ESE's works engine tuner

[F5 Dave]

So as I lay awake last night I pondered the multi cylinder engine with pipes tuned to different peak power as a curve extension method vs just using less aggressive cones on all 4. The lower peak would have to have some serious over rev though. This must happen, or be accounted for, to some extent with rear pipes lack of cooling.

[andreas]

So as I lay awake last night I pondered the multi cylinder engine with pipes tuned to different peak power as a curve extension method vs just using less aggressive cones on all 4. The lower peak would have to have some serious over rev though. This must happen, or be accounted for, to some extent with rear pipes lack of cooling.

Maybe a servo controlled wind tunnel system for back pipes, although the whole idea seem to work better as a lullaby.

[ceci]

combustion takes place above the piston, so it's the displacement above the piston that count's.

It's funny that it indicates as the most powerful of the 125 2S engines, when its design only allows half of its combustion chamber to be filled

[wobbly]

Yea , but you are ignoring pipe supercharging - the delivery ratio is well above unity, and the scavenging efficiency/trapping efficiency are thru the roof.

[wax]

Does any one have a source for low friction oil seals, I know you can buy ptfe seals but for the life of me I cant find some one who sells them

[Brett S]

Does any one have a source for low friction oil seals, I know you can buy ptfe seals but for the life of me I cant find some one who sells them

We have all common sizes for 100cc and 125cc karts in stock in perth, all japanese ptfe lipped.
Strike Products 08 9303 4915

[jato]

I have checked ProX & Hotrods. I wanted to just change the rods out but in this case it would require shredding the crank, Welding up the crank holes. Bore and Jig grind or EDM the new holes to a smaller pin diameter. The rods on the crank now have a 26mm big pin and the rod length is 135mm. I would prefer to go to a longer rod but I have a over all height I must retain because of the rules for the class. My Build is a Arctic cat ZRT-800 engine. The stock stroke is 65mm. So Stock is a 72X65. I am building a 70X70 3 cylinder for drag racing. I dont have a problem with loose rollers. I am just not sure of the .7mm gap between all of them?? Is that to much or not enough??

I reckon a .7mm gap would be ok but the gap will be .7 of a 4.5mm roller (3.15mm) and so those rollers are going to be constantly very slightly skidding/bunching up away from the load (a bit like modern day apprentices) and eventually there will be rod damage and failure - it might take a while though... no doubt you are planning on using steel thrust washers to stop them digging into the piston bosses. good luck.

[peewee]

the only place ive known to use cageless needles was in dirt bike swingarms and theyre coated with thick grease for lubrication. yes it seems like they would bunch up and skid in a conrod application. ive no experience with a hardened insert in the small end but it may work for a short run engine. other wise maybe custom make some suitable conrods. can a crankshaft from another engine be used ? ive bored the crankpin holes larger with sucess but ive never tried to make the hole smaller. not sure if they can still be found but ktm used to have 135mm conrods with 24mm lower pin and 18mm upper

[wolfie]

Mercury Marine 2 strokes used to use loose rollers in the little ends.

I did my apprenticeship on them in the 70's, great motors.

https://www.ebay.com/itm/1980-Mercury-50-HP-outboard-2-Connecting-Rods-and-Bearings-Wrist-Pins/143391068408?hash=item2162c610f8:g0UAAOSwoSldh4nQ

Dave

[Niels Abildgaard]

You must admit , to actually convince them ( and yourself ) that 70 Hp and 30,000 rpm were even remotely possible takes a class one narcissistic character , or a bare faced bullshit artist with no shame at all - tough call there I would say.

A sad indictment on shite over substance.

The HCCI process can do 500 rps (and does in 2.5ccm model aircraft engines) and that was how I read it.
Was it stated anywhere that the 125ccm had done 500 rps or was expected to?

[Flettner]

lot of talk on a KTM site about TPI, usual wankers that don't even own one or even ridden one or for that matter even know how TPI works, have it that KTM don't know what they are doing regarding oiling.
I am not allowd to post stuff thats not KTM on their thread but was asked by peter1962 about my oiling system. Here is a picture, crank spiggot fits into this small seal. Seal cover is off at the moment. Cover holds the seal in position and is where the autolube oil line bolts up to. Oil direct to the bigend. Autolube pump is crank driven, cable operation ( normaly off the twist grip) now is activated via the power valve.

