ESE's works engine tuner

[ranasada]

I'm searching for a piston with certain dimensions and i figure i search in your knowledge too, it might speed up my process a lot

Demands:

Diam 66.5-67mm
1x piston ring with retainer pin 6 O'clock
18mm wristpin

Compressionheight isn't that very important, but around 38mm would be nice.

Rgds
Patrick

https://www.scafutopistoni.it/5-pistoni#s

[jbiplane]

One my coleguae produce 236cc 2-cylinder inline engines with one common mikuni carb and magneto ignition. Enhine based on Husqvarna 3120 chainsaw cylinders. When one start one of this engines it produce 30hp at 9500 rpm with propeller. 30 second later engine on a full throttle rpm drops to 7500 and power decreased. On 7500 rpm engine can work long time. The same behavior for 4 engines. Any idea how diagnose and correct situation like this?

[Frits Overmars]

One my coleguae produce 236cc 2-cylinder inline engines with one common mikuni carb and magneto ignition. Enhine based on Husqvarna 3120 chainsaw cylinders. When one start one of this engines it produce 30hp at 9500 rpm with propeller. 30 second later engine on a full throttle rpm drops to 7500 and power decreased. On 7500 rpm engine can work long time. The same behavior for 4 engines. Any idea how diagnose and correct situation like this?

So the engine runs with a propeller that absorbs 30 hp at 9500 rpm. At 7500 rpm that same propeller will absorb (7500 / 9500)^3 x 30 hp. That's 14,8 hp.
So maybe one cylinder has stopped working at all after the first 30 seconds.
I've seen this happen before in a twin with both cylinders firing at the same time, but that was on an engine that heavily depended on pipe suction for its power,
something one hardly expects from a 236cc twin producing 30 hp. What kind of exhaust system is fitted? And do both cylinders operate on a common crankcase?

[wobbly]

Simple - you cant diagnose anything without data.
Fit egt and cht , this will tell you what is going on.

[Frits Overmars]

True, without data it's only guessing. But before going through the trouble of fitting EGT and CHT sensors, Valery might put his hands on the exhaust headers .
The side that doesn't hurt should be the culprit .

[TZ350]

The side that doesn't hurt should be the culprit .

Harrrr, that is a test I can understand and I am probably dumb enough to do it myself .... Ouch dam bugger, well, that one is working .............. .

[wobbly]

Haha , me thinking too hard as usuall Frits.
Best egt sensor in the world - your hand.

[Leed]

One my coleguae produce 236cc 2-cylinder inline engines with one common mikuni carb and magneto ignition. Enhine based on Husqvarna 3120 chainsaw cylinders. When one start one of this engines it produce 30hp at 9500 rpm with propeller. 30 second later engine on a full throttle rpm drops to 7500 and power decreased. On 7500 rpm engine can work long time. The same behavior for 4 engines. Any idea how diagnose and correct situation like this?

heat soak, or maybe the fuel being shaken up?
I mean this is an air cooled 2T motor running tandem north/south (hot/hotter). or is it jacketed
without a cooling run fuel etc, the intake and cases will be much hotter than starting run (charge density) and piston/bore clearance


with one carb and small differences in porting and manifold would there be a preference for one cylinder to do more work - but I guess the would happen on run 1.
A cheap IR temp gun would determine temp of each cylinders exhaust pipe

[Pursang]

So the engine runs with a propeller that absorbs 30 hp at 9500 rpm. At 7500 rpm that same propeller will absorb (7500 / 9500)^3 x 30 hp. That's 14,8 hp.
So maybe one cylinder has stopped working at all after the first 30 seconds.

Now that's Engineering at work!

cheers, Daryl.

[jbiplane]

Thanks for responce. The more information is on producer site.
http://sibaero.ru/%d0%b4%d0%b2%d0%b8...-sibaero-2r-i/
I nether see this engine working, only read information on Russian amateur aviation forum. Both cylinders are working (have the same themperature).

[Flettner]

left foot kick start and bob weight parts.
Ready for finish grinding, EN39B.

[jonny quest]

Haha , me thinking too hard as usuall Frits.
Best egt sensor in the world - your hand.

Even better, use wd40 or spray can with nozzle. Quick spray right at header you'll know real fast what's hot or not. Spit works good too.

[TZ350]

Been playing on the dyno again tonight. Just in case you wanted to know. Green and Red lines are both standard, un modified NSR MC21 cylinders on de stroked rotary valve Suzuki GP100 bottom ends. Everything is much the same between the two engines, timing, heads, pipes etc except the Green line is on a case with much more crankcase volume and fuel injection. Interesting that both engines show little bumps in their curves in much the same places.

[Grumph]

Thanks Rob. Have you actually measured the primary compression ?

You're giving me an excuse to be lazy and leave the Villiers primary compression as it is....

[TZ350]

Thanks Rob. Have you actually measured the primary compression ?

Sadly not all that carefully but I estimate its about 770cc crankcase volume without including the transfer ducts. If I include the transfer duct volume I am guessing at about 1.1:1 primary compression ratio for a 110cc engine. But remember, you need a good pipe to make this work.