Reaching 50mph on 66/80cc

Next mods to push over 45mph

  • Mz65 pipe

    Votes: 0 0.0%
  • Stuffed crank case

    Votes: 0 0.0%
  • Advanced timing

    Votes: 0 0.0%

  • Total voters
    3

indian22

Well-Known Member
Dec 31, 2014
3,646
3,939
113
Oklahoma
Most likely at some speed Tyler, but there is some variance between setups. Some off the rack bikes have more positive trail in the fork/head setup which provides more stability at speed. Others may have an inch or two of extra length wheel base, axle to axle. Very few factory bicycle frames have over 49" WB, most are less than that and your frame at 68 lbs. with motor isn't really that light.

I live in Western Oklahoma and we've got high winds and a lot of hills to contend with year round. Side winds in gusts are the problem on a moto bike & speed on two wheels isn't your friend in high wind....slow down. Save the bragging pulls for nice quiet days. Fifty is just a number of interest not something to be repeatedly experienced on public roadways. What is really impressive, to me, is a bike that will cruise safely and dependably at 30 mph plus for hundreds of riding hours with a 48cc or 66cc single speed motor. That same bike may well also run fifty plus if asked to do so occasionally & that's just icing on the cake. It's a complete package that really works and a good motor deserves to power a well designed bike.

I like bikes that make some extra power though the rpm band width, not just peak power. The same for gearing. If you've got to pedal to get moving from a dead stop or slip the clutch... you're geared too high and whatever top speed, on the flats,you record is not impressive. Same goes for hills. No pedaling on hills, mountain grades...perhaps.

Rick C.
 
  • Like
Reactions: dogcatcher

Tyler6357

Well-Known Member
Mar 15, 2012
1,115
162
63
Santa Barbara, CA
Most likely at some speed Tyler, but there is some variance between setups. Some off the rack bikes have more positive trail in the fork/head setup which provides more stability at speed. Others may have an inch or two of extra length wheel base, axle to axle. Very few factory bicycle frames have over 49" WB, most are less than that and your frame at 68 lbs. with motor isn't really that light.

I live in Western Oklahoma and we've got high winds and a lot of hills to contend with year round. Side winds in gusts are the problem on a moto bike & speed on two wheels isn't your friend in high wind....slow down. Save the bragging pulls for nice quiet days. Fifty is just a number of interest not something to be repeatedly experienced on public roadways. What is really impressive, to me, is a bike that will cruise safely and dependably at 30 mph plus for hundreds of riding hours with a 48cc or 66cc single speed motor. That same bike may well also run fifty plus if asked to do so occasionally & that's just icing on the cake. It's a complete package that really works and a good motor deserves to power a well designed bike.

I like bikes that make some extra power though the rpm band width, not just peak power. The same for gearing. If you've got to pedal to get moving from a dead stop or slip the clutch... you're geared too high and whatever top speed, on the flats,you record is not impressive. Same goes for hills. No pedaling on hills, mountain grades...perhaps.

Rick C.
I agree 100% man. I usually cruse about 30-40 mph but it's nice to have that extra power when I need it like if I want to pass a car that is turning right or pulling over or something, or maybe just to beat the light. When I first put the Mukuni carb on, one of the first things I noticed was a better throttle range, I mean there was actually a middle range, not so much just throttle on or throttle off. But gearing is huge, I've been thinking of moving from a 36T to a 38T just to see how it is.
 
  • Like
Reactions: indian22

indian22

Well-Known Member
Dec 31, 2014
3,646
3,939
113
Oklahoma
I agree 100% man. I usually cruse about 30-40 mph but it's nice to have that extra power when I need it like if I want to pass a car that is turning right or pulling over or something, or maybe just to beat the light. When I first put the Mukuni carb on, one of the first things I noticed was a better throttle range, I mean there was actually a middle range, not so much just throttle on or throttle off. But gearing is huge, I've been thinking of moving from a 36T to a 38T just to see how it is.
I actually use a 38t on my hybrid. I ran a 36t on the bike before I added electric power because of the extra 30lbs.of extra weight with the e-hub and battery pack. I don't know where the sweet spot for gearing on your bike will be, but if you have a 44 or 42t on hand to try it will give you some idea of how much or how little gearing change will be required.

The Mikuni is hard to beat. It's an all round good performer and nice upgrade for modified motors, plus it's got tuning adjustments that the Dellorto clone lacks. With your x-pipe you should have a defined mid-range improvement and the carb helped uncover it. A small change in gearing is also useful to keep the rpm's in the power band that each motor develops, but 36t might be where you end up...though I suspect 40t or so will be an improvement for you and perhaps for me as well. I tried 44t & it was a bit too low for me and I didn't have a 40 or 42 to try. I use the electric to get me rolling so low gearing isn't really helpful on my hybrid, but my mid-range response was better going to 38t & my motor just loafs along at 35 to 40mph though my bike is more than twice the weight of yours.

