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View Full Version : So I'm 17 soon, 125 or mods



LEWINS
07-14-2014, 02:32 PM
Would would be faster and cheaper? An aprilia sx 125 restricted to 11kw or my aprilia sx 50 with an airsal 80 kit and a racing carb, also would I be breaking the law with a modded sx 50 on my cbt at 17?
Cheers

Zav
07-15-2014, 01:21 AM
Your illegal,at the moment so why does it matter ahaa

at 16 I was running a a rs50 with a full airsal 15hp setup with top speed of 80mph+ and I never got done and still haven't now when I'm 18

and if your having problems with the sx50 don't even bother tuning it or looking at a sx125 as it will make things a lot harder for you plus you don't exactly seem to know what a airsal 77 needs to be fitted and setup also needed to actually see a gain over a 50cc I'll but it blunt and straight to point

need case mods to make sure the barrel and piston get it's air and fuel right otherwise it will run crap and low powered

24mm atleast or it will run crap

atleast a uprated crank and bearings best to go for is Doppler endurance then airsals crank for the kit (this is the biggie as I've seen a airsal 77 kill a stock crank in under 100 miles and the stock crank only had 1000 soft miles on it

next your need a decent pipe or it won't run right

then a clutch I found best is polini plates with malossi springs with my spacers

And that's just get it to run right and with a good noticeable power if miss one of them it will eather kill your engine. Run crap. Run underpowered

even I've not bothered with a 125 2t for road use as 90% have been thrashed and always blow up the rest have had a good life then gets thrashed and dies so that's why I've pre ordered a brand new wr125x for September when the new plate come out and my Rx insurance runs out as it means no problems with prev owner free repairs for 3 year and I can have a slip on, de cat pipe as long as shop I brought it from fit it and re dyno it for me

apriliamandan
07-15-2014, 12:22 PM
Depends on what you want from the bike or any bike for that matter. Tuning is great fun, highly educational and very rewarding! Nothing better than your self tuned 70cc screamer pissing on other 125's on the road!

Decent big bore cylinder kit = 150
21mm carburettor = 50 including jets
Malossi reed set (0.3,0.35.0.4) = 21
Tuned pipe = 150
Uprated clutch springs = 20 (or machine up some spring spacers for free!)
Range of sprockets = 25

The cost probably matches the cost of buying a 125, but I tuned my 50 (70) despite costing more than getting a 125 for fun of it and it was and still is a big learning curve!


Its down to you buddy!

LEWINS
07-15-2014, 02:23 PM
Depends on what you want from the bike or any bike for that matter. Tuning is great fun, highly educational and very rewarding! Nothing better than your self tuned 70cc screamer pissing on other 125's on the road!

Decent big bore cylinder kit = 150
21mm carburettor = 50 including jets
Malossi reed set (0.3,0.35.0.4) = 21
Tuned pipe = 150
Uprated clutch springs = 20 (or machine up some spring spacers for free!)
Range of sprockets = 25

The cost probably matches the cost of buying a 125, but I tuned my 50 (70) despite costing more than getting a 125 for fun of it and it was and still is a big learning curve!


Its down to you buddy!

Which would be faster? An 11kw 125 2 stroke or a tuned sx 50 with all mods you said
and what about a crank? I will be using it every day for an hour or so

apriliamandan
07-16-2014, 11:22 AM
Which would be faster? An 11kw 125 2 stroke or a tuned sx 50 with all mods you said
and what about a crank? I will be using it every day for an hour or so

Hard to say, 15hp can be gotten out of a kitted 50/70 in a much lighter frame than a 125! I know which one would be more fun there! ;) Cheaper to insure aswell!
A decent fully balanced and stuffed crankshaft rated for higher rpm will give a small gain in performance and piece of mind, well worth 140 there.

