ESE's works engine tuner

[jbiplane]

Anyone can give good reference how easy calculate tension and compression force acting on conrod of 2-stroke?
Gas dynamic + acceleration... Any tool like engmod2t doimg that?

[F5 Dave]

Since we've mentioned a few foul-stokes here, (i'm in the middle of thinking about the conrod problem, and this talk reminded me) i'm converting 4T bottom end to take a 2T topend because the rules never said i couldn't.

what method would you use to block up all the holes in the 4T oil soaked crankcase? JB weld, braze, MIG, TIG? only really concerned about making an oiltight seal and not structural work.

That all seems a little nonsensical, however if it is making a mockery of some badly written rules then I'm all for it. Pictures when you are in the guts of it please.

[Muhr]

Anyone can give good reference how easy calculate tension and compression force acting on conrod of 2-stroke?
Gas dynamic + acceleration... Any tool like engmod2t doimg that?

Do not know what is easy in life but, you may think it is worth reading.

https://hal.archives-ouvertes.fr/hal-01305936/document

[wobbly]

Sorry to derail the 2T talk guys , but its a 1/4 midget , so must use the XR/XL200 as a base.
Crank for the XR125 is as you say already a short stroke with the same basic forging, but the CB100 is alot nicer machined piece.
Moving the pin bore out to 51.8 is easy and using the shorter 98mm KTM rod gets the ratio back to a more suitable 1.89.
70mm bore is about it , offsetting the sleeve 1.5mm towards the exhaust - and im using a Yamaha 225 piston as it has a bigger 16mm stronger pin that matches the rod.
Biggest issue to me is that there is no 30/37 silver flat cage bearing available that I can find, there is in 38 ( with an extra needle as well )
and IMHO that is far more important for reliability than the roller size.
The old copper M cage is completely shite no matter what needle.
Race alloy roller rockers are made for the smaller Honda clone pit bike engines and using the spastic XR200 Megacycle cam makes
a correctly matched lobe profile easy to do with oversize Kibble valves and beehive springs/titanium retainers.
Not really my thing - but gives me a chance to use EngMod 4T for a change.

[Michael Moore]

Inertia load of reciprocating parts from Irving "Tuning for Speed" (pulled from a little spreadsheet I made)

Load at TDC in pounds = .0000142 W Nsq S (1+ S/2L)
Load at BDC in pounds = .0000142 W Nsq S (1 - S/2L)
W=weight of components in pounds
N = RPM
S = stroke in inches
L = length of con rod in inches

"sq" is squared, so RPM squared

I attached a copy of the spreadsheet that has some numbers I was looking at for a 200cc vintage single

Be sure to verify the numbers before applying to your project! This was made for my own use and I don't claim to be a professional spreadsheet creator.

cheers,
Michael

[husaberg]

Sorry to derail the 2T talk guys , but its a 1/4 midget , so must use the XR/XL200 as a base.
Crank for the XR125 is as you say already a short stroke with the same basic forging, but the CB100 is alot nicer machined piece.
Moving the pin bore out to 51.8 is easy and using the shorter 98mm KTM rod gets the ratio back to a more suitable 1.89.
70mm bore is about it , offsetting the sleeve 1.5mm towards the exhaust - and im using a Yamaha 225 piston as it has a bigger 16mm stronger pin that matches the rod.
Biggest issue to me is that there is no 30/37 silver flat cage bearing available that I can find, there is in 38 ( with an extra needle as well )
and IMHO that is far more important for reliability than the roller size.
The old copper M cage is completely shite no matter what needle.
Race alloy roller rockers are made for the smaller Honda clone pit bike engines and using the spastic XR200 Megacycle cam makes
a correctly matched lobe profile easy to do with oversize Kibble valves and beehive springs/titanium retainers.
Not really my thing - but gives me a chance to use EngMod 4T for a change.

I haven't seen the 225 piston
TKRJ do a 20mm ish wide 30-37 in silver but i have not seen the cadge. Not even sure what its for other than its for a Yamaha.
the early hondas had roller bearing crank (on one side Mag)as well as fully machined the 100's were generally 2mm narrower or something in the rod plus i think 14mm pin.
Also be aware the early stuff has a different spline on the primary there is a work arround but i cant remeber what it is maybe a mid model had the right 3.3 ratio primary rather than the 4.05 and the early spline and visa versa.
the cb100 box is 2.5-.965 from memory far nicer ratios thna the 6 speed.
That KTM rod was available in MMC no bearing a few years back, half the weight good for a year. according to the blurb

