3 speed jack shaft

[Dan]

Is it a brand new engine Cam? I have only had one 4 stroke and was a lil disappointed with the take off power at first. After she broke in, was thrilled. Weird part was there was no "AHH" moment and never felt her break in. Just had more UMPH one day. Again, is my first so dunno

Again awesome build and thanks for sharing.

 

[wildemere]

I hope it all works out well, there is a guy in NZ with 6,000miles on a setup like yours.

I however blew 4 or 5 with a SBP shifter kit.

A good point however is the ability to shift while stopped.

Keep the shifts slow, steady and don't shift under power, all all should be well.

The drive pawls are the weak link, some units had the wrong heat treatment. I suspect the batch I was using had this issue.

Links to the 3 speed bikes I built if anyone's interested

http://motorbicycling.com/f15/shifter-bike-v2-0-a-3763.html

http://motorbicycling.com/f15/shifter-kit-installed-2785.html

 

[NEAT TIMES]

Cam, Nice Fabrication. I Have A Few Of Those Chain Drive Trannys. Neither Here Or There (makes No Difference) I Came Up With 3.25:1 Tranny Ratio. Your Tranny Output Shaft Is Cool. Have Been Thinking About Using A `split Shaft Coupler` To Extend To Rite Side For Shift Kit. The Out Put Spline Is A Bit Over 1/2" And Could Put A Key In One Of The Splines. Did You Make A Whole New Out Put Shaft?? Hope The 3 Speeds Hold Up, It Will Be Cool. Ron

 

[camlifter]

the engine is new, it's a replacement engine for a mantis rototiller, got it at the local implement and lawn store, they come ready to run, even have a gas tank on them, for $220. took the stock output shaft out of the gear box and made a new longer one. 8" long. the way it's made you could use a hub like i did to drive the left side of the rear wheel, or forgo the hub and go down to the crank and freewheel drive it the traditional way. the longer shaft and extra suport bearings should keep the gear box alive.
with the 3 speed and the extra reduction from the jack shaft sprockets she will take off without pedaling in first gear. i'll be giving it a few pedals any way but it will do it.

 

[camlifter]

more pics of the build

 

[UncleKudzu]

oh my gosh, i saw the shifter end and cable and the light went on: the 3-speed hub is part of what's mounted behind the seatpost. so that hub is your gearbox? that's brilliant!

sorry to say, though, that i've also heard that some of those Shimano 3-speed internals were junk. let's hope that's not the case here.

please keep us posted on how this works out!

 

[UncleKudzu]

Im starting to feel stupid.

you're not alone. i know what a an internal gear hub is and i still didn't quite understand what i was looking at til i saw it with the cable attached on page 5 of this thread.

so, if this works well, 3, 4, 5, 7, 8, and 14-speed internal gear hubs are available...

 

[camlifter]

got the shifter and the detents working the way i want today, rode it for about a 1/2 hour. everything is working great, shifts are smooth and not jerky. time to start working on the fenders and get ready for paint. i'm love'n the 4 stroke ride.

 

[Dan]

yea, the 4 smoker is a whole different critter

 

[HoughMade]

you're not alone. i know what a an internal gear hub is and i still didn't quite understand what i was looking at til i saw it with the cable attached on page 5 of this thread.

so, if this works well, 3, 4, 5, 7, 8, and 14-speed internal gear hubs are available...

In one sense, more gears are better, but in another sense- especially with the 4 stroke, I'm not entirely sure more than 3 speeds is necessary....I'm even thinking 2 speeds may be enough for 90% of people.

 

[UncleKudzu]

In one sense, more gears are better, but in another sense- especially with the 4 stroke, I'm not entirely sure more than 3 speeds is necessary....I'm even thinking 2 speeds may be enough for 90% of people.

HoughMade, i'd like to hear your reasoning on this. do you think that 2-strokes would benefit more from having more gears available? seems like some of those 50cc 2-Stroke Gran Prix racers from the 60s had something like 9-speed gearboxes. do 4-strokes have more torque available on the bottom range so as to make going through gears less necessary to get up to speed?

i'm fascinated by this thread, and am eager to hear anything related!

 

[HoughMade]

Those old 2 stroke race engine had a very, very narrow power band. They just would not make power at lowers rpm. they made great power in their power band, but because road racing involves acceleration, deceleration, then acceleration again, that peaky power band was a problem- they solved it by allowing using the gearing to keep the engine in its power band over a wide speed range- of course, that involves a lot of ratios.

The 2 stroke bike engines are not that peaky, but they do not have as wide a power band (or as flat a torque curve) as a typical 4 stroke, even though a given engine may make more peal power.

In the real world, most of us are not racing and have been making due with 1 speed. For my purposes, one low gear to take off from a standing stop, then shifting to the cruising gear is enough. Three might be better, but i don't think I need more than that just to ride around. Keep in mind that, living in Indiana, I don't have big hills to contend with.

