Kings of 50cc help with my Scootermotard

[rabidnz]

just got an sm50 gas gas , pretty nifty for a "scooter".
Anyone here know the difference between a minarelli am5 and an am6 engine?
As I can find parts for the am6 galore, but not much about the am5.
Also it says giraldoni on the cylinder, would this mean it is aftermarket?
May explain why its running like a bag of shit even after I cleaned out the thimble sized carby :)

[Yow Ling]

Nothing is going to be awesome with a 12mm carb, CDI is probably holding it back too.

[SS90]

just got an sm50 gas gas , pretty nifty for a "scooter".
Anyone here know the difference between a minarelli am5 and an am6 engine?
As I can find parts for the am6 galore, but not much about the am5.
Also it says giraldoni on the cylinder, would this mean it is aftermarket?
May explain why its running like a bag of shit even after I cleaned out the thimble sized carby :)

Gilardoni is the name of the company who makes cylinders for pretty much all the Italian manufactureres, 4 or 2 stroke, as well as cylinders for Rotax and so on.

They specialize in stuff for large production runs mainly, so stuff that is for the (now defunct) 125 GP for example where made elsewhere.

Actually they are about 300 meters from Moto Guzzi's head quarters.

As far as I am aware, the AM5 is a five speed and the AM6 is a six speed gear box, and the cylinders are different regarding exhaust port time area....would make sense if they saw fit to put another ratio in.

These engine have been pretty much the mainstay of Italian manufacturers for the last 15 years, and have been in pretty much every Aprilia RS 50, Pegasso 50, tuerno 50 so on, and the later model stuff all got the AM6.

Like a lot if stuff, Minarreli engines have been copied by all the Asian markets.

I am pretty sure that like has been said, the CDI will be the hold back, and the wee carb is going to be an issue, and of course the pipe as well.

Guys in Europe can get the 50's to over 19ps (mainly the Dutch guys), but the term "high revving" takes on a new meaning.

I seem to remember that a simple carb increase, performance pipe and CDI change will bring 12 or 13 PS, and the 75 kits get about 14.

The main power gains with these engines is with the pipe, carb, and CDI.

If I was doing it on a budget, getting the carb to something like 18mm would be my first move, but then I think the pipe and CDI would start to drag the chain.

It's a bit of a test of a tuners worth when it comes to 50's - I have met very accomplished tuners that have had engines in the pipelines for more than 5 years, and still have no plans to finish them!

There is a few spotty faced kits that have these type of engines in their bikes in the town I live in, and once they are derestricted (blind eye from the plod when it comes to tuned 50's) I would say they would make 110km/h, and not too shabby in how long it takes to get there either.

If yours is a road legal one that was E4 spec (most likely) it will only be set up to do about 50 km/h.......... I am pretty sure there will be a heap of tuning parts available from the Asian market, as this engine has been copied exactly (as has the bike design) and I see they are for sale all over Europe at a fraction of the cost of the European brands (which are all made in China anyway)

[F5 Dave]

Other diff was the AM5 barrel was ally & the AM6 for some queer reason was Iron, maybe to aid sales of aftermarket barrels which they also made? I am told the hot setup was AM5 barrel on an AM6, but of course you can buy after market stuff easily if you have no rules to abide by.

[rabidnz]

Thanks heaps for the input guys.
I have read posts with these engines tuned to 28hp, and an am-6 even holds the land speed record for a 50cc!! 160 mph or something crazy like that.

I realise she is really choking on the 12mil carb, and factory pipe, but it feels like it isnt just a minor issue of needing a bit more poke, it feels like it is revving out at about 6k. Anyway im going to go out and give her a proper good clean, then get the engine out and take the jug off, corsa motorcycles has piston kits for the rs50 for 70 bucks , cant go wrong there.

Should i need to pay for a cylinder hone or is that a box of beers job?

[SS90]

Thanks heaps for the input guys.
I have read posts with these engines tuned to 28hp, and an am-6 even holds the land speed record for a 50cc!! 160 mph or something crazy like that.

I realise she is really choking on the 12mil carb, and factory pipe, but it feels like it isnt just a minor issue of needing a bit more poke, it feels like it is revving out at about 6k. Anyway im going to go out and give her a proper good clean, then get the engine out and take the jug off, corsa motorcycles has piston kits for the rs50 for 70 bucks , cant go wrong there.

Should i need to pay for a cylinder hone or is that a box of beers job?

You may well find the pipe has a restrictor in it, somewhere near the header normally...... I wouldn't rush into pulling the cylinder off (jug?????? Are you American by chance?)

If the engine starts and idles well, then personally I would be skeptical about opening the top end, if it just won't rev out, then it is every chance it is E4 spec, and what they deem a "Mofa", and only allowed to produce a paltry 2ps and only go 49.9 km/h

I would suggest just pulling the pipe off and have a look down the header pipe, and that carb at 12 mm has to go!

I am interested as to what you find.

28ps? That I have not heard from a geared 50, the most I have heard about is low 20s, but that is not to say it isn't true.... The European scootermatic boys get around the high 20's regularly (gotta love that CVT )

[F5 Dave]

First off, what are you trying to achieve? A usable roadbike? A Bucket?

pipe could also just be hella clogged with oil residue, that stops them revving too.

[rabidnz]

My aim is to get the missus onto 2 wheels for summer, with the thoughts in the back of my mind of spending a grand on her and havin a rather interesting convertible (road legalable) f5 or f4 bike, maybe not competitive speed wise but thats ok because its just for fun, and the brakes and suspension on this thing are better than my last 4 bikes put together :P (albeit their combined age is rather close to 100(although their combined caliper piston count numbers ~30)

Yeah it does feel like this mofa you speak of :P
I have looked into the throat and arse of the spannie and cant see any washers in either end, have stuck a footlong bendy magnet stick in along the inner wall and it doesnt seem to hit anything , but i could be wrong. Also i found the snorkel to be off the airbox, and it was covered in kids skate stickers so i guess someone already had a crack at derestricting it. It has a 75 mainjet in there now, not sure if its standard but the exhaust can is pretty damn gunky wondering if its overjetted or the carb just cant put enough air through her ?
The pipe doesnt feel blocked but perhaps the endcan is saturated give it an open cat bypass this afternoon instead of rushing to pull her head off.

