Re: Fastest Suzuki FA50? Hoping to hit 70mph

It's just a miracle bike that defies physics? lol

Re: Fastest Suzuki FA50? Hoping to hit 70mph

Mikey Antonakakis /

Either your speedo is wrong, you're not actually doing 70 (or 80? Which is it? That's a huge difference), you're not making only 8hp, or most likely all of the above.

I think 60mph from a stock derestricted RS50 is generous from everything I've read, although I've never owned/ridden a stock RS50 so I am not an authority.

Douglas Binder, who posted in this thread recently, is doing 50cc land speed record stuff. He has done more research/analysis on power requirements for top speed that he might share, but in a nutshell you need a good bit more than 8hp with a non-streamlined bike to get to 70mph; you'll almost certainly need over 10hp, probably not more than 15hp, depends entirely on the shape of the bike and your body when it is hanging off of the bike. Tuck vs no-tuck on my Peugeot for instance is easily a 5mph difference.

Re: Fastest Suzuki FA50? Hoping to hit 70mph

Russell Huddy /

Even if 8 hp is enough (it's not) for 70mph a 70cc kit on a bike that's like 2hp stock isn't going to get you close to 8hp. (edited)

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> Mikey Antonakakis Wrote:

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

> Either your speedo is wrong, you're not actually doing 70 (or 80? Which

> is it? That's a huge difference), you're not making only 8hp, or most

> likely all of the above.

>

> I think 60mph from a stock derestricted RS50 is generous from everything

> I've read, although I've never owned/ridden a stock RS50 so I am not an

> authority.

>

> Douglas Binder, who posted in this thread recently, is doing 50cc land

> speed record stuff. He has done more research/analysis on power

> requirements for top speed that he might share, but in a nutshell you

> need a good bit more than 8hp with a non-streamlined bike to get to

> 70mph; you'll almost certainly need over 10hp, probably not more than

> 15hp, depends entirely on the shape of the bike and your body when it is

> hanging off of the bike. Tuck vs no-tuck on my Peugeot for instance is

> easily a 5mph difference.

Ok I'll break it down for you. The RS50 was derestricted when I bought it but as far as I can tell was stock other than a non-coolant heated intake, different carb, a foam air filter on the carb (no stock airbox), and a 41 tooth rear sprocket. In this configuration with the full fairings it would do 65 all day long with no tuck and 70 when tucked.

Over last winter I refreshed it with a new (stock) top end, V-Force 8petal reed block, Top Performance Red CDI, high-mount Technigas pipe and silencer, and new chain and sprockets with 13/41 gearing (up one tooth on the front from 12/41). I also removed the bodywork because the pipe and silencer need to be modified to fit inside the fairings and in the tail section (for undertail exhaust). So in this naked form it would cruise 70 untucked, 75 tucked, and 80 tucked either with a tailwind, drafting close behind a car/truck/semi, or on a slight downhill. This is all read off the stock speedometer with a stock size front tire so unless Aprilia messed up on their speedo design/calculations those should be accurate speeds (and judging from the speed of the cars around me I'd say they were accurate or at least within 5mph)

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> Russell Huddy Wrote:

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

> Even if 8 hp is enough (it's not) for 70mph a 70cc kit on a bike that's

> like 2hp stock isn't going to get you close to 8hp.

The FZ50 is 3.2hp stock so with the carb and downdraft intake from the FZ on the better FA case design I would expect about 3.5hp with a stock 50cc cylinder, stock head, stock reeds, and stock exhaust. Now adding the 60cc cylinder, raising it with 5 base gaskets to fully expose the ports, decking it 1.5mm to maintain squish band and compression, milling the head flush with the cooling fins to increase compression, adding the dual-stage reeds, running a larger carburetor, and installing an expansion chamber exhaust I'd expect to be more in the 5-8hp range

Re: Fastest Suzuki FA50? Hoping to hit 70mph

Mikey Antonakakis /

Okay, so you are far from stock. On a motor like the AM6, a good pipe will make a very big difference. Those V-Force reeds will also make a difference. And a 5mph difference is still significant. To go from 65 to 70, you need 25% more power, for instance.

Stock speedos are not accurate, they are often off by up to 5mph at those speeds even in fancy expensive cars (and they often read higher than actual). Your RS50 was designed from the factory to go 33mph - you trust the accuracy of the speedo at more than twice that speed?

