Restricted 50cc scooters and exhausts
Discussion
I was giving my bike a wash and check on saturday and noticed the exhaust pipe was very rusty after about 3 and a bit months. I wasn't sure what the pipe was at first becasue it has a little screw/nut type thing on it. Whats this for? Is it what restricts scooters doing over 30mph by restricting their exhaust gases or is that something inside the engine? And if it is the restrictor, by it "falling out" would my bike then be fully derestriced and ok to ride or would it need something over the little hole?
Heres a pic of it:
Heres a pic of it:
All mopeds by law are restricted to 49cc & 30mph max although in theory you may get 35 if your lucky.
Restriction comes in many forms, the most popular being the exhaust, usually a washer or restrictor pipe in the exhaust neck, occasionally in the box itself, the washer and neck restriction can be overcome very easily, the washer in the box cant, an aftermarket pipe will usually resolve this.
the second method is to restrict the air fuel mix entering the engine, this can be achieved by a blanking plate on the carb inlet side, again a relitivlyt easy fix.
the third option is the electonic version, although used on some of the italian machines it usually a simple switch on / off variety, as the bikes are all usually from the same plant, they dont have to worry about country specifics unlike cars.
finally athough derestiction is possible, you open up a can of worms.
you will invalidate any warranty you have remaining on the bike.
you will invalidate any insurance you have on the bike.
You will have to have the bike replated as its rated output exceeds the registered power capacity.
And finally derestiction would require that the service intervals and lubricants used must be of the highest spec, no more tesco,s own 2 stroke oil, they do have a habit of being fragile once they are unleashed
On the other hand, if you take that nut out it may just sound like this...
Restriction comes in many forms, the most popular being the exhaust, usually a washer or restrictor pipe in the exhaust neck, occasionally in the box itself, the washer and neck restriction can be overcome very easily, the washer in the box cant, an aftermarket pipe will usually resolve this.
the second method is to restrict the air fuel mix entering the engine, this can be achieved by a blanking plate on the carb inlet side, again a relitivlyt easy fix.
the third option is the electonic version, although used on some of the italian machines it usually a simple switch on / off variety, as the bikes are all usually from the same plant, they dont have to worry about country specifics unlike cars.
finally athough derestiction is possible, you open up a can of worms.
you will invalidate any warranty you have remaining on the bike.
you will invalidate any insurance you have on the bike.
You will have to have the bike replated as its rated output exceeds the registered power capacity.
And finally derestiction would require that the service intervals and lubricants used must be of the highest spec, no more tesco,s own 2 stroke oil, they do have a habit of being fragile once they are unleashed
On the other hand, if you take that nut out it may just sound like this...
Apparently there is some info on modified/derestricted mopeds + other useful stuff here:www.network54.com/Forum/26489/
The restrictor is probably the blind branch heading off into the top left. Its effect can be negated by taking a pair of mole grips and squeezing it flat where it comes off the main pipe. However, you seem to have another branch not doing anything, so I'm a little unsure of what's going on. Dunno what the bolt is. Place for an exhaust probe of some kind? Take it out and see what's behind it.
Pigeon said:
The restrictor is probably the blind branch heading off into the top left. Its effect can be negated by taking a pair of mole grips and squeezing it flat where it comes off the main pipe. However, you seem to have another branch not doing anything, so I'm a little unsure of what's going on. Dunno what the bolt is. Place for an exhaust probe of some kind? Take it out and see what's behind it.
Heres another pic so you can see the pipe structure:
The little pipe that goes into the silver thing, I havn't got a clue what the hell this does, or where it goes for that matter...
I might take it out tomorrow and see what happens. Could it harm anything if I take it out and ride my bike?
Ah, that makes it clearer... OK, now I can see stuff, the lower pipe with the flattened end is the restrictor and the top pipe that goes into the silver thing is the one I'm not sure about. The silver thing is in the area where I'd expect the carb to be, so perhaps it's exhaust gas recirculation? Or a fuel pump operated by exhaust pressure fluctuations?
Another possibility might be a lubricating oil injection system operated by exhaust pressure fluctuations, in which case you'd better not take it off...
Having said that, this exhaust on ebay has neither additional pipe on it, so perhaps it isn't critical, or perhaps there's some other thing in the exhaust kit that sorts it out.
Yes, you do get washers in there to literally restrict the flow, and there may be some of them as well, but the blank pipe on m1spw's exhaust is another kind of restrictor, that works by buggering up the exhaust pipe resonances.
Another possibility might be a lubricating oil injection system operated by exhaust pressure fluctuations, in which case you'd better not take it off...
Having said that, this exhaust on ebay has neither additional pipe on it, so perhaps it isn't critical, or perhaps there's some other thing in the exhaust kit that sorts it out.
numbnuts said:
The restricters are normally in the bit where the exhaust mates up to the barrel.
