I was hoping that the chap making the hubs was still doing it but I'm sure he wasn't able to compete with the main stream. Just not a big enough niche to make a go of it.
Steve.
Steve.
Bike builders that have machine tools/shops
- Thread starter Tom from Rubicon
- Start date
Fellas, I got those rims in yesterday and looked them over. They look like pretty good quality and check to see that they were
running true. There was a 36 tooth sprocket on them and I am going to try it to see how it does? I might have to go with a
smaller sprocket since I was running a 34 tooth on the bike before with a hub adapter. Both rims are setup for disk brakes
and that is something I will have to buy later on. The building never stops I guess?
running true. There was a 36 tooth sprocket on them and I am going to try it to see how it does? I might have to go with a
smaller sprocket since I was running a 34 tooth on the bike before with a hub adapter. Both rims are setup for disk brakes
and that is something I will have to buy later on. The building never stops I guess?
A couple of packages by the door this last Thursday, one from Motion Industries with another Martin 41b13 sprocket. The other from MSC had my 1/4;28 flat head torx drive screws for mounting the sprocket.
Woke up early Fri. AM coming down with a cold, went to work cause feeling like crap is worth getting paid wages.
Home Friday no shop time, colds require lots of fluids ingested so I did. Mostly barley pop and finished with chardonnay. Back at it today, locked the Martin sprocket in the emergency collet and bored the I.D. to .770" , 19.55mm and faced the hub to .240", 6.09mm. Now it's in the mill bore indicated zero, zero. Tomorrow it gets drilled and reamed to .251.
Funny thing is I bought the second sprocket because the first one I machined was odd in that it machined like
Meehanite cast iron and the one machined today was the same. Are small sprockets now being made of iron?
I mean I know iron wears like iron but they were until recently made of steel. So now I have two 41x13 sprockets of the same material.
Upside is chain line is nearly as perfect as man can make.
Tom
Woke up early Fri. AM coming down with a cold, went to work cause feeling like crap is worth getting paid wages.
Home Friday no shop time, colds require lots of fluids ingested so I did. Mostly barley pop and finished with chardonnay. Back at it today, locked the Martin sprocket in the emergency collet and bored the I.D. to .770" , 19.55mm and faced the hub to .240", 6.09mm. Now it's in the mill bore indicated zero, zero. Tomorrow it gets drilled and reamed to .251.
Funny thing is I bought the second sprocket because the first one I machined was odd in that it machined like
Meehanite cast iron and the one machined today was the same. Are small sprockets now being made of iron?
I mean I know iron wears like iron but they were until recently made of steel. So now I have two 41x13 sprockets of the same material.
Upside is chain line is nearly as perfect as man can make.
Tom
Yes Rick, I went with the mag wheels to try out and if they don't work out I'll be going with the 11 ga. spoked wheels.
Getting the tires to seat good on the rims was the biggest problem since the rims are narrow and they say that the
2.125" tires fit the rims. I found that there is a big weight difference between the old rims and the mag wheels.
The 36" sprocket is too dangerous to use with this torque monster. Have to be careful with the throttle it wants
to break loose the tire and raise the frontend. My old 750 Kawasaki was way too dangerous if it got traction so
I'm Leary of putting too much throttle to this one since it's a bicycle frame. I took it into town and the gearing was
pretty docile for putting around town. I might get hold of Lynn and try a 32 or 30 tooth sprocket to soak up that
torque. Most of my riding is distance on a flatlands with wind and no need for acceleration even though the 34
sprocket had plenty. I pulled the governor out of this engine along with the low-oil sensor and I suspect that the
engine still isn't fully broke-in yet. I did manage to get the mechanical speedometer working on the rim. I put a
new 41 chain on the bike so it should hold up good for awhile until the 212 breaks something else.
The CVT makes all the difference on these bikes and very little vibration with smooth take-off. You need to look
into building a 79cc with one. I doubt that a 49cc would have enough hp to turn them since they will use some hp.
A nice 20-25 mph cruise speed and the hills/wind don't affect it. Th power is good getting out of the way of idiots
in the cars. I do think a motorcycle frame is the way to go with this engine and even a 420cc engine to safely use
that torque.
Dennis
I'll get those photos out in a few days for you fellas.