[SS90]

My aim is to get the missus onto 2 wheels for summer, with the thoughts in the back of my mind of spending a grand on her and havin a rather interesting convertible (road legalable) f5 or f4 bike, maybe not competitive speed wise but thats ok because its just for fun, and the brakes and suspension on this thing are better than my last 4 bikes put together :P (albeit their combined age is rather close to 100(although their combined caliper piston count numbers ~30)

Yeah it does feel like this mofa you speak of :P
I have looked into the throat and arse of the spannie and cant see any washers in either end, have stuck a footlong bendy magnet stick in along the inner wall and it doesnt seem to hit anything , but i could be wrong. Also i found the snorkel to be off the airbox, and it was covered in kids skate stickers so i guess someone already had a crack at derestricting it. It has a 75 mainjet in there now, not sure if its standard but the exhaust can is pretty damn gunky wondering if its overjetted or the carb just cant put enough air through her ?
The pipe doesnt feel blocked but perhaps the endcan is saturated give it an open cat bypass this afternoon instead of rushing to pull her head off.

I'm gonna take a bit of a stab in the dark here, because I don't have any experience with this model, but, when I worked on aprilia almost ten years ago, any small 2 stroke that was restricted had a 2 piece header, and where the header had a join, it was by 3 nuts, which where tack welded in place.

I just wonder if your header is the same.

It was just a case of grinding the welds off the nuts to separate the two halfs, and that exposed a conical restrictor in the exhaust, which was tack welded in, and you had to again grind the welds off to remove it.

Of course if your header is not like this, disreguard all that!

[rabidnz]

nah its a proper expansion chamber, all smooth and welded, no bolted joins, though i have read about the kind you speak of ! cheers mate. I had wondered if there is a restrictor further into the pipe that I havent located, Gas Gas NZ is no help whatsoever unfortunately.

Regarding the compression, I can easily turn the engine over by spinning the flywheel with my thumb and forfinger, doesnt feel very tight, but then again its a lawnmower engine :P

[Spearfish]

This link could help a we bit

http://www.sgnc.dk/documents/00020.pdf

Check your pipe first they often fit a washer by the head.
Check out scootling for small engine parts

http://shop.scootling.co.nz/index.php?act=viewCat&catId=29
http://shop.scootling.co.nz/index.php?act=viewCat&catId=30
http://shop.scootling.co.nz/index.php?act=viewCat&catId=9
http://shop.scootling.co.nz/index.php?act=viewCat&catId=86
http://shop.scootling.co.nz/index.php?act=viewCat&catId=32

Tuning has a domino effect though so make sure you really know what you want it to do.

[F5 Dave]

Huh, I just had a quick look at one of those links. Shite! that's cheap for a PWK.

Surely it's a Koso or whoever replica. . . Sure enough ". . . This PWK type carburetor feature. . . " Hmm, not saying it but it isn't kosher I bet.

If it's a roadbike get it to std unrestricted form & stop there. That's why I asked. Carb swaps mean you will have to tune the carb, does that then affect how the oil pump is operated?, what about an airbox.

and it gets more detailed from there on.


A race bike is a race bike, a road bike is a road bike. Never more so than on a 50, esp if you find a hill.

[rabidnz]

if there is a washer in the header section, is it going to be obvious? or "around the bend" a bit? As i said i have stuck a magnet stick up each end and it doesnt seem to hit anything.

Just took the can off and it is pretty little black sambo'd, so is it fair to assume the spannie and the piston may be looking somewhat similar?

[rabidnz]

its my little project bike, so i dont mind tinkering and hunting and trialing things, thats why i bought it, and have a decent amount of carb tuning experience for 2 strokes, hell only having one carby is a dream come true, and id much rather have some control over what is flowing down the throat, as the little piddly carb on there now has just a main jet and an emulsion tube, and im at sea level pretty much and would like at least an idle mix and needle position adjustment.

[TZ350]

Those PWK type carbs from Scootling look very much like the Taiwanese OKO copies of the Keihin PWK and Chambers is using a modified OKO on his RD125 engine.

If it is the OKO carb, it’s bad point is that its bored straight through with a parallel bore instead of the tapered bore found in the real Keihin and the std OKO flowed slightly less on our test rig than a real Keihin did. But after a few mods it was much the same and way better than the std GP125 carb.

The good thing we found about the OKO was that it was made of a better, stronger alloy that machined well and all the std Keihin jets and needles fit.

We also found the real Keihin’s die cast body to be relatively soft and easily crushed in the jaws of the lathe, a common problem with most makes of carbs and we had to make special holding fixtures when maching them but don’t need to with the OKO as its strong enough to be gripped securely by the lathe chuck.

[rabidnz]

I have a mikuni tm-28 in my box of bits, but im guessing that this is going to be a bit over the top for what im needing, and will end up very difficult to tune. If anyone wants to swap a 17-21mm suitable slide card id be happy to.

Also I can turn the engine over from the magneto with just a pinch, it gets tighter at a point, but is at no point hard to turn. What compression would i expect to see on the guage, if my rings and piston werent worn out (new ones in the mail regardless, its a 50, its gonna need them eventually and only 80 bucks)

[SS90]

Well, 28mm is a shade on the big side (under statement) you really want something in the area of 18 to 20mm in my opinion.
I recon the guys getting high 20's ps will be using carbs around the 28 mm mark...maybe bigger.

I will go vistit a local mofa dealer and in dorm him of your problem tomorrow, hopefully he can help.....I am pretty sure your situation is caused by a level of restriction.

When it comes to 50s, compression is something that many people fool themselves into thinking is too low (also, if it is a Dyke ring piston, don't for bet the compression when Turing over with your hand is always much lower than when it is kicked!

My experience with tuned 50's is pretty minimal (well, compared to the guys in this part of the world anyway) and I can honestly say I have never tested the compression with a compression gauge.

I am actually building an am6 this winter in the deluded hope of competing in next years European 50 cc Endurance race (already lost 10kgs now just need to lose 10 more)

I base my calculations on cylinder head volumes and trapped compression, and what I get in the sense of bar or psi to me seems irrelevent......

Personally, like I say, if it starts ok and idles, I would not suspect the top end too much....bit, as you say, not much work to check!

[bucketracer]

I have a mikuni tm-28 in my box of bits, but im guessing that this is going to be a bit over the top for what im needing, and will end up very difficult to tune. If anyone wants to swap a 17-21mm suitable slide card id be happy to.

