ESE's works engine tuner

[kel]

Methanol is over 130, and with its very high latent heat its great for all types of 2T, especially Aircooled.

But its toxic as hell (even more so for children). A cumulative poison which leads to blindness and eventually death that pours out of exhausts , thank goodness its banned from use in buckets! Now Ethanol's a different story, if we used E100 we could mix the left overs at the end of race day with a little coke ...

[TZ350]

Page ... 1170

Lots of good info on engine/gearbox oil here:
http://www.ducatimonsterforum.org/in...p?topic=1912.0

What do you think about roller bearings in this transmission ? one behind the front sprocket and one behind the clutch basket. i dont see any reason not to do it, although they would need a ring groove cut in them.

I don't see any basic problems for a roller bearing behind the sprocket, but it's a different kettle of fish behind the clutch basket. The remaining ball bearing on the clutch shaft will have to cope with the full force of all the clutch springs. Is it up to that?

EDIT: There are no big axial forces working on the secundary gearbox shaft (unless you have bevel gears driving a cardan shaft), but it still has to be kept in place.
So although you could use a roller bearing behind the front sprocket, it would require that the remaining ball bearing on this shaft is axially fixed in both directions, and in the cases as well as on the shaft. Could complicate things....

EDIT # 2 (it takes a while, but once I've got my brain in gear, it won't stop): unless you have a primary transmission with straight-cut gears, there will be axial forces acting on the clutch shaft in both directions, depending on whether the engine is driving or being driven. Violent up- and down-shifts, you know...

Re the gearbox bearings - its common to have a roller on the output as there is no axial load and the chain pull is a heavy load easily coped with by the rollers.
But with or without helical drive there is still a heavy axial load on the input shaft from activating the clutch,this is why there is a double row ball on a RD/TZ/RZ etc
behind the clutch, with a full circle circlip into the case - not a 1/2 clip like the mains.

Original posted by Husa

From memory there was some comment made about the inertia of the gas column in the transfer duct and that one with a smaller cross section was easier to rapidly accelerate into the cylinder than a large fat one.

I thought it was short and fat is better than long and skinny?

A gas column with a smaller cross section has to accelerate more rapidly in order to transfer the same amount of air/fuel mass as a column with a large cross area.
But the rate of acceleration depends on the pressure difference between crankcase and cylinder, which in turn depends on the blowdown time.area and the efficiency of the pipe. At high revs, when the available time for transfer becomes shorter and shorter, small transfer cross sections may be less than desirable.

I don't have the cylinder yet, so this will be an educated guess at best; what would yield the best results here? Case transfers are too wide - widen cylinder transfer duct entry 5mm on each side or epoxy the case to match?

As always its impossible to say what would be a good mod if only half the info is available.

Grinding or epoxying would depend entirely on the case com ratio.

If its already way too small then grinding is needed as the case com ratio would have a way bigger positive effect than the cross sectional change may be a downside.

But that cylinder for sure needs a big radius on the duct/bore edge.

Re the gearbox bearings - its common to have a roller on the output as there is no axial load and the chain pull is a heavy load easily coped with by the rollers.

But with or without helical drive there is still a heavy axial load on the input shaft from activating the clutch,this is why there is a double row ball on a RD/TZ/RZ etc
behind the clutch, with a full circle circlip into the case - not a 1/2 clip like the mains.

Rule of thumb ex-port size maxed out thoughts.

Lets assume a single ex-port taken as wide as can be done between the the tight studs and still not up to the "% of bore" you like to have.

OK, let's assume the studs are in a square, so close to each other that they almost touch the bore. Even then you can fit in a 70% wide exhaust port, which is the optimum width anyway. That single exhaust port may not give you sufficient blowdown angle.area, but widening it will not help either because wider ports require bigger corner radii to keep the piston ring happy, and those bigger corner radii would eat into the upper part of the port area, where it counts.

With the ex-port/header area at approx 90% of the effective port already, would it still be advisable to rise the duration to gain blowdown STA even if this gives a "higher ex duration then desirable"?

From a resonance point of view 180° effective exhaust timing is optimal; that will be 190° geometrical, or a tad more. The RSA's 202° is the best compromise between resonance, blowdown angle.area and rpm. Not because it's a racing engine but because of the laws of physics. And sufficient blowdown is not only important for power; it also lessens the risk of spent gases entering the transfer ducts and overheating the cylinder.

The max Ex port width is dependent upon the bore size as well. when dealing with small pistons like 50cc or similar.
You can safely go out to 75% as the bore to supported ring section ratio is skewed in the small pistons favor.
This is a proven safe width in many small engines, but at the end of the day you will be limited by the worst STA number.
If this is the transfer ports, then over spec'ing the blowdown will simply make the thing peaky and hard to tune.
The actual Ex STA is pretty much irrelevant, except to match its effective area to the outlet size.

True. The Honda NSR50 engine as standard has a single port whose width is 77% of the 39mm bore, and they can be and are thrashed mercilously with total reliability

[Kickaha]

thank goodness its banned from use in buckets!

Didn't you see my proposed rule change?

[TZ350]

Didn't you see my proposed rule change?

Methanol for 2T's open fuel for all Buckets, anything goes including nitro, I would love that, absolutely ... ... lets get rid of all the unnecessary restrictions so Buckets can be the preeminent development class again ...

