Kings of 50cc help with my Scootermotard

[F5 Dave]

Ahh, so 50cc is 70 or 94cc? that makes the HP/l more believable, if still impressive.

Fun? I've tried a modern scooter around a tight track. Fun wasn't the word I'd use to describe the experience.

[SS90]

Ahh, so 50cc is 70 or 94cc? that makes the HP/l more believable, if still impressive.

Fun? I've tried a modern scooter around a tight track. Fun wasn't the word I'd use to describe the experience.

I know this sounds hard to believe, but this is scootermatic stuff, and not what I am talking about.

In September every year, they have the European 50cc endurance race.

50cc means 50cc no more.

This isn't scootermatic racing, it is for geared motorcycles.

As I have eluded to before, the Dutch tuners have an amazing culture around 50s ( and have had for years), and it seems that a lot of Germans in the north that boarder the Netherlands (places like Köln and Aarchen) also drink from the same water supply.

A few years ago, I was introduced to one of Europes best tuners, and he told me about this race, where the top guys where getting " much more than 20 ps from a 50"

"yea right" says I...... But I assure you it is true..... When you remember that there was Austrian tuners getting mid 20 ps from customer spec 80cc engines in the late 60's ( much more for the factory gp teams), it becomes reasonable to believe that it is possible from a modern 50.

So, I had a wee go. Yup, with some time and effort, you can make an AM6 based engine do 20 ps..... However, for myself, I cannot yet make one that will last the 4 hours required, and, like I say, there are guys getting well over 25, AND finishing the 4 hours (riders that weigh about as much as one of my gloves, with 2 fingers cut off)

There is plenty of big bore kits available, but you can get some high-tech 50cc off the shelf items too, and from what I understand, some people convert some of the ultra high tech scootermatic cylinders to fit an am6 engine.

The interesting thing about it all is that you don't find websites, chat rooms or stuff like that around the really clever stuff, as it was explained to me " The cutting edge technology surrounding two strokes isn't on some website, written by who knows what, it is in small workshops and friends garages, populated by small cliques (most of whom work in the industry) who share their information with each other, and a few years later, small tid bits trickle through to the general public."

I paraphrased a bit, but that is the gist of it.

I have looked a few times for information on really high tuned 50s, in two languages, but I always end up with sone American guy telling everyone how great he is, because he can get 17 ps from a 75 kitted am6..... My hero.....

But like I say, there really are guys (and girls) in Europe that get "more than 25ps" from a 50cc am6 engine, and they last a 4 hour endurance race, revving "over 20,000."

[SS90]

I guess I made it sound like a bigger problem than it is, all I meant was that once you get the jets right it can go off song again in just a few hundred kms giving the impression something else is wrong other than a simple dirty filter.

If fogging or stand-off occurs mostly before getting "on the pipe" can it happen again once I've gone past the peak and revved high enough to be off the pipe again?

Juts to clarify, are you saying that you have been jetting your carb, and it goes off after a few ams (like when the engine gets warm?)

I would suspect that you are simply too rich.... Liquid cooled 2 strokes take quite sone time to get to normal operating temperature, and you should always jet your engine at normal operating temperature.

An engine that is jetted too rich will go great when it is cold (it needs more fuel anyway), but when up to temperature, the power will fade, because the jetting is too rich for a warm engine.

Have a look at the ESE thread, they spent months chasing their tails with that problem........

[Spearfish]

I know this sounds hard to believe, but this is scootermatic stuff, and not what I am talking about.

In September every year, they have the European 50cc endurance race.

50cc means 50cc no more.

This isn't scootermatic racing, it is for geared motorcycles.

As I have eluded to before, the Dutch tuners have an amazing culture around 50s ( and have had for years), and it seems that a lot of Germans in the north that boarder the Netherlands (places like Köln and Aarchen) also drink from the same water supply.

A few years ago, I was introduced to one of Europes best tuners, and he told me about this race, where the top guys where getting " much more than 20 ps from a 50"

"yea right" says I...... But I assure you it is true..... When you remember that there was Austrian tuners getting mid 20 ps from customer spec 80cc engines in the late 60's ( much more for the factory gp teams), it becomes reasonable to believe that it is possible from a modern 50.