I have some spare 22mm round slide Mikunis from GP100's. You can have one for free if you want, to play with. PM me.

[rabidnz]

thanks ss90 , please keep us informed on youre build, and progress towards the enduro champs, huge luck to you!

As the only 50s ive dealt with before are lawnmowers and stock nifty 50s, im not really sure how much compression there would be, it just felt as if there was significant blow by past the rings, as just as it should be gettin on the pipe it hunkers down, definitely not leaning out as the pipe are plug are rather sooty. I am heading down to get some muffler packing and a new plug, also going to try her with a race filter instead of the airbox, before i start playing with jets.

I would be stoked to try one of those carbs bucketracer, ive sent you a pm with offererings of beer.

Another thing, on the intake manifold one of the screws looks like a blank head, ie its just flat, i am proably just going to try and vice grip it off, and replace with a hex cap, never seen this type of security bolt with just nothing whatsoever to grab hold of.

[SS90]

Another thing, on the intake manifold one of the screws looks like a blank head, ie its just flat, i am proably just going to try and vice grip it off, and replace with a hex cap, never seen this type of security bolt with just nothing whatsoever to grab hold of.

I have a funny feeling that since there is a "break head bolt" on your manifold,( a factory bolt with a specific wasted section so that whether bolt is torqued up to spec, the head breaks off, leaving a somewhat "permanent headless fastener" holding the object in place. It could be fair to say that there is every chance there may well be a restictor in the reed block..... As in Europe all restrictors have to be "perminant" (like welded nuts holding pipes together and so on), I feel pretty confident to say that you are on to something there.

[F5 Dave]

Ahh, cunning. UK MB50s used to have extra fins cast into the barrels to limit the travel of the reeds.

I use a 28mm on a full house 50 after playing around with 24 & 26mm flatslides. Getting the 26 was interesting. It will be waaay too big for a std motor.

Forget the compression gauge, just pull the top off & measure the ring end gap. the guage will only work as a comparison tool once you have the initial numbers & it virtually worthless on a small engine.

People wibbile on about them on ATV forums & I'd never considered using one but I decided to try on my dirtbike 200 (also a GasGas) tried & measured the proper way & then with a com gauge. Raised the com, measured again & then with the comm gauge. oh yes, I see. So then I lowered the com a bit as it was too high & measured with the gauge. No change. yeah ok, stays in the box.

[rabidnz]

dont like the sound of that breakhead bolt, which is exactly what it looks like to me now i know they exist, do you think it would be possible to ezout, or probably a drill job? First ill try cutting a slot into it and hitting it with the impact driver or rattlegun.
Though i have read that the restrictor on the reeds is 12mm, which is the bore of the intake, and that it shouldnt restrict me unless I am trying to make more power than stock.
I repacked the can today and it made a decent difference to the top end, feels like i might be pulling 60ks now, which is probably "mofa spec". If i put a bigger front sprocket i should get around 65 hopefully, and also the gears will be longer as they are all done in about 50 metres at this stage.

Thanks for that tip dave, how do i measure the ring end gap, is that the distance between the two ends of the ring or the ring and the cylinder?

[SS90]

Don't panic about the break head bolt, they come out easier than you think - just use a small cold chisel on the edge, and knock it round a few times until, it unscrews - they (in my experience) never have loctite or anything on them and I have never had a problem.

Bike manufacturers use them for holding on ignition switches mostly.

I can't see you having to use an ezy out personally, vise grips can be a last resort, because as I say, they aren't really that tight.

To measure the ring gap, just remove the rings from the piston and put them one at a time half way down the bore ( with the gap facing the cylinder wall, not a port) and measure the gap between the ring ends with a feeler gauge.

Rule of thumb is 3 thou per inch of bore for an air cooled bike, and a smidge less for a water cooled.

In such a situation an "eye crometer" will give you a ball park figure!

[SS90]

I spoke to o a local mofa dealer, and he was pretty helpful.

Apparently all mfoa are restricted differently, but now most are done via the reed block as you suspect (the break head bolt is the giveaway)

The pipe will be costing a bit of power, but he said that it's not as much as you would expect.

The trick for pimple brigade seems to be to use a 21mm PHPH delorto, but I am guessing that will means you will need to change the inlet manifold (if you have a lathe and access to a welder you could make one in a dew hours I would say), as well as, like you suggested change the gearing.

Every single one I see around these parts has a performance pipe (way too loud, and this town has a bi law restricting motorcycles use to after 6am and until 10pm) and as best I can ascertain, with a pipe, carb and gearing change, over 100 km/h is possible, and I am flawed as to just how fast they get there (lord only knows what they rev to...... It's really high), but I am told as there are so many variances in market models, some may have a CDI that is restricted as well, and if you have still have a problem, let me know the number on the CDI, and apparently the most common ones only require a resistor to over ride rev limits (but others not)

I hope this helps.

[F5 Dave]

yeah as said take the rings off carefully, (evenly) & poke say 10mm down barrel, with a ruler or old piston so they lie flat.

feeler gauge rubbed between until dragging resistance. new should be say 0.3-05mm & after .6, .7 they are replacement time. At least that is from the top of my head for my 50, check a manual for an AM6, should be heaps of torents around.


You can asertain barrel wear to an extent by moving the rings to an area that the rings don't rub by checking the difference, but doesn't check ovality. The very top 2mm of the bore can be misleading to use as gets carbon on it.

As a comparison a std RG50 will indicate 118kph in perfect conditions which is a genuine 105kph

[rabidnz]

i will see if there is a reed restriction today, thanks for the tip ss90, was worried with images of drilling into nice soft ally.
I am gonna give her a couple of early xmas presents , carb and intake for now, cylinder and pipe later, as Id like to be eligible for f5 if i choose to be, so Im guessing ill need to have a factory cylinder on there, what about the pipe?

carbs im tossing up between

replica 19mm for $65
http://newmanz.co.nz/shop/index.php?main_page=product_info&cPath=55&products_id=116

replica keihen 21mm ? for $140
http://shop.scootling.co.nz/index.php?act=viewProd&productId=165

real deal dellorto pbhg 19mm $170
http://shop.scootling.co.nz/index.php?act=viewProd&productId=752

so far the first cheap one is winning , unless im missing something :P

and for the inlet manifold

http://shop.scootling.co.nz/index.php?act=viewProd&productId=766
not cheap but it allows some rotation for different positions of the carb since space is tight.

or just something plain that fits?


or

[rabidnz]

ps: i sure wish i knew it was now only 10 bucks less that registering my real bike for a year i sure woulda flagged a scooter, assumption surely mothered this fuckup :P

[Spearfish]

ps: i sure wish i knew it was now only 10 bucks less that registering my real bike for a year i sure woulda flagged a scooter, assumption surely mothered this fuckup :P

Yeah other than needing a bike licence there is no financial reason left to own a small engine scoot/bike. Might as well own a bike up to either a licence limit or rego class limit. Bring on the power weight restrictions rather than CC and save us some bucks!.

