What i can expect going from 49cc to 72cc?

[ratdog]

I have limited experience with aftermarket CDI boxes. I have tried only two and of course the stock box. I got no better 0-25 times on the after market boxes. We actually lost a little top end, and the 0 to 1/2 mile times were longer and top speed at 1/2 mile slightly less. The after market boxes were much harder to start. I also have a bad problem with first start up. The bike dosent want run above idle and will actual stall if you open the throdle. Thakes a while befor the bike is even drivable. The after market boxes made this even worse

If you do put a after markent box in, try some runs, then switch back to stock to really see if it’s helping you

[AtariGuy]

I would definitely agree a 47mm bore upgrade is worth its weight in drivability.

If you want a simple way to consider upgrades, imagine a 3 speed bicycle. If a non-athletic person rides it, they'll be a little slow off the line, and can still get it up to speed but takes awhile and some downhill. Thats the 39mm stock bore.

But if that non-athletic person trained, rode, and became more athletic, stronger, they would be able to get that bike up to speed quick and spin them pedals in top gear as fast as they can - pretty much reaching the limits of the bike. That's like putting it up to a 47mm bbk.

If you also had a second bike similar to the first but with 3 more taller gears (6 total now), the youthful non athletic rider would have looooads of trouble turning them higher gears, acceleration would be lots slower and they might not reach top gear because they arent strong enough. That's like using 49-17 (2.88) gears on a stock bore. But the athletic rider would be able to push them gears to their potential. Acceleration again wont be like the 3 gear bike, but top speed would be way better.

I guess i use that metaphor a lot, but it really helps to explain the difference between power and gearing in a way. Forgive me if its toooooo winded

[jwinn]

Aug 15, 2018 3:04:09 GMT -5 AtariGuy said:

I would definitely agree a 47mm bore upgrade is worth its weight in drivability.

If you want a simple way to consider upgrades, imagine a 3 speed bicycle. If a non-athletic person rides it, they'll be a little slow off the line, and can still get it up to speed but takes awhile and some downhill. Thats the 39mm stock bore.

But if that non-athletic person trained, rode, and became more athletic, stronger, they would be able to get that bike up to speed quick and spin them pedals in top gear as fast as they can - pretty much reaching the limits of the bike. That's like putting it up to a 47mm bbk.

If you also had a second bike similar to the first but with 3 more taller gears (6 total now), the youthful non athletic rider would have looooads of trouble turning them higher gears, acceleration would be lots slower and they might not reach top gear because they arent strong enough. That's like using 49-17 (2.88) gears on a stock bore. But the athletic rider would be able to push them gears to their potential. Acceleration again wont be like the 3 gear bike, but top speed would be way better.

I guess i use that metaphor a lot, but it really helps to explain the difference between power and gearing in a way. Forgive me if its toooooo winded

Damn, i love that metaphor. Seeing how i was an amatuer cyclist in my younger years. Cruising speed around 20. Sprint speed around 28. But yeah, that's from riding roughly 50-60 miles per day on weekdays, around 100 per day on weekends. And yes, all the gear on a $800 bike and clean shaven...everywhere.

[ratdog]

Pretty much about everything has been said and imho is correct. A big bore kit will give you more torque. Torque is what we “feel” and most call “power”. Said a million times, there is no substitute for cubic inches. The difference between taking off from an intersection stock and with a BBK is very much worth it.. you should use a “big bore” head with a BBK. BBKs are increasing your compression, and therefore increasing the heat in the engine. CDIs pretty much do nothing good for you. Last weekend I used a timing light to “check out” 4 different CDI units. The stock cdi advances the timing with the RPM. The aftermarket CDIs I tested had an fixed advance. Same as the stock cdi at higher RPM. How anyone could think this was “better” I don’t know.

IMHO, the most important ting in these little motors is to get the mixture right. Any change you make will almost certainly change your mixture. What each of us runs for jetting can only be used as a rough guild. Unless you live next door to me, your jetting will most likely be different from mine. If you are going to make mods to your engine, please buy a jet kit. I see them advertised for 10 to $15 on line. You have to get good at pulling your plug to check the mixture. There is a procedure to it that I call a “plug chop”. Running too lean can kill your engine. Too rich, and you limit your preformance. When you do your BBK, I would suggest you go to premium gas. This is to protect your engine, not to give you more power.

Your speed is limited by the gearing of your bike. I could double the HP of my bike, but (in my case) I’m still going to go 45 mph at 8500 rpm. I have the power to go to higher rpms, but the more rpms you run, the more wear and tear you put on thes little engines. Basicly, you need another gear. Just thinking out load, but it might make for a longer lasting engine with a BBK if you changed the final drive. Messing with weights and spring will effect you acceleration. But you front pulley can only get so big and the rear can only get so small, so no matter what I do, I’ll still be doing 8500 rpm at 45 mph. Only changing the final drive will effect that.

Hope that kinda sums up all the good advice you got here

Craig

[GrumpyUnk]

jwinn, I had a co-worker back in the 80's that ordered bearings for his cyle. For the pedals.

