Performance Carburetor Options

Also, BEST advice for any larger mods :bigger carbs, bigger exhaust (or OPEN exhaust),any head porting with STOCK INTERNALS................6oz oil with fuel , swap OUT roller bearing for brass, or bronze (supposedly HARDER), stay BELOW 25 mph, and just enjoy the fact it runs.
 
And dont try to play all innocent like........

???

Let's see... Seized one chainsaw solid, burned the piston on a bike, done my share of work on these things... Oh, I have been learning what I can about these engines. Here goes nothing.

1) supposedly, the port-timing (in degrees) is biased toward low-end, with a power peak of ~ 5000 rpm. (I wish I had the URL where I read that, but did not save it. Duh...)

2) there have been a fair number of comments on the board about 'wrist pin bushings' and overall engine fragility.

2-B - pictures, and actually seeing one of the engines myself. They didn't spend more time or money on these things than they had to.

3) Based on what I've seen and read, a too-large carb tends to make for poor low-speed running - and with one gear, that's a source of trouble.

Is 20mm 'too big'???

Now, some questions for *you*:

What's your jetting look like? (Main, pilot, needle position, etc.) A larger carb means less velocity at all engine speeds, which usually means larger jets. (and poorer fuel atomization at low throttle openings... Poor idle, loss of low-speed manners, perhaps a tendency to foul the plug? Oh, and worse fuel consumption.)

Your plug - its color?

You spoke of '35-40 miles an hour' as being an irresistable lure. That would seem to indicate top end performance is what you want - and yes, a larger carburetor *will* help there - as will cleaning up the ports, a freer-flowing exhaust (or, better, a tuned pipe), or potentially adding duration to the exhaust and intake ports.

What I meant was 'you pays your money, and you takes your choice' regarding these engines. Your later post more or less summed up what else I was thinking, with this possible addition: brief bursts of full throttle. Long wide-open stretches at 'max revs' tend to cause trouble for engines in general.
 
"A too-large carb tends to make for poor low-speed running -and with one gear, thats a source for trouble." Like HOW is this a source for trouble? Do you possibly refer to "bogging"........a problematic, repetitive occurence, in which TOO much air is mixed in with the fuel due to a larger airflow oriface??? Is this of what you speak? Zounds! Sorry,No bogging, sir. My shinobi sinner ran like a champ once it was dialed in. Even with a 36t.........it would GET up and GO, Zero hesitation!.......the carb looked like a kienin , I bought new off of honda trails bike.com. Stock jet was a #89. Currently, it has #87. I bought the jet kit for $10. from the same store. I tryed everone of em several times to make sure. (The #89 is better for winter) The needle I set ONE step richer than stock.........the air idle mixture is set roughly TWO turns out from the seat............and thats it. This carb is PERFECT!!!!!!!!! My plug is an IDEAL tan color. Already use a tuned pipe...........47cc pocketbike , triple stage exhaust from daves discount........ 40 bones...........freeflowing ....but not too large. Very copacetic. Regardless .........I'm NOT interesting in mincing words.......I had to LEARN the hardway..........my first engine.......... I didnt know jack about it. Never owned or operated a two stroke before..... Didnt find a moto bicycle site until a few months AFTER I bought it. Where nobody wants to volunteer any EMBARESSING accounts about HOW their injun took a dirt nap. Didnt even know there was a DAX.com until EGOR mentioned it on that same web site. (by the way, thank you for your posts, EGOR......I like the way you think!) It all boils down to this...........the "happy-time" engine"s potential is what draws you in......but, ultimately........the crappy, p.o.s. ENGINEERING repels you. This sucker could , originally, and quite possiblly ,be made for a 80 pd china dude to commute..............in a CROWDED , URBAN setting..........where speed WASNT of much precedence. Even WITHOUT modifying, or IMPROVING anything on the happytime engine ........it would eventually die anyway just from the simple fact........it IS simple. This unit isnt built for speed ........I can see this now.........(although, theres still loopholes to be found. albeit at cost)............a four stroke or pocketbike engine IS more forgiving. Unfortunately, the USEFULLNESS of both these engines wasnt compatiable for frame mounting in a mtb with a 26" wheel at the time when I discovered this ardent hobby. By the way.......its "you pays your money and you takes your CHANCES".......I think this phrase from madmax says it better......"speed is a question of money...how FAST do you wanna go???"
 
Sorry, but its in my DNA to WANT to make things better. I have trouble leaving stuff alone .....sometimes. Thats why I like "soft-performance" mods. Simple stuff.......that if it didnt work.......you take it off and try something else until it DOES work. Besides........hotrodding is AMERICAN! What......you WANT stock china **** engines??? Be honest............you wanna go fast,yo.(Otherwise, you wouldnt have bought the engine kit in the first place.) You want durability. you want power. You want the rush. Admit it.........come on............................come on....................if youre still young and spry,its natural to wanna see how fast this engine can go. And THERES the rub..............sprockets that allow 35-40 mph, are.....nix that ...........WERE there .......tempt you further. "Lets modify the exhaust...lets try the boost bottle.....lets try hobby fuel"............STILL get the gears in your noggin turning, mate. This is a FUN , LOW COST, LOW SCALE hobby for gearheads or anyone with mechanical aptitude. You make it sound like its a crime to try to IMPROVE something, prism. Oh, my bad. I should have said *you*.......since you have a rather dasterdly habit of INDIRECTLY addressing another member. Hmmm.
 