Sorry, a bit off your topic.

I guess you could give up the road use and fit into track only spec? $400 saved on the rego goes a long way to preparing a dedicated track bike. If your GF takes to riding she will outgrow the 50 quickly so at least she has this rego to find out.

[rabidnz]

turns out the nzta site is a bit gammy, it says it is 394.38 for petrol bike 0-60cc and and 405.63 for 61-600cc, which is what sent me into a tizz, as it mentions nothing about "mopeds" so I assumed they got rid of that classification.
Just got off the phone with nzta and it will be $166 per year. So big smiles and sigh of relief. So there is still a logical reason to have a scooter, apart from low purchase pprice brand new and low fuel consumption/maintenance or just being too scared of a real bike :P
Otherwise i woulda track biked it, but i coulda got an fxr on the track for the same price, and have parts support and a good knowledge base.

Glad thats sorted, now i can get my wallet back out :)

[Spearfish]

turns out the nzta site is a bit gammy, it says it is 394.38 for petrol bike 0-60cc and and 405.63 for 61-600cc, which is what sent me into a tizz, as it mentions nothing about "mopeds" so I assumed they got rid of that classification.
Just got off the phone with nzta and it will be $166 per year. So big smiles and sigh of relief. So there is still a logical reason to have a scooter, apart from low purchase pprice brand new and low fuel consumption/maintenance or just being too scared of a real bike :P
Otherwise i woulda track biked it, but i coulda got an fxr on the track for the same price, and have parts support and a good knowledge base.

Glad thats sorted, now i can get my wallet back out :)

Thanks for clearing that up I looked at the site myself, Its confusing because I just paid 188 for a years rego on a fifty.

Your project is going to be an interesting one however it turns out.

[rabidnz]

i cant find my cdi, i dont think :P
all i can see is what i think is the coil and the reg/rec
here is a couple of pics of them just in case im retarded and the reg rec is built onto the side of the coil

[F5 Dave]

do a search about rules or look on MNZ site. Basically non competition parts inside the engine but pistons, ign, carbs, pipes or chassis are free.

That inlet looks heinous, but what is space like behind cylinder?

bike pic link?


hmm, looks at bad internet pic. . . looks ok for straight inlet.

[F5 Dave]

CDI is in the coil.

[rabidnz]

ok so does that mean i will need to ditch the whole unit and get a cdi and a coil?
how specific is the coil to the cdi? will pretty much any single coil be ok?

[Spearfish]

http://www.gasgasmotos.es/en/manuals/search-rookie.html

Its the closest I've found

[rabidnz]

cheers mate, got that one already, more of a user guide though, although the speedo instructions will come in handy once my replacement arrives.

heres some photos,
first couple showing the oodles of room behind the cylinder, but the most room is immediately left or right of the intake, which is why that right angled intake could be perfect. There is heaps of room where the airbox lives, but you have to squeeze past the shock a bit, which could cause trouble there.

next is the difference between the baby stocker and a tm28, that little baby has to go asap! also there is the restriction i found in the carbs, obviously this isnt restricting anything at the moment as you can see the bore of the inlet manifold is equally as tiny, ill remove it, but will probably fit an aftermarket reed cage at some point.

now the last two pictures are a curiosity a boy racer pointed out to me, he said my front tyre is on backwards, and it sure looks like it to me, ive never seen a tread pattern that would appear to collect water to the center of the tire before? It is clearly marked as a front tyre, with the arrow showing that it is mounted in the correct direction... was someone having a siesta at the tire factory on that day?

[Buckets4Me]

now the last two pictures are a curiosity a boy racer pointed out to me, he said my front tyre is on backwards, and it sure looks like it to me, ive never seen a tread pattern that would appear to collect water to the center of the tire before? It is clearly marked as a front tyre, with the arrow showing that it is mounted in the correct direction... was someone having a siesta at the tire factory on that day?


a metzeler tyre by any chance if so sll the ones i've seen (on the big HD's) all look like that on backwards
thats how they are

http://www.us.metzelermoto.com/en_US/browser/attachments/pdfCatalog/moto/MV_LASERTEC.pdf

[gatch]

a metzeler tyre by any chance if so sll the ones i've seen (on the big HD's) all look like that on backwards
thats how they are

Avon race tires look the same I think.

[TZ350]

If they look backwards at the top, have a look and see what they are like at the bottom where the tread contacts the road, the tread will point in the correct direction.

[rabidnz]

cool, just making sure as it does look kinda odd.

Now for the ignition system, will i need to ditch the combined cdi/coil, and pick up something like this

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Electrics/auction-319801156.htm

and this?

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Chains-sprockets/auction-318564339.htm

is there any benefit in paying for chinese aftermarket brightly coloured stuff?

[Spearfish]

The cdi will be no better than the one you have.
Some daytona CDI's give you 3 or more map settings + it has no rpm limit. The different ignition maps are quite different depending on what stage your at with mods. But they are very expensive I paid 200 just for the single map version, slightly better curve top end and no rev limits. I also had to go up 1 jet size for insurance.

[SS90]

next is the difference between the baby stocker and a tm28, that little baby has to go asap! also there is the restriction i found in the carbs, obviously this isnt restricting anything at the moment as you can see the bore of the inlet manifold is equally as tiny, ill remove it, but will probably fit an aftermarket reed cage at some point.



Looking at the picture of the reed block and stuffer, that is a really common reed block set up, and used on pretty much any standard 2 stroke set up (some use the stuffer, some don't) ranging from 50s to 135 big bore kits.

Personally I do not see the need to replace the reed block in my opinion, I know such an assembly with a malossi 133cc kit can be set up to produce 20 horsepower, so changing that will net you very little.