The wheels were BBR wheels from Ebay for $109: https://www.ebay.com/itm/BBR-Tuning-26-Inch-Heavy-Duty-Front-Mag-Wheel-for-Mountain-Bikes-Beach-Cruisers/173688390255?epid=26021813969&hash=item2870a2826f:g
xIAAOSwoDFcEV7II was surprised to see them get to me so fast they were shipped FedEx. I had to shim rear wheel out since that darn
cassette used a wider rear fork spacing and some of the original spacers and added washers helped get the wheel
aligned. I didn't want to disturb the original engine/CVT alignment on the bike. I will need to order a rear pedal
sprocket that goes on the wheel. I am currently not concerned with a pedal chain setup until I decide on how I'm
going to remount the engine using a different engine mounting plate. I've already put 20 miles on the bike and will
be looking for problems so the wheels will be a ongoing test to see if any problems show up. The wheels are also
made for disk brakes which at a later date I will have to look into.
Back in the shop this afternoon to drill, ream, and counter boring the three bolt holes 82 degree bottom .093" deep of full dia. using a 82X.375 dia. countersink.
I modified three 1/4-28 X 3/4" flat head torx screws. I turn the heads down to .365" dia. to fit the counter bore.
The modified flat head has more head engagement than Pat' Low Heads not much but more is better.
Dropped the sprocket onto the reduction drive body and all screws mate without friction.
Some comparison photos of a stock sprocket and my Frankensprocket and accompanying fasteners.
I modified three 1/4-28 X 3/4" flat head torx screws. I turn the heads down to .365" dia. to fit the counter bore.
The modified flat head has more head engagement than Pat' Low Heads not much but more is better.
Dropped the sprocket onto the reduction drive body and all screws mate without friction.
Some comparison photos of a stock sprocket and my Frankensprocket and accompanying fasteners.
Attachments
So after work yesterday 8/26/19 I did what I thought would do a final assembly of the reduction drive. Bolted up with Loctite blue the 41b13 sprocket to the aluminum carrier hub that on the opposite side carries the 35a42 sprocket, the total of which creates the reduction drive. All assembled, and slipped into the bottom bracket. All was mission ready to go until I spun the sprocket cluster. I am seeing what to me is a huge run out of the 41b13 sprocket. I am not pleased with what I am seeing. Is eccentric run out acceptable and to what degree? Here is what I measured with a Starrett Last Word indicator.
Spinning in my Logan Lathe spindle in a 5C collet gripping the reduction drive pedal crank shaft which the reduction drive is pressed onto. The following readings.
These indicator measurements are from the aluminum hub sprocket carrier.
The #35 sprocket O.D. , 2.375” indicates .015 TIR
The #41 sprocket O.D. , 1.575” indicates .026 TIR
The pedal shaft .003 TIR
The face of the 35a41 sprocket mating surface .002” TIR
The indication measurement over to #41 sprocket teeth is .026” TIR
When drilling and reaming the three mounting screw holes in the 41b13 sprocket I can account for only a .002 TIR run out total. With out saying more. Is this sprocket run out within acceptable range ?
Last year I never experienced any what I would call pulses in power delivery so is this .026” eccentric runout to be ignored and just ride it like I stole it?
I would prefer a minimum of eccentric runout. Feed back guys. I would like the get some seat time before frost bite season.
Tom
Spinning in my Logan Lathe spindle in a 5C collet gripping the reduction drive pedal crank shaft which the reduction drive is pressed onto. The following readings.
These indicator measurements are from the aluminum hub sprocket carrier.
The #35 sprocket O.D. , 2.375” indicates .015 TIR
The #41 sprocket O.D. , 1.575” indicates .026 TIR
The pedal shaft .003 TIR
The face of the 35a41 sprocket mating surface .002” TIR
The indication measurement over to #41 sprocket teeth is .026” TIR
When drilling and reaming the three mounting screw holes in the 41b13 sprocket I can account for only a .002 TIR run out total. With out saying more. Is this sprocket run out within acceptable range ?
Last year I never experienced any what I would call pulses in power delivery so is this .026” eccentric runout to be ignored and just ride it like I stole it?
I would prefer a minimum of eccentric runout. Feed back guys. I would like the get some seat time before frost bite season.
Tom
Tom minimal is a matter of personal perspective, but minimal is good. I'm not an advocate of shoddy work and know your not like that either. So with that disclaimer I'll reveal my true nature and add a but....
I've built 5 of these offset reduction drives running on the pedal bracket shaft using nothing more than off the shelf go cart jack shaft sprockets welded back to back...well a bit more than that but basically a simple design. Three run fine two are junk. I'm certain your tolerances, at the moment, are much tighter than mine have been, don't know 'cause I didn't check, just mounted on the pedal shaft and gave them a few spins while eyeballing a straight edge. Real world results: three work under power and the Harley dynos 14.5 hp and the Simplex about 12 hp and both tied to 5 speed transmissions. Quite a few miles & a couple of years latter I've not worn the brackets, sprockets or broken chains so I'm golden with what I have. What I suggest to all who will listen is about proper basic setup: with the chain lines perfectly straight & the wheel assembly centered and perfectly aligned with constant, proper chain tension, regulated by a properly mounted spring loaded tensioner, the last optional but highly recommended....then ride it like you stole it!