Zav
07-16-2014, 12:41 PM
May I add that there roughly same weight and the tuned sx will be more powerful but less top speed and will blow up more and drink more fuel and the sx125 is a dam seight better looking and better build quality

Spudgun60
07-16-2014, 01:02 PM
It's ye old story. Higher power = Shorter life. Yes, it is possible to get an increadable amount of power out of a moped engine, but at what price? As of yet, nobody has managed to get the power of a restricted 125 out of a moped and keep the durability intact. Even Stephen Hawking can't change the Laws of Physics.

Zav
07-16-2014, 01:13 PM
It's ye old story. Higher power = Shorter life. Yes, it is possible to get an increadable amount of power out of a moped engine, but at what price? As of yet, nobody has managed to get the power of a restricted 125 out of a moped and keep the durability intact. Even Stephen Hawking can't change the Laws of Physics.

My rs shore did a good try I did 8000 miles kicking out 15.2hp at rear wheel before I crashed and my Rx is kicking out about same and is a hell of a lot more reliable than the rs but it cost me a good 400 just for engine spec never mind polo carb. Tecnigas exhaust. 15/44 sprockets. MVT inner rota kit. And the rest

the only prob
em with the sx is the engines wank if want it for everyday the am6 engine is a hell of a lot better for everyday use but is less powerful

there is actually a kit called mxs 94 that makes 34hp and with port work they have got 37hp but it only lasts 100 miles or 2 hours before rings need changing and double for pistons

apriliamandan
07-16-2014, 01:50 PM
As I say, I like tuning, its satisfying and rewarding. Theres more to bikes than just speed.

Spudgun60
07-16-2014, 02:07 PM
As I say, I like tuning, its satisfying and rewarding. There's more to bikes than just speed.

Yeah. Like getting it to work in the first place! Then there's keeping it working.

mattology
07-16-2014, 09:32 PM
It's ye old story. Higher power = Shorter life. Yes, it is possible to get an increadable amount of power out of a moped engine, but at what price? As of yet, nobody has managed to get the power of a restricted 125 out of a moped and keep the durability intact. Even Stephen Hawking can't change the Laws of Physics.

Alright, I'll bite.

A simonini 90 with a good pipe and a 28mm carb will likely get you there, but if you abuse it, it will still blow up.

LEWINS
07-17-2014, 08:42 AM
You guys know my carb needs rejetting, right?
Well can I just put a 21mm carb on instead of rejetting it?

LEWINS
07-17-2014, 10:24 AM
21mm is too big for 50cc, it would b impossible to get the jetting wright and would clog up the engine with too much fuel, 19mm or 19.5mm is max, but someone here correct me if im wrong

So could I put a 19mm on and be done? No need to rejet?

LEWINS
07-17-2014, 11:21 AM
you would have to rejet as every carb is made to fit a huge number of bikes, you could buy a genuine dellorto phbg19mm that might come with the correct w7 needle and pilot jet, or save some money and get the stickyparts or naraku tiwan copy black racing edition phbg19mm that comes with the wrong w16 needle and buy a w7 needle and size 50 pilot jet from dellorto, in the airsal 70cc manual it recommends to use a 95 main jet with a 19mm carb providing the owner is using the standard airbox

So I would need 105 main jet?
is this one any good? http://www.pedparts.co.uk/product/1198/stage6-dellorto-19mm-race-carb-black-edition

or am I better off just rejetting my original carb?

LEWINS
07-17-2014, 11:26 AM
with pod style filter about 102-105, the main jet size for phbg carbs are the smaller 5mm

Im not sure if I have a full leovince exhaust now, I can't see anything that says leovince on the front pipe, only on the back

LEWINS
07-17-2014, 12:03 PM
forgot to mention, the black screw on trumphet on that carb is 40mm so youll need a 40mm ramair filter unless the 1 u already have is 40mm or if u still have the standard airbox and rubber?