So, I had a wee go. Yup, with some time and effort, you can make an AM6 based engine do 20 ps..... However, for myself, I cannot yet make one that will last the 4 hours required, and, like I say, there are guys getting well over 25, AND finishing the 4 hours (riders that weigh about as much as one of my gloves, with 2 fingers cut off)

There is plenty of big bore kits available, but you can get some high-tech 50cc off the shelf items too, and from what I understand, some people convert some of the ultra high tech scootermatic cylinders to fit an am6 engine.

The interesting thing about it all is that you don't find websites, chat rooms or stuff like that around the really clever stuff, as it was explained to me " The cutting edge technology surrounding two strokes isn't on some website, written by who knows what, it is in small workshops and friends garages, populated by small cliques (most of whom work in the industry) who share their information with each other, and a few years later, small tid bits trickle through to the general public."

I paraphrased a bit, but that is the gist of it.

I have looked a few times for information on really high tuned 50s, in two languages, but I always end up with sone American guy telling everyone how great he is, because he can get 17 ps from a 75 kitted am6..... My hero.....

But like I say, three really are guys in Europe that get more than 25ps from a 50cc am6 engine, and they last a 4 hour endurance race, revving over 20,000.

I guess the only way to find out what they have done would be to get hold of an engine built for the race and dissect it, but talking to guys like that you get the reasons behind it.

In the mean time poor ol rabidnz is just trying to get his bike going a little better and his thread has wandered off the topic..a little.
Still its farkin interesting though, always a nugget of info that's new, to me anyway.

[Spearfish]

Juts to clarify, are you saying that you have been jetting your carb, and it goes off after a few ams (like when the engine gets warm?)

I would suspect that you are simply too rich.... Liquid cooled 2 strokes take quite sone time to get to normal operating temperature, and you should always jet your engine at normal operating temperature.

An engine that is jetted too rich will go great when it is cold (it needs more fuel anyway), but when up to temperature, the power will fade, because the jetting is too rich for a warm engine.

Have a look at the ESE thread, they spent months chasing their tails with that problem........

Yeah I had a problem with being rich when warm/hot, even more so with the different air temps from winter to summer.(I found that hard to believe at first but I guess the carb is only 400mm off the hot tar )
Its just the pod type filters are vulnerable to the shyt from the rear wheel plus the surplus oil (fog). Even with the standard cylinder/carb/pipe the small airbox drain had 2t oil dripping. If it possible to modify the airbox flow its worth working on it

[rabidnz]

Hehe i dont mind the hijacking, SS90 has got awesome information its been very interesting hearing about the true "kings of 50cc" so thanks.
I have taken off the airbox and it sounds terrible, far too loud for the speed its travelling, performance is about the same, I now think the coil is topping me out at 75 on the speedo, though if i sit there for a while and head on the tank it can creep up to 84 the speedo is pretty far out , i think its about 10ks optimistic, probably worse the higher you go. I will also inspect the clutch sometime soon, as that could be slipping at high revs causing big losses in go go.

The gearing is also ridiculously short, and finding a front sprocket for an am5 engine is ridiculously hard, though maybe SS you could find one locally in old stock or something ?? I have mailed all the european scooter tuning type shops and the only ones I can find are going to cost around 75 bucks after shipping. Its the same as the 5 speed aprilia 50's which i thought would make it easy, but no such luck. It has a funny 10 tooth spline which seems very rare.
Instead ill take the rear sprocket off and take it down to the shop, see if I can get 3 bolt holes at least to line up with one of the sprockets on the wall. It has 6 bolt holes but they are in 3 groups of two, does this ring a bell to anyone?

and last but not least, who needs a gps to read my real speed, when I have excellent high tech speed recording equipment located in many handy locations around town. Also what a good show of police efficiency, that was only two days ago! Was stoked to get this in the mail today ...........

[F5 Dave]

Hmm, he's right, Z12 spline is usually on larger chain sizes.

Try Calamari in the States, they'll do them no drama. Or any Metrakit place for sure.


hmm, actually maybe they won't but if you get on the AF1 site there will be heaps of info

[rabidnz]

they are all z12, cant find a z10 to save my life, just to confuse it, the sprocket is engraved with z12, because it has 12 teeth outside, whereas standard sprocket z numbers are the number on the spline, very frustrating, may just have to get the one from spain for 50 bucks plus shipping, better be made of adamantium !