[lodgernz]

Methanol for 2T's open fuel for all Buckets, anything goes including nitro, I would love that, absolutely ... ... lets get rid of all the unnecessary restrictions so Buckets can be the preeminent development class again ...

But it wouldn't be. Instead of a class where leading edge technical development was taking place, it would be a class where cranks and rods and crankcases and barrel and head mountings got beefed up to use increasingly crazy fuels.
Porting and timing and scavenging and CRs would all become very removed from the diminishing real world of racing 2-strokes that we are trying to improve.

[TZ350]

But it wouldn't be. Instead of a class where leading edge technical development was taking place, it would be a class where cranks and rods and crankcases and barrel and head mountings got beefed up to use increasingly crazy fuels. Porting and timing and scavenging and CRs would all become very removed from the diminishing real world of racing 2-strokes that we are trying to improve.

True, but the blowups would be spectacular........ .... we could learn about using alternative fuels and how to apply the sustainable fuels like natural gas, methanol, ethanol and hydrogen.

[seattle smitty]

Methanol can be made from garbage, so two problems are addressed. (Not advocating anything in particular; just sayin'.)

Outboard and Inboard racers in the USA, with decades of being around rich-running methanol fueled engines both on the course and to some extent in the pits, are growing old while retaining their eyesight (as much as any old people) and such brains as we ever had. In the Twenties and Thirties, board-track auto racing was a popular sport in the US, with grandstands full of spectators exposed to the alcohol-burning racecars and motorcycles, but I have never heard of any revelations of health problems related to that. But you certainly have to be aware of your fuels, and it should be regarded as one of the responsibilities of racing organizations to make certain their members are educated about the risks and the needed safety measures. One such risk is that a fire involving straight alcohol is colorless, and possibly the first clue that you have a problem might be the interesting sight of things melting for no obvious reason . . . .

I love the story of Karl Benz, when he was building some of the very first I.C. engines. At that time (1870s-80s), as I understand it, gasoline had no commercial application, and was considered merely a laboratory curiousity. Benz had procured some, and one evening, just before closing up the shop, he decided he make a first quickie experiment. He had a brass casing from an artillery shell, and into this he put one good big drop of gasoline; then he put a cork in the open end of the shell casing and waited for the gasoline to evaporate.

Benz described (my recollection of his account, not his exact words) the moment he removed the cap from the casing and passed a match across the open end: "There was a loud report that startled me greatly; the shell wobbled drunkenly on the table for a moment before falling on its side, . . . and in that moment, I knew I had found my fuel!!"


But given its various dangerous properties, if gasoline were just now being proposed as a possible fuel to be put into very widespread use by ordinary citizens, do you really think government regulatory agencies would allow it? Not a chance! Think of all the useful substances that have been taken away from us for our ostensible protection (at least in the US): zinc chromate primer for aluminum, pentachlorophenol wood preservative, carbon tetrachloride and Stoddard solvent for cleaning, just some of the things I could use when I was a young man but not anymore. I'm not saying that these things, or methanol, are to be dealt with casually, nor am I trying to diminish Kel's legitimate concern by offering a different perspective.

[seattle smitty]

(double-post, deleted) (I once asked a librarian, after yet another rage-inducing computer experience, if she thought anyone would mind if I smashed my laptop to bits against a nearby post. She said that yes, some would surely be annoyed by the disturbance, but that others might stand and applaud . . . ).

[Kickaha]

Methanol can be made from garbage

So we can make it out of two stroke motorcycles then?

[TZ350]

Methanol can be made from garbage

So we can make it out of two stroke motorcycles then?

............ ... so true

[husaberg]

Found this never seen them on the site two rings though and unlikely to be a commonly stocked item either.
http://www.tkrj.co.jp/goods/m-AS8060X-21A04-21A14.php.
They are supling the RG500 ones as well same deal.

I am picking they will both be in 2 ring config though.

[adegnes]

I don't have the cylinder yet, so this will be an educated guess at best; what would yield the best results here? Case transfers are too wide - widen cylinder transfer duct entry 5mm on each side or epoxy the case to match?

[speedpro]

One you can undo the other you can't. I know which one I would be trying first. Well actually you could devcon the transfers if grinding them didn't work so well. There is of course a preferred taper and ratio between the bottom of the duct and the port at the cylinder.

[peewee]

wobbly what do you think about roller bearings in this transmission ? one behind the front sprocket and one behind the clutch basket. i dont see any reason not to do it, although they would need a ring groove cut in them

i picked up some skf roller crank bearings with polymer cages at a good deal. if i was to weld the center crank pin (not around the full circumference of the pin but just one spot on each side opposing each other) do you rekon enough heat would transfer through the cheek and melt the bearing cage ? i didnt even give this consideration until just today.

[speedpro]

But its toxic as hell (even more so for children). A cumulative poison which leads to blindness and eventually death that pours out of exhausts , thank goodness its banned from use in buckets! Now Ethanol's a different story, if we used E100 we could mix the left overs at the end of race day with a little coke ...

Of course Toluol which is about 30% of unleaded fuel is completely safe, and unleaded fuel combustion products are safe(r) as well than leaded fuel combustion products. Provided that those combustion products are passed through a "working" catalytic converter. If not then more worse than the original leaded fuel exhaust if I recall the paper I read correctly. Not sure how petrol engine exhaust compares with Methanol engine exhaust as far as toxicity goes. Be interested to find out from someone educated in these matters.