I would just enlarge the manifold (you can take the stuffer out of you like, but perhaps f5dave can relay some experience with 50cc and stuffers)

As far as the ignition goes, I will have a look around the wholesalers here to see what is offered, I am pretty damned sure you can just buy an cdi/coil set up that has a higher rev limiter and will plug straight in, rather than
pissing about with new looms and so on.

Did you take up the 22 mm carb offer? I am pretty sure that would be close to ideal for you, as the expensive carbs will only be a real gain if you go "all in" with your tuning.

[rabidnz]

hey thanks man, the reeds seem to be well engineered like you say, they still look new with no light shining thru so they will stay, i took out the stuffer and didnt really notice any difference - it looks as if it was actually smoothing out some of the bad casting lines in the carb.

I took up the offer on the free carb, but it is from a rotary valved gp100, and as such there is no way to mount an air filter on to it besides using gaffer tape. So those gp100 carbs are up for offer to whoever wants them for free, pm me ya addy.

I have found some cheap cdis with no rev limit and 3 adjustable timing settings for about fifty bucks, think ill dig into the wallet this week and splurge on a new inhaler for this emphycemic little beast

[bucketracer]

Hi Rabidnz

Glad you received the carb Ok. It might not be the one that eventually suits your bike best but it was something to start with/look at. Passing it on, if it's not going to work for you is a good idea and the Bucketeers way.

The team are now looking to use modified "OKO" brand, Keihin copy carbs, its easy and realitivly cheep to get the jets/needles etc for them.

It might be worth looking to see if Scooterazzi has anything. http://www.scooterazzi.co.nz/

I Goggled “motorcycle carb” and found a couple of good links about carb tuning to look up if you want too. Not everything on the net is true gold but when you look around a bit you can pretty quickly sort the chaff from the hay.

Motorcycle Carburetor Theory

http://www.justkdx.dirtrider.net/printcarbtuning.html

And

http://www.dansmc.com/carbs2.htm

Please keep posting pictures and details of your work, it’s interesting to see how others are getting on with their projects.

Regards Bucket……

[SS90]

hey thanks man, the reeds seem to be well engineered like you say, they still look new with no light shining thru so they will stay, i took out the stuffer and didnt really notice any difference - it looks as if it was actually smoothing out some of the bad casting lines in the carb.

I took up the offer on the free carb, but it is from a rotary valved gp100, and as such there is no way to mount an air filter on to it besides using gaffer tape. So those gp100 carbs are up for offer to whoever wants them for free, pm me ya addy.

I have found some cheap cdis with no rev limit and 3 adjustable timing settings for about fifty bucks, think ill dig into the wallet this week and splurge on a new inhaler for this emphycemic little beast

I got curious just now and had a wee look what is available, and it seems every supplier has the same stuff as you would expect!



From what I have read over the last 10 minutes, it would seem that you need to have 20,000 rpm.

This ties in with the story I was told that the 50s doing over 25ps spin to "more than 23,000 rpm"!

In this link you will see a malossi ignition kit (second one down on the left..... (You will need a translator for it, as it a German only site), for, what I can ascertain is suitable for your bike (expensive but) there are a few other cheaper options available on this site

http://www.racing-planet.de/index.php?shop_ID=1&sessID=41je8m2hptb2atbstqkquest8a14rf0v&olevel0=11133&olevel1=11166&olevel2=11168&level0=11133&level1=11166&level2=11176

Just change the options, and you can see what else is available for the AM6 I see they have a Tasinari reed blocks (they would be the only reed block worth buying in my opinion, they work really well)

from what is written I would say the key to getting your bike moving is simply enlarge the inlet manifold, fit a bigger carb, change the gearing and unlimit the coil.

I don't think it will be a costly exercise in the slightest.
I realize it is expensive stuff, but I assure you that you can find this all second hand on Ebay all over the world cheap as chips.

[rabidnz]

yeah mate, I think you have hit the nail on the head, the most expensive thing will be the carb i think . i will start by locating a dellorto phbg as they are well documented and rather common, then make an intake manifold to suit.

As far as cdis go,are the cheap chinese adjustable timing/no rev limit ones bogus?

I have my eye on both the major ebays scouring for deals, will let yas know how it goes.

PS fixed the speedo today, it reads 75km at top speed, which i reckon is more like 60-65 , so thats probably pretty close to what its supposed to make im guessin, especially with a 90 kg sail breaking its little back

[SS90]

yeah mate, I think you have hit the nail on the head, the most expensive thing will be the carb i think . i will start by locating a dellorto phbg as they are well documented and rather common, then make an intake manifold to suit.

As far as cdis go,are the cheap chinese adjustable timing/no rev limit ones bogus?

I have my eye on both the major ebays scouring for deals, will let yas know how it goes.

PS fixed the speedo today, it reads 75km at top speed, which i reckon is more like 60-65 , so thats probably pretty close to what its supposed to make im guessin, especially with a 90 kg sail breaking its little back

Yea, so may of the Asian brands have moved on from simple scootermatics to things like the "Mofa Motards" because in Europe anyway, that is where the growth market is, and they have been making the bikes for the European manufacturers for the last ten years anyway.

Personally I think if you can find unrestricted coil suitable for your bikee cheap, I would say go for it, from what I have read, the only one that is different is when they fitted an immobiliser and I am sure that is model brand and year specific.

All the really expensive ignitions are pretty top end stuff, and unless you are trying to make over 20ps I recommend just a unlimited coil anyway.

[rabidnz]

Ok cheers for that, but if i get a new coil will I need a new cdi also, as it appears since they are part of the same unit, they are connected internally?

Just ordered a dellorto pbhb 21mm carb and malossi intake (not the giant bulky thing) , and a decent foam filter to suit and will get some spark plugs and jets to get it set up.
I have a couple of jets 100 and 105 i think, if anyone wants to swap for a couple between 80 and 95 id be stoked.
I'll try port matching the reed stuffer with the new intake manifold, as the bike was definitely smoother stock when I had it in, much more jerky off the power now.
The reed cage is pretty poo as well, lots of moulding marks and sharp ridges in the wrong places.
Also with the airbox gone ill have room to try out this tzr250 shock, which looks like just about a direct fit with a couple of spacers, worth a try as the one on there is set up for a small child. Ill space up the forks too and put a slightly heavier oil in.
Last of all ill probably gut the spannie as I beleive their is a cat of some form in there, but like this reed cage stuffer this is supposed to help it out in stock trim.