Yes, you do get washers in there to literally restrict the flow, and there may be some of them as well, but the blank pipe on m1spw's exhaust is another kind of restrictor, that works by buggering up the exhaust pipe resonances.
First stage of derestriction is a simple matter of removing the spacer on the variator, effectively limiting top speed through the gearing.
Unless you have a death wish and enjoy travelling in the gutter at snails pace ( slower still uphill into wind ) I would suggest removal was carried out ASAP.
This will not harm the engine in any way, in fact mostly the spacers are afterthoughts for countries with ridiculous legislation such as England.
A quality semi synthetic oil is a must for any decent 2 stroke mixed with Optimax or similar for engine life and performance.
Ignore the blank threaded into the exhaust, it is used in fuel injection models and for maintenance purposes.
Unless you have a death wish and enjoy travelling in the gutter at snails pace ( slower still uphill into wind ) I would suggest removal was carried out ASAP.
This will not harm the engine in any way, in fact mostly the spacers are afterthoughts for countries with ridiculous legislation such as England.
A quality semi synthetic oil is a must for any decent 2 stroke mixed with Optimax or similar for engine life and performance.
Ignore the blank threaded into the exhaust, it is used in fuel injection models and for maintenance purposes.
freddytin said:
First stage of derestriction is a simple matter of removing the spacer on the variator, effectively limiting top speed through the gearing.
Unless you have a death wish and enjoy travelling in the gutter at snails pace ( slower still uphill into wind ) I would suggest removal was carried out ASAP.
This will not harm the engine in any way, in fact mostly the spacers are afterthoughts for countries with ridiculous legislation such as England.
A quality semi synthetic oil is a must for any decent 2 stroke mixed with Optimax or similar for engine life and performance.
Ignore the blank threaded into the exhaust, it is used in fuel injection models and for maintenance purposes.
Firstly, I don't have a death wish but I have had the bike for over 3 months now and its still restricted. Mainly because I don't want to lose my licence if I'm caught and then have problems getting car insurance next year.
I always use Shell fully synthetic 2 stroke oil, but just use normal unleaded petrol - would using optimax give me better performance, or does it just preserve the engine life?
You seem to know a lot about this kind of thing - if I removed the little 'blank thread' would this act as removing part of the restrictor and so give the bike a higher top speed?
Removing the blank will make it slow and noisy.
The scooters seem to coke up less on Optimax giving better performance , even if you don't raise the compression ratio.
At the end of the day even with the scooter fully de restricted and running sweet no one is going to bother you if you are riding sensibly
The scooters seem to coke up less on Optimax giving better performance , even if you don't raise the compression ratio.
At the end of the day even with the scooter fully de restricted and running sweet no one is going to bother you if you are riding sensibly
I agree that cutting them off and welding plate over the holes is the preferable method. However, if you don't have a welder, a thorough job of squeezing closed, which includes folding the flattened bit over on itself, and is performed as close as possible to the main pipe, will not leak and will do nearly as well. What you're trying to do is get rid of the resonance of the closed stub, so as long as said stub isn't there any more you're OK.
20 years ago I had great fun de-restricting mopeds and even passed my full motorcycle test on a mental Honda MB5 - just derestrict it and re-register it as a standard motorcycle. Fun memories aside, even 20 years ago there were a number of restrictors in place to hold back the power and top speed. From memory though:
Cylinder Head
Piston
Barrel
Carb
Carb to Airbox Pipe
Reeds
Exhaust
Gear Sprockets
Having replaced all of that lot off the shelf from a friendly dealer in Holland I was able to hit the magic 60 mph and scream around like the young nutter I was. The fact that it wasn't a simple thing to do, even in those days, shows just how keen Honda were to comply with the law. I cannot imagine things have got much easier today but as manufacturers produced models for all of Europe, I guess it can't be too difficult to buy the proper bits you need from abroad?
Cheers,
Dave.
Cylinder Head
Piston
Barrel
Carb
Carb to Airbox Pipe
Reeds
Exhaust
Gear Sprockets
Having replaced all of that lot off the shelf from a friendly dealer in Holland I was able to hit the magic 60 mph and scream around like the young nutter I was. The fact that it wasn't a simple thing to do, even in those days, shows just how keen Honda were to comply with the law. I cannot imagine things have got much easier today but as manufacturers produced models for all of Europe, I guess it can't be too difficult to buy the proper bits you need from abroad?
Cheers,
Dave.
hey there.
I seriously need some help!
I have a HONDA X8R-S 50cc scooter and i really wish to know how to remove the washer in the variator which i believe is easy to do.
Can any1 get back to me as i am am very new to this and dont really have a clue. I have already done the CDI and exhaust, now just the variator,
regards
d.oldham
I seriously need some help!
I have a HONDA X8R-S 50cc scooter and i really wish to know how to remove the washer in the variator which i believe is easy to do.
Can any1 get back to me as i am am very new to this and dont really have a clue. I have already done the CDI and exhaust, now just the variator,
regards
d.oldham
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