ESE's works engine tuner

**TZ350** · 13th March 2022, 12:06

.
Team ESE exploring the possibility of fitting a Suzuki GP125 rotary valve assembly to a Suzuki RG50.

Also in the works is a small turbocharger with a much lighter bespoke 6061 aluminum exhaust turbine housing for turbocharging a 70cc two stroke. Aluminum should be Ok for the turbine housing as the exhaust gas is much cooler on a two stroke than a four stroke. We also want to make bespoke turbine housings so we can get the A/R ratio more suited to the capacity of the engine.

A rotary valve converted RG50 with an over bored turbocharged 70cc water cooled cylinder. With the turbo we plan on a draw through carb, but I am also tempted to fuel inject it directly into the turbo intake or maybe just after the turbo on the discharge side.

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**F5 Dave** · 13th March 2022, 15:21

Nice collection of potential projects there Rob.

Some (long) while ago I was looking at spare RG cases and thinking "hmm. V-Twin"
Never happen now but,

**ken seeber** · 13th March 2022, 16:32

Originally Posted by F5 Dave

Nice collection of potential projects there Rob.

Some (long) while ago I was looking at spare RG cases and thinking "hmm. V-Twin"
Never happen now but,

Can you guys still find suitable 100 cc 2 stroke bikes to make buckets from? Any over here are rare and sort of valued and held onto by collector types. Maybe you can get them from SE Asian countries I guess.

I often think that the bucket class could include 125 TAG kart engines. Using their clutch driving thru a jackshaft to attain the reduction required, meaning a single gear ratio. Could have them standard as per their karting homologation rules or also have a modified class as well.

Anyways, just a thought from someone 5000 km away.

**F5 Dave** · 13th March 2022, 19:47

As an increasing old man exhausted from riding my Beta today I have to say racing looks increasing expensive and unappealing.

I bought a $1300 RS125 with 2 years supply of tyres, sold the engine for $600, instant $500 chassis. Circa 1990.

But I don't know what I'd do if I re entered as an old man trying to emulate my occasionally dominant position which is very unlikely given my trail ride skills I showed today. My 1978 MB100 was, ahh fuk it. There's probably a 150 that could. .

Ok no fuk it I'd still wanker it. I just need to be 20 years younger.

**PVO** · 14th March 2022, 02:15

Originally Posted by husaberg

May i ask why your own rods?

Certainly, the main reason is because most snowmobile manufacturers don’t sell the rods individually or the rods they offer are too short. The 850 Etec produced by Rotax, for example, has a rod that would probably work well, however Rotax only sells complete crank assemblies. This is most likely due to the fact the rod is a two piece design that uses a fracturing process to split it. Couple this with the split cage needle bearing and improper assembly and you have a disaster on your hands if it isn't done right.

The other obvious rod options are from Polaris and Arctic Cat. Bore and stroke on these engines are 85mm x 74mm and 85mm x 70mm respectively. My belief is these rods will be too short. I'm still hunting for donor rods but haven't found anything yet and will make one if I have to. I could also concede to having an over square engine but I really don't want to do that.

**PVO** · 14th March 2022, 02:25

Originally Posted by Niels Abildgaard

Very,very interesting that 850 Etec thing
What advantage do You expect going from stock inline to own V2?
Do You have acces to parts for rough measurements or photos?

There are a few big advantages in my application: near perfect primary engine balance, a much narrower package, and an expectation that I can make the V2 lighter than a parallel twin.

I have familiarity and friends with all three major brands. The necessary donor parts will be procured as needed.

**Niels Abildgaard** · 14th March 2022, 04:29

Originally Posted by PVO

There are a few big advantages in my application: near perfect primary engine balance, a much narrower package, and an expectation that I can make the V2 lighter than a parallel twin.

I have familiarity and friends with all three major brands. The necessary donor parts will be procured as needed.

I did a lot of crankshaft speculation for a low mass aircraft engine and a pressed up crank is not low mass.

[URL="https://www.homebuiltairplanes.com/forums/threads/side-valved-two-strokes-for-angels.32119/"]

If You are interested and give me some dimensions I will love to try some alternatives for mass calculation and I know how to balance a V2.

**Condyn** · 14th March 2022, 11:49

PVO it seems rods on large bore snowmobile applications are always too short. I think it is because the deck height has constraints to fit in todays tightly packaged chassis.