Also, keep in mind that those 50cc racing bikes operated over a speed range from below 5 mph to over 80 mph and needed gearing to accomodate that. Even the 2 stroke bike engines typically will not operate over 40 mph and therefore, even if they were as peaky as the racing engines, (they are not) they would only need 4 to 5 the gears to the engine in its power band over that speed range.

Work with an engine with a broader torque curve over a speed range between 0 and 40 mph in a casual riding context, not GP racing, and less gears are necessary.

I am mulling over the simplest, lightest, least drag, most dead simple 2 speed transmission anyone could imagine...still in the "thinking" stage and would never be manufactured for sale, but I think it may happen.

 

[Creative Engineering]

Last spring I started working on a similar set-up to be used with the HT 2 stroke.

http://motorbicycling.com/f3/super-spoilers-part-1-a-7191.html

The customer decided to go with a 6hp Morini that revs higher than the HT so I nixed the idea of using a hub for a transmission. The 5.8hp version of this engine is known to have a broad, useable, rpm range.

In sourcing the internal hubs the customer talked to a lot of bike shops and the general consensus was that the SRAM is a tough hub. Attached to a 6hp morini I'm not sure if it would have held up.

Using a small 4-cycle engine, the multi-ratio set-up will really shine! Good job Camlifter!!!

Hough's right...2-speeds would be totally adequate, and three wouldn't hurt, especially if the engine produces max torque at a low rpm.

Jim

 

[UncleKudzu]

awesome information, HoughMade and Creative Engineering! it's great to hear such a depth of knowledge.

i wasn't really daydreaming about a 14-speed Rolhoff hub, BTW, but it's good to know that 2 or 3 would be plenty sufficient for those who think about going beyond 1 gear.

 

[Egor]

Has anyone been able to tear up one of the NuVinci hubs yet? This thread is got my mind in a blur, I have been mulling over this for a long time, this build makes it the simplest way to do it. I have a bunch of little Honda 50 gearboxes, been trying to find a way to use one. I also have a box out of a Cushman three wheeler!, has reverse. LOL. I have a GX35 in the garage never thought to use it, Sure looks cool, I would leave the covers off. Have fun, Dave

 

[BarelyAWake]

On that note - I saw cable actuated NuVinci hubs at my local bike shop for significantly less than I've seen elsewhere, just sittin' on a shelf all dusty and forgotten. They're not listed in the catalog and it may well have been a "special" price quoted just for me lol but if yer lookin' I'd give 'Bath Cycle & Ski' a call: Bikeman

A lil warning though - the prices there vary wildly depending on who you talk to, so if it's unreasonable just call back later

 

[camlifter]

if i make any changes to this or build another one i will use a 5sp hub, the 5 speeds have 2 under drive ratios, 1st is -33% and 2nd is -25% then 3rd is 1-1 and on up. as far as more gears go you couldn't go to much higher unless you used a bigger more powerfull engine. the 3 pseeds are working great on this build, the gx35 is about the same power as a stock 49cc grubee. it pulls 3rd on flat ground well but if theres any incline i have to shift down to 2nd. the best part for me is that 1st is under driven and gives good take of speed. it would be even better with the lower under drive you could get with a 5 sp. all the 7 and 8 speed hubs i found had no under drive, they started out 1-1 and went higher from there, you would need a huge rear sprocket for them and then the motors might not pull the higher ratios anyway. i'm still amazed at how smooth and quiet this bike is, i may never build another 2 stroke for myself again. i'm a true 4 stroke convert now.

 

[Egor]

CamLifter - You guys have a pic of a twin engine set up. Have you made it run yet? Looks cool I had the same Idea. Have fun, Dave

 

[camlifter]

CamLifter - You guys have a pic of a twin engine set up. Have you made it run yet? Looks cool I had the same Idea. Have fun, Dave

click on the link in my sig, then look in the videos, theres a vid of it running.

 

[The Newbie!]

Ok so that V-twin is just too cool! I'm building well several bikes, but 1 of them is a 1 off trike, based off the OCC platform, and I want that engine for it!!!! So where can I get 1, or does it hafta to be custom built? I'm not necessarily wanting it for the hp, cuz it probably still wouldn't be as much hp as 1 of those Morini's (wow), I'm just thinkin it's more Harleyish, and it would be an awesome addition to the theme of the whole thing, as there doesn't seem to be any chopper type trikes out there, at least not that I've seen! If anybody can link me to some that would be great! I also have a 3 speed hub that I was considering turning into a jackshaft, then I saw this thread n thought cool, there are people out there as smart as me (just kidding I'm really not that smart), but I did actually think of doing that, last nite in fact, then saw this thread, thought I'd see if I could get some tips n such! Great thread!