Simson 50cc high end porting

Kilian Münscher /

I am going to port a 50cc stock cylinder that should in the end produce somewhere between 11hp and 16hp.

I am going to cut in 3 more ports to the existing ones and try to match the new ports to the aprilia rs125 design.

And of course to get a fitting amount of blow down time area I will cut auxiliary exaust ports and raise the exaust port timing to about 178 to 184 degrees, because I still want to have a wide powerband to fit the 3 gear engine I have.

I am going to use a reed intake system now here I am starting to get problems, as I never have worked with reeds before (only with piston ported an rotary valve engines) I don't know what reed I should use.

I am thinking of a 28mm carburetor.

Should I use a malossi reed?

V force would be nice but I think they are to expensive for me.

Any suggestions?

Thanks

Re: Simson 50cc high end porting

I think your estimates are pretty extremely optimistic, especially porting stock air-cooled 50cc, but this is still awesome and for sure you can get a lot more power out of it. just maybe more like double instead of 4x

Re: Simson 50cc high end porting

Kilian Münscher /

Yeah

Probably I was overestimating the power.

I will use a malossi vl17 or vl18 reed.

I am also thinking about building a engine dyno to tune up the engine, like the one mark atkinson built.

Does anyone kown a good pipe (will need to be modified to fit the engine) for high rpm low displacement engines.

Max hp at about 12.000rpm

Re: Simson 50cc high end porting

that much of a jump in hp is going to require more than just port timing changes. Changing the squish profile is going to be important. I'd suggest reading about that.

Re: Simson 50cc high end porting

probably one of the 1 speed kids competition dirtbike pipes are a good bet, they squeeze pretty incredible power outta those and it's entirely with crazy revs

Re: Simson 50cc high end porting

Kilian Münscher /

I am in the moment on vacation but in about 1 week or so I am going to start working on the zylinder.

I am only going to tighten the squishband to 0.8mm as the shape of the used cylinderhead is really good for high power applications.

As soon as i get home and have good internet again I will post a picture of a dude that did the same to an engine he had a 60cc cylinder but he produced 18hp of it.

The cylinder has a steel liner witch will be pressed out and the i weld or glue on material to get more space for the ports.

Re: Simson 50cc high end porting

I mean if youre expecting power in that range you should absolutely build a pipe specifically for this application. The RS50 only makes like 12hp btw.

I cant imagine getting that much HP out of 50cc. Can you link that engine build?

Re: Simson 50cc high end porting

Kilian Münscher /

I will like that engine built if I find it. I have thought about building a pipe to i even built one before its just time consuming and annoying.

But this time I will buy the bent pice of the pipe case that really annoying to build.

Re: Simson 50cc high end porting

Kilian Münscher /

and the post is from a german forum so it will proberbly not help you

Re: Simson 50cc high end porting

Kilian Münscher /

I found a screenshot of the 60cc engine but not the website it came from.

1 picture is the ported 60cc cylinder

2 is stock cylinder

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Re: Simson 50cc high end porting

I ported and decked my stock hobbit jug similar to this. Added aux ports, lots of piston mods, etc.

I saw this is a 3 speed, should be great if you don’t fuck up

My hobbit was fast as fuck, made big power at 9.5k-11.5k

I kept porting afterwards to find how far I could go. Eventually started snagging rings but it was an experiment I wanted to end and move on to a big boi kit. (edited)

Re: Simson 50cc high end porting

Kilian Münscher /

Its 3 gear and not support to be drivable a just want it to be fast on long straights.

What kind d of pistoring thickness did you run i am thinking about a barikit pe 65 piston with 0.8mm piston ring which should hold up up to 16.000rpm so enough and the piston os nice quality and not to expensive 65€

Re: Simson 50cc high end porting

Kilian Münscher /

do you have a picture of the hobbit zylinder.

Re: Simson 50cc high end porting

Kilian Münscher /

I am thinking about swapping the reed intake for a rotary one.

