Bicycle Motor Works Exhaust

Look for a local scooter store. Tons of two stroke chinese pocket bike pipes out there for much cheaper. I paid ten bucks apiece for the last four I built...
You're going to have to cut and weld any pipe you get anyway, find one that fits your bike like you want.

The chamber is a bit small. I like a fatter chamber for better torque

please post info and pictures of your build. it would make it easier to make recommendations.

djpass7 said:

It is a stock set up with a RT Carb and long offset intake manifold. I have it running rich right now for break in. It does 21 top speed, due to the richness of my air fuel mix. I will post pics tonight when I get home.

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Hi you say it has a stock set up, but what motor are you using?

Hi I just read through the owners manual of your 2 stroke manual, during the run in period ( break in ) you should not go more than 20 KP h or 14.43 miles an hour.
Also your bike should not be running rich it should just have a higher oil to gas ratio.
this motor should not be operated more than 1/2 hour at a time and it will need to cool off completely before using it again during this break in period that last 500 Kilometers which is around 310 miles give or take.
We can help you make your motor perform better and perhaps run faster but if you continue running the way it seems you are you will need more than add on performance parts you will need to replace the engine prematurely.
there are other helpful routine maintenance procedures in the manual that if you haven't read I suggest you do so right away.
these little motors are very inexpensive but labor intensive and costly in terms of your time to go through a correct break in period but without investing your time correctly the first time you are doomed to repeat it.

If I was you I would read the manual again and check and recheck every single serviceable part on the motor to check for damage. if none is found continue with the break in procedure. if the motor shows signs of excessive wear to the cylinder walls you may consider buying another kit and using the old motor for spare parts.
It would suck to suffer through a break in period on a motor that is already on its way out due to improper operation during this period.

I wont say your alone on this as I bet that many people here have done the same thing with their motors some get lucky others don't then blame the cheap kit. I cannot say for sure that you have damaged the motor however from your post that I have read it deserves an inspection.
the manual has very specific instructions for routine maintenance if followed properly from day one there is still no guarantee that everything will go as planned but you have a better chance if after the break in period is over and you followed the manual to the letter you will have a better performing motor.
one that is worth the effort and cost adding aftermarket performance parts.
At this point I don't see any reason to buy performance parts as a proper running motor may perform well beyond your expectations once you get through the break in period.
once your past the break in period and your bike is tuned properly and still need more power and more speed you have many options higher compression head with larger cooling fins, the intake it seems you have addressed already however the new manifold may require porting and polishing to make it flow better. a chambered exhaust system will help with scavenging effect most importantly your motor must be tuned and the maintenance done on a regular basis. if you neglect the air filter for example which the manual claims should be cleaned every 5 to 20 hours which is very frequently any performance upgrades wouldn't work as designed.
So I would have a stock of filters so I can clean one and have 2 or 3 more ready to be used. as they are easy to clean but also easy to neglect.

I think the exhaust you have picked out will work fine for your engine the expansion chamber is small but I think effective for a 2 stroke motor even with the porting work your planning on.

if your really wanting a reliable well tuned 2 stroke motor check this company out as they have many coating options to maximize the efficiency of your engine and chambered exhaust system.
http://www.dprracing.com/scec.html#2strokepiston

I am still in the planning stage of my build but what ever gas motor I decide to use will be disassembled and the parts that this company can coat I will have done. it may be expensive compared to the price of the entire kit but I think the effort anyone has to put in to these tiny motors getting through the break in period is worth it with less problems and a better performing engine in the end.

djpass7 said:

Thank you for all of your consideration and I assure you that I am breaking it in properly, I run it at about 12-15 mph for less than 30 minutes every time I ride it. I use opti2 oil mixed at about 75:1 and the engine is still gaining power with about 120 miles on. I rarely test the top speed about every 50 miles and I strictly follow all of the maintenance routine in my manual. I am NOT going to do anything to the motor until it is completely broken in, I am only planning ahead. The only reason I changed out the carburetor is because the stock NT was terrible and leaking. The intake is because the RT carb was to too big to fit on the stock manifold

