A Question to Ponder

FlyGuy · Apr 3, 2011

Lost In the search for the best engine performance modifications I find lots of unanswered questions.

Why port if the engine will not last?

Why spend money on pipes and carbs if porting is no good?

What is the best we can expect to get out of the engine?

What can we do to overcome the limitations?

wheelbender6 · Apr 3, 2011

Hopping up anything decreases the service life. However, China girl motors and parts are cheap. If you blow the bottom end while zooming on your ported China Girl, you can buy a replacement motor for 80 bucks or so and install the old ported cylinder on it.
For best results, do intake mods, porting and expansion chamber.

bairdco · Apr 3, 2011

Why port if the engine will not last?

who says the engine won't last? i have a heavily modified 66cc chinadoll with almost 10,000 miles on it. i ride it hard almost every day, and haven't had any motor-related problems at all. just got back from the Long Beach ride and it was one of the fastest bikes there.

Why spend money on pipes and carbs if porting is no good?

if you don't know what you're doing when you're modifying your engine, the pipes and carbs become aftermarket bolt-on expenses that will get you a little more power, but will work much better after you learn how to "blueprint" and tune up the engine itself.

What is the best we can expect to get out of the engine?

again, depends on if you know what you're doing or not (assuming you didn't get a defective motor.) some people can expect thousands of trouble-free miles, and others can make a boat anchor out of it in one day.

What can we do to overcome the limitations?

learn all you can from those who've already done it, and get your hands dirty doing it yourself. then take it to the next level and figure out things yourself.

timboellner · Apr 3, 2011

Well put Bairdco,
It's kinda like getting a haircut...
No matter how good the scissors are, it's only going to turn out right if the guy using the scissors knows what he's doing with them....

????
TiM

FlyGuy · Apr 4, 2011

Yes i agree Bairdco.

I have quite a bit of experience with the HT motors.

The start of this project takes it to the next level. Anyway
Iv'e spent many hours pondering........ How could this little Engine Be Irmproved ?????
I much favor the 2 Stroke Engines prefering the sound feel and smell.
Many moons have passed and with them neverending mindbending experementation and one day it hit me. This is it it just cant get any better.

Now the question i ask is What better little engine can i find that sounds feels and smells Like the little gem before me. Ohh Ohh in excitement my mind did fly. Better yet if i could build it from parts i could buy.

So now i ask...

What standard parts could one find from an engine of a better kind?

And how can we put them together to create a much better system?

And first what would be or could be better?

My thoughts......

Variated with a CVT......
Belt Driven ......
Piston Ported Reed Cylinder ......
Balanced Racing Crankshaft .....
Upgraded Electrical Sys.....
Secure Mounting ........

Other Than Buying a Morini where could i find these things?

Has anyone acomplished this allready?

I'm sure it will be many hours of fun work and i'd sure like to try.

mobike91 · Apr 6, 2011

ill tell you what the best way to do things is. dont port anything. you dont have to. it would be a waste of your time and effort. get bolt ons. you will find the best results out of things you can just bolt on and swap later when you have to get a new jug and piston. get the

billet intake.
expansion exhaust.
34-38 tooth sprocket

with those things alone you will find lots of performance and speed. and when they say you will ruin your motor from those. they are wrong. when you run stock exhaust it restricts your motor to much making to hot and thats one of the leading reasons these motor go junk. if you can keep your motor cool then it will keep runing. while using appropriate mix of course. witch is anywhere from 32:1 - 46:1 which i run. you will find more problems if you keep it the stock exhaust. the motors always run way to hot with those crazy restricting pipes. first thing i do with a stock exhaust pipe is go inside it. drill a bunch of holes, and cutt a lot of junk out. to much heat equals your pistom mating with your cyclinder wall and you going nowhere.

mouting your motor makes a big deal too. if it isnt mounted right it wont ever run correctly.

dont run your motor to lean either. that will blow a piston.

hope this is helpfull.

mobike91

BarelyAWake · Apr 6, 2011

Well, TBH port matching is actually pretty important, there's little point in investing in quality bolt-ons if everything is restricted anyway. The stock stuff is appalling and even quality aftermarket intakes and exhausts rarely match up perfectly, the gaskets never do.

There's a coupla ways to go about "porting" a motor, some do some basic clean up, some enlarge, some go to extremes and even alter port timing - it's up to you to accept the more profound the mod, the more likely something will get messed up...

I will say that there's another oft overlooked aspect that tends to skew the feedback & that is, the more performance mods you do, the more likely you'll expect performance, the more likely yer gonna beat the bike... It's a rare rider that goes through all that effort - and then joins the '20mph Club' lol

mobike91 · Apr 6, 2011

BarelyAWake said:
Well, TBH port matching is actually pretty important, there's little point in investing in quality bolt-ons if everything is restricted anyway. The stock stuff is appalling and even quality aftermarket intakes and exhausts rarely match up perfectly, the gaskets never do.

There's a coupla ways to go about "porting" a motor, some do some basic clean up, some enlarge, some go to extremes and even alter port timing - it's up to you to accept the more profound the mod, the more likely something will get messed up...

I will say that there's another oft overlooked aspect that tends to skew the feedback & that is, the more performance mods you do, the more likely you'll expect performance, the more likely yer gonna beat the bike... It's a rare rider that goes through all that effort - and then joins the '20mph Club' lol

well what i meant is that if your going to port your jug then you take the chance of later down the road having to get rid of it cause your cylinder ceased making your time spent on porting useless. if your going to port. dremel the bolt on part to match. cause you can always take it off and put it on a differnt top end.

so far iv rode a good 1000 miles on my set up. first things i did before even running it was getting the mod parts. iv ran stock pipes and every time blown a piston. with a chamber pipe iv never ruined a top end. the heat is the issue. the last time a junked a piston the top of it was flaking from heat. at the rings decided to they liked the side walls of the jug way to much. sent me skidding down the road 10 miles from home. aka 20mph club. heres a quick mod that makes a difference.

just drew it lol

mobike91 · Apr 6, 2011

easy to do. drill and dremel. or hack saw and file. you decide

FlyGuy · Apr 6, 2011

Thank you both for the good info.
If we ask the right questions we can find the right answers.