:cool:Dang, Brian!

I could've written all those hotrodding dreams and aspirations you quoted!:eek:

Except for your personal remarks, of course.:cool:

Myron
 
sonofjustice

This is a FUN , LOW COST, LOW SCALE hobby for gearheads or anyone with mechanical aptitude. You make it sound like its a crime to try to IMPROVE something, prism. Oh, my bad. I should have said *you*.......since you have a rather dasterdly habit of INDIRECTLY addressing another member. Hmmm.
Wow. Take it easy!

People with the 2-stroke fundamentals that user prism has are not that common on a message board forum such as this one. You might find them on a legitimate racing forum, but...

Also, I couldn't really tell who was talking to whom in this thread, so please, let's not get our panties in a knot. LOL.

The bench racing in this thread is good. Please keep the attitudes at bay. Thanks!


See, the thing is, these Happy Time engines are REALLY inexpensively made and although I'm with you on the fun-with-modifying part, there's not a lot to be gained without a thorough remanufacture and using stuff like a higher-dollar crank, rod, roller bearings and piston.

Once we really improve this little engine's output, we'll discover the next weak link in the chain of power... whatever that is on these motors.

I say take what the Happy Time is, and blueprint it (if the measurements are available) or at least balance the rotating assembly.

For now, however, I'm content to let my 80cc version break in without breaking. Heh.
 
Last edited by a moderator:
Just curious but I wonder what types of costs would be associated with a high quality happy time engine...I mean Dax is apparently trying to get some US company to make high quality gearbox/carriers for his engine....suppose somebody took a happy time to a manufacturer and asked them to essentially copy the engine and see what a US production run of the same engine would cost (of course we would want essentially the same engine with improvements such as better materials, better porting, bearings etc...)THAT would seem like a good solution to our performance desires ;-)
Andrew
 
"You make it sound like its a crime to try to IMPROVE something, prism. Oh, my bad. I should have said *you*.......since you have a rather dasterdly habit of INDIRECTLY addressing another member. Hmmm."

1) It isn't a crime to improve anything. (I think I posted something earlier in this thread - see 22 mm carb and entries thereafter) as to what it would take to do so and have an engine that will run for any real length of time.

1-A) The chief issue with a larger-than-stock carb (mostly when you go a *lot* bigger) is abruptly opening the thing at low rpm. One of two things happens then: A) reversion (spitback) causes air to go past the slide-needle-jet *three* times. Each time, it picks up fuel, making for a very rich mixture. Gargle, choke, belch vast clouds of blue smoke... (Just like the Kawasaki did on cold mornings.)
B) air velocity drops off so much that your mixture goes too lean to support combustion - hence bogging.
Cure for both troubles is an 'educated' throttle hand, one that opens the throttle slow enough to stay out of trouble.

1-B) Referencing another, later posting regarding making a 'high-quality copy' - that would give an engine where it would be worth one's while to 'hot-rod'. (Now if I can only get access to a foundry...)

2) That 'indirect addressing mode' is due to recalling *what* someone wrote while simultaneously losing track of precisely *who* said it - while trying my hardest not to be impolite. (I'm rather clueless regarding such niceties, in spite of substantial effort to *not* be so. I'm not merely partly deaf physically - born without a right ear - but also mostly deaf and blind in a *social* context. The whole mess is utterly counter-intuitive, unlike 'engines' and their like. I understand those fine.)

3) I talked with someone yesterday who visited China and had a chance to observe these engines being used where they were made. His comments were most enlightening.
Firstly, I guessed as to the likely 'cruising speed' - mid to high teens - and his comments proved surprising:

"they're darting in and out of traffic at speeds between five and fifteen miles an hour... They don't have that much money, and they want to save what they have, so they're intersted in fuel economy over performance..."

4) To get some 'history', google 'NACC Archive', and look at what they have there. Especially, look under the terms Raleigh Wisp -> Wasp, Velosolex, etc.

5) My first postings to the list indicated my own strange ideas about 'speed', namely I planned on gearing (rack-mount) for a 'crusing speed' of between ten to twelve miles an hour. (with top speed between 16 and 19 miles an hour) Why?
A) most trips I need to make are within a fifteen mile radius - too far for me to realistically pedal with bad knees, especially while towing a loaded trailer.
B) I want to avoid undesired attention. I've seen a number of signs indicating the 'expected' speed of bicycles is about ten miles an hour. If I go that rapidly (and 'hide' the engine and oversized muffler under a suitable cover) then Mr. Gendarme is likely to ignore me. (at least, I hope he/she ignores me.)
C) Maybe I'm turning into an 'elderly gas blob' (old fart) and am not interested in traveling at the more-rapid speeds of my youth.
D) I'm certain I don't enjoy the noise, crowding, and vibration associated with buses. Given their average door-to-door speed is about eight miles an hour, ten to twelve miles an hour without drunken abusive thugs and screeching toddlers starts to look *very* attractive.

Hope this is of help.
 

Attachments

  • engine2.jpg
    engine2.jpg
    14.7 KB · Views: 302
Back
Top