I do think I could pull it off and I think it will gain me some power in the low end as well as in the high end with the right valve timing.

Does anyone got experience with rotary valves would it even be worth it for the power I would gain?

Re: Simson 50cc high end porting

You’re starting from a disadvantage using a stock cyl, but if you add a ton of material to the cyl and add rotary intake it’s totally doable and would be better than reed if you do it right. Lots of hurdles to jump over tho

Only limit is your skills with fuckery.

I like doing things like this too.

Making something into something totally different with only your will. Good luck

Re: Simson 50cc high end porting

Kilian Münscher /

Seems to be the way I am gonna take as I really like to take the rocky way gonna get the cylinder in about a week or two so then its time for business.

Re: Simson 50cc high end porting

Sander Mulder /

> Kilian Münscher Wrote:

> -------------------------------------------------------

> I am thinking about swapping the reed intake for a rotary one.

>

> I do think I could pull it off and I think it will gain me some power in

> the low end as well as in the high end with the right valve timing.

>

> Does anyone got experience with rotary valves would it even be worth it

> for the power I would gain?

Power gian on high end?, yes, but low end, im afraid not.

But if you want max hp, i would choose rotary valve.

How much rpm do you think you’re going to make?

Re: Simson 50cc high end porting

Kilian Münscher /

I am doing research on rotary valves at the moment but as far as I am concerned when you don't get to extrem with the timing you can gain low as well as high end power over a reed because there is no resistance in the rotary valve which helped in low end power.

Or at least thats what i heard.

Re: Simson 50cc high end porting

Kilian Münscher /

Rpm?

Well there I can only make an educated guess.

For the blowdown time area I am hoping to get the engine shoul rev really high.

To about 13k but in the end this is only a guess

Re: Simson 50cc high end porting

Simsons are coll bikes. Check this crazy clear transmission cover someone made for them. We need this for an e50, or even better a za50!

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Re: Simson 50cc high end porting

Kilian Münscher /

Has anyone tried to mix ther own e85.

So just mix in ethanol you can get in the grocery store and mix it in the gas, as using e85 would eliminate the cooling problem the engine would have as it is air-cooled.

Re: Simson 50cc high end porting

If you’re doing all this why not do a water cooled head? It’s very very nice to have. My bikes run cold in extreme conditions.

Re: Simson 50cc high end porting

Kilian Münscher /

Only watercooled head ?

I haven't heard of that one.

Do you convert the head for watercooling or do you get a new head?

Re: Simson 50cc high end porting

Specific head for water cooling. it has a spigot in and out for fluid, and channels that move the liquid around the cylinder for cooling. Not sure you can do your own without some major work.

Re: Simson 50cc high end porting

Kilian Münscher /

Gonna think about that but I am gonna start with the air-cooled one for simplicity.

Re: Simson 50cc high end porting

Lol you’re talking about doing 13k with fucking diyrotary intake and wc is too complex? Sorry but that’s funny (edited)

Re: Simson 50cc high end porting

Kilian Münscher /

Yeah.

I don't think it is to complex you just need more parts that are expensive like the radiator, plumbing, pump etc.

While I personally have almost all the parts needed to built a rotary valve.

Re: Simson 50cc high end porting

Wc stuff is the bees knees

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Re: Simson 50cc high end porting

Kilian Münscher /

Nice e50 built and cool watercooled head.

Re: Simson 50cc high end porting

Kilian Münscher /

I am now back home

The zylinder sadly hasn't arrived yet but I hope it arrives soon.

My plans changed a little bit.

I am going to use a reed intake instead of the rotary as the rotary will not give me that big of an advantage over the reed and it is not worth the work.

Below I have 2 pictures of the zylinder that was on the engine previously, which was the first zylinder I ever ported a few years back. It was producing about 8.5 hp. It is a 63cc big bore zylinder for that engine.

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