If you can feel the bike pulsing it's out of the tolerance range you're working with, perhaps, on the reduction gear assembly itself, but I'd not think that's the problem. Eyeballing chain lines and wheel alignment/placement and chain tension is for most installers much less precise and therefore much more suspect when dealing with drive line problems. If you run a spring loaded tensioner it's a great indicator of total drive line eccentricity when it levers wildly to keep the chain tension constant, but if you choose to run a free chain with no tension device in line, you can slowly rotate the tire though it's entire range constantly checking for any spots that the chain deviates from the proper tension mid-chain. Loose, tight, perfect in each rotation is very bad.
Properly setup I think your good to go, but I've been wrong before. You know your machine and your skills...so trust what you know! It takes less time to check it out on the bike than to worry about it.
Rick C.
I've built 5 of these offset reduction drives running on the pedal bracket shaft using nothing more than off the shelf go cart jack shaft sprockets welded back to back...well a bit more than that but basically a simple design. Three run fine two are junk. I'm certain your tolerances, at the moment, are much tighter than mine have been, don't know 'cause I didn't check, just mounted on the pedal shaft and gave them a few spins while eyeballing a straight edge. Real world results: three work under power and the Harley dynos 14.5 hp and the Simplex about 12 hp and both tied to 5 speed transmissions. Quite a few miles & a couple of years latter I've not worn the brackets, sprockets or broken chains so I'm golden with what I have. What I suggest to all who will listen is about proper basic setup: with the chain lines perfectly straight & the wheel assembly centered and perfectly aligned with constant, proper chain tension, regulated by a properly mounted spring loaded tensioner, the last optional but highly recommended....then ride it like you stole it!
If you can feel the bike pulsing it's out of the tolerance range you're working with, perhaps, on the reduction gear assembly itself, but I'd not think that's the problem. Eyeballing chain lines and wheel alignment/placement and chain tension is for most installers much less precise and therefore much more suspect when dealing with drive line problems. If you run a spring loaded tensioner it's a great indicator of total drive line eccentricity when it levers wildly to keep the chain tension constant, but if you choose to run a free chain with no tension device in line, you can slowly rotate the tire though it's entire range constantly checking for any spots that the chain deviates from the proper tension mid-chain. Loose, tight, perfect in each rotation is very bad.
Properly setup I think your good to go, but I've been wrong before. You know your machine and your skills...so trust what you know! It takes less time to check it out on the bike than to worry about it.
Rick C.
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I'd "just ride it like I stole it" to give it a trial run. 
to give it a trial run. EZL I couldn't believe the low price on those cast wheels. I hope you get disc brakes sooner than too later!I'd "just ride it like I stole it"
Rick C.
I'm thinking of a spring tensioner on mine but a belt drive would be the smoothest ride! I checked that factory 36 tooth
sprocket for alignment and it didn't have any run out. I did notice a variation on chain tension when the wheel was
rotated by hand? There's no pop in the chain which is what a fella doesn't want! I always checked the old bike by
rolling the bike by hand to listen for a popping sound in the chain which would tell if the sprocket was aligned right.
I came across a expensive laser alignment tool which would tell more and would be good to have. Firing up the engine
and watching the chain and the noise it seemed ok. I might still try a spring tensioner and see if there's any bounce in it.
I'm still thinking of going with a smaller sr
Dennis
Yeah, I hear you on that. I don't run this thing in a big metropolitan area and I mostly ride it in the country.
I retained that darn v-brake in front and removed that v-brake in back and went with a new brake on the
back from Lynn. The braking is good but a set of disk brakes would be the best. The bike with the CVT
likes to roll it's not like that transmission on the "Ghost Racer 7G" bike. That bike seems to have a lot of
engine braking and I haven't had any problems with the belt on it and that's a wonder!
Dennis
Thanks for the come back Rick, and your advice.
I was never aware of any pulsing in the drive train.
I wasn't looking for any either and when I originally set the bike up. It didn't produce any problematic symptoms to alert me of this run out condition.
As is, I know what some Winter evenings and a weekend or two will be devoted to. Reverse engineering the aluminum sprocket carrier. Fussiest thing will be the pocket for the bearing. Heat shrink on the bearing pocket for sure.
