thats on the flats !!!!!!!!!!!!!!! no down hill it's registered on my speed --o it's a fact
cheap 66cc engine mods
- Thread starter bradentonmotorbikes
- Start date
I bog down with a 36 tooth sprocket on some of the biggest hills in southern Indiana (home of the Hilly 100) right up at the top- I'm talking a mile long and very steep, and I'm pushing 200 lbs-
But now I'm in Florida where it's flat- so I'm keeping the 36 on as planned.
With the smooth narrow tires 27x1.25 front and 26x1.75 back, I must be topping 30 fairly easily- I don't open it up much, because I don't want either breakdowns or risk falling at that speed.
One day I might try to get a short speed reading on some flat...
But now I'm in Florida where it's flat- so I'm keeping the 36 on as planned.
With the smooth narrow tires 27x1.25 front and 26x1.75 back, I must be topping 30 fairly easily- I don't open it up much, because I don't want either breakdowns or risk falling at that speed.
One day I might try to get a short speed reading on some flat...
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I run a 35t on one bike with some mod work done and a fancy pipe and yet have I reached above 42mph! I use to run a 36t and still couldnt get 42mph! on my new build Iam gonna run a 39t to see if I can get some more RPM's for the top end. but 46mph with a 36t on flat ground! Iam a non believer on that one!
I am sure the accuracy of the speedo comes into play here....
I once thought I got up to 45mph, but when I used an accurate speedo (GPS) I was given a reality check, big time. It was ten mph less than I previously thought.
I once thought I got up to 45mph, but when I used an accurate speedo (GPS) I was given a reality check, big time. It was ten mph less than I previously thought.
So would you consider Spookytooth's guarantee of speed increase to be false advertising?:
36 Tooth Speed Sprocket for Motorized Bicycles
A 10mph increase sounds very tempting for $25!
Bumpitty!
So chances are if I go to 36T then my bike will have a harder time climbing hills and I won't really get an 8-10mph increase?
So chances are if I go to 36T then my bike will have a harder time climbing hills and I won't really get an 8-10mph increase?
I'm always amazed that with a hobby based on bicycles how often the fairly basic concept of gearing is misunderstood - given the assumption that at some point, someone might have actually pedaled while using gears 
Picture trying to pedal from a dead stop up to 30mph using just first, then picture trying to pedal up to 30 from a dead stop using only your highest gear.
ANY single gear being a compromise between those two examples, bear in mind NO gear will provide any "extra" power - reduction in sprocket sizes only helpful for top speed if you're redlining anyway. While I wouldn't say Spooky's claim to be "false" advertising, there's simply way too many variables to give a concrete example. Weight, drag, environment, engine output (stock/modded), rim size, the list goes on....
The short story? Even if you've a shift kit - gearing is a fine-tuning experiment to get your engine in an RPM range you're comfortable with, relevant only to your bike, dependent on your performance specifics. Speed gains stem from the more involved engine performance, sprockets merely utilize that.
While you may see a increase in top speed by reducing sprocket size - you will pay the price in acceleration, there's no "free ride"
Picture trying to pedal from a dead stop up to 30mph using just first, then picture trying to pedal up to 30 from a dead stop using only your highest gear.
ANY single gear being a compromise between those two examples, bear in mind NO gear will provide any "extra" power - reduction in sprocket sizes only helpful for top speed if you're redlining anyway. While I wouldn't say Spooky's claim to be "false" advertising, there's simply way too many variables to give a concrete example. Weight, drag, environment, engine output (stock/modded), rim size, the list goes on....
The short story? Even if you've a shift kit - gearing is a fine-tuning experiment to get your engine in an RPM range you're comfortable with, relevant only to your bike, dependent on your performance specifics. Speed gains stem from the more involved engine performance, sprockets merely utilize that.
While you may see a increase in top speed by reducing sprocket size - you will pay the price in acceleration, there's no "free ride"
X2.......There`s always a give and take in that situation.....I learned that in motorcycle drag racing.....You can either be fast off the line and maybe run out of gear on the top or slow off the line and have some killer topend mph....I'm always amazed that with a hobby based on bicycles how often the fairly basic concept of gearing is misunderstood - given the assumption that at some point, someone might have actually pedaled while using gears
Picture trying to pedal from a dead stop up to 30mph using just first, then picture trying to pedal up to 30 from a dead stop using only your highest gear.
