Seeking honest advice...

[BikeNewberry]

Hi. I am a California resident & I've been doing lots of research on 2-stroke engine kits and I was seeking some honest advice. I have my mind set on purchasing an engine kit from Venice Motor Bikes after reading all the terrible reviews on Motovelo. But here is my goal: To accomplish riding at 40 mph...consistently. What are the list of upgrades that I would need to purchase with the kit in order to meet that speed goal?? I'm wondering what the best expansion chamber would be, and Sprocket tooth count, recommended bicycle tire size etc... From what I understand, two-strokes are prone to not being as "reliable" as 4-strokes, but tinkering and "building" my 2-stroke is half the fun anyways. I appreciate, and welcome your guys' advice, thanks! p.s. -I'm planning on getting the 66/80cc 2-stroke, not the 49cc one. Oh! And which aftermarket performance carb do you guys recommend? Good thing BikeBerry has the Hardware replacement kit...saves me the time I'd spend hunting around at the hardware store for them all. Anyhow, I welcome any and all recommendation on what to do and what to buy and install on the 2-stroke for max speed without having to worry too much about blowing up my engine. I hope this isn't too much of a noob question, but if I don't ask...I'll never get an answer. (^_^)

 

[crassius]

Just like a car, a 2-stroke will only run reliably at about 2/3 of its rated speed. If you put your car in first gear, floor the accelerator, and drive that way all day, you won't like your results. To ride at 40, you'll need one with a top end of maybe 60 or 70.

I'd say; "go 4-stroke and go large in the 200cc or bigger class".

You can make a 2-stroke hit 40, but if you don't ride it at 20-25, you'll blow it up.

 

[scotto-]

Norm at Venice Motor Bikes can answer your questions and take care of your needs. Give him a call.

 

[GearNut]

Wise, sage words there crassius.
Bairdco has plenty of engines that have successfully carried him at 40+ MPH for a good distance, but he also has a large stockpile of self-destroyed parts.
Somewhere in this forum there are pictures of his stockpile.

 

[scotto-]

Just like a car, a 2-stroke will only run reliably at about 2/3 of its rated speed. If you put your car in first gear, floor the accelerator, and drive that way all day, you won't like your results. To ride at 40, you'll need one with a top end of maybe 60 or 70.

I'd say; "go 4-stroke and go large in the 200cc or bigger class".

You can make a 2-stroke hit 40, but if you don't ride it at 20-25, you'll blow it up.

Or you can build a little 49cc 4-stroke like I ride daily and cruise 30-35mph all day long, everyday.

Or build a monster 212cc bike like I race a go whatever speed you like.....40, 50, 60 or even 70mph. Not recommended for street use though lol.

49cc 4-Stroke

212cc 4-Stroke

 

[BarelyAWake]

"20-25mph" may be a bit overstated (understated?)... a stock but well tuned 66cc two stroke kit is perfectly capable of running at 35mph for thousands of miles (excepting the quirks of quality control ofc) - it isn't until you start trying to push beyond the 35mph barrier with major modifications that the increase in power & RPM starts taking it's toll, that for the cost in reliability & preformance parts, the desire to break 40 may make you seek an engine alternative.

That "mere" 5mph may not seem like much, but it is in fact the dividing line between the feasibility of an inexpensive kit, and a not so inexpensive DIY project - every mph above 35 hard fought for in parts and price, that's when the "savings" of the inexpensive kits starts working against you.

This is where the decision lays, are you interested in the cheap two stroke in an effort to save money and/or ease of build, even just as an introduction to motorizing a bicycle? If so, go for it & don't sweat a few MPH, tinker w/it & bolt a few extras on and you'll have fun, learn a lot and come close enough.

If cost & kit aren't the primary considerations and you are interested in true lightweight preformance, there are more options available than four stroke utility engines which while viable - have their own complications & incurred expenses, for the speeds you wish they're not going to be a kit either. There's other, less well known two stroke motors that have far higher preformance & reliability capabilities, such as the 49cc Morini, KTM & their less expensive clones in 6,9 & even 12hp variants - none of which are kits, but may well prove less costly in the long run than attempting a sustained 40mph w/the 66cc kit, or even a four stroke build - depending ofc on what you choose to pursue & how you choose to build it.

Every build is a compromise between what you wish to have, what is feasible with what you're willing to pay for and what you're able to build yourself - which is "best" only you can decide lol

 

[Venice Motor Bikes]

Making a HT 2-stroke go 40MPH is reasonably easy to do... but you have to understand that you are reving the heck out of it, & when you do that, the risk of it failing goes up.

I've personally had many bikes that could do 40 all day long & never had a problem with them.
It's better to build a bike that can do 40MPH, & then just cruise it all day at 30-35MPH (& make it last for years).

Another thing to keep in mind is that breaking the engine in correctly really helps extend the engines life... Don't modify it until you've run a few gallons of gas through it first.

 

[BikeNewberry]

Wow, thanks SO MUCH everyone...I didn't expaect to actually hear from some of the legends of Motorbicycling.com! If I could only get your autograaaaaphs. The advice I received is exactly what I needed to hear and I want to thank you all VERY much for responding. Honestly, money isn't too much of an issue at all, I would just rather be doing wrenchwork on my bicycle as a hobby, rather than buy some cheep chinese super pocket bike that isn't even road-legal. It would be great to have been able to easily accomplish my speed goals, but it looks like I'll have to live with life on the asphalt at lower speeds. Until, of course, I decide to go "Dr. Frankenstein" on a new bike and install a 110cc pit bike engine on a stretch beach cruiser!

