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| Hidden Snake |
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Hidden Snake
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 Posted: 12:16 - 17 Oct 2012  Post subject: Derbi Senda 2009 model - best combination |
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Hi, I am quite new to small bikes. I have recently bought Derbi Senda 2009 model and mount it with Leo Vince V6 TT exhaust. What I am looking for is recommended best setup of sprocket, jet, carb to get best ballanced power output. Currently I am getting decent power boost, however it is only very very high on revs and it is very peaky (I know it is small engine). I am getting max speed around 78-83 km/h (bike is carrying me plus comb = 100+kg). It is not restricted, and I am not looking for max speed - more for allaround performance.
https://www.youtube.com/watch?feature=player_embedded&v=wcoSN3i2bEw |
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| Matt- |
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Matt-
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| Hidden Snake |
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Hidden Snake
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| Posted: 13:07 - 17 Oct 2012 Post subject: |
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Is there any good manual how to open the carb and change the jet?
I have hands of office rat (plus size of hulk)
Also I would like to avoid choking the engine with too rich spray (hmmm how to say that in english)  |
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Hidden Snake
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| P.addy |
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P.addy
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| Hidden Snake |
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Hidden Snake
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| P.addy |
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P.addy
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| Hidden Snake |
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Hidden Snake
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P.addy
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| Posted: 17:29 - 23 Oct 2012 Post subject: |
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It was directly related and not abusive, it was me telling you how it is.
A bigger carb on a non tuned engine... this won't work |
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| Hidden Snake |
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Hidden Snake
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P.addy
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| BigDMUFC |
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BigDMUFC
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| _Iain_ |
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_Iain_
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| Posted: 00:30 - 24 Oct 2012 Post subject: |
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And i quote.
| _Iain_ wrote: | With 90% of bikes even set up correctly you will loose power & severely fuck the driveability.
And when it rains (and we are coming in to winter...) it'll hoover up shitloads of water damaging engine internals and making it cut out every thirty seconds, leaving yourself pushing it home.
Which isnt fun. 
The exhaust & rejet will make a massive difference as the OEM exhausts are designed to be made cheaply & to restrict the power output of the engine. Swapping it out for something thats designed to INCREASE the power & has had extensive dyno testing to get everything out of it will make a big difference - if the carb is set right.
More powerz.
Decent big bore kit. If its the AM6 engine then you'd be wanting one of theese;
https://www.athenaparts.com/files/pdfs/P400130100004_05-MinarelliAM6_ING.pdf
However note that an engines components need to be tuned to work together, rendering your fancy leo vince pipe restricting the engine again.
Price it all up? Over a grand in parts. assuming you dont change the exhaust, in which case i'd budget another £300.
A total engine build by a decent tuner to further optimise it all to run together? With that spec, i'd make a guess pushing it towards £2000 for the engine build.
It'll probbably make as much power as a restricted 125 for around 500 miles, then go hand grenade as every extra horsepower you squeeze out of it makes it less reliable. It'll be a cunt to start in the morning. It will cost the earth in expensive two stroke oil. Piston rings will probbably need replacing every week (assuming you ride it ONLY to school and back like a little old lady)
£2k for a couple of weeks worth of use? 
I did my CBT, bought a 125 that was less than a year old, bought all my gear AND paid the years insurance in full for that money!
Just WAIT. be happy with how it is for now, get a bigger bike when you're old enough. Pissing around with a 50 anymore than de-restricting it with a new exhaust just isnt worth it.
Might not be what you want to hear, but it's constructive. |
Had you read the link fully, you'd have seen the section at the bottom where athena reccomend carb choices specificly FOR that cylinder.
Now,
The engine is setup with a balance of performance, reliability, and useability. Adding performance will thus decrease reliability & useability.
Example -
SR20DET optimised for power;
https://www.youtube.com/watch?v=91QG8dDVWXE
Note all the power has been shifted to the high end of the rev range, and the car will barely idle as a result. The engine will make next to no power till it hits around 6,000rpm, and it'll make peak power around 10,000rpm. Which is good for a race engine, as power wins, and you'd be in that band of power the whole time.
SR20DET factory setup;
https://www.youtube.com/watch?v=cCh3S-7C6fY
Note the difference in the way the car runs? However, as a result the engine will start to make power from around 1500-2000rpm, and it'll probbably peak around 7,000.