ANY single gear being a compromise between those two examples, bear in mind NO gear will provide any "extra" power - reduction in sprocket sizes only helpful for top speed if you're redlining anyway. While I wouldn't say Spooky's claim to be "false" advertising, there's simply way too many variables to give a concrete example. Weight, drag, environment, engine output (stock/modded), rim size, the list goes on....
The short story? Even if you've a shift kit - gearing is a fine-tuning experiment to get your engine in an RPM range you're comfortable with, relevant only to your bike, dependent on your performance specifics. Speed gains stem from the more involved engine performance, sprockets merely utilize that.
While you may see a increase in top speed by reducing sprocket size - you will pay the price in acceleration, there's no "free ride"
Thanks BarelyAwake. I understand gears and ratios and such and have been riding geared mountain bikes since I was just a wee sprout. I just am not familiar with what the exact number of teeth on the sprocket should be. I'll keep it at 44T for now.
You can always get better acceleration with 36T by using NOS right off the starting block. I know how much you old timers approve of NOS lol
You can always get better acceleration with 36T by using NOS right off the starting block. I know how much you old timers approve of NOS lol
I just went from a 44t down to a 41t and it is a noticeable change.....
I just have to peddle a little more before letting out the clutch lever.....
I just have to peddle a little more before letting out the clutch lever.....
40 tooth does me very well. Great for cruising around at 25 or maxing top speed of 35...
however going slow is terrible (15mph an under)
however going slow is terrible (15mph an under)
I'm new to this hobby but I've played with hp 2 strokes for a few years and while I don't claim to to be any kind of guru I do know some solid basics as fact and Bairdco is right with this post. I want to add to it though. First and foremost the Cycle must be sound, good lubed bearings, trued wheels and everything lined up. You can't possibly go fast if you have a bearing dragging or a sticky brake. DO NOT UNDERESTIMATE HOW MUCH FRICTION KILLS PERFORMANCE! Everyone goes straight for the motor but any good racer will tell you that horsepower won't do anything for you if it can't get it to the ground.porting helps a lot. on the intake, dremel out as much as you can to match the intake port on the engine. be careful not to go overboard. the engine port is bigger than the welds on the intake. while you're grinding away, get up inside of the intake manifold and smooth out the casting burrs.
the exhaust can get the same treatment, but again, there's not enough material to match the port exactly, so just do as much as you can.
pay attention to your spark plug's color till you get that dialed in.
make sure your bike's tuned up. good tires, straight wheels, no loose parts, greased bearings, etc. will help. the less rolling resistance that motor has to push, the faster it'll go.
as far as sprockets go, it depends on your weight and where you ride.
i'm 135 and i've got a 32 sprocket. works great on the flats, but bogs on steep hills. i can get an average of 37mph.
i had a 36 which worked great overall, and it averaged about 34.
nos and boost bottles are just gimmicks, don't waste your money. buy a tuned pipe instead. (haven't tried one myself, but everyone else swears by them.)
whenever you're adding a part, tuning something up, or modifying something, do it one piece at a time. that way you'll know what actually works for you and what doesn't. it'll also help you find problems. if you do ten mods at once and your bike stops running, you've got ten times the problems to figure out why.
despite what people say, don't expect much over 35mph, unless you're willing to spend money and tons of time fine tuning it. everyone likes to believe they're getting more out of their cheap little engine than they really are. (including me
Next, the motor must be in a good state of tune and repair. From what I've read you pretty much have to replace or rebuild everything on the motor. Lets keep it cheap and real by doing the simple stuff that seems reasonable.Replace the hardware with good stuff, it sucks trying to get a broken steel fastener out of aluminum and loc-tite the new stuff. Replace the spark plug, plug wire and cap with quality stuff. Use a quality premium fuel and oil, I like spectro oil and from my experience 40:1 is plenty of oil. Make sure all of your gaskets do not block the passages. Clean up the intake and exhaust like Bairdco said by making sure everything matches up but I wouldn't expand your ports unless you at least do some research but fair warning it gets incredibly complex. In short porting is a waste of time unless you can do something with the exhaust and intake. McDizzy's two stroke forum is a great place to learn. Spend the $15 for the joining fee and be blown away by all the information, it's a good thing but it will be too overwhelming to someone just starting out.