[SS90]

You can buy a coil that works the same as your current one, just with no rev limit.... That's the one to buy at this stage in my opinion..... The high-tech stuff won't make a lick of difference at this point, if you found a need to buy one of the ultra high end cylinders, crank etc and had a massive carb and so on, then you would really need one, but for a standard cylinder, you just want more revs - nothing else.

Personally I would suggest a pipe too, but by all means try it first.

[Spearfish]

Did you score a set similar to scootlings trade me auction?


http://www.trademe.co.nz/a.aspx?id=320031768

I'm finding a pod filter will clog up inside 200 kms with oil from the fogging mentioned in another thread (don't know how to find the thread), and its been crap riding over winter I almost went back to the airbox.
Brilliant for summer and the better air flow meant a 2 size jet increase but its high maintenance. The other thing is the induction noise its like a rabid chainsaw so it draws attention, often unwanted.

[rabidnz]

ss im not even sure that my coil is limited at all? I think i just need better gearing and more juice. Also the stock pipe seems to be tuned rather high in the rev range compared to other stock 2ts ive ridden, im thinking gutting it may make a big enough difference so that i dont need to change it.

and spear i did buy that exact auction, but i swapped the stack for a filter and made them knock the price down a bit. Keen to hear more about the fogging you have mentioned , anyone got a link? May have to attempt some sort of airbox revival., though id rather ditch it so I can fix a better shock.

[woodyracer]

ss im not even sure that my coil is limited at all? I think i just need better gearing and more juice. Also the stock pipe seems to be tuned rather high in the rev range compared to other stock 2ts ive ridden, im thinking gutting it may make a big enough difference so that i dont need to change it.

and spear i did buy that exact auction, but i swapped the stack for a filter and made them knock the price down a bit. Keen to hear more about the fogging you have mentioned , anyone got a link? May have to attempt some sort of airbox revival., though id rather ditch it so I can fix a better shock.

I took one of these bikes for a ride not too long ago around mt wellignton track, and yeah they go good!, bloody fun to ride, anyhow this particualr bike had power valve problems which make the bike feel how you've described. Maybe look in to that?

[F5 Dave]

Good point Max. I agree 150%. There can be no other option.

Now if you'll just explain where it is located. . .

[rabidnz]

hehe well if they were boyesen power reeds, he wouldnt be 100% wrong :D
I had the reeds out and visually they seemed fine, shined a light from behind them in a dark room and none coming out, they may have gotten weak so i will try to find some replacements .

im eyeing up this chamber and can as a possible candidate for chopping and turning al little till she fits...http://www.trademe.co.nz/Browse/Listing.aspx?id=320531947

[woodyracer]

Good point Max. I agree 150%. There can be no other option.

Now if you'll just explain where it is located. . .

OH IM SORRY....i dont have a PHd in 50cc engines.....:gob:
silly me messing with the majestical, mechanical mind of F5dave :facepalm:

wow gota love kb

[F5 Dave]

hehe well if they were boyesen power reeds, he wouldnt be 100% wrong :D
I had the reeds out and visually they seemed fine, shined a light from behind them in a dark room and none coming out, they may have gotten weak so i will try to find some replacements .

im eyeing up this chamber and can as a possible candidate for chopping and turning al little till she fits...http://www.trademe.co.nz/Browse/Listing.aspx?id=320531947
Reeds should be ok, won't be high mileage.

Not even sure what that pipe is off. But I'll tell you now there won't be a section worth using on a 50.

[F5 Dave]

. . .

wow gota love kb
Yeah you do huh? People who clearly don't have a clue giving advice. PV on a 50, you'd be lucky.

[SS90]

Yeah you do huh? People who clearly don't have a clue giving advice. PV on a 50, you'd be lucky.

Hum, yea.

Im not saying your not correct Dave, but would you be able to elaborate why a variable exhaust port height/trapped compression ratio is unsuitable for a fiddy.......... You and I both know why, but clearly Mr Spotty here does not.... and it could make for some interesting discussion.

[rabidnz]

maybe you could even start a thread about power valves and why they arent in 50ccs :D :violin:

I may have to get a pipe program and build one myself, tack it up and then have the welding done by someone a bit tidier than myself, as pipe prices are pretty ridiculous, looking at least 200 pounds, plus god knows what shipping, plus having to then cut and twist your expensive new pipe, just not worth paying 700 bucks for a scooter exhaust imo

[SS90]

just not worth paying 700 bucks for a scooter exhaust imo

That's cheap if you think about it, but you can find a cheapy on ebay almost every day..... postage is a killer, but keep you eyes peeled and you will find a good un'.... I built a 20 hp fiddy 2 years ago with a pipe I brought on Ebay..... engine didn't last the distance but.....:third:

[rabidnz]

well affordability is all relative, for the exhaust to cost half as much as the bike seems a lil crazy to me, so i will continue the ebay scavenging :) Im not sure my pipe is such a big wall to her performance, the baby exhaust port is probably the next thing in the way, but i dont think that can be cured without a cylinder replacement, which in turn will warrant a piston, which in turn will warrant a crank :D
Just gotta think of the rego and gas savings, not to mention servicing of a single cylinder 2t instead of an inline 4 4t :D

What is this oil fogging of the pod filter you speak of? Is this caused by your reed valves being worn, causing gas to come back out the intake, collecting the injected oil and depositing it on the filter? Couldnt find anything with the search?
Anyway if this is the case I will make a small extension tube angling up a little, to allow the oil to flow back down to the carb and rejoin the intake massive.

[SS90]

maybe you could even start a thread about power valves and why they arent in 50ccs :D :violin:

I may have to get a pipe program and build one myself, tack it up and then have the welding done by someone a bit tidier than myself, as pipe prices are pretty ridiculous, looking at least 200 pounds, plus god knows what shipping, plus having to then cut and twist your expensive new pipe, just not worth paying 700 bucks for a scooter exhaust imo

Uh, oh....

The "Stand off" question....

I think what you are referring to is the situation where a tuned engine is running "off the pipe", and the resulting mistimed exhaust pulses (sometime referred to as resonance ) as well as intake resonance cause problems with the intake tract, causing a situation where the the incoming air/fuel mixture meets with a closing reed /or disc valve, causing this incoming charge to revert back out the intake to atmosphere.

