Old School 100cc Megatopic

Now I’m dropping a bucket list item here…brought home yesterday by my brother. Working on it today and tomorrow. Taking it to the track (Jesolo) in 2 days
Very, very special one




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Living the dream. Have not seen this appendage on a rear bumper before. Is it to help with push starting?

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Yes! It’s lift/push handle!

This is a Jolly Kart (Gianniberti). Small batch

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Delicious. Do you have a Rotax DSD/DSE yet? I have a D left over from the 90’s. I’d love to have a lefty D or E sometime with a fat 30mm slide.

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Yes, I have a DSE R. DSE or DSD L are super cool as they were able to angle the carb upwards for better flow, great piece of kit!

Braaaap, another vid from yesterday’s session. This time with my Italsistem ML21.

Great engine with really punchy mid/top

Enjoy

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Deep 100cc kart engine development lore here

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That’s pretty cool, I love learning about all the different things that where tried in the 90s

I believe the DSE and DSC share the same bolt spacing etc on the rotary valve cover so the dual carb one could potentially bolt directly onto a DSE-L

Ill just leave this here

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Any advice regarding tuning would be great.

Tuning rotary engines with ibea l2 2 jet and 3 jet carbs on various engines

  1. I ran the two jet on a tt38 with low on 1 and high on 1.5. Ran around 10 session over a few different days and always ran a bit rich. No issues at all.

  2. Ran the same carb and tune on a titan rv2 and was good for a 10 lap session then next session seized coming out of low speed corner in a few laps.

  3. Again the same tune as a basic setup in my mv31 ital and seized in 3 laps. Plug showed lean on the low jet.

Just so weird the tt38 ran rich as and no issues then two other engines were hand grenades.

Can anybody suggest base runes to start and how to tune strategically? Eg richen each jet every 2 laps, or choke more etc?

Hard to answer but interesting to hear others tuning strategy

Same carb for all of them? Engines will have different jetting needs but really those screw setting should be rich in almost any conditions.

I’d suspect a carb or carb install/gasket issue, or a big change in air. Maybe fuel starvation.

It’s not uncommon to use the first practice session to find out where super rich is while driving around and going from there. Each lap go a 1/16 of a turn out on the high jet until it won’t rev cleanly, then start leaning it from there.

You could be dealing with different failure types with two engines too.

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That is a rich setting, would have been safe in my ears

I’d suspect some form of air leak on your other engines

Interestingly they were both low speed seizes and plugs showed lean on the low speed.

Carb gaskets were all new on each engine and carbs with fresh kits in them.

I had another guy suggest low speed should start at 1.25 and high 1.5.

The default starting points I thought were 1 and 1.5 low and high which was safe. I’m also choking twice a lap. I could do it 3 times I guess.

Even with the ital seize the session before I did about 10 laps on same settings. Half way through then session I would slow and choke and look behind and check for a nice puff of smoke to ensure rich which it had and also on lap 10 of session.

Quite confused

I usually run 1h 10mins at low jet. Plenty of fuel

When you switch from valve to reed, you need to open low screw and tighten a bit the high. As a general rule of thumb

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Whopppaaa!

Got my first rotary today, pretty stoked.

Vortex VR95, the equivalent to my all time favorite VL95 reed. It will be fun and challenging to learn more about this engine

It will be paired with a gold 30mm slider Baroni :fire:



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Ohhhh FSA spec. Have you run the bigger carb on anything else yet?

Oh yeeees, lovely stuff!

No I haven’t since the carb was included in this package :grin: Thrilled to try

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Another carb acquired, a red Tryton Vamec 24mm.

After restoration the red color really popped. Hope it is as fast as it looks :raised_hands:t2:


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For those interested in the old stuff… how do you and Alan find this stuff?