Try it with GPS, find a flat road with little to no wind, do not draft behind cars and trucks, do it in both directions and take the average. 5mph due to speedo error and 5mph due to drafting gives you a 10mph error - more with wind. 65 to 75 requires 54% more power... In other words, my moped will do 100mph if I drop it off a cliff, but that doesn't mean it's a 100mph moped.

Part of the reason for us not being on the same page is that we are not on the same page - Everything I'm talking about (and I suspect everyone else who is trying to adjust your expectations) is more along the lines of "official" top speed, trying to neglect factors like hills, tail winds, drafting, etc - what will your bike do with no help other than its own engine, and whatever position you can contort your body? Your RS50 is likely making much more than 8hp with those mods, your actual indicated top speed on it was 75 (indicated), your speedo is probably off by a fair amount, etc. So again, you have to re-think this 70mph Suzuki scenario.

Re: Fastest Suzuki FA50? Hoping to hit 70mph

Mikey Antonakakis /

Your mods probably have you at probably 4hp, maybe 5, on the Suzuki. To get 8hp you will have needed to do significant port work with that cylinder. It has basically the same ports as stock. See this, which is linked in the Wiki article you've mentioned a few times:

https://www.mopedarmy.com/w/images/0/05/Kit_vs_stock.pdf (edited)

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> Mikey Antonakakis Wrote:

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

> Your mods probably have you at probably 4hp, maybe 5, on the Suzuki. To

> get 8hp you will have needed to do significant port work with that

> cylinder. It has basically the same ports as stock. See this, which is

> linked in the Wiki article you've mentioned a few times:

>

> https://www.mopedarmy.com/w/images/0/05/Kit_vs_stock.pdf

I pulled my cylinder just now and measured my ports and I guess the machine shop actually decked my cylinder 2-2.5mm because my exhaust port is 25.5mm from the top of the cylinder, the side ports 32mm and the top port 33mm.

So in addition to fully exposing the ports at BDC this should have the same effect as porting the top of the ports 2-2.5mm, correct?

Re: Fastest Suzuki FA50? Hoping to hit 70mph

Mikey Antonakakis /

No, if they milled the topd of the cylinder it would only change your compression, not timing. Unless they cut down the base of the cylinder the timing is the same, and if they did cut the base, your timing would be less and your bike would be slower as a result.

Higher compression ratio is generally a solid benefit for a stock-ish setup, you might see about a 10-15% improvement in power across much of the rev range if the stock compression ratio was really low. But that's not going to make you much faster, that's worth maybe 3 or 4 mph on the top end, and slightly better acceleration.

To make more power, you need to get more air into and out of the cylinder, and that only happens with improvements to ports, reeds, carbs, and pipes. If you add a base spacer, you can bump up the timing of all the ports, but that's not the ideal way to do it because then your port floors don't line up with the piston crown at BDC, and that hurts the flow (more important for transfers than exhaust, though).

One relatively easy way to get a good bump in power is to raise the roof of the exhaust port (and widen it as much as possible - 70% of bore diameter max). But this will give you a peakier power band because it increase your blowdown. This strengthens the effect of your pipe, but in a narrower band of revs - at resonance you make more power, but outside of it, you make less. If you have CVT then it's not a big deal, but with a one or two speed you can pretty easily end up with a power band that is far too narrow, that makes so little power outside of the peak range that it doesn't let you accelerate up to the range that the pipe hits, and even perfect clutch tuning can't fix it. I can draw a graph if you'd like, but as you accelerate, the power required increases exponentially (as a factor of speed cubed). Even if your peak power is enough to sustain whatever max speed you're geared for, if at any point below that you make less than the required power, you won't be able to get to that top speed.