I may also change to the Mikuni this Summer and see how she runs, but got projects running out my ears at the moment

Rick C.
 
Last edited:

Tyler6357

Well-Known Member
Mar 15, 2012
1,115
162
63
Santa Barbara, CA
I actually use a 38t on my hybrid. I ran a 36t on the bike before I added electric power because of the extra 30lbs.of extra weight with the e-hub and battery pack. I don't know where the sweet spot for gearing on your bike will be, but if you have a 44 or 42t on hand to try it will give you some idea of how much or how little gearing change will be required.

The Mikuni is hard to beat. It's an all round good performer and nice upgrade for modified motors, plus it's got tuning adjustments that the Dellorto clone lacks. With your x-pipe you should have a defined mid-range improvement and the carb helped uncover it. A small change in gearing is also useful to keep the rpm's in the power band that each motor develops, but 36t might be where you end up...though I suspect 40t or so will be an improvement for you and perhaps for me as well. I tried 44t & it was a bit too low for me and I didn't have a 40 or 42 to try. I use the electric to get me rolling so low gearing isn't really helpful on my hybrid, but my mid-range response was better going to 38t & my motor just loafs along at 35 to 40mph though my bike is more than twice the weight of yours.

I may also change to the Mikuni this Summer and see how she runs, but got projects running out my ears at the moment

Rick C.
Well, when I first built my bike the idea was to put a shift kit on it. I had planned to get it built and then put the shift kit on it as an upgrade later. I had a 7 speed rear hub and derailleur already on to make the transition quick and easy, I had put on a 40T direct drive using a rear sprocket adapter until I got the shift kit. However, shortly after this the reed valve became popular and I decided to get one of those. It seemed to give me enough extra power that I decided I don't need all the gears of the shift kit for low end hill climbing. So at this point I decided to get mag wheels, I figured they would be stronger and easy to keep true. I could ditch the sprocket adapter and use the disc brake mounts for the rear sprocket and ditch the derailleur and just go with a single speed on the peddle side and it was at this time that I switched to the 36T sprocket. The last thing I did was put the Mukuni on, but this was only after I had switched to the 36T. Performance might be different with the 40T and the Mukuni. I also have a 38T I could try too. The latest thing I got is a larger reed valve intake manifold so I can fit the Mukuni on without using a vacuum hose and thread tape with clamps, haha, but I haven't tried it yet. I guess that's what I find fun about this hobby, just trying out different stuff.
 
  • Like
Reactions: FOG and indian22

indian22

Well-Known Member
Dec 31, 2014
3,646
3,939
113
Oklahoma
Tyler I think you've got a mild case of the unique bike virus that is hard to get rid of. One symptom is having fun while solving problems and selecting alternative outcomes that at times are failures, but get you one step closer to your goal. There is no real cure, but enjoying the process more than offsets the frustrations.

I'm glad you have those two sprockets in hand & my guess is one or the other will suit you, but that's the fun of guessing and I've been wrong before. The main thing is finding the correct ratio for your purpose & not about what I think will work.

I've cobbled stuff together in the past with what I had on hand, but it's nice to finish off with something that both works and looks good too. The Mikuni and reed with piston window should work and look good too.

I'm not a shifter kit hater, there are some really nice builds that feature them, but I can't bring myself to trust that small chain transferring 5 hp with "cross chain" shifter chain lines a couple of hundred miles from home. I snapped a pedal chain on my 500 mile trip last Fall and it was setup perfectly straight. With my hybrid I still had two motors, one with chain, to get me home and this lesson fortified my distrust of pedal chain strength and this was just the latest bike chain failure of many suffered in my 72 years of biking, well 67 years to be exact.

Rick C.
 

EZL

Well-Known Member
May 13, 2016
271
542
93
Chenoa, Illinois, USA
Tyler I think you've got a mild case of the unique bike virus that is hard to get rid of. One symptom is having fun while solving problems and selecting alternative outcomes that at times are failures, but get you one step closer to your goal. There is no real cure, but enjoying the process more than offsets the frustrations.

I'm glad you have those two sprockets in hand & my guess is one or the other will suit you, but that's the fun of guessing and I've been wrong before. The main thing is finding the correct ratio for your purpose & not about what I think will work.

I've cobbled stuff together in the past with what I had on hand, but it's nice to finish off with something that both works and looks good too. The Mikuni and reed with piston window should work and look good too.

I'm not a shifter kit hater, there are some really nice builds that feature them, but I can't bring myself to trust that small chain transferring 5 hp with "cross chain" shifter chain lines a couple of hundred miles from home. I snapped a pedal chain on my 500 mile trip last Fall and it was setup perfectly straight. With my hybrid I still had two motors, one with chain, to get me home and this lesson fortified my distrust of pedal chain strength and this was just the latest bike chain failure of many suffered in my 72 years of biking, well 67 years to be exact.