Mobike91

You are correct about everything except for the porting.
Porting is very valuable and certinly portmatching.
Now if you approach porting by grabbing a file or dremel.........
And in a whim of wild imagination start cutting away...............
Then yes you spent a whole lotta time and maybe youll get lucky.

BarelyAwake
You hit the nail on the head with the often overlooked skewing.

Mobike91

Lets take all this a step further and analiyze our thoughts.

Thought 1
Is porting alone going to make a huge difference by itself ?

Thought 2
Will any single modification by itself make a huge difference ?

Thought 3
Will any combination of some modifications make a huge difference ?

Logically if we make every modification we can, we should see a decent improvement.....

I think we can conclude that if we treat the system as a whole and modify the system as a whole rather than a piece of the system then we should see a decent improvement of the entire system....................

The only question left to ask now is what dose it cost to upgrade the whole system ?

Or maybe what else can we put together for similar cost and where can I find it ?

mobike91 · Apr 6, 2011

if you look at this top end you will see inside the cyclinder for the exhaust port it has a piece in between there. thats for the piston rings. its so they dont expand to far out of the cyclinder and grab on the side walls when the piston comes back up and down. so even if you port your little engines port it wont have that. and then you can help in damaging it. which wouldnt be good. a jog for out little bikes is under 20 dollars. cheap casted dime a dozen top ends. if we could make something like these puch top ends fit on nicely we would be in the busness.

HERO PUCH 65CC CYLINDER KIT MOPED TOP END piston bore - eBay (item 300499323296 end time Apr-29-11 17:23:12 PDT)

check out this vid of a guy who modded this puch and ht engine

YouTube - 2 stroke hybrid puch motorized bicycle

mobike91 · Apr 6, 2011

the true questions for these bikes is can we get an upraded crank, better top ends with bigger ports, and better pistons. thats my questions

ferball · Apr 6, 2011

The thing I like about this hobby is that the two stroke engine is genius in its simplicity. It can be modified with simple tools and a little know-how. The other thing for the about this hobby is that you can stay of the engine all together and do a few bolt ons and focus more on the bike itself, different mounts, jack shafts, tires, cogs cranksets etc..

FlyGuy · Apr 6, 2011

Mobike91

Thats an outstanding Idea worth thinking about.
If we can make top ends from some other engine fit........
Why not cranks pistons excetera.

I seen a top end with reeds somewhere.
Now i got to go investigate the situation.

Ferball
Yes building the bike is just as much fun.

FlyGuy · Apr 6, 2011

PS

That hybred Puch is ammmmazzzzziiiinnng.

FlyGuy · Apr 9, 2011

I broke down and orderd a K-Star top end kit.
Piston Ported Reed Intake style.

Should come in some time next week.

I dont have a bottom end to put it on so i'll be started measuring everything.
This way i can figure what to cut and where befor i do anything.

The rest of the engine will be setup for the top end so i guess it's the place to start.

Anybody have any suggestions what to do next?

mobike91 · Apr 10, 2011

FlyGuy said:
I broke down and orderd a K-Star top end kit.
Piston Ported Reed Intake style.

Should come in some time next week.

I dont have a bottom end to put it on so i'll be started measuring everything.
This way i can figure what to cut and where befor i do anything.

The rest of the engine will be setup for the top end so i guess it's the place to start.

Anybody have any suggestions what to do next?

you have a link for that top end id like to see it

FlyGuy · Apr 10, 2011

Here is the kit i ordered.

Heres the head i got.

Now if only i had a solution for a bottom end.

DaveC · Apr 12, 2011

Depth that the jug sets in the block might be a problem and most likely rod length, too. I've got the same head, works great for raising the compression on a stock motor.

I'll be watching this, I thought of doing the same thing, except for my exceptions

FlyGuy · Apr 12, 2011

Well as to those exceptions to overcome...........

Iv'e been researching and researching and researching.

Constructing a plan to create a custom engine for myself.
I have the cylinder and the head and have gleaned a great deal of information from them allready.

I am employed by a company that machines Aerospace Bearings. This provides me with a multitude of very high prescision measuring tools. ( Zeiss CMM and a Zeiss Contour Tracer ) These machines measure any kind of feature you can imagine within an accuracy of better than .0001".

Due to the nature of work, the machine shop is tooled out to the max. A myrrid of CNC Machining Centers that even includes robotic machining cells.

So long story short if i come up with a design i have the resources needed to machine anything provided it's on my own time.

Watch for my other posts to see how we work past those exceptions.

Sometime this week i'll post the measurements from the head and cylinder and piston in there stock form.

Then we can figure out how to put the proper squish in that head. I plan to machine the combustion chamber and the piston top to match.

Since i know i'm gonna use a E50 crank with a 43MM Stroke we can figure out the Ex-Port timing.

I Need to know how much im going to cut off the top of the ex port before i can calculate the compression.

I plan on running around 10:1 but my be leaning more towards 9.5:1.

I think there is alot of meat left in that head to work with. I'm figuring on cutting the taper and rounding off the sharp corner at the center of the head. With a 70cc cylinder it seems that the comp ratio unmodified is much greater than 10:1.

Now what i got to do is figure out these questions.

Ehaust Port Timing ???
Squish Band % ???
Compression Ratio ???

Then i can figure out how to modify things.

A Question to Ponder

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