All the bolt circle drill patterns have been developed and were proved when the steel sprockets were machined.
So I guess I won't send Pat a nasty gram like I was thinking of doing but this is shoddy workmanship to me.
Dennis,
The first time I rode this bike last August it was ride it like you stole it from the get go. The engines were designed for it.
My wanting this critical part of the drive train to be the best it can be is motivated by my having another 79cc Predi engine to be sent to AGK for the full treatment to boost a three horse engine to five horse.
Same guy did the voodoo in Pat Dolan's Bonneville record holders.
Tom
I was never aware of any pulsing in the drive train.
I wasn't looking for any either and when I originally set the bike up. It didn't produce any problematic symptoms to alert me of this run out condition.
As is, I know what some Winter evenings and a weekend or two will be devoted to. Reverse engineering the aluminum sprocket carrier. Fussiest thing will be the pocket for the bearing. Heat shrink on the bearing pocket for sure.
All the bolt circle drill patterns have been developed and were proved when the steel sprockets were machined.
So I guess I won't send Pat a nasty gram like I was thinking of doing but this is shoddy workmanship to me.
Dennis,
The first time I rode this bike last August it was ride it like you stole it from the get go. The engines were designed for it.
My wanting this critical part of the drive train to be the best it can be is motivated by my having another 79cc Predi engine to be sent to AGK for the full treatment to boost a three horse engine to five horse.
Same guy did the voodoo in Pat Dolan's Bonneville record holders.
Tom
Tom the AGK engines have taken home a lot of trophies in the carting world & build great power and survive. I suspected Pat used them for his race engines long before he posted them as a resource. The Predator is a great Chinese clone at an unreal price point, every bit as good as the Honda & really affordable. One can buy a lot of aftermarket parts with the left over dollars!
Pat's race bikes hold together on the salt at 80 mph + which is the equivalent of 90 mph + on asphalt; so he's doing a lot really right.
Rick C.
Pat's race bikes hold together on the salt at 80 mph + which is the equivalent of 90 mph + on asphalt; so he's doing a lot really right.
Rick C.
Cant passs 20mph!I got a bike phone holder to check speed ..and it wont pass 20mph!thats when it starts to hold back I've road it across town about a 15min drive and 15 mins back..around the block, store..38 tooth sprocket,throttle low and mid fine but the full throttle is what's frustrating me..i kno she got more in her!...did 16:1 one time due to the second time it was going lean or something and the gas was sucked up quickly..then changed to 20:1mix..still on..since I've put jet #75 it finally idles better and bike barely gets hot as it used to.. Not sure if I should try jets 71-74..I took the plug out and took more pics from the run across town and around the block..and I weigh 220lb
Just a heads up 4izzy. Double posting the same question on multiple threads in the forum is rather frowned on. Also select the topical help thread category related to specific topics for answers...this helps us help you better & keeps the threads rolling smoother as well.
Rick C.
Rick C.
I don't blame you for being picky on a new engine with tolerances. The Predator engines give a lot of bang for the buck!
The drive train is what gives us the biggest problems. Darn time is flying and it's going to be Winter before we know it
and I feel like I'm not getting enough done before then. I got to get out of here and go work on the lawn tractor now.
Dennis
So from the replies the votes are in and for now it is run it like you stole it.
When I got home from a very good day at work,
I completed both projects that were my current workload. Grab a barley pop and down to the shop where I got the reduction drive out of the lathe, stored the indicator, and reinstalled the R.D, with shims and spacers to reduce the pedal crankshaft side play, A little more adjusting and it will be ready for chains.
But first thing tomorrow is a road trip to Minneapolis for a couple of days or more. Brother in Law Mark turns 74 and we rarely miss helping him wish he wasn't so old
I was supposed to take advantage of this Northerly trip and extend it to visit Bike Camp but that isn't working out as I had hoped. So do your best to keep this thread alive until I return.
Tom
When I got home from a very good day at work,
I completed both projects that were my current workload. Grab a barley pop and down to the shop where I got the reduction drive out of the lathe, stored the indicator, and reinstalled the R.D, with shims and spacers to reduce the pedal crankshaft side play, A little more adjusting and it will be ready for chains.
But first thing tomorrow is a road trip to Minneapolis for a couple of days or more. Brother in Law Mark turns 74 and we rarely miss helping him wish he wasn't so old
I was supposed to take advantage of this Northerly trip and extend it to visit Bike Camp but that isn't working out as I had hoped. So do your best to keep this thread alive until I return.
Tom