Rick C.
I ran into a problem trying to find a long length of bicycle chain for the 212cc build. I really doubt that I'd want to try to pedal that bike
even with breaking the chain link on the CVT but the good thing about pedals on the bike, a cop doesn't bother you if you run the
212cc like it's a 49cc. I went ahead and ordered some master links for the bike chain and thought, what the heck I have all of that
soft 415 chain laying around with extra master links so I tried using it! Believe it or not, 415 will work as bicycle chain--OverKill!
I got the master links in and I'm hesitant in messing with the 415 since it is working out. BTW, the #41 chain can't be beat on this
setup. A lot has changed on the ole bike, different engine mount, Mikuni carb, ManicMechanic chain tensioner and many other
things changed. The ManicMechanic chain tensioner sprocket I replaced with a good quality nylon unit which works better for
chain alignment. I have a trailer coming in that connect to the seat post and I might add, the Mikuni made a BIG DIFFERENCE
over the factory carb even with it's oversize jet. The Mikuni is a real Japanese Mikuni slide carb not a knockoff Chinese. The
HP increase and torque off of the engine is more responsive and I wouldn't dare try a hole shot with the bike! The e-ring on
the carb has to be set higher to lean it since it was running too rich but the fist pull on this carb had the engine come alive.
I have to now get a set of disk brakes and a suspension for on the bike. The bike is fun to ride with more than enough power
to get you out of the way of idiots on the street with their careless driving.

As far as Covid-19 the people in the heartland are ignoring it EXCEPT A FRIEND of mine who is scared of contracting the
flu-virus. Do not venture out if your immune system is low I am thinking people are developing immunity from a "Herd immunity"
which is what has been stated by MDs. LET THE SUN SHINE AND RIDE!

Dennis
 
  • Like
Reactions: indian22

Tom from Rubicon

Well-Known Member
Apr 4, 2016
1,018
1,819
113
Rubicon, Wisconsin
EZL,
Pedal side on my Sportsman Flyer I used https://theshadowconspiracy.com/product_feature/the-shadow-interlock-supreme-chain/
It takes a special tool to break it and make it. Cheap it is not but excellent it is. I came up short by a few inches and had to get another length. Every link is a half link.
Strong? Jeff Wolf of Culver City Classics has used it as drive chain on some of his builds.
Food for thought.
Tom
 
Last edited:
  • Like
Reactions: EZL and indian22

EZL

Well-Known Member
May 13, 2016
271
542
93
Chenoa, Illinois, USA
EZL,
Pedal side on my Sportsman Flyer I used https://theshadowconspiracy.com/product_feature/the-shadow-interlock-supreme-chain/
It takes a special tool to break it and make it. Cheap it is not but excellent it is. I came up short by a few inches and had to get another length. Every link is a half link.
Strong? Jeff Wolf of Culver City Classics has used it as drive chain on some of his builds.
Food for thought.
Tom
I hear you on "short by a few inches!" I had plenty of the 415 and didn't want to cut #41 which is far better quality chain.
I've had to buy several lengths of the standard chain from Walmart but I definitely don't want to have to pedal this heavy
bike very far and my old 49cc was bad enough to pedal when I had problems with the engine a few years back. The
Predator 212 is far more reliable from what I have found out.
Dennis
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,115
162
63
Santa Barbara, CA
Tyler I think you've got a mild case of the unique bike virus that is hard to get rid of. One symptom is having fun while solving problems and selecting alternative outcomes that at times are failures, but get you one step closer to your goal. There is no real cure, but enjoying the process more than offsets the frustrations.

I'm glad you have those two sprockets in hand & my guess is one or the other will suit you, but that's the fun of guessing and I've been wrong before. The main thing is finding the correct ratio for your purpose & not about what I think will work.

I've cobbled stuff together in the past with what I had on hand, but it's nice to finish off with something that both works and looks good too. The Mikuni and reed with piston window should work and look good too.

I'm not a shifter kit hater, there are some really nice builds that feature them, but I can't bring myself to trust that small chain transferring 5 hp with "cross chain" shifter chain lines a couple of hundred miles from home. I snapped a pedal chain on my 500 mile trip last Fall and it was setup perfectly straight. With my hybrid I still had two motors, one with chain, to get me home and this lesson fortified my distrust of pedal chain strength and this was just the latest bike chain failure of many suffered in my 72 years of biking, well 67 years to be exact.

Rick C.
Yes, another reason I decided against the shift kit was the bicycle derailleur. I wondered how it would hold up with the chain flying through it at those speeds. The chain also worried me too. Could it break under load? Would it become twisted? Would it probably need to be replaced often? I didn't want to deal with that and the reed valve gave me what I wanted anyhow. But I'm not a shift kit hater either, it probably is good on the engine, since the gears allows the engine to run at lower RPMs so it don't have to be screaming to get it up to speed.