Another Harbor Freight Attempt

[MaxPower]

I've been reading a lot about various Harbor Freight Grayhound builds. I saw tyrslider's video (YouTube - ShellyBelly WhisperDrive) and I was hooked. putt...putt...putt...putt.... I'm drooling while I type. It got me thinking if I could attempt the same thing on my tandem shifter cruiser. The two stroke that's on it now is so 2009. It'll be steep learning curve but that's the fun of it....right...? The first thing I need to figure out is if my idea is even plausible. check out the picture I've attached. I'll help with visualizations.

I'd like to use a timing belt from the engine to the jackshaft but I have no idea if it's appropriate in this situation. Will the speeds and distance be too much? Would a V-belt or chain be better? My math may be a little fuzzy but I think I will need a 12"-14" pulley on the jackshaft input. Is that right? It'll make a heck of a flywheel. where can I even get a timing belt pulley that big?

I plan to use tyrslinder's universal mount so I've got that taken care of and I'm confident the frame is large enough. Except for the 12" pulley, the jackshaft is already complete. That was maybe the hardest part when I first built this bike.

I also have to figure out a belt tensioner. I'll leave that for a future thought.

My plan seems possible to me at least. I don't have access to high tech equipment, just hand tools and a dremel that I can't live without. I can bug my friend who has some nice stuff but he has a life. Steps I think I'll have to take

1. Am I content with life. Do I need to do this to my Motorized bike?
2. Figure out gear ratios and weather or not to use a timing belt
3. Find a pulley large enough, a belt long enough, and a clutch that's compatible (max-torque HTD)
4. Come up with some DIY belt tensioner
5. Use Univeral motor mount to mount the