Cannondale/Honda GX31 GoCart Transmission: Show me some Love

[Albula vulpes]

This is what I've got:

VTG Cannondale M300 Mountain Bike that I converted to a Street Commuter

Honda GX31 4 stroke Engine

GoCart Transmission: I opened it up it looks strong and durable. has 83 teeth on the spur gear, and 12 teeth on the pinion gear. The outside drive sprocket on the transmission has 8 teeth.

Was looking to mount the engine/transmission on the Cannondale.

What are your ideas/suggestions?

Thank you

 

[ocscully]

That's a real interesting setup you have there. The reduction from the gearbox while a lot more than most is still not enough for a 26 in. wheel bike. The other factor about the gearbox you have is that since it uses only two gears internally it reverses the direction of rotation. which means the out put sprocket turns in the wrong direction to drive a sprocket on the left side of the wheel. You could turn the motor around and then run the output sprocket to a set of freewheeling chainrings on the crankset for a frame mounted set-up and have the use of your rear cogset for both the pedals and the motor, or you could rack mount the motor and trans. and then jackshaft the output back to the left side and drive a single sprocket mounted to the left side of the wheel. What ever way you go you are in the world of building a custom drivtrain and this can get expensive very quickly. As a form of research look at the kits offered by Thats Dax bicycle engine kit, bike engine, bicycle engine, bicycle motor and Sick Bike Parts LLC - Performance parts for your motorized bicycle also try www.thescooterguy.org

ocscully

 

[jcchappy]

If you get the gearing sorted that cannondale with its light aluminum frame will fly! I had a 90 something cannondale that i was going to put a china girl on but traded it for an old schwinn bf goodrich to build. Super light bikes.

 

[Albula vulpes]

Thanks,

I do not have that much experience, however I was hoping on keeping/making it inexpensive. If I understand correctly the gear ratio that is needed to turn a 26 inch wheel in the 20-30mph range is around 18-to-1 with these size engines. Am I correct? I'm not completely sure how to figure out the ratio on this gear reduction gearbox. I think it is the number of teeth on the big gear divided by the number of teeth on the little gear, which would be 83teeth/12teeth = 6.9166-to-1 reduction, thus I'm short and further reduction is needed. I understand that the engine/gearbox does rotate the way that would require me to drive from the right hand side of the bike if other items were not added(jackshaft) to make it run on the other(left) side. I was kinda hoping on keeping it simple and making/keeping it drive off of the right hand side. I saw a thread with someone that took the rear 7 speed cassette off and put two single cog right hand threaded freewheels on that worked independently of one another. One freewheel was connected to the pedal drive chain and one freewheel connected to the engine drive chain, thus making a right hand engine drive possible. Is this correct? or did this not work out for the guy?

If this is possible then to drive from the right hand side of the bike with the dual RH threaded freewheels, and further reduction is needed to achieve a ratio in/around the 18:1 number, then the additional reduction that would be needed is around 2.7. So if i get 6.9166 and multiply it by 2.7, I get: = 18.67-to-1 which would be ideal right? The guy i got the engine/gearbox from had/put on a 8 tooth pinion/output drive sprocket that is on the gearbox now. So if I got a say a 22 tooth single cog freewheel for the engine drive chain to run on and mounted it on the right hand side of the bike this would make a ratio of 2.75 additional reduction, thus making 6.9166 * 2.75 = 19.02-to-1 ratio. Is this right? The engine drive sprockets seem small. What effect will/would this have?

As far as the mount is concerned, I would like to mount it inside the frame for a lower center of gravity, and because i would like to use the rear rack for cargo. If I had to make it fit on a rack on the back, I probably could construct a rack to hold the engine/gearbox. It fits it in the frame, and clears the pedals without me even having to loose the gas tank. I would like to ditch the gas tank though for a greater capacity size tank that would fit on the rear cargo rack, and that would even give me even greater pedal clearance with the stock tank gone.

I still am not sure how to build the rear dual RH freewheel drive, but have been studying it, and was hoping on utilizing this method for an inexpensive drive for this gearbox. Right now I'm at a standstill scratching my head and trying to put the pieces together, hoping this motor bicycle would be a reliable, simple, and economical mode of transportation as a daily commuter.

Thanks for your help, and if you can see any mistakes or any future problems/obstacles that would occur with me and making this motorbicycle work shown in the above idea/plan, please tune in/speak up. I know others have come before and done there own D.I.Y. motorbicycles. Some sage advice is appreciated from those that have taken that leap, and built there own.

Thanks again,

 

[corgi1]

grease the trans.gears

 

[corgi1]

If you are going to center frame it ,I think I would use a jackshaft and run from the left

 

[Nohandle]

Long term lurker, probably 2 years now. But I had to post. I have built about 6 gas bicycles under the oregon gas asisted scooter law that allows sub 35cc engines and a sub 24 mph speed bicycles to be exempt from insurance registration title and license laws.