[Niels Abildgaard]

I have checked ProX & Hotrods. I wanted to just change the rods out but in this case it would require shredding the crank, Welding up the crank holes. Bore and Jig grind or EDM the new holes to a smaller pin diameter. The rods on the crank now have a 26mm big pin and the rod length is 135mm. I would prefer to go to a longer rod but I have a over all height I must retain because of the rules for the class. My Build is a Arctic cat ZRT-800 engine. The stock stroke is 65mm. So Stock is a 72X65. I am building a 70X70 3 cylinder for drag racing. I dont have a problem with loose rollers. I am just not sure of the .7mm gap between all of them?? Is that to much or not enough??

Jawa has made many mopeds with loose rollers and I have a set and can measure if need be.

https://www.jawaparts.com/Connecting...0-555-d510.htm

[TZ350]

Attachment 313942

On my way home I saw this pile of junk put out for the rubbish collection. I recognized that the crank was from a two stroke and grabbed it.

Attachment 313943Attachment 313944

Center main reed valve and split big end bearing and deflector top piston. My guess is, its from an old 2T Mercury V6 outboard.

Attachment 313941Attachment 313940

There had been an old Lola fitted with a 6 cylinder 2T boat engine, well it went pretty good so it was Banned of course ......

Possibly the most unusual T294 to have competed is Pietro Raddi's car, HU81, which is powered by a 2-litre Mercury engine from a powerboat.

Early Mercury outboard engines had split rod and loose crowded rollers in the big and little end bearings.

[Frits Overmars]

... the small end of the connecting rod ID is 27mm... The piston we want to use is a off the shelf Rotax piston with a 18mm wrist pin. The way I see it I will either need to sleeve the small end of the rod with a hardened needle bearing race. (Seems like a bad idea) Or use 4.5mm loose needle bearings. If my math is right 27mm - 18mm = 9mm / 2 = 4.5mm + 18mm = 22.5 X pie / 4.5 = 15.7 needles. So I would be installing 15, 4.5 X 23.8mm loose needle bearing rollers. What do you guys think??

If you insist on using both that con rod and that piston, I'd reluctantly go for a hardened sleeve. The other option, a cageless crowded needle small end bearing, has been used by Jan Thiel in his world championship-winning 50cc Bultaco racer, still the prettiest 50cc bike I've ever seen.

In your case it is paramount that you take the slack out from between the needles, or they will skew, skid and overheat. It can be done with one smaller-diameter needle that fills the gap.
A needle with a diameter of 3,0838 mm would completely fill it, but you need to use a somewhat smaller diameter, because the filler needle must not be allowed to carry any weight, otherwise it would be wedged between its neighbours, jamming all needle rotation.

The clearance will also allow for lubricant between the needles that are all rubbing against each other with a relative surface speed of double their circumference velocity. Reducing this rubbing is the main reason for using caged bearings.
In a small end bearing, with its limited rotation speed and swaying angle, you may get away with a cageless bearing. But in a big end bearing,
with its additional orbiting g-force flinging the needles against each other, you might just as well bin the crankshaft right-away.

The red filler needle in my drawing below is kept in place by its blue neighbours. If its diameter were less than 2,63 mm, it could radially move in- and outward through the gap between the blue needles. A diameter of 2,8 mm should be about right for this layout.

[Zrt1200]

I reckon a .7mm gap would be ok but the gap will be .7 of a 4.5mm roller (3.15mm) and so those rollers are going to be constantly very slightly skidding/bunching up away from the load (a bit like modern day apprentices) and eventually there will be rod damage and failure - it might take a while though... no doubt you are planning on using steel thrust washers to stop them digging into the piston bosses. good luck.

Thanks for all the replies. Yes the .7 gap is what concerns me as well. Yes I was planning on steel thrust washers on each side of the needles. I would just sleeve it but I am sure a press fit in the small end would result in a broken rod.

Yes KTM has the correct rod but its not a simple fix to install that rod. I need to weigh out the cost of just selling this crank and getting a new one built with the KTM rods on it VS plugging the current pin holes and going to the smaller big end pin with the KTM rods on it.

A have seen a lot of loose needle bearing rollers, Mostly in Outboards and Skidoo/Rotax snowmobile engines.

I have priced what it would cost to have pistons made up and for the price of 12 pistons (Minimum that they would do) I can have a new crankshaft built and use off the shelf parts.

This crank originally was to be used in a 1200cc ProMod class which they outlawed after I had the crank built so I figured I would use it in a different build.