So as I've said before, the cylinder you've got *might* be capable of supporting a pretty high top speed - 70 is out of the question, 60 might be theoretically possible if you cut additional transfer ports into the cylinder - but your power band would probably end up so narrow that you wouldn't be able to accelerate up to that speed, even with a two speed. This is why I'm curious to see what your bike is capable of the way it's set up right now, having that baseline is critical to figuring out how to go faster. I'm guess you'll be right around 40mph in a flat road/both directions/no wind/no drafting/GPS situation. If so, we could probably help get you to maybe 50 if you're lucky, but to go faster than that you'll really want to find a better cylinder. (edited)

Re: Fastest Suzuki FA50? Hoping to hit 70mph

Mikey Antonakakis /

Oh and on the topic of carb sizing, 14mm is pretty small, especially for 50mph. 50 would likely require somewhere around 8hp, check out the Dell'Orto manualfor a good chart for recommended carb sizes vs power. 14mm works well for 2-6hp, for 50mph you'll probably want a 17-20mm carb. A smaller PHBG might be a nice option for you, or something like a VM18. (edited)

Re: Fastest Suzuki FA50? Hoping to hit 70mph

Brent and Mikey are the new Click and Clack.

Re: Fastest Suzuki FA50? Hoping to hit 70mph

Mikey Antonakakis /

I am not nearly that enthralling and entertaining!

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> Mikey Antonakakis Wrote:

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

> No, if they milled the topd of the cylinder it would only change your

> compression, not timing. Unless they cut down the base of the cylinder

> the timing is the same, and if they did cut the base, your timing would

> be less and your bike would be slower as a result.

They did mill the top of the cylinder so with a single base gasket it would increase compression, however since I'm running 5 base gaskets the compression stays the same, the ports are just raised so they're fully exposed at BDC

>

> Higher compression ratio is generally a solid benefit for a stock-ish

> setup, you might see about a 10-15% improvement in power across much of

> the rev range if the stock compression ratio was really low. But that's

> not going to make you much faster, that's worth maybe 3 or 4 mph on the

> top end, and slightly better acceleration.

I used a digital caliper to compare the stock FZ50 head to the milled FA50 head and it looks like they took off right around 2mm. Taking the stock compression of 6.5:1 and factoring in the 2mm reduction it increases compression to 8.8:1 (if I did my math and equations right: 6.5x=37.4+x where 37.4 is the stroke. Subtract x from both sides and you get 5.5x=37.4 then divide by 5.5 and x=6.8mm at TDC. Subtract 2mm that was milled off the head and you get 4.8mm. Then the equation for the new compression ratio would be x(4.8)=37.4+4.8 >> x(4.8)=42.2 divide by 4.8 and get x=8.8). I understand this is still not the 11.5:1 that my Aprilia has but there's not much of a way to get any more compression without a different head design (the piston crown protrudes above the top surface of the cylinder as it is right now)

>

> To make more power, you need to get more air into and out of the

> cylinder, and that only happens with improvements to ports, reeds,

> carbs, and pipes. If you add a base spacer, you can bump up the timing

> of all the ports, but that's not the ideal way to do it because then

> your port floors don't line up with the piston crown at BDC, and that

> hurts the flow (more important for transfers than exhaust, though).

I did add a base spacer in the form of 5 base gaskets because in stock form the port floors sit 2.6mm below the piston crown at BDC (per the Performance Tuning wiki). With the 5 base gaskets the ports are fully exposed at BDC

>

> One relatively easy way to get a good bump in power is to raise the roof

> of the exhaust port (and widen it as much as possible - 70% of bore

> diameter max). But this will give you a peakier power band because it

> increase your blowdown. This strengthens the effect of your pipe, but in

> a narrower band of revs - at resonance you make more power, but outside

> of it, you make less. If you have CVT then it's not a big deal, but with

> a one or two speed you can pretty easily end up with a power band that

> is far too narrow, that makes so little power outside of the peak range

> that it doesn't let you accelerate up to the range that the pipe hits,

> and even perfect clutch tuning can't fix it. I can draw a graph if you'd

> like, but as you accelerate, the power required increases exponentially

> (as a factor of speed cubed). Even if your peak power is enough to

> sustain whatever max speed you're geared for, if at any point below that

> you make less than the required power, you won't be able to get to that

> top speed.

This makes total sense, but I think for now I'm going to avoid raising the port roof of the exhaust port to keep a wider RPM range and not have such a peaky powerband. If I find I'm not making enough power to pull through the gearing and get up to speed then I might try raising the exhaust port roof at that time, after first doing as much clutch tuning as possible.

>

> So as I've said before, the cylinder you've got *might* be capable of

> supporting a pretty high top speed - 70 is out of the question, 60 might

> be theoretically possible if you cut additional transfer ports into the

> cylinder - but your power band would probably end up so narrow that you

> wouldn't be able to accelerate up to that speed, even with a two speed.