Obviously your 6.9 to 1 roger box is super cool. Could you post some links to where you bought it. When my account matures i'll post some pics. Finally nothing is more important than chain alignment and tension, then possibly sprocket concentricty. Good and your idea of useing the other dudes double sprocket is excellent, or you could just get a double sprocket from staton. Thanks.

 

[jcchappy]

since the gear will be on the right side anyway you could use a freewheel front crank to drive the rear wheel. some ross road bikes had them stock.

 

[ocscully]

I kind of remember the dual freewheel thread you are talking about and I seem to remember that the guy modified a couple of Staton Inc's freewheel adapters so they would slip onto the cassette hubs freehub? I can't for the life of me find the thread using the search, every query seems to generate the same 500 hits. It seems to me also that Staton also has some type of dual drive sprocket set up for their Nuvinchi Hubs but I not sure just how it is accomplished /done. You might want to spend some time there checking out all of his various adapters. Your gearbox I believe is one of Dave Staton's early gearboxes? As for you ratio #'s they appear to be accurate to my eye. There is a ratio calculator sticky at the top of this section of the forum.

ocscully

 

[Nohandle]

I'm very familiar with most of the staton boxes. Again this looks very similiar. I'm really hoping for a source of geared roger boxes that are inside drive. That aren't american expensive, i know i i'm terrible. This one's,effective 7/1 ration allows alot of benifits as in using stock freewheels on the back. I would still like to know where you got it. Thank you.

 

[Albula vulpes]

Thanks for the replies, It keeps the juices flowing and the feet moving forward,

Thanks for the advance notice on greasing the gearbox. I'm not too gear savvy, and would have probably run it like it was if I got this bike going. It looked greased to me. I still have not ruled out jackshafting it and running it on the left, but that would require alot of additional items. I.e. Jackshaft, and then i would have to get a left hand threaded hub, and left hand threaded freewheel. Last time i checked the hub was $109.00 on stanton's website, I'm not too interested in using the rubber 9 bolt sprocket-to-spoke squeeze method. I did this on a previous build i got as a kit on ebay and broke spokes. It seems to me the driving from the hub is the best way to transfer power from the engine to the ground.

Thanks for the compliment on the gearbox. I do not know who the manufacturer is. (I typed "roger box" in google search) and got nothing. If anyone knows who the Mfg is, please let me know. There is no markings on it. I got it from a guy that had this engine and gearbox mounted on a gocart/pedal car that was a father/son project. I checked stanton's website for a "double sprocket" in his sprocket section. I didn't see one and not sure what you are talking about. If you could patch me a link, I would appreciate it.

Thanks for the idea about the freewheel crank that some Ross bicycles had. Did a little research to find out what you were talking about and this is what I came up with:

VINTAGE SHIMANO INTEGER BICYCLE 52/39 FREEWHEEL CRANKS - eBay (item 390181830501 end time Jun-10-10 17:16:59 PDT)

It looks like back in the 70's Ross used this system on some of there bikes. It is called a Shimano Integer FF Freewheel Cranks. Good idea. Looks like the same concept as the Sick Bike Parts Freewheel cranks?

Thanks for the info about the gear ratio conversion tool. Does anyone know what the RPM of this engine is that I should put in the RPM field in the gear ratio conversion chart/tool? It is a Honda Gx31 Four Stroke.

I saw this on YouTube from thescooterguy. I'm not sure if it is in production, but it looks slicker than snot. Same concept as the double single cog RH freewheels, you just get greater range with the pedal cranks.

YouTube - secondary right side drive

I like the looks of it, not sure if it would work for my application though. The Engine drive sprocket looks large. I still am not sure if this is correct. If my gearbox is 6.9 to 1 and if I got a 22tooth freewheel for the rear to drive the engine chain on the 8tooth output gear on the gearbox, then I would get:

6.9 * 22/8 or (2.75) = 19.02 to 1. Would this be sufficient reduction to turn the 26 inch wheel in/ around the 20 to 30 mph range?

I like the idea of the front freewheel cranks because that would allow me to use the derailleur in the rear to have more engine gear range, keep the engines output on the right side, keep the cassette, and use gears to help the motor transfer power to the ground more effectively. With the Sick Bike parts freewheel cranks, I see that they are square taper. Since I have enough pedal clearance with the stock bottom bracket and cranks I have now. Would all I need from Sick Bike Parts be the Cranks, the two Chain Rings, the freewheel adapter, bolts, and a chainring spacer? and i would be good to go? Or in order for the Freewheel Cranks to work do I need the sick bike parts bottombracket/axle to mount the cranks too? Also looking at the pictures on there web site it is hard for me to decipher, Does the engine drive chain drive off of the back chainring that is closest to the bike, or the outer chain ring that is furthest from the bike?