I have not been following your planning closely, are you wishing to sleeve down the cylinders and increase stroke length to square? I could be wrong, but my gut instinct would tell me In order to achieve a 2:1 r/s ratio with the longer stroke the case volume would rise dramatically, unless you are planning to add to the topside of the cylinder which ends up being a lot of work.
How long are the factory 850 rods?

**TZ350** · 14th March 2022, 15:37

.
Next step. Filling the area that the rotary valve is going to go with Knead It polymer repair compound.

Will fill the rest of the case then mill a pocket for the rotary valve back plate.

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**wobbly** · 14th March 2022, 15:58

Quote " Aluminum should be Ok for the turbine housing as the exhaust gas is much cooler on a two stroke than a four stroke " .
Really TeeZee - I have done two project 2Ts that regularly saw 1280*F , and most all see 1200 all day ?

**F5 Dave** · 14th March 2022, 17:31

Interested in what your ignition and power source solution will be Rob.

**husaberg** · 14th March 2022, 18:41

Originally Posted by PVO

Certainly, the main reason is because most snowmobile manufacturers don’t sell the rods individually or the rods they offer are too short. The 850 Etec produced by Rotax, for example, has a rod that would probably work well, however Rotax only sells complete crank assemblies. This is most likely due to the fact the rod is a two piece design that uses a fracturing process to split it. Couple this with the split cage needle bearing and improper assembly and you have a disaster on your hands if it isn't done right.

The other obvious rod options are from Polaris and Arctic Cat. Bore and stroke on these engines are 85mm x 74mm and 85mm x 70mm respectively. My belief is these rods will be too short. I'm still hunting for donor rods but haven't found anything yet and will make one if I have to. I could also concede to having an over square engine but I really don't want to do that.

Hot rods and others sell the bits you need
Making rods as small runs is quite expensive.

http://www.transcanimports.com/downl...ing%20Rods.pdf
https://www.pro-x.com/prox-connectin...ensions-brand/
https://www.wandamotor.com/connectin...2253_2540.html
https://www.kimpex.com/en-ca/product...onnecting-rods
https://www.mitaka.co.uk/MDP.htm
http://catalog.vesrah.co.jp/list/product_parts.asp
http://www.samarin.nl/webshop/index....ewCat&catId=32
https://www.tkrj.co.jp/product/m-con...g-rod-kit.html
https://www.twsgb.co.uk/hot-rods-con-rods-37-c.asp
http://http://www.samarin.net/?productos
http://www.pvlsverige.se/vrm/index/index22.html

Polaris 700 and 900
C-C 152.1 mm
SE od 27mm
BE od 40mm
SE Width 20mm
BE Width 20mm
SE bearing 22 x 27 x 25 mm

**TZ350** · 14th March 2022, 20:51

Originally Posted by wobbly

Quote " Aluminum should be Ok for the turbine housing as the exhaust gas is much cooler on a two stroke than a four stroke " .
Really TeeZee - I have done two project 2Ts that regularly saw 1280*F , and most all see 1200 all day ?

My guess is that 1280*F was seen in the header near the cylinder. I was planning on following these layouts where the Turbo is attached at the stinger. If it is still to hot there I will attach the Turbo to the mid section, where I expect the exhaust gas is at its coolest.

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**TZ350** · 14th March 2022, 20:56

Originally Posted by F5 Dave

Interested in what your ignition and power source solution will be Rob.

At this point I am planning on a DC-CDI Ignitec and total loss 18V 5A/hr electric drill battery. I hate total loss because it so often catches you out with a flat battery but I can't really see what else is possible or practical. Maybe super magnets around the clutch hub. Pole piece with coil fastened outside with the poles reaching through slots in the clutch cover. I think I will start with total loss before this becomes a rainbow bike. You know, the pot of gold at the end of the rainbow. You just never seem to get there.

**husaberg** · 14th March 2022, 22:42

Originally Posted by TZ350

At this point I am planning on a DC-CDI Ignitec and total loss 18V 5A/hr electric drill battery. I hate total loss because it so often catches you out with a flat battery but I can't really see what else is possible or practical. Maybe super magnets around the clutch hub. Pole piece with coil fastened outside with the poles reaching through slots in the clutch cover. I think I will start with total loss before this becomes a rainbow bike.

I once seen a mini ignition mag like a KTM 50 rotor mounted on the inside right next to the carb.
it scared me. But your pilot might be braver than me.