What do you think of this ignition, would it work in my bike?
http://www.trademe.co.nz/Trade-Me-Mo...-320229588.htm

or should I just find a coil like this
http://www.trademe.co.nz/Trade-Me-Mo...-320353097.htm
and then a cdi like this
http://www.trademe.co.nz/Trade-Me-Mo...-321387533.htm

im still a little confused by the sparky bits :P

[SS90]

Sure if anyone needs anything from this part of the world, just say so. my girlfriend speaks German,Flemish (Dutch),Russian, English and some French, so we have lots of options.

I don't mind sending stuff back home, but just be aware - postage is a killer, for something like a cylinder, allow $NZ60..... (10days) Sea frieight is not much cheaper and takes 20 times longer.

[rabidnz]

thats awesome if there is any way you can find an 14 tooth sprocket for an am5 engine then your blood would be worth bottling, hopefully the postage would be a little more forgiving. What are the prices like over there before the shipping kills them? Im guessing unless your earning euros things are pretty pricey?

[SS90]

thats awesome if there is any way you can find an 14 tooth sprocket for an am5 engine then your blood would be worth bottling, hopefully the postage would be a little more forgiving. What are the prices like over there before the shipping kills them? Im guessing unless your earning euros things are pretty pricey?

Sure, a sprocket would be easy to find I am sure. I live only 20km from Matichofen (where KTM is) and so around these parts 50s rule the road.

A sprocket would be about €5 to buy and €30 to ship 10 day, so better to get a little more, as the minimum charges are where they make their money. I think for the same shipping cost you could get a sprocket plus a coil, a carb and a cylinder head...... and perhaps a bottle of Märtzen.

I sent my nephew and niece their birthday presents last month, and that was the cost and approximate weight.... Actually, there was 2 bottles of Märtzen.

Buy it on e-bay or where-ever and get it sent to my address, and I'll send it to NZ.

[rabidnz]

hell yeah, how strong do you drink your beer over there? I cant stand the watery piss they try and pass off as nectar of the gods around these ways, though Emersons belgian style and dunkelweiss are pretty good though they cost about 10 bucks a pint from the bottle store.

I just found some sprockets on ebay at, 15 euro each, but only 8 shipping to nz, would economy interational mean they are sending it by boat? Its in germany, not austria though. Im hoping they speak some english so I can get the shipping combined, 38 euro is what i was looking at paying for one sprocket, and ill go for a 14 and a 15t for experimentation.

When you say replace the restricted coil, do you mean the whole cdi/coil unit? or just the coil?

[SS90]

hell yeah, how strong do you drink your beer over there? I cant stand the watery piss they try and pass off as nectar of the gods around these ways, though Emersons belgian style and dunkelweiss are pretty good though they cost about 10 bucks a pint from the bottle store.

I just found some sprockets on ebay at, 15 euro each, but only 8 shipping to nz, would economy interational mean they are sending it by boat? Its in germany, not austria though. Im hoping they speak some english so I can get the shipping combined, 38 euro is what i was looking at paying for one sprocket, and ill go for a 14 and a 15t for experimentation.

When you say replace the restricted coil, do you mean the whole cdi/coil unit? or just the coil?

We are coming into winter so the beer is at it's strongest just now, but yea, it makes you a real snob when you drink anything outside of mainland Europe... The take it really seriously.

That is a really good price for the freight, and it is 21 day delivery, just delivered in a courier bag, you won't get hit on GST at that price either.

From what I know about your model, there is no seperare cdi... The coil and the cdi are the sane unit... Is that not correct?

[SS90]

I can't find anyone willing to share too much of 50 tuning, but I was referred to good old YouTube for a small sample.

Ok, nothing to do with endurance racing, but here is some Swedish guy with an old air cooled Zundapp.


http://www.youtube.com/watch?v=tYNBO...e_gdata_player



No idea how much power, but it goes to show what can be done with an old air cooled engine.

[rabidnz]

yep ss it is combined, which is why I thought this
http://www.trademe.co.nz/Trade-Me-Mo...-320229588.htm
was probably perfect, depending on how specific a cdi is to the electrical system of each bike.