Id be opening up the breathers as well.
One of the ATCs plus the TLR200 have bigger fined cylinders.

problem with them is one cam no ability to experiment with overlap.
Likely the only reason people raced Triumphs back in the day.
plus the Honda head was great in its day but there is little room to raise the ports.
But best 4t trail bike motor ever made,

[jbiplane]

I attached a copy of the spreadsheet...
Be sure to verify the numbers before applying to your project

Do not know what is easy in life but, you may think it is worth reading.
https://hal.archives-ouvertes.fr/hal-01305936/document

Thanks Muhr & Michael.
I did something similar in excel, but any additional references are very usefull

Parts of kreuzkopf engine for my respective customer (alternate to Ruger).

According my estimations will work better. Weight of moving parts equal to stock piston.

[TerraRoot]

That all seems a little nonsensical, however if it is making a mockery of some badly written rules then I'm all for it. Pictures when you are in the guts of it please.

Entirely nonsense and it'll probably take the better half of two years, provided i don't sire any more kids..

Thanks Michael for your response, but the holes are pretty big:


That ain't the exact crankcase but it's similar, for giggles the specs will be a honda c50 41.4mm stroke crank and a 45mm mb5 topend, gotta sort a longer conrod to package the lot in and allow a roller cage small end.
if it made 10bhp i'd be happy, if it made 7 i'd still be happy because it would sound better.

I'm leaning toward the JB weld solution myself, anyone gonna tell me no?

[husaberg]

That all seems a little nonsensical, however if it is making a mockery of some badly written rules then I'm all for it. Pictures when you are in the guts of it please.

The original husky that became the husaberg was made out of a two stroke bottom end.
they used reed valves controling crankcase compression and splash from the cam chain to move te oil arround.

[TZ350]

I'm leaning toward the JB weld solution myself, anyone gonna tell me no?

Having glued up a fair few two stroke engine crankcases myself I would definitely go the glue way. I use Devcon F Aluminium putty myself but expect JB weld would be just as good. Glue from both sides of the hole with maybe a bit of light fiberglass matting worked in for good measure. Gluing from both sides locks the plug in. If you want to be doubly sure smear some clear Silicon glue over the out side to seal any air leaks if the plug works loose. You will be able to tell if there is a leak because the fuel will discolor the Silicon. Silicon is not fuel proof but sure seals air leaks and is a good tell tail. Anyway that is my thoughts. I like the idea of your project.

[guyhockley]

Looking at the work you're going to have to do to get a good seal around the crankcase, would it be worth seeing if you could transplant an existing 2T case into it?

[Frits Overmars]

Looking at the work you're going to have to do to get a good seal around the crankcase, would it be worth seeing if you could transplant an existing 2T case into it?

How about a simple tin can? Or even better, a heat-insulating synthetic can?

[Grumph]

Looking at the work you're going to have to do to get a good seal around the crankcase, would it be worth seeing if you could transplant an existing 2T case into it?

Might be easier to simply fabricate a sheetmetal crank shroud - same shape as the inside of a 2T case.
All it's got to carry is a pair of seals so it doesn't have to be particularly strong.

Frits would appear to have faster internet than me, LOL.

[ken seeber]

Piston forces. During the Ryger period, I wrote a spreadsheet to get an understanding of the piston forces.

At the time, I did try posting it, but it was rejected as an Invalid file. Then a couple of days ago, Michael Moore successfully posted his spreadsheet. So, I sent mine to MM and he observed that mine had a file extension of .xlsx, rather than the .xls of his. He then converted it back to .xls, and voila, it worked. Cheers MM.

So, have a giggle if you want. Suggest you read the Explanation sheet first, you may get some understanding of it.

Warning…… Point 2 might be entirely correct.

Piston Force, Vel and Accel 090319 Ken Seeber.xls

[mike schmidt]

Might be easier to simply fabricate a sheetmetal crank shroud - same shape as the inside of a 2T case.
All it's got to carry is a pair of seals so it doesn't have to be particularly strong.

Frits would appear to have faster internet than me, LOL.

My vote would be to set it up on a rotary table and mill the existing "shroud" away and at the same time mill a shallow pocket into the crankcase. Then turn some heavy walled aluminum pipe/ tubing to the correct I.D. / O.D. Cut it off so it sits a few thousands proud of the mating surface of the case. Bandsaw and belt sand it to fit the best you can. Clean everything, goop it up with epoxy and clamp everything together. Once it is cured, mill or lap the mating surface flush.

?????


Michael