already been covered, but I was wondering about ring pin positions.

I've done a bit of work for a mate who is working on his benelli and having a little issue with the pin positions on his pistons. They run in the middle of the transfer port and I'm worried about ring snag. Apparently in the stock motors the ring pin is on either side of the ex port but I have never seen that done before and was curious what the reasons behind that are?

Cheers,

-Sketchy

[kel]

Hi guys,

sorry if this has already been covered, but I was wondering about ring pin positions.

I've done a bit of work for a mate who is working on his benelli and having a little issue with the pin positions on his pistons. They run in the middle of the transfer port and I'm worried about ring snag. Apparently in the stock motors the ring pin is on either side of the ex port but I have never seen that done before and was curious what the reasons behind that are?

Cheers,

-Sketchy

If we are talking C port then absolutely fine, has been done on many motors including my own. The angle of the C port at 55 odd degrees eases the ring back in without any snag issue. One thing I would suggest is the bottom of the C port is lower than the ring position at BDC.
Reason is to maximise transfer port area. Or do you mean why do they run either side of the exhaust? I have no idea why you would do that.