> This is why I'm curious to see what your bike is capable of the way it's

> set up right now, having that baseline is critical to figuring out how

> to go faster. I'm guess you'll be right around 40mph in a flat road/both

> directions/no wind/no drafting/GPS situation. If so, we could probably

> help get you to maybe 50 if you're lucky, but to go faster than that

> you'll really want to find a better cylinder.

I'm also curious to see where I'm at currently so as soon as the weather breaks I'll definitely get on with the test rides. Since the FZ50 with these mods can hit 40 with the taller final gearing I'm thinking I'll probably be more around 50 with the FA final gearing and properly tuned clutches, with 60 being the end goal

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> Mikey Antonakakis Wrote:

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

> Oh and on the topic of carb sizing, 14mm is pretty small, especially for

> 50mph. 50 would likely require somewhere around 8hp, check out the

> Dell'Orto manualfor a good chart for recommended carb sizes vs power.

> 14mm works well for 2-6hp, for 50mph you'll probably want a 17-20mm

> carb. A smaller PHBG might be a nice option for you, or something like a

> VM18.

I want to say that the carb on my Aprilia is a 20 or 21mm, so like I said I will probably start with that carb on the Suzuki

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> jayson sumpter Wrote:

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

> Brent and Mikey are the new Click and Clack.

Had to look this up as I'm too young to get the reference lol

Re: Fastest Suzuki FA50? Hoping to hit 70mph

We are the exact same age........

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> jayson sumpter Wrote:

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

> We are the exact same age........

I guess I was too sheltered then. Haven't ever heard of Car Talk before

Re: Fastest Suzuki FA50? Hoping to hit 70mph

More sheltered than NPR??

Fuck. That’s rough.

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> jayson sumpter Wrote:

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

> More sheltered than NPR??

>

> Fuck. That’s rough.

Yeah lol like no offense but once the TV was invented families kinda stopped sitting around the FM radio at night

And in the car there was always music on, not talk radio. So I guess I was too sheltered from things like Car Talk

Re: Fastest Suzuki FA50? Hoping to hit 70mph

wait did dude just claim his rs50 goes 80 mph?

Re: Fastest Suzuki FA50? Hoping to hit 70mph

DrGeorgeTompson (Alan) /

> Graham Motzing Wrote:

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

> wait did dude just claim his rs50 goes 80 mph?

>

> https://giphy.com/explore/alrighty-then

I mean, i guess it's not impossible. The stock RS50 gearing for the 99-05s was 12/47 and, unrestricted, it would do ~62mph at 12k RPM. 13/41 puts it somewhere around 76 mph at the same rev. so with no rev limit i could believe it, i guess. maybe after 5 miles of drafting a semi in full tuck idk

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> Brent Saxsma Wrote:

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

> I think you guys are all missing the point here that gearing is the key

> once you have a potent enough engine. I know my Aprilia RS50 makes more

> horsepower than the Suzuki does stock but I'd like to think that with

> the mods I've done to the Suzuki and the fact that it's got 20% more

> displacement now that it should be close to the stock RS50. Then the

> only difference really is the gearing, and the Aprilia can hit 80 in 6th

> gear, with a nice powerband from about 7,500-11/12,000. Getting 9k out

> of the Suzuki should really be no problem and with my gearing that

> equals 70 in 2nd gear

For an experiment... You should take your rs50 out, and try and hit 70 with only using the top two gears. Then see how it works getting it to move anywhere.

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> Graham Motzing Wrote:

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

> wait did dude just claim his rs50 goes 80 mph?

>

> https://giphy.com/explore/alrighty-then

You read that right. I guess sorry you don't have a 6speed manual on your ped...

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> DrGeorgeTompson (Alan) Wrote:

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

> > Graham Motzing Wrote:

>

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

>

> > wait did dude just claim his rs50 goes 80 mph?

>

> >

>

> > https://giphy.com/explore/alrighty-then

>

> I mean, i guess it's not impossible. The stock RS50 gearing for the

> 99-05s was 12/47 and, unrestricted, it would do ~62mph at 12k RPM. 13/41

> puts it somewhere around 76 mph at the same rev. so with no rev limit i

> could believe it, i guess. maybe after 5 miles of drafting a semi in

> full tuck idk

idk dude, on all the stock-ish am6 bikes I've ridden, 6th gear is almost useless on stock gearing. You gotta have a pretty long very flat road to wind it out in 6th. Going up that much you probably couldn't even get into 6th.