I've got the materials laying around our shop to make a motor mount that would allow me to make a clean mount of the Gx31 inside the frame.

If you could please answer the questions above to keep the feet moving more forward on this motorbicycle, I would appreciate it. The juices are still flowing and I'm starting to see the light at the end of the tunnel, that would give me confidence to start making forward progress by cutting materials and ordering/buying needed parts.

Many thanks to those who have contributed already,

 

[5-7HEAVEN]

Index of /ratiocalc

That will help you set up gearing. An 18.75:1 seems to be the standard we builders strive for. It is what Staton gears his chain drive kits for. Your 19:1 ratio is a good start.

Spin the clutch drum counterclockwise, to see which way the output shaft turns. If the shaft turns clockwise, then the drive gear will be on the same side as the bicycle sprockets. If the shaft turns counterclockwise, then the engine clutch faces left. An intermediate jackshaft will then be needed to add extra sprockets to align with bicycle sprocket and freewheel.

 

[5-7HEAVEN]

The engine will drive the outer chainring.

I have a scooterguy project going on for a year, mounting a Mitsubishi/Tanaka/whatever engine and driving thru the gears. Still working on it.

Then I started thinking about installing the Mits engine midframe like SBP has for the Honda X50/Huasheng/style. SBP sells the motormount/jackshaft combination which would work well for you. Just need to redrill mounting plate to accept your smaller Honda engine. Unfortunately, my bike's seat tube and downtube are oversize. I need to look for another bike in order to use their equipment.

Please contact SBP at their website, as they are very helpful guys. In fact, I'm surprised they haven't chimed in here, as they frequent this forum. To make life easier, buying most of what you need from scooterguy or SBP would be an option.

 

[Goat Herder]

I kind of remember the dual freewheel thread you are talking about and I seem to remember that the guy modified a couple of Staton Inc's freewheel adapters so they would slip onto the cassette hubs freehub? I can't for the life of me find the thread using the search, every query seems to generate the same 500 hits. It seems to me also that Staton also has some type of dual drive sprocket set up for their Nuvinchi Hubs but I not sure just how it is accomplished /done. You might want to spend some time there checking out all of his various adapters. Your gearbox I believe is one of Dave Staton's early gearboxes? As for you ratio #'s they appear to be accurate to my eye. There is a ratio calculator sticky at the top of this section of the forum.

ocscully

I think it was Neat Times that made that free wheel set up . http://motorbicycling.com/f36/cvt-rack-mount-7265.html

 

[Albula vulpes]

Please excuse the mixup in the title. We have verification this is an Older Stanton Gear box. I got the engine and gearbox from a guy that had it mounted on a gocart. Hoping you can help me resurect it and get it on a bicycle.

Looking at the SBP or Thatsdax Freewheel Cranks minus jackshaft to make it work. Please check the numbers below and let me know if this is right.

Stanton Drive Gear Teeth: 12

Stanton Driven Gear Teeth: 83 = 6.92-to-1

Stanton Gearbox Output Sprocket Teeth: 8

SBP or ThatsDax Outer Chain Ring Driven Sprocket Teeth: 36 = 4.5-to-1

SBP or ThatsDax Inner Chain Ring Drive Sprocket Teeth: 24

My back Cassette Driven 8 Speed Sprocket(11 teeth -thru- 30 Teeth)


High = 24/11 = .46 -to-1 = 14.27 -to-1 TOTAL HIGH END REDUCTION

Low = 24/30 = 1.25 -to-1 = 38.91 -to- 1 TOTAL LOW END REDUCTION


So If I got the SBP or Thatsdax Freewheel cranks, I would have an available gear reduction ratio from 14.27 to 38.91?


Is this correct?

Please let me know. If someone could also please tell me what size chain turns the outer freewheel chanring on the SBP or Thatsdax freewheel cranks, I would appreciate it. The outdrive sprocket that came on the stanton box looks like it fits a rather large chain, and I would need to know what size sprocket to get with a 5/8" bore to replace the one that is on the stanton box now to make it mesh with the chainrings on the SBP or Thatsdax outer/drive chainring.

Many Thanks,

 

[corgi1]

Honda GX31.....is that 31cc ?.........If it is would the gear ratio need to be higher for hills and rider weight,maybe 25/1 ?