Everything is about balance. If you want power, you WILL sacrifice the driveability of the engine! get used to it. Fitting a bigger carb will make this even more of an issue, as it'll make the engine even more peaky!
Honda had an interesting way of getting around the issue on a four stroke with a system called VTEC. Which basicly had two seperate cam profiles, one for performance & one for driveabilty/economy. When it hit a certain rev, it would click over onto the performance profile & allow the engine to make maximum power. Hence the 160bhp 1.6 litre engine.
https://www.youtube.com/watch?v=AcT_ZyY3F0k
For a two stroke engine, powervalves were developed. The valve alters the exhaust port timing. Two strokes have no camshaft, and the way the barrel is ported is what affects the port timing. Which massively affects the power delivered & power availible to be made, it basicly affects the engine in the same sort of way as a four stroke engines cam profile.
The powervalve allows the exhaust port timing to adjust given certain revs, throttle openings etc, to try and improve the driveability. A barrel can then make the same power at the top end, but with double the midrange grunt making it a lot more useable. Like so;
https://i8.photobucket.com/albums/a35/BigPoppa05/Taper.jpg
A tuned RS125 two stroke (with a powervalve) and the following; Jim lomas SS system, 34mm Carb, V Force 3 reeds, HPI Racing cdi, Mitaka Barrel and piston kit
Makes a dyno graph like this;
https://i1148.photobucket.com/albums/o574/_Iain_/dyno.jpg
Note the engine revs along the bottom. It makes no power whatsoever till 6000rpm. Then it suddenly shoots up & trails off at around 9250rpm. It revs out at 11,000 so i'm assuming it hit the limiter and the dyno operator shut the engine down. Thats well over the redline!
The engine makes decent power for 3000rpm. The rest of the time it's flat as a fart & makes the power of a moped. Totally and utterly useless unless its going to be spending all its time above 7,000revs. And then it'll blow up very quickly as it'll be thrashed to death.
Now, the dyno from the R125. Yamaha's sporty four stroke;
https://www.motorcycleraceparts.co.uk/shopimages/Yamaha%20YZF-R%20125%2008-09%20dyno%20graph.jpg
Note how it pulls from 2,000 all the way to 9250? The shape of the graph?
It's smooth predictable power, which is what you're asking for. You're trying to get this power, and power curve out of a two stroke 50cc. It just wont happen!
Hence, i reccomended the cylinder kit to yourself in the first place, explained that it was more than it was worth, and just to sell up & get a bigger bike.
I'll make it simple;
NOTHING, AND I MEAN NOTHING, YOU CAN DO WILL MAKE THAT ENGINE MORE DRIVEABLE WITHOUT SACRIFICING OVERALL POWER OUTPUT.
So, if you would please accept this & either spend the 2k getting an awesome engine built (and by all means do it if its a lulzy project, because i'd realy like to see what the dyno figures came up to & nearly bought an RS50 with a fubar'd engine to try it.) or just get a bigger bike.
Nobody hates you, the idea, the bike etc etc, its just we're trying to tell you it REALY isnt worth the money, time and aggro as the only thing you'll do is end up with a realy expensive pile of scrap metal instead of an engine after a few weeks!
Now can we please stop posting theese silly threads. 
____________________
Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340 |
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| Hidden Snake |
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Hidden Snake
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| Posted: 07:08 - 24 Oct 2012 Post subject: |
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| _Iain_ wrote: | And i quote.
| _Iain_ wrote: | With 90% of bikes even set up correctly you will loose power & severely fuck the driveability.
And when it rains (and we are coming in to winter...) it'll hoover up shitloads of water damaging engine internals and making it cut out every thirty seconds, leaving yourself pushing it home.
Which isnt fun.
The exhaust & rejet will make a massive difference as the OEM exhausts are designed to be made cheaply & to restrict the power output of the engine. Swapping it out for something thats designed to INCREASE the power & has had extensive dyno testing to get everything out of it will make a big difference - if the carb is set right.
More powerz.
Decent big bore kit. If its the AM6 engine then you'd be wanting one of theese;
https://www.athenaparts.com/files/pdfs/P400130100004_05-MinarelliAM6_ING.pdf
However note that an engines components need to be tuned to work together, rendering your fancy leo vince pipe restricting the engine again.