My rieju all stock with an 8 petal, derestricted CDI box, and better unifoam air filter would only do 58 wound out in 6th and it was tough getting there. (edited)

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> «tyler » Wrote:

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

> > Brent Saxsma Wrote:

>

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

>

> > I think you guys are all missing the point here that gearing is the

> key

>

> > once you have a potent enough engine. I know my Aprilia RS50 makes

> more

>

> > horsepower than the Suzuki does stock but I'd like to think that with

>

> > the mods I've done to the Suzuki and the fact that it's got 20% more

>

> > displacement now that it should be close to the stock RS50. Then the

>

> > only difference really is the gearing, and the Aprilia can hit 80 in

> 6th

>

> > gear, with a nice powerband from about 7,500-11/12,000. Getting 9k

> out

>

> > of the Suzuki should really be no problem and with my gearing that

>

> > equals 70 in 2nd gear

>

> For an experiment... You should take your rs50 out, and try and hit 70

> with only using the top two gears. Then see how it works getting it to

> move anywhere.

If you're trying to compare that experiment to the 2speed Suzuki I get where you're coming from but it would be more like 3rd and 5th based on the gearing of the 2 speeds in the Suzuki. I'm sure I could accomplish it, although it would take a lot of clutch slipping. Hence why I'm anticipating having to run very heavy springs in both clutches on the Suzuki, causing them to slip quite a bit as the speed increases, revs drop, and they fully grab

Re: Fastest Suzuki FA50? Hoping to hit 70mph

> Dave & Bummerzz Wrote:

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

> > DrGeorgeTompson (Alan) Wrote:

>

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

>

> > > Graham Motzing Wrote:

>

> >

>

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

>

> >

>

> > > wait did dude just claim his rs50 goes 80 mph?

>

> >

>

> > >

>

> >

>

> > > https://giphy.com/explore/alrighty-then

>

> >

>

> > I mean, i guess it's not impossible. The stock RS50 gearing for the

>

> > 99-05s was 12/47 and, unrestricted, it would do ~62mph at 12k RPM.

> 13/41

>

> > puts it somewhere around 76 mph at the same rev. so with no rev limit

> i

>

> > could believe it, i guess. maybe after 5 miles of drafting a semi in

>

> > full tuck idk

>

> idk dude, on all the stock-ish am6 bikes I've ridden, 6th gear is almost

> useless on stock gearing. You gotta have a pretty long very flat road to

> wind it out in 6th. Going up that much you probably couldn't even get

> into 6th.

>

> My rieju all stock with an 8 petal, derestricted CDI box, and better

> unifoam air filter would only do 58 wound out in 6th and it was tough

> getting there.

It's not always easy to get to 6th and yes, there's not a big difference between 5th and 6th, but it can get there and when wound out it would hit 80 on the factory speedo (which is likely off 5ish mph). So an indicated 80 or actual 75. I'll confirm with GPS once I get it rebuilt and find a test rider

Re: Fastest Suzuki FA50? Hoping to hit 70mph

yeah dude you're smoking meth. Your rs50 doesn't do anywhere near 80. This one only does 77

https://thekneeslider.com/worlds-fastest-50cc-motorcycle-project/ (edited)

Re: Fastest Suzuki FA50? Hoping to hit 70mph

lol pictures of a confirmed almost 80mph 50cc rs50.

Metrakit crank, 8 petal, heavily modified metrakit 50 top end, metrakit pro race pipe, selettra inner rotor ignition, and custom fuel injection and nitrous

(edited)

Re: Fastest Suzuki FA50? Hoping to hit 70mph

DrGeorgeTompson (Alan) /

> Dave & Bummerzz Wrote:

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

> yeah dude you're smoking meth. Your rs50 doesn't do anywhere near 80.

> This one only does 77

>

> https://thekneeslider.com/worlds-fastest-50cc-motorcycle-project/

I have been successfully converted to a non-believer.

Re: Fastest Suzuki FA50? Hoping to hit 70mph

St. John Indiana has a lot of lead in there water.... That would probably explain it.

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