will my bike cruise at 40 mph????

[jtgolden]

I know some are going to highly dislike this question but..... I am buying the 66cc engine from piston bikes, the jet race engine, I plan to get the ngk iridium spark plug and change the plug wire. It apparently has the new and improved cns high performance carb on it as well, but i am prepared to do a lot of adjustments on it to be sure it is perfect thanks to BIKNUT!!!!!!!! My dad is a machinist and has years of involvment with dirt bikes so he has planned to help build a new exhaust for the kit as well. If anyone has any custom exhaust "blue prints" that they would like to share that would be great. This is my first build and I hope to use this for commuting, which is why I need the highest cruising speed possible. O and I will be using a 44 tooth sproket attached to manic mechanic rear hub adapter!!!

Thanks for all help!

 

[moonshiner]

i think you need about a 36 tooth sprocket to get 40 mph..

 

[DuctTapedGoat]

After you get the CNS dialed in and the expansion chamber installed, you can do 40, if not close.

Since your dad knows dirtbikes, ask him to teach you to polish, match and port the top end.

 

[The_Aleman]

Cruising at 40MPH with a 44T sprocket (assuming you have a 26" wheel) is wishful thinking. That's over 9000RPM. The motor isn't going to live long at that RPM, if it will live at all.

With a 36T, you're looking at over 7500RPM for 40MPH. That's much more feasible, but I still wouldn't consider that a cruise RPM. Maybe a short blast here and there. You might be better off with a shift kit.

 

[Pilotgeek]

My 40 tooth cruises at about 26. I think you'd need a 36 tooth, or preferably a shift kit.

 

[DuctTapedGoat]

My 48cc hit 34.7 on a 44T, I was pushing near 40 when I blew a seal.

A 66cc will be able to do that just as easily.

 

[Pilotgeek]

Wow, will it? I thought the 66 was too unbalanced to get to those rpms. Well, at least mine seems to not like the higher rpms.

 

[DuctTapedGoat]

I never had a speedo on my 66cc, and people say it doesn't like to hit the top rpm, but I could just about keep up with traffic on 40mph speed limit roads (tough to judge with speeders).

 

[The_Aleman]

My 48cc hit 34.7 on a 44T, I was pushing near 40 when I blew a seal.

A 66cc will be able to do that just as easily.

Over 9000, no suprise you blew something. And the smaller chinas tend to rev better than the 66s. Don't tell people here they can do 40 with a stock sprocket and a 66 easily, unless you want to take responsibility for blown motors.

Wow, will it? I thought the 66 was too unbalanced to get to those rpms. Well, at least mine seems to not like the higher rpms.

Many of the 66s don't like the higher RPMs at all. Some are more balanced than others. I blew up my first one just trying to hit 30 with a stock sprocket. That was over 6000RPM, which some sites used to say is redline. Motors tend to live longer if you don't overrev them.

I never had a speedo on my 66cc, and people say it doesn't like to hit the top rpm, but I could just about keep up with traffic on 40mph speed limit roads (tough to judge with speeders).

Keywords: no speedometer. Many times, traffic slows down to pace a fast-moving MaBer because they're amazed it can go that fast. I wouldn't put any stock in cruising 40MPH with a stock sprocket, because the engine is not going to live long at that RPM. Go ahead and try to prove me wrong, it's your engine. Hope you got a spare.

 

[DaveC]

About the only way to have any longevity in a 40 MPH bike is to go Morini and the S6T 5.4 HP motor. They will spin up over 9000 RPM(OVER 9000!!!) and hold together unlike the Chinee stuff. By the time you pump enough money and time into a Chinee motor you might as well have bought a Morini(a hard lesson to learn as I found out).

There is sooo much weak about the HT motors that if you don't really go into a rebuild then there's no sense in doing it. You can do a bunch of top end mods and have a chump bearing go to powder and seize up the bottom end.

Besides, most states have a 30 MPH limit on mopeds and motorized bikes. Getting a Chinee motor to live at 30 MPH is enough of an accomplishment

 

[Greg58]

Most that say they want to cruise at 40 learn real quick that you can't see with your eyeball's vibrating, 25 to 26 is a good ride!

 

[Pilotgeek]

With no speedometer, I do have trouble believing your claims or near 40. I had a cheap speedometer on my bike for some time, and I would cruise at what I thought was 25ish. Turns out I had it miscalibrated and I was only cruising at about 22. It certainly /felt/ faster than that.

 

[rustycase]

IIRC, "cruising speed" is defined as somewhere around 75% max engine speed, and also infers long distance, or time periods. Basically, running at reduced engine power for the purpose of longevity and economy.

IMO, there is NOTHING in the china girl class of engines capable of such a goal.

Near as I can tell, what you are looking for, in our Fun Zone, is the HF 6.5 Greyhound 4 cycle engine. Best advice at this time is that will fill the bill.

IMO, (again ! ), that kind of speed would be less than 'safe' on a 'bicycle'.

Good luck to you!
rc

 

[Tohri]

Like the rest of the guys here: Possible, but improbable. Your whole machine needs to be set for it, not just the motor. Good brakes are a must, good tires, at least a front suspension, and then make sure you replace just about every component of the engine kit with high quality parts.

 

[KCvale]

IIRC, "cruising speed" is defined as somewhere around 75% max engine speed, and also infers long distance, or time periods. Basically, running at reduced engine power for the purpose of longevity and economy.

I couldn't agree more rusty, and with a stock drive cruising with a 48cc is ~28MPH and ~32MPH with a 66cc in my experience on 26" wheels.

If you want to cruise 40+MPH Jackshaft it.

Gears change everything. This is my personal ride and I cruise along with 40MPH traffic comfortably sitting up on it @~5500RPM.

66cc Skyhawk and SBP Jackshafted NuVinci 170 hub with Disc Brake.
SBP Expansion Chamber with my own custom glass pack muffler and high performance electrical system.

This is really not for the beginners first build however.
Chances are you'll have your motor in and out multiple times and that is not easy once you attach the jackshaft to the motor.

Once you get your MB feet wet though, that's what you want to look at for a new world of riding flexibility ;-}

 

[Mike B]

Nice exhaust!

 

[Cabinfever1977]

i think cruising at 20 is better, just leave early.

 

[Pilotgeek]

I feel right cruising at like 25. That's where it just starts to feel fast for me.

 

[Drewd]

I max out at 25mph with a shifter kit but I'm geared for all torque and hill climbing... I can even tow 250 lbs easily

 

[benutne]

I couldn't agree more rusty, and with a stock drive cruising with a 48cc is ~28MPH and ~32MPH with a 66cc in my experience on 26" wheels.

If you want to cruise 40+MPH Jackshaft it.

Gears change everything. This is my personal ride and I cruise along with 40MPH traffic comfortably sitting up on it @~5500RPM.

66cc Skyhawk and SBP Jackshafted NuVinci 170 hub with Disc Brake.
SBP Expansion Chamber with my own custom glass pack muffler and high performance electrical system.

This is really not for the beginners first build however.
Chances are you'll have your motor in and out multiple times and that is not easy once you attach the jackshaft to the motor.

Once you get your MB feet wet though, that's what you want to look at for a new world of riding flexibility ;-}

How do you like the NuVinci? I can't even begin to think about spending that much money on my bike right now but I'd like to imagine that it is possible in the future. Did you lace up your own wheel or have someone do it for you? Or did you buy the whole wheel/hub together?