Price it all up? Over a grand in parts. assuming you dont change the exhaust, in which case i'd budget another £300.
A total engine build by a decent tuner to further optimise it all to run together? With that spec, i'd make a guess pushing it towards £2000 for the engine build.
It'll probbably make as much power as a restricted 125 for around 500 miles, then go hand grenade as every extra horsepower you squeeze out of it makes it less reliable. It'll be a cunt to start in the morning. It will cost the earth in expensive two stroke oil. Piston rings will probbably need replacing every week (assuming you ride it ONLY to school and back like a little old lady)
£2k for a couple of weeks worth of use?
I did my CBT, bought a 125 that was less than a year old, bought all my gear AND paid the years insurance in full for that money!
Just WAIT. be happy with how it is for now, get a bigger bike when you're old enough. Pissing around with a 50 anymore than de-restricting it with a new exhaust just isnt worth it.
Might not be what you want to hear, but it's constructive. |
Had you read the link fully, you'd have seen the section at the bottom where athena reccomend carb choices specificly FOR that cylinder.
Now,
The engine is setup with a balance of performance, reliability, and useability. Adding performance will thus decrease reliability & useability.
Example -
SR20DET optimised for power;
https://www.youtube.com/watch?v=91QG8dDVWXE
Note all the power has been shifted to the high end of the rev range, and the car will barely idle as a result. The engine will make next to no power till it hits around 6,000rpm, and it'll make peak power around 10,000rpm. Which is good for a race engine, as power wins, and you'd be in that band of power the whole time.
SR20DET factory setup;
https://www.youtube.com/watch?v=cCh3S-7C6fY
Note the difference in the way the car runs? However, as a result the engine will start to make power from around 1500-2000rpm, and it'll probbably peak around 7,000.
Everything is about balance. If you want power, you WILL sacrifice the driveability of the engine! get used to it. Fitting a bigger carb will make this even more of an issue, as it'll make the engine even more peaky!
Honda had an interesting way of getting around the issue on a four stroke with a system called VTEC. Which basicly had two seperate cam profiles, one for performance & one for driveabilty/economy. When it hit a certain rev, it would click over onto the performance profile & allow the engine to make maximum power. Hence the 160bhp 1.6 litre engine.
https://www.youtube.com/watch?v=AcT_ZyY3F0k
For a two stroke engine, powervalves were developed. The valve alters the exhaust port timing. Two strokes have no camshaft, and the way the barrel is ported is what affects the port timing. Which massively affects the power delivered & power availible to be made, it basicly affects the engine in the same sort of way as a four stroke engines cam profile.
The powervalve allows the exhaust port timing to adjust given certain revs, throttle openings etc, to try and improve the driveability. A barrel can then make the same power at the top end, but with double the midrange grunt making it a lot more useable. Like so;
https://i8.photobucket.com/albums/a35/BigPoppa05/Taper.jpg
A tuned RS125 two stroke (with a powervalve) and the following; Jim lomas SS system, 34mm Carb, V Force 3 reeds, HPI Racing cdi, Mitaka Barrel and piston kit
Makes a dyno graph like this;
https://i1148.photobucket.com/albums/o574/_Iain_/dyno.jpg
Note the engine revs along the bottom. It makes no power whatsoever till 6000rpm. Then it suddenly shoots up & trails off at around 9250rpm. It revs out at 11,000 so i'm assuming it hit the limiter and the dyno operator shut the engine down. Thats well over the redline!
The engine makes decent power for 3000rpm. The rest of the time it's flat as a fart & makes the power of a moped. Totally and utterly useless unless its going to be spending all its time above 7,000revs. And then it'll blow up very quickly as it'll be thrashed to death.
Now, the dyno from the R125. Yamaha's sporty four stroke;
https://www.motorcycleraceparts.co.uk/shopimages/Yamaha%20YZF-R%20125%2008-09%20dyno%20graph.jpg
Note how it pulls from 2,000 all the way to 9250? The shape of the graph?
It's smooth predictable power, which is what you're asking for. You're trying to get this power, and power curve out of a two stroke 50cc. It just wont happen!
Hence, i reccomended the cylinder kit to yourself in the first place, explained that it was more than it was worth, and just to sell up & get a bigger bike.
I'll make it simple;
NOTHING, AND I MEAN NOTHING, YOU CAN DO WILL MAKE THAT ENGINE MORE DRIVEABLE WITHOUT SACRIFICING OVERALL POWER OUTPUT.