 

[Nohandle]

mmm. its early dave. I was really hoping the chinese had built something good. How dumb am I. Anyway because i build mini-bikes mostly with out pedals, i have 2 with pedals. A roger box is a reverse direction gear box. Because most of my projects are right side drive and direct drive i need more reduction than most and again and inside drive rights side output on the tranny helps me alot. All of daves more advanced boxes don't roger or drive right( the way i want to center the motor and avoid a jackshaft. The easiest solution for you with all that reduction would be to go with the scooterguy/sickbikeparts freewheeling front cranks. I think you would just need a larger input sprocket, 14 or 16 tooth instead of an 8 to exploit the full rear gear cassette. The honda is such a little guy. But i say build it and in one ride you will know what side tranny sprocket you neec and changing it should be cheap and easy. Thanks for clarifieing. I thought when you said go kart instead of pedal car the dream of cheap chinese was born..

 

[Albula vulpes]

Excellent, Thanks.

The engine is 1.5 hp. It looks like this might have been a complete unit(engine and gearbox) that stanton had sold some one a long time ago considering that from what I understand stanton touts Japan when it comes to engines. Considering how everyone is now saying that the Honda's are now made in Thailand, and it seems like most MB kit makers are pushing the Subaru Robin eh035 because it is still made in Japan. This engine is a Honda 1.5 hp and it says made in Japan on the case.

I would like to get the ball rolling on this, however i'm still at a standstill scratching my head trying to figure out what size(CHAIN) output sprocket I would need on the stanton right drive box to mesh with the outer drive chain ring on one of the freewheel crank kits. WHAT SIZE CHAIN RUNS ON THE OUTSIDE CHAIN RING OF THE THATSDAX OR SICK BIKE PARTS FREEWHEEL CRANKS? If you don't wish to disclose this info in an open forum, please send me a PM and let me know. I don't put the cart before the horse.

The other thing with this box though and getting a larger size output sprocket is that it does not have that much clearance from the output shaft and the gearbox case. It only has about 5/8" of clearance, so Im not sure if a 14 tooth sprocket would fit.

Also are these engines able to be mounted on a slight angle? say a 15 degree incline?. I think this might be necessary to clear the gearbox with the output chain going to the chain ring on the freewheel cranks?

Thanks,

 

[ocscully]

The folks at Sick Bike Parts use Standard BMX/Single Speed chain (1/2 X 1/8, #410) for the right side to the freewheeling sprocket. To go with the wider #415 causes clearance problems. The chain rings you've chosen 36t as the driven and 24t as the driver seem on the low side to me. On the 4-stroke shift kit I'm currently riding with the gxh50 and a 3.7:1 primary reduction gearbox I'm using a 48t driven and a 36t driver to a 13t - 30t Speed cassette. Sick bike parts offer several different drivers that fit 5/8 in. shafts that are optomized for the narrow 410 chain. I know they have 9t, 10t, & 11t.

ocscully

 

[Albula vulpes]

Thank you, Thank you, Thank you, Thank you, Thank you, Thank you, Thank you, oohhh, and Thank you. I'm so happy with this. I have to admit. I got this from the guy that had it mounted on a go-cart because if It didn't work out I could always throw the engine on a friction drive kit. This would have been my next step after two botched/failed china 68.5/80cc kits. I Love this setup. I took it out this morning and It hit 30mph on a flat. I only weigh 150lbs though, but it wasn't in the highest gear. Not that I was looking for a rocketship, but this thing is only 31cc's and it would eat my china 68.5/80cc kits. Thank you so much for recommending the Freewheel Cranks for this project. I thought that Sick Bike Parts only made the jackshaft shifter kits for the china kits. This combo seems like it best serves my needs. Right now I'm in Florida, but I'm going to take it with me to the N.C. mountains. I believe it is going to climb the hills/mountains like a champ.

Here are some photos I took today,

<img src = "http://i199.photobucket.com/albums/aa178/bonefish1855/DSC03722.jpg"
<img src = "http://i199.photobucket.com/albums/aa178/bonefish1855/DSC03739.jpg"
<img src = "http://i199.photobucket.com/albums/aa178/bonefish1855/DSC03742.jpg"
<img src = "http://i199.photobucket.com/albums/aa178/bonefish1855/DSC03744.jpg"
<img scr = "http://i199.photobucket.com/albums/aa178/bonefish1855/DSC03743.jpg"

I custom made the motor mounts out of scrap aluminum we had laying around our shop, and I used the bicycles frame water bottle mount holes to attach the aluminum motor mounts to the frame, so I didn't drill thru the frame and jeopardize it's integrity.

Thanks to all those who had a hand in making this happen. This hopefully will serve as a daily commuter for me. I installed a 1 gallon gas tank on the back cargo rack that will also serve as a place where I can store my backpack with laptop, so my back doesn't get all sweaty when I ride.

Thanks again, and I'm happy I'm not pedaling as much any more,