In all truth, an engine that performs like this is fairly normal, and in actual fact, this occurs at such a low RPM (well, low as in terms of BELOW any real power, and, as such, well below any reasonable operating rpm for a tuned racing engine....like for example if a tuned racing engine starts producing usable power at say, 7000rpm, up until 10,000 rpm....you may well find this engine has a"standoff" situation about, say, 4,000 rpm...)

In such a scenario, you operating the engine at tis low rpm is a complete waste of time.

My advise id´s to not worry about this "standoff", it occurs far below operating rpm of a racing 2 stroke, and other than a bit of mess for an engine with no air box, it has no real effect on either the power or the main jet setting....needle perhaps.

[rabidnz]

cheers mate, clears it up alot. With the factory tuning of this pipe, nothing even happens till the last 2krpm anyhow, im sure it is standing off badly at low rpms, you can even see it comin out the carb, but its pretty well full throttle everywhere with this lil beast :) in fact, operating the engine wont even wake up for low rpms, so it may not be such a problem. I guess i will find out. hopefully soon, as my carb and manifold and filter arrived today, but the fecking manifold is bent into an oval out of the packet, looks like something has smashed it in the courier van, and im going to send it back to scootling, as for that price i expect something bloody perfect. :)

[F5 Dave]

Hum, yea.

Im not saying your not correct Dave, but would you be able to elaborate why a variable exhaust port height/trapped compression ratio is unsuitable for a fiddy.......... You and I both know why, but clearly Mr Spotty here does not.... and it could make for some interesting discussion.
Grammatically that should be ". . you're not correct. . ." . But of course I am -and I should know. I'm an internet expert.:innocent:

The real reason the AM6 engine doesn't have a PV is cost. The only reason RG150s have them is 'cause it was easier to leave it on from the RGV250 origins.

Can you imagine the typical 16ers in UK & Europe trying to maintain such a device with little more than a rounded screwdriver at the local servo?


My point was the AM6 don't got one, so trying to fix it would be the ultimate exercise in futility.

Of course on a tuned racebike the powerspread is somewhat thin. It could seize from lack of use:shutup:.


I did however at one stage look at making a manual powervalve, principally a sealed half-moon sectioned bolt so one could adjust the port height down for short tracks. Sealing it & the available metal was unfeasible.

[Henk]

Woody

If I recall the gasgas mini motard you took out for a few laps of Mt Wellington with all the road gear fitted and no nylon was a 125.

[SS90]

Grammatically that should be ". . you're not correct. . ." . But of course I am -and I should know. I'm an internet expert.:innocent:

The real reason the AM6 engine doesn't have a PV is cost. The only reason RG150s have them is 'cause it was easier to leave it on from the RGV250 origins.

Can you imagine the typical 16ers in UK & Europe trying to maintain such a device with little more than a rounded screwdriver at the local servo?


My point was the AM6 don't got one, so trying to fix it would be the ultimate exercise in futility.

Of course on a tuned racebike the powerspread is somewhat thin. It could seize from lack of use:shutup:.


I did however at one stage look at making a manual powervalve, principally a sealed half-moon sectioned bolt so one could adjust the port height down for short tracks. Sealing it & the available metal was unfeasible.

Fair enough.

For my latest fiddy plan, I would like to incorporate a power valve, and like you I thought a bout a self made blade, but it would seem that is not feasible.

Do you remember the Honda "Beat", it was a 50cc water cooled CVT scooter in the eighties/nineties.

It simply used a foot pedal operated version of Hondas "V-Tac" (anagram time)

Which, simply had an extra chamber cast in the side of the cylinder head, and when the valve was open (normal operation), it allowed for a lower trapped compression (higher volume), which gave an increase in performance outside the expansion chambers tuned rpm range, and when the valve was closed (pedal down), it raised the trapped compression ratio (lower volume i.e, only that of the combustion chamber), allowing the correct trapped compression ratio for the tuned rpm range of the pipe.

Simple, and, no real maintainance (like you say, spotty youths with blunt screw drivers)

They had a LED rev counter to show when there was enough rpm to operate the valve........

A modernised version of that would work on a fiddy racer I believe, just adapt a Rotax system (the vacuum operated units) that operate the blade type systems to actuate a valve on a bespoke cylinder head.

It sounds easy.... I'll make one after lunch.:blink:

[Spearfish]

Uh, oh....

The "Stand off" question....

I think what you are referring to is the situation where a tuned engine is running "off the pipe", and the resulting mistimed exhaust pulses (sometime referred to as resonance ) as well as intake resonance cause problems with the intake tract, causing a situation where the the incoming air/fuel mixture meets with a closing reed /or disc valve, causing this incoming charge to revert back out the intake to atmosphere.

In all truth, an engine that performs like this is fairly normal, and in actual fact, this occurs at such a low RPM (well, low as in terms of BELOW any real power, and, as such, well below any reasonable operating rpm for a tuned racing engine....like for example if a tuned racing engine starts producing usable power at say, 7000rpm, up until 10,000 rpm....you may well find this engine has a"standoff" situation about, say, 4,000 rpm...)

In such a scenario, you operating the engine at tis low rpm is a complete waste of time.

My advise id´s to not worry about this "standoff", it occurs far below operating rpm of a racing 2 stroke, and other than a bit of mess for an engine with no air box, it has no real effect on either the power or the main jet setting....needle perhaps.

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?

[Yow Ling]

It simply used a foot pedal operated version of Hondas "V-Tac" (anagram time)

Which, simply had an extra chamber cast in the side of the cylinder head, and when the valve was open (normal operation), it allowed for a lower trapped compression (higher volume), which gave an increase in performance outside the expansion chambers tuned rpm range, and when the valve was closed (pedal down), it raised the trapped compression ratio (lower volume i.e, only that of the combustion chamber), allowing the correct trapped compression ratio for the tuned rpm range of the pipe.