Cheers mate, once I get pics I will buy the carb if I think I'm up to fitting it, also I my air filter manifold isn't long enough to go into the air box

Zav
07-17-2014, 01:58 PM
21mm is too big for 50cc, it would b impossible to get the jetting wright and would clog up the engine with too much fuel, 19mm or 19.5mm is max, but someone here correct me if im wrong

Your wrong 29mm is too big as 28 mm is the max you can run on a ported 50cc 21mm is max you can run on a decent piped stock 50cc and 19.5 is max can run on standard pipe and 50cc but saying that I'm running a polini 19.5 on my tp rose kit and runs fine and I get very good mpg and a lot of low end power for wheelies :P

Zav
07-17-2014, 02:00 PM
So could I put a 19mm on and be done? No need to rejet?

Have you not learned anything

even if you clean a air filter or change reeds or even change manifold you should check jetting in case you need to up jet or down jet
so if you change/ clean/ repair
exhaust
barrel
head
seals
manifodl
reeds
reed blcok
carb
airfilter

Zav
07-17-2014, 02:02 PM
you would have to rejet as every carb is made to fit a huge number of bikes, you could buy a genuine dellorto phbg19mm that might come with the correct w7 needle and pilot jet, or save some money and get the stickyparts or naraku tiwan copy black racing edition phbg19mm that comes with the wrong w16 needle and buy a w7 needle and size 50 pilot jet from dellorto, in the airsal 70cc manual it recommends to use a 95 main jet with a 19mm carb providing the owner is using the standard airbox

Im running a 85 main jet with 19.5 polini carb so don't use jet sizes as advice on anything as know one knows and he's prob brought wrong stuff now so he will blame you and so on

what he should be doing is what I said to start with post pic of spark plug but he hasn't as I'm guessing he doesn't know what one is maybe ? I dunno as he never replied

Zav
07-17-2014, 02:03 PM
with pod style filter about 102-105, the main jet size for phbg carbs are the smaller 5mm

Are you mad even my airsal 70 with 24mm didn't have that high main jet it had a 99 in that was with pod filter arrow exhaust and flowed cases

LEWINS
07-17-2014, 02:13 PM
Im running a 85 main jet with 19.5 polini carb so don't use jet sizes as advice on anything as know one knows and he's prob brought wrong stuff now so he will blame you and so on

what he should be doing is what I said to start with post pic of spark plug but he hasn't as I'm guessing he doesn't know what one is maybe ? I dunno as he never replied

You never said I need to post a pic of my spark plug? You said my jets, but I'm not confident enough to strip the carb down yet, your going on like I'm a bike mechanic, I start my course September, and that's for cars, I'm 16, not 30

Zav
07-17-2014, 02:18 PM
Omg you likes. Friend of mine he's just finished level 3 and still doesn't know how to take a carb apart ahaa and I knew more about bikes when I was 14 than you do now

LEWINS
07-17-2014, 02:20 PM
Omg you likes. Friend of mine he's just finished level 3 and still doesn't know how to take a carb apart ahaa and I knew more about bikes when I was 14 than you do now

I know about everything but carbs, and I've got an aprentiship, learn more with that

Zav
07-17-2014, 02:21 PM
Same route he took good luck to ya :lol:

So you took spark plug out yet

LEWINS
07-17-2014, 02:25 PM
Same route he took good luck to ya :lol:

So you took spark plug out yet

I will tomorrow, and start a new thread and show you, my dad also has a mate who used to work for yamaha, he will teach me how to work on it

Zav
07-20-2014, 01:22 PM
sounds like the main jet needed for my 21mm is more closer to 92 or 90 than a 95 with standard airbox, although gophman got his sons sx working with 92 and pod filter, im proper gasping to get the engine all rebuilt before its too late and summers over, but just spent all the dosh on a recurve bow and expensive carbon fibre arrows lol

when people ask me to recommend a main jet size on here im better off answering that question when ive had more experience with my 21mm and hopefully a 24mm carb in the future☻

this is a reply to zavs post, not sure how to make that grey speech bubble reply to question thing show lol

No you main jet needs to be higher as you premix I get away with low main jets as I run good fuel very good oil and i hardly ever sit flat out I mainly use 6 to 9 k revs as that's mainly where my powerband is due to my small carb but if I want to I can rev it very high for very long time when I have my cover on but I can't when I have it off as it starts to die due to too much air but my cover slightly makes it rich