So, if you would please accept this & either spend the 2k getting an awesome engine built (and by all means do it if its a lulzy project, because i'd realy like to see what the dyno figures came up to & nearly bought an RS50 with a fubar'd engine to try it.) or just get a bigger bike.
Nobody hates you, the idea, the bike etc etc, its just we're trying to tell you it REALY isnt worth the money, time and aggro as the only thing you'll do is end up with a realy expensive pile of scrap metal instead of an engine after a few weeks!
Now can we please stop posting theese silly threads. |
thx for info .... please I am not that noob and young ... I am fully aware of the limitations of the engine. On the other hand I am looking for best ballance. Actually top speed like 80+ kmh is useless for me, I am more looking for the punch and how the punch is accessible.
So far it looks like I will give it to guys in scootland and let them dynojet the baby and set the carb/plug properly. |
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| P.addy |
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P.addy
Red Rocket
Joined: 14 Feb 2008
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| Posted: 08:54 - 24 Oct 2012 Post subject: |
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Iain has just basically said... it is pointless, you are wasting your time.
If you want something with more oomph, get it.
You won't get much punch out of a 50cc 2 stroke, see Iain's post as to why.
If you want something thats going to give you stupid acceleration and around 70mph top end, you'll be best off getting a DRZ400 and down gearing it. I down geared my TT600R supermoto and it was fantastic.
That had a whole 40hp, about 32 more than yours and very usable.
What is stopping you getting a bigger bike? Just pop down your local DAS place and hop on. |
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| _Iain_ |
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_Iain_
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| Posted: 15:24 - 24 Oct 2012 Post subject: |
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Put the bike back to stock jetting, stock exhaust etc.
It comes optimised for best balance from the factory, the barrel is ported as such.
You put a fancy pipe on it which is designed to make more power & thus shift the powerband up the rev range.
Factory pipe = driveability and "balance"
Leo pipe = performance and a peaky powerband.
Read the post. I've now said this to you many times and even gone in depth with you on the theory as to why you cannot have what you are asking for. The laws of physics and the design of the engine defy it.
Regarding the n00b comment, you are a noob. You're on about fancy filters to make it go faster, you're on about dynojetting a 50cc bike, you're on about fitting autochoke. You can be twice my age, infact you can be 70 years old for all i care, you dont know a damn thing about what you're on about! the punch and how the punch is accessable IS the driveability of the engine, as i've written a lengthy post to explain to you, you CAN NOT have this with the power! you have modified the engine to shunt the power further up the rev range already!
1. Fancy filters cause problems not solve them. They wont work. The airbox on a modern bike is designed to improve the performance, especially so on a two stroke. I'm not going to go into why because you blatantly ignored the last post i spent over an hour typing for your benifit.
2. A dynojet ket is an aftermarket jetting kit which gets you roughly in the ballpark to get better fuelling based on approximate settings. What you're on about is wanting someone to re-jet your bike and do a carb setup on a dyno. Dynojet is a brand. Dyno is a tool in a workshop. The whole point of a dynojet kit is that it can be done at home, or in a workshop without a dyno to set it up on! You pay £50 for £5's worth of jets. The other £45 is to cover the dyno time they've spent testing this setup on a bike like your own & making sure it'll work WITHOUT a rolling road/dyno setup!
3. Autochoke requires fitting a control module, temp sensor, autochoke solenoid, associated wiring, and a carburettor thats got the autochoke function on it!
Again. Its not cause we dislike you, the bike etc. ITS BECAUSE THE LAWS OF PHYSICS DO NOT MAKE WHAT YOU ARE ASKING FOR POSSIBLE!!
____________________
Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340 |
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| stevo as b4 |
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stevo as b4
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Joined: 17 Jul 2003
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| Posted: 17:01 - 24 Oct 2012 Post subject: The OP sounds like a pretty big lad |
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The OP sounds like he's a bit of a big lad for a 50cc bike, and yet he is getting around 50mph from it. Sounds like he's already having his cake and eating it.
The poor bike must be working it's knackers off to get all that mass up to 50mph, and he's asking for more performance from a 49cc cylinder? |
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Old Thread Alert!
The last post was made 13 years, 261 days ago. Instead of replying here, would creating a new thread be more useful? |
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