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Again I suggest to check over the manual as your running what seems to be a incorrect mixture. for break in period the manual suggest 16:1 and 20 :1 after the break in period
I see your using what looks like a quality 2 stroke lube but I wouldn't go that route until the break in period is done.
Also the manual clearly states that to never exceed the 20 KPH until the break in period is completed. Your motor does not care if you do it only once in a while as that is too much.
But this is your motor, your bike do with it as you please. same with my advice
do with it as you please. just know each thing that you have changed from the factory specs has an effect and not always a positive effect from the over sized carb and fuel oil mixture to every once in awhile running it a wide open throttle only to find out your top speed is way off from where it should be.

if the stock carb leaks fix it or replace it with the same size carb you simply cannot change one part of an internal combustion engine without effecting the performance and reliability of the rest of the motor. Defiantly leave the experimenting to be done after the motor is broken in or go all in with a known and proven performance upgrade kit from the start. the kit should get you more air and fuel mixture in your higher compression motor and the properly designed exhaust should help get more of the spent fuel and air mixture out all while helping pulling more air and fuel into the motor at the same time.
Anyway you look at it if your bike is running too rich it is creating too much carbon build up in the combustion chamber with the potential to wash the grit from the carbon and damage the rings pistons and cylinder. if you don't believe me pull the head or put a scope down the plug hole and look for yourself.

nelsonk1969 said:

Again I suggest to check over the manual as your running what seems to be a incorrect mixture. for break in period the manual suggest 16:1 and 20 :1 after the break in period
I see your using what looks like a quality 2 stroke lube but I wouldn't go that route until the break in period is done.
Also the manual clearly states that to never exceed the 20 KPH until the break in period is completed. Your motor does not care if you do it only once in a while as that is too much.
But this is your motor, your bike do with it as you please. same with my advice...

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It's long been generally accepted the "manual" isn't even remotely accurate, the theory is the 16:1 mix ratio is a holdover from it's 1940's Russian predecessor, where & when actual two-stroke oils were difficult or impossible to obtain & most likely substituted with whatever lubricant they might have had handy, motor oil, lamp oil - heck coulda been donkey ear wax given the recommended ratio lol... never exceeding 20 kph/12.4mph during this time is equally as excessively unnecessary.

Most folks go with whatever a quality two stroke oil's manufacturer recommends for their product (usually 32:1 for non-synth) & even the most conservative say the speeds aren't important, but to avoid any sustained high RPM range until break-in is complete, varying the RPM/speed is the usual procedure...

...however, I'm of the "ride it like ya stole it" camp from the get-go, running 100:1 Amsoil synthetic. While I don't recommend this to everyone, none of my two smokers have ever had an issue with this, so even a 32:1 non-synthetic for break-in is obv jus' peachy lol

BarelyAWake said:

It's long been generally accepted the "manual" isn't even remotely accurate, the theory is the 16:1 mix ratio is a holdover from it's 1940's Russian predecessor, where & when actual two-stroke oils were difficult or impossible to obtain & most likely substituted with whatever lubricant they might have had handy, motor oil, lamp oil - heck coulda been donkey ear wax given the recommended ratio lol... never exceeding 20 kph/12.4mph during this time is equally as excessively unnecessary.

Most folks go with whatever a quality two stroke oil's manufacturer recommends for their product (usually 32:1 for non-synth) & even the most conservative say the speeds aren't important, but to avoid any sustained high RPM range until break-in is complete, varying the RPM/speed is the usual procedure...

...however, I'm of the "ride it like ya stole it" camp from the get-go, running 100:1 Amsoil synthetic. While I don't recommend this to everyone, none of my two smokers have ever had an issue with this, so even a 32:1 non-synthetic for break-in is obv jus' peachy lol

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Not to be argumentative but when a 2 stroke motor or any motor is not properly broken in and in its early life is showing signs that it is not functioning properly it is safe to say something went wrong.