 

[BikeNewberry]

'Nother question for everyone...seeing as how I'll be replacing most of the components that are already included with the 2-stroke engine kit with either performance versions or better quality versions...would it be wiser to just order the parts piece-by-piece, or break the engine in 100% factory stock and slowly add performance parts and replace low-quality components with better ones?

 

[crassius]

One thing to note is that in some places a power assisted bicycle that has automatic transmission is classed as a moped & requires registration and license. A 4-stroke that has centrifugal clutch is considered an automatic transmission in some of these places.

 

[Sidewinder Jerry]

I don't know what the terrain is like where you live but if you have steep hills consider a shift kit.

 

[GearNut]

In California it must be an automatic transmission.
Any power plant installed in a bicycle that requires the operator to shift is not legal in California.
Still, I want a shift kit on my next build.
I will be walking in the grey area of "Shifting is not required, but I want to shift it. I live on the top of a really steep hill"

Centrifugal clutches fall into the legal area.
Manual clutches fall into the grey area, but at least with Chinagirls there is only 1 speed so you would not be using the clutch to shift any gears. That would fall into your favor with any questions the popo may have.

 

[BikeNewberry]

What is the best/most recommended automatic shift kit avail. for an 66/80cc 2-stroke engine kit?? I kill cops on my free time, so the PoPo and the law are the least of my worries...but either way, I'd just rather "get on and go" and not have to worry .bout shifting and downshifting.

 

[The_Aleman]

I'd get a 49cc 4-stroke for sure. I dabbled in the 2-strokes for 4 years then 4-stroke kits started getting decent. Long-term the 4-stroke has it beat.
A simple single-speed 4G kit from B-E or if you want to spend a lot more, an EZM Q-Matic. But 40? maybe with a tailwind or downhill.

Really, over 30 or so the danger really increases, and the wear on your bicycle brakes will increase quite a bit should you need to stop quickly.
If you insist on a 2-stroke kit, get yourself a 36T sprocket and you should be good for an easy-ish 30 cruise.

In California it must be an automatic transmission.
Any power plant installed in a bicycle that requires the operator to shift is not legal in California.
Still, I want a shift kit on my next build.
I will be walking in the grey area of "Shifting is not required, but I want to shift it. I live on the top of a really steep hill"

The thing is, the SBP kit is a single-speed pedal crank assist device. All it does is assist the crank, the jackshaft itself doesn't shift.
Some bicycles simply have gears, an SBP kit put on a singlespeed bicycle would not be illegal. Shifting jackshafts is illegal regardless tho.

You can easily reduce the engine ratio further (using 70+T #35 outer sprockets or the like) to get it so your engine redline in any gear is closer to your maximum pedal redline in any gear. This would further enhance the fact these are Motor-assisted Bicycles not to mention increase gas mileage, get you exercise, and greatly enhance acceleration.

Pedaling should be done IMO, and the most versatile bicycles have gears.

 

[BarelyAWake]

Gentlemen, while ofc everyone has their own opinions & feedback is appreciated... I would feel safe making the suggestion that as this new member posted in the two stroke section, asked about two strokes & then disregarded anything other than two stroke replies... he may not actually be interested in four strokes?

Granted, it's an assumption lol - but one worth some consideration I figure

 

[The_Aleman]

Well, when one is going for a first build that is reliable and legal in Cali, something a man might have to rely on lol, best to consider all options available.

After all, he wants to go through Norm @ Venice, well he has 4-stroke kits, too. Blame Scotto for opening that door with the beautiful pics of reliable machines!

But seriously, I wouldn't not look at the 66 myself. I had a lot of fun in North Dakota with several with 34T from '06-'08, Montana for 3 months, and Cali for a year.

Easy quiet (moreso than my 4-stroke) 20-30 cruise and capable of 40+ for bursts. Set up tall (52+/11) pedal MegaRange gearing and off you go

I've put over 5K miles on both HT66 and HS49, I have to say I'd rather have a HS49 for a legal, consistent engine that fills easier and doesn't need oil for months tho!
In the end, the HT66 is outright more powerful, smokes and smoking, it's a greedy engine, mesays

 

[crassius]

In California it must be an automatic transmission.
Any power plant installed in a bicycle that requires the operator to shift is not legal in California.
Still, I want a shift kit on my next build.
I will be walking in the grey area of "Shifting is not required, but I want to shift it. I live on the top of a really steep hill"

Centrifugal clutches fall into the legal area.
Manual clutches fall into the grey area, but at least with Chinagirls there is only 1 speed so you would not be using the clutch to shift any gears. That would fall into your favor with any questions the popo may have.

The take-away here seems to be that if you do not have any kind of license, you should avoid auto-trans & centrifugal in California. I think that a manual shift-kit is not automatic, but in gray areas of the law, one may need to argue it out in court.

 

[GearNut]

Auto trans and centrifugal clutch are highly preferred and extremely legal.

If you do not have at least an M2 license outright (yes they are available) or endorsement on your class C drivers license, you cannot legally operate any motorized bicycle, period.

Motorized stand up scooters however do not require any sort of license, buuutttt... they also have a top legal speed of 15MPH. You can have a seat on one, but it cannot interfere with your ability to stand upright on it.

 

[crassius]

yes, that's where it gets gray - every legal def of motorized bicycle includes the auto trans part, but that may take a long court case

 

[2door]

A good lawyer could argue that a China Girl doesn't have a transmission. It has a clutch but in essense it is a direct drive coupling much like the old in and out box that was used in early drag racing. One gear and a clutch doesn't make it a transmission. But, as I said, you'll need a good lawyer to convince the judge. That said, when you add a shift kit, now you have a transmission with changable/selectable gearing.
I wonder if there are lawyers who specialize in mechanical law.

Tom