He got so irritated that they came with seals, or didn't, it has been a while, which would add friction.

The bearings were apparently also factory packed with what must have been grease. Ummh, I was not surprised at that.. but he was going on and on about how much more difficult it would be to operate these pedals because the bearings were soooo stiff.
I just let him go on and on... made a comment here and there... The new bearings were a bit 'stiffer', but not so much that I thought them defective. Clean them with some trichlorethylene.. trike .. (ha! won't find it any more) and they'd be ready for the 3-in-1 or the synthetic watch oil he was going to use. I exaggerate.
One brother, of 6, had a friend that he rode with. He used rat-trap pedal 'covers?', not for me! If I want to get off that thing, I don't want to be trying to wriggle free of the pedals as I head for the gravel, cement, rocks or concrete. It's always those, never any soft grass or un-cut hayfields...
tom

[ratdog]

“Damn, i love that metaphor. Seeing how i was an amatuer cyclist in my younger years. Cruising speed around 20. Sprint speed around 28. But yeah, that's from riding roughly 50-60 miles per day on weekdays, around 100 per day on weekends. And yes, all the gear on a $800 bike and clean shaven.”


I love riding bikes! When riding with the local club, we do 27 mph in a pace line for many miles. When my Son and I do weekend rides, we advrage about 18 mph on the road (don’t count the time getting more bananas). Of course we ride pace line style swapping off the lead. We often pick up other riders that join in our “pace line” which helps us keep that speed up. When we ride the trails ( have a lot of rails to trails around, it is quite different. There we advrage about 10 mph

I use cadence and heart rate to set my speed.. basicly shifting cogs to keep 80 rpm at a heat rate of around 120.

My trail bike is a Cannondale Quick 4, on the road I ride a lightspeed.

Back when I was racing, I shaved my legs. Now a days as I’m old and lazy I don’t shave anything

I’m getting close to 70 btw

[lilpinny]

23 more CCs 😜

[ratdog]

Grumpy

Not exactly understanding the story about the bearings. Are you talking about bearings for the pedals or the bottom bracket? Bearing for the pedals are almost always sealed bearings. Their main concern is keeping the weather out. But bearings in the pedals would have about zero effect on the effort required to ride the bike. The bottom bracket bearing are a different story. Bottom bracket bearings have almost no resistance. Most of the old bikes have loose B.B. bearings, and how tight or loose they are is mostly determined by how tight the cones are tightened.

I ride with “clips”. Basicly the bottom of my cycle shoes lock into the pedal. The theory is that you can pull up with one leg while pushing down with the other.

[ratdog]

[GrumpyUnk]

It was the bearings at both ends of the pedals. Count of 4. I figured they should be sealed. Back when I was young, the bearings on the pedals of my 'English racer' as we called a bike with skinny tires and a 'sturmey-archer' 3-speed were open. The outer had a cap(which had a hole for oil to be dripped in as I recall) while the inner was totally open. I do remember taking them off and cleaning them.

The front bearings on a Taotao are also sealed. And a PITA to change. Replacements installed, but I could not tell the difference in the 47mm operation. The originals rotated as if there was some sand installed along with the grease. The 47mm (72cc) has more 'grunt' than a 39mm. A 44mm has some good power also, if one considers that as acceptable. I have one of each now, and was surprised at the 44mm performance. But. It may be due to the muffler having a hole rusted in it. A bit noisy also.
tom

[katt]

My 38mph at 8000rpm went down to 35 after belt broken in. doh, perhaps i should use smaller belt?

[ratdog]

That is interesting. The workings of the CVT still aren’t clear to me. Of course different bikes may have different final drives, but at 35 I’m only a little over 7600 rpm. 8000 rpm gets me over 40! I don’t know enough to advice on the the CVT, but it would seem to me that you are getting some slippage. I thought when you got to about 7500 you would have solid lock up.

Just wondering, do you have 10” wheels?

[katt]

Aug 19, 2018 13:00:58 GMT -5 ratdog said:

That is interesting. The workings of the CVT still aren’t clear to me. Of course different bikes may have different final drives, but at 35 I’m only a little over 7600 rpm. 8000 rpm gets me over 40! I don’t know enough to advice on the the CVT, but it would seem to me that you are getting some slippage. I thought when you got to about 7500 you would have solid lock up.

Just wondering, do you have 10” wheels?

Yeah i got 10" and 3.5" tires. I inspected the belt it looks a bit squashed on the sides, i installed it less than month ago, perhaps angle of the belt does not match angle of the variator face so it only connects on the widest part of the belt?

[katt]

Whats the approximate variator weight i need to use to achieve better acceleration and keep top speed around 40mph

i am 190lb.

I am not asking ask for magic formula i just need to buy different weights and theirs too many options from 5 grams to 13 i don't know where to start.

[katt]

News flash i already had 47mm installed probably from factory. Someone on Russian forum told me they commonly do this on Chinese scooters, how come no one here know about it?

Good news one i ordered from eBay as 47mm BBK turned to be 50mm kit so its sort of upgrade after all even though not by much.