I have rebuilt many engines in my professional career as a mechanic, and I have followed many procedures for break in all of which were in the manual that you choose to blow your nose with. I have heard it all from lazy uncaring untrained people that what I was doing was excessive, anal ,unnecessary .yet not one of the motors that I rebuilt ever had a single problem and each time the customer got his vehicle back they all claimed that it ran better than new.
from my view point it is easy to see why people like you turn away from the manual and justify this by spouting off random stuff that comes to your mind because your just another one of those lazy people that look at the work that is needed to do the job right and decides those instructions must be wrong because it is too hard to comply with.
I will be the first to admit I have found many things printed in a factory service manual is plain wrong, when I came across this working for Mitsubishi for example I would contact the factory show them their error and once their engineers saw the mistake for themselves they would issue a service bulletin correcting the mistake.
The same thing can be done with any service manual if your caring enough to do so.
I am guessing since your on this forum and riding a gas powered bike, it is probably safe to say that you are not a successful mechanical engineer that has more money than time. I know I am not ,this is why I embrace a factory service manual and printed instructions. if the manual is wrong prove it and better yet do something about it.

I can tell you the last advice the original poster needs it to drive it like he stole it.
Most people on this forum are nice and helpful to each other which is all I am trying to be. again I am no expert I just have many years under my belt as a successful well trained mechanic.

djpass7 said:

It has been proven over and over that running more oil than 24:1 actually damages these little motors, so obviously you have little to no experience with these China girl engines.

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Or perhaps it has been proven over and over many people that use the cheapest kit they can find and bolt it on to the cheapest bike they can find
simply to get back and fourth to work cannot afford to do a proper break in
with the proper ratio oil as it would take too long to make the trip to work.
once they find out that this little motor cannot take the abuse that it was not designed for they look for a band aid by adjusting the fuel oil ratio.

its funny people get bent out of shape at the mere mention that what they are doing may be wrong.
If you haven't figured it out by now that this China Girl motor is not intended to be run at wide open throttle all the time.
the manual that I refer to often, is meant for those of us that use the motor as intended. not trying to blast down the road to get to work on time.

if you need to drive this way of course the ratio will need to be changed to try and accommodate operating the motor in a way it was not designed for.

I guess I am barking up the wrong tree as it seems that the majority of people on this forum or at least the ones that I have interacted with have unreasonable expectations of these cheap motors.

you have to remember one thing these motors are being bolted on to a bicycle
which should assist the operator in getting to its destination.
but most people here seem to think just because their bike has a motor that it is a motorcycle that it can and should be driven at its highest rpm with no assist from the rider at all.

if you have that mentality hey that's fine the motors are cheap keep replacing them over and over while your pushing the bicycle to its limits and beyond.

my comments are not meant for those of you that choose to ride your bicycle in a way that it wasn't intended.

if you ride as fast as you can every where you go disrespecting traffic laws EPA and noise regulations you must be prepared to pay the consequences
this of course means blowing your nose with the service manual as it clearly doesn't apply you.

I bet this guy thinks he is riding his bike in a legal safe manor that the motor and bike was intended for. the speeds that he is going shows me that this should be registered as a moped and not to be driven in the bicycle lane.
if you ride your bike like this or push it even harder of course you cannot follow the manual
specifications.
http://www.bing.com/videos/search?q...&mid=D3FB582BCDBFF408ED33D3FB582BCDBFF408ED33

nelsonk1969 said:

Not to be argumentative but when a 2 stroke motor or any motor is not properly broken in and in its early life is showing signs that it is not functioning properly it is safe to say something went wrong.

I have rebuilt many engines in my professional career as a mechanic, and I have followed many procedures for break in all of which were in the manual that you choose to blow your nose with. I have heard it all from lazy uncaring untrained people that what I was doing was excessive, anal ,unnecessary .yet not one of the motors that I rebuilt ever had a single problem and each time the customer got his vehicle back they all claimed that it ran better than new.
from my view point it is easy to see why people like you turn away from the manual and justify this by spouting off random stuff that comes to your mind because your just another one of those lazy people that look at the work that is needed to do the job right and decides those instructions must be wrong because it is too hard to comply with.
I will be the first to admit I have found many things printed in a factory service manual is plain wrong, when I came across this working for Mitsubishi for example I would contact the factory show them their error and once their engineers saw the mistake for themselves they would issue a service bulletin correcting the mistake.
The same thing can be done with any service manual if your caring enough to do so.
I am guessing since your on this forum and riding a gas powered bike, it is probably safe to say that you are not a successful mechanical engineer that has more money than time. I know I am not ,this is why I embrace a factory service manual and printed instructions. if the manual is wrong prove it and better yet do something about it.

I can tell you the last advice the original poster needs it to drive it like he stole it.
Most people on this forum are nice and helpful to each other which is all I am trying to be. again I am no expert I just have many years under my belt as a successful well trained mechanic.

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You've made some ...interesting assumptions.

Suffice to say I would suggest that the "manual" included with these two stroke kits is not comparable to Mitsubishi, that indeed doing your own research, evaluating the actual findings of all the hundreds if not thousands of others that have had more relevant, direct experience to ascertain the more practical procedures they've developed then what is included with what is to be blunt - a poorly manufactured & supported product in every way... well, I'd say learning in full everything that's been offered by others & then utilizing it to complement your own hands-on experiences is hardly the act of "lazy uncaring untrained" people.

I would also caution that this forum is populated primarily by the experimenter, the bold DIYer, the ones that tend to scribble outside the lines to see what can be done rather then just what "should" be done, such as bolting a motor to a bicycle in the first place.

I would heartily recommend perusing the forum before making such assurances, it may also assist you when and if you decide to get a gas kit of your own - but should you choose do do so, bear in mind not all "expertise" is relevant, not all offerings are what they seem, that the following should be kept in mind when reading any advice offered, no matter by whom or the well-seeming intention;

Advice about advice

If you then cannot see the fallacy of the so-called instructions included with these motor kits in particular, if you're still more comfortable following without question what so many others have found to be questionable, that's fine. It's your bike, your motor & your mind to make up as you will...

...but do not resort to insult when alternatives are suggested, this forum is for the friendly exchange of information & sharing what we've created, the intent a civil exchange of views for the betterment of all as outlined here: the rules.

djpass7 said:

How do you like the amsoil? I was thinking I might try the saber pro later on, have you tried opti2 at all?

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I haven't tried the opti as they don't sell it 'round these parts, but here's a thread on primarily opti if you're interested: http://motorbicycling.com/showthread.php?t=9850&page=113

I've no cause for complaint with Amsoil... but I should mention I don't use if for any other reason then I needn't bother to buy as much, it's really the ratio rather then any supposed benefit - so w/that in mind it's again what ratio a quality oil manufacturer recommends for their product & not so much anything else.

If you like the opti, I'd keep runnin' it

BarelyAWake said:

You've made some ...interesting assumptions.

Suffice to say I would suggest that the "manual" included with these two stroke kits is not comparable to Mitsubishi, that indeed doing your own research, evaluating the actual findings of all the hundreds if not thousands of others that have had more relevant, direct experience to ascertain the more practical procedures they've developed then what is included with what is to be blunt - a poorly manufactured & supported product in every way... well, I'd say learning in full everything that's been offered by others & then utilizing it to complement your own hands-on experiences is hardly the act of "lazy uncaring untrained" people.

I would also caution that this forum is populated primarily by the experimenter, the bold DIYer, the ones that tend to scribble outside the lines to see what can be done rather then just what "should" be done, such as bolting a motor to a bicycle in the first place.

I would heartily recommend perusing the forum before making such assurances, it may also assist you when and if you decide to get a gas kit of your own - but should you choose do do so, bear in mind not all "expertise" is relevant, not all offerings are what they seem, that the following should be kept in mind when reading any advice offered, no matter by whom or the well-seeming intention;

Advice about advice

If you then cannot see the fallacy of the so-called instructions included with these motor kits in particular, if you're still more comfortable following without question what so many others have found to be questionable, that's fine. It's your bike, your motor & your mind to make up as you will...

...but do not resort to insult when alternatives are suggested, this forum is for the friendly exchange of information & sharing what we've created, the intent a civil exchange of views for the betterment of all as outlined here: the rules.

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I tell you what you people in this forum are trivial and argumentative.

Clearly you and nearly everyone I have interacted with so far are mechanical geniuses and don't need my input.

I will be happy to leave this forum as I don't have the patients to deal with this petty behavior.