A boost bottle will not make power ever, It isn't designed too. They store an air/fuel charge to help eliminate bog when getting on the throttle like when coming out of corners or shifting gears. Some snowmobile manufacturers still do use them to this day. I don't know for sure but I don't think they even work at all on a small cc motor.
A properly designed expansion chamber is one of the most important parts of a two stroke motor in making power. It works like a supercharger by pulling the fuel charge through the motor and then by means of sound waves pushes a fuel charge that would have normally been pushed out the exhaust back into the combustion chamber under force to be re burned by the next power stroke. The pipe works on sonic waves(speed of sound) that is why you can alter the power characteristics by lengthening or shortening the head pipe. Prior to the invent of tuned pipes racers would use megaphone pipes which helped scavenge some of this charge. For optimum effect the pipe must be designed to the port timing, displacement and running rpm of the motor. Each part of the pipe and total length has a role in the character of the pipe. Just about any tuned pipe is better than the factory pipe so that would be a safe buy.
A properly sized and jetted carburetor is really important. I don't see anyone offering Mikuni carbs for some reason. If you built everything else text book it wouldn't be worth anything without a good tunable carb.You will have to increase the amount of fuel on the main jet if you made any real motor improvements or it will burn down.A truly tunable carb allow specific fuel metering at different throttle positions for good throttle response.On the stocker put a little gasket sealer on the outside of the intake tube then slide the carb on, this will seal off unwanted air leaks.
A motor is just an air pump, the more air it pumps the more power you get. If you hog out the ports and don't do anything before or after the cylinder you will likely hurt performance. The same goes for improving the intake or exhaust unless that area was already lacking. These motors are seriously lacking everything so I would dare say most of the performance products offered will improve your performance some what. You can do more to make them even better but it's a package deal. Your not going to buy one product and have a screamer. They all work together in proportion, don't go hog wild on one thing and ignore the rest. It all works together.
As far as some people getting better speed than others it's no surprise. The quality control on these motors is horrific, some are bound to go better than others. Not to mention the infinite other variables like types of bikes and components, tire size and design, rider weight and probably the most deceptive of all thing the speedometer. There's no way you can put much stock in what a bicycle speedo says. I hope this helps shed some light on the subject
15mph and under...terrible with a 40T?
This is caused by one of three problems...you weigh 500lbs...you have a P.O.S. engine...you have fouled-up your engine and it is so out of tune that even the Chinese would laugh at it...
Jim
Yeah I saw that and thought the same thing. How is it terrible at anything under 15mph?! I for one find going 7mph the cut off on where it starts to get horrible on the stock 44t. I doubt the loss of 4 teeth double that speed.15mph and under...terrible with a 40T?
This is caused by one of three problems...you weigh 500lbs...you have a P.O.S. engine...you have fouled-up your engine and it is so out of tune that even the Chinese would laugh at it...
Jim
Yer right ruppster & ya know... I had the thought that a sprocket swap isn't really a "cheap engine mod" anyway lol
http://motorbicycling.com/f13/basic-porting-time-fer-teh-lolz-16646.html
and it only costs some dremel time FTW
http://motorbicycling.com/f13/basic-porting-time-fer-teh-lolz-16646.html
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Nah I'm 205, and got a beach cruiser, and for me its real jerky around 13mph an under, comfortable cruising is at 25+ for me
ok all these statements about hitting 39mph and up need some proof please!
i had my 32 tooth sprocket on a road bike 700cc slick tires stock everything and hit maybe 34 or 35mph tops maybe 37 downhill and pedalling my ass off but i think either alot of you guys have your speedometers set wrong, or whoever was following you in a car lied to make you feel better. especially running 44t sprockets. cmon.
i had my 32 tooth sprocket on a road bike 700cc slick tires stock everything and hit maybe 34 or 35mph tops maybe 37 downhill and pedalling my ass off but i think either alot of you guys have your speedometers set wrong, or whoever was following you in a car lied to make you feel better. especially running 44t sprockets. cmon.