From Wikipedia

"Honda V-TACS

The "V-TACS" - Variable Torque Amplification Chamber System - works differently from the "AETC system" and it will only work when it is used in conjunction with a tuned muffler. Tuned mufflers/expansion chambers increase power but only at the RPM they are designed for and can actually cause a power loss outside their tuned RPM. "V-TACS system" takes advantage of using an expansion chamber without losing power outside the expansion chamber's tuned RPM. Within the head and cylinder of the engine, there is a chamber that is sealed by a valve. This sealed chamber is vented onto the exhaust port when the valve is open. At low RPM this valve is open, this has the effect of increasing the exhaust manifold volume and negating the power loss that would normally be apparent at low RPM with an expansion chamber. At mid RPM the valve is closed, this enables the expansion chamber to work. It is identified by the head and cylinder, being much larger than normal for its displacement, the cylinder balls is also cast with the wording VTACS on it.

V-TACS was a foot-operated power valve system made by Honda on some of its small two-stroke bikes and scooters, like the Honda FC50."

My understanding is that it changed the volume of the chamber at low revs and killed the mistimed exhaust pulse, it just makes it less bad off the pipe

[F5 Dave]

. . .
Do you remember the Honda "Beat", it was a 50cc water cooled CVT scooter in the eighties/nineties.

Only that they had a belt driven water pump that a mate used on a bucket. . . .or was that the Lead (125 version with an unfortunate name if you think about it)




For my latest fiddy plan, I would like to incorporate a power valve, and like you I thought a bout a self made blade, but it would seem that is not feasible.
.......

A modernised version of that would work on a fiddy racer I believe, just adapt a Rotax system (the vacuum operated units) that operate the blade type systems to actuate a valve on a bespoke cylinder head.

It sounds easy.... I'll make one after lunch.:blink:
yeah I have a couple of vacuum units left over from my Trinity kit. Yamaha had experimented with variable comp on the YZR500, not sure if it really progressed any. Theoretically you could get away with steeper baffle cone & get acceptable over rev.

Most powervalves work for road & dirt applications masking the negative effects of the pipe when out of frequency. On a 50 or any small high output 2 stroke you only really care about 2000 rpm. It's death anywhere else anyway. If you had a PV that operated quick enough in that area you could extend the peak power a little, giving a useful increase in mean power in between gear changes.

[SS90]

From Wikipedia

"Honda V-TACS

The "V-TACS" - Variable Torque Amplification Chamber System - works differently from the "AETC system" and it will only work when it is used in conjunction with a tuned muffler. Tuned mufflers/expansion chambers increase power but only at the RPM they are designed for and can actually cause a power loss outside their tuned RPM. "V-TACS system" takes advantage of using an expansion chamber without losing power outside the expansion chamber's tuned RPM. Within the head and cylinder of the engine, there is a chamber that is sealed by a valve. This sealed chamber is vented onto the exhaust port when the valve is open. At low RPM this valve is open, this has the effect of increasing the exhaust manifold volume and negating the power loss that would normally be apparent at low RPM with an expansion chamber. At mid RPM the valve is closed, this enables the expansion chamber to work. It is identified by the head and cylinder, being much larger than normal for its displacement, the cylinder balls is also cast with the wording VTACS on it.

V-TACS was a foot-operated power valve system made by Honda on some of its small two-stroke bikes and scooters, like the Honda FC50."




Wikipedia Ist für Schulkinder und die Hersteller von 3 Rädern Fahrzeuge, die hinter einem anderen Fahrzeug abgeschleppt werden.

[SS90]

From Wikipedia



My understanding is that it changed the volume of the chamber at low revs and killed the mistimed exhaust pulse, it just makes it less bad off the pipe

My bad, yes it changed the header volume, not the trapped compression, it was another anagram that changed the primary compression, I just cannot recall it just now...... Yamaha I think it was, just trying to find something that the "Hoi Polloi" could relate to.......

[F5 Dave]

So the hole is actually in the head for that to work? No I haven't seen one.


Ideally you have a floating head like Rainey's bike used for a while I believe. Didn't Polini make some kit? Can't have done much, all sort of went away like antidive.

[SS90]

Only that they had a belt driven water pump that a mate used on a bucket. . . .or was that the Lead (125 version with an unfortunate name if you think about it)


Most powervalves work for road & dirt applications masking the negative effects of the pipe when out of frequency. On a 50 or any small high output 2 stroke you only really care about 2000 rpm. It's death anywhere else anyway. If you had a PV that operated quick enough in that area you could extend the peak power a little, giving a useful increase in mean power in between gear changes.


This is where The crux of the whole situation exists..... 50s have this anomaly of having a disproportionate amount of power for the displacement, however, it is over such a small rev range ( 20000 rpm....... I wish....something like 1500rpm is best I can do, and, short of a 7 Speed gear Box ......... (hence my sudden interest in variable volumes)

The Top guys over here all take different approaches for the Same results..... The Same Peak Power and torque, very different exhausts, and very different Cylinders....... But the frightening thing is they all have the same parts cost (not labour, just parts) €10,000 (yup $NZ20,000)..... This years winners had 27ps by all accounts.....

[F5 Dave]

well it depends what you call 'in the power', the rev range used is more decided by the gear box ratio spacings.

That is crazy money & wayy more crazy power. So these are the silly rev monsters? what basis are they starting from? that is 540hp per litre. I struggle to fathom that. Top flight GP bike is 400. Drag race engines?

[Spearfish]

well it depends what you call 'in the power', the rev range used is more decided by the gear box ratio spacings.

That is crazy money & wayy more crazy power. So these are the silly rev monsters? what basis are they starting from? that is 540hp per litre. I struggle to fathom that. Top flight GP bike is 400. Drag race engines?

Google: "Polini Big Evolution" for info.
Big money, big power, small life span.
I would imagine they would be a hell of a lot of fun on a sprint track but the cost would kind of go against the best parts of real bucket racing.

[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-Motors/Motorbikes/Parts-for-sale/Electrics/auction-320229588.htm

or should I just find a coil like this
http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Electrics/auction-320353097.htm
and then a cdi like this
http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Electrics/auction-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=tYNBObmXj5k&feature=youtube_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-Motors/Motorbikes/Parts-for-sale/Electrics/auction-320229588.htm
was probably perfect, depending on how specific a cdi is to the electrical system of each bike.

[SS90]

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

Well, it could be, I can't really say for sure,RM80b's are a pretty old machine by any standard, and perhaps it would be wise to get some specifications before purchasing, retail price for a model specific unrestricted coil is about 50 Euro.

[rabidnz]

hey, im clueless when it comes to cdi's, what sort of specs would I need to look for to do a comparison? as it seems pretty hard to find any information about the ducati cdi/coil unit which is in there currently/