hey guys, im eventually looking to get my 48cc bike up to 55 mph to make it capable of in-city highways, as I have a long way to go to achieve this im gonna tell u all what ive done so far and plan to do so u guys can tell me if I missed something, I have a 48cc silverjet with a ghetto air filter (4 layers of fabric softener sheet with steel mesh on both sides sandwiched to the carb with the black plastic insert), muffler cap removed, and a 32 tooth sprocket. I can cruise at 35 with bursts up to 45. I intend to add a serious expansion chamber, stuff my crank case, and grind the lip off my head to increase compression. I also intend to buy a HP ported cylinder and balance my crankshaft to increase my peak rpm. any ideas suggestions or criticisms are welcome except the old "that's to fast" stuff, I did the math and without air resistance being a factor with these mods my MB could potentially hit 80 but that's suicide without shocks
48cc power mods
- Thread starter C.A.H.
- Start date
You said any criticisms are welcome except the old "that's to fast"...
I'll say it differently then, maybe your motor should not go that fast. Ever have an engine blow compression on you while going 30mph+? How bout a back tire shredding on you or a bike rack breaking and getting wrapped around the tire? Or having the hub break and the back tire almost fall off? Or the motor chain break while in use?
All I am trying to say is that you should not go that fast because things often go wrong.
Do what you are going to do man, but make sure you be safe about it. Get better brakes, a stronger chain, better tires, double walled rims...
Finally, do you think going on inter-city highways is smart? In CA there are signs prohibiting motor-driven cycles on such road ways. People drive like asshats around me on my bike on normal roads; I can't imagine it being any better on a highway.
I'll say it differently then, maybe your motor should not go that fast. Ever have an engine blow compression on you while going 30mph+? How bout a back tire shredding on you or a bike rack breaking and getting wrapped around the tire? Or having the hub break and the back tire almost fall off? Or the motor chain break while in use?
All I am trying to say is that you should not go that fast because things often go wrong.
Do what you are going to do man, but make sure you be safe about it. Get better brakes, a stronger chain, better tires, double walled rims...
Finally, do you think going on inter-city highways is smart? In CA there are signs prohibiting motor-driven cycles on such road ways. People drive like asshats around me on my bike on normal roads; I can't imagine it being any better on a highway.
Ive only had minor issues as of yet and I only ride with full protective gear, im not afraid of failure at speed, mostly because ive blown a rear tire going 65 on my 4-wheeler and hit a tree bare-chested. not that fun. and also I live in a city that really doesn't mind MBers too much. I know going on the highways may not be a wise idea but I need a more fuel efficient method of getting across town, not to other citys, I find myself burning more gas on backroads and id like to have access to a more direct route (4 lane roads) and id also like to go the same speed as traffic (45-55ish). im thinking about jerry-rigging motorcycle wheels as the strength offered will dramatically improve my confidence in my bike. another point is that people tend to respect me more when my bike is loud as they can hear me for about a quarter mile or something like that, ive only broke 2 chains so far and my homemade tensioner seems to have fixed that issue. the only thing im really scared of failing is my forks as they are roughly 30 yrs old and are my frames only weak point. the compression mod is only an idea at this point but one I think will work. I use a #41 chain from a tractor store now that I learned #415 metric is weak and stretches too much, I don't know what to do about brakes yet as my bike only mounts the standard v-caliper type, any ideas?
What you need is a small motorcycle or a factory built moped to go those speeds, a bicycle will not hold up for long. If you can cruise at 35 that's pretty good.
my criticism is that you could have left out how you "ghettoed" up your bike to achieve your current top speed. (just tell us its basically stock) I dont think veterans on the forum are likely to believe in you. you need to take a very thorough approach towards reaching high speeds safely, not just your muffler cap off and putting dryer sheets on your carburetor. thats just making it louder.
However,the steps you intend to take will probably get you going faster and safer and more reliable.
However,the steps you intend to take will probably get you going faster and safer and more reliable.
the purpose of the air filter and exhaust cap removal is to minimalize air flow resistance and allow the engine to breathe better. ive also gapped my sparkplug and gave my bike some old 10-speed handlebars.ive tuned the fuel mix in my piece of s*** nt speed gen b carb I have spent nothing on my bike since I got it and im getting 35-45ish
the purpose of the fabric softener sheets is to give me something that protects better than the factory sponge thingy and has better airflow.
I removed my muffler cap because restriction decreases performance of the engine
restriction = slow, so loud by removal of restriction = faster (except for engine balance but I cant help that yet)
I removed my muffler cap because restriction decreases performance of the engine
restriction = slow, so loud by removal of restriction = faster (except for engine balance but I cant help that yet)
CAH - let me just start by saying I mean no offense by what I'm going to tell you. You seem to think you know a lot about the subject you are inquiring about so why are you asking questions on a forum full of VERY knowledgable and helpful people and then rejecting or disbelieving their answers? Yes, airflow in and out of an engine is a very important factor, but there is much more to it than that. If you really want learn what makes a 2-stroke engine tick read all of what Gordon Jennings had written.
As far as riding on a 4 lane highway, It's NOT a good idea. There's a term for someone willing to ride a MB in 55+MPH traffic - Darwinism. Your bike gets 130+MPG, fuel economy doesn't get much better than that. Just get a bigger gas tank & enjoy the back roads & live longer.
As far as riding on a 4 lane highway, It's NOT a good idea. There's a term for someone willing to ride a MB in 55+MPH traffic - Darwinism. Your bike gets 130+MPG, fuel economy doesn't get much better than that. Just get a bigger gas tank & enjoy the back roads & live longer.
There is no "bicycle" record speed class at Bonneville.
Your time frame of a decade sounds about right though. .....LOL
getting rid of the chain tensioner on the drive side will add signifigantly to your preformance, until you do that anything else is just fighting that.
I haven't yet got around to taking links outta my chain, so im using the kit tensioner reinforced with aluminum barstock held to the frame with u bolts, its a pretty free running setup with little resistance, doubt its the problem atm, but I know youre right I just gotta take out a couple links
if you can get it right, no chain tensioner is best, but you can always move it to the pedal side. My setup had no issues before, it was spot-on and seemed like very little resistiance, but removing it made a very large difference on preformance on my 48cc. better acell, better topend, better starting, all around better. Single handed the best 'preformance mod"
i woder how many cc this is
http://digg.com/video/man-goes-207-mph-on-rocket-powered-bicycle?utm_source=digg&utm_medium=email
http://digg.com/video/man-goes-207-mph-on-rocket-powered-bicycle?utm_source=digg&utm_medium=email
If you wanna go fast you'll need to do 2 things. Mod the engine yourself and replace all those stock parts. They don't hold up...get a better carb. I live in southwest Ohio where some of the Olympic cyclists train and live. There bikes brake down all the time from there crazy ass rides. If there's brake down then what's stopping that 30 year old fork from impaling you? Or worse you get run over from behind. I wanna go just as fast as you man but for me to do that I need to be able to balence my crank and everything. Also a jack shaft kit from sick bike parts helps...but remember...a regular bicycle isnt ment to replace a motorcycle. Its a hobby engine at best. Now as for the rocket bike...it sat next to that race car and it was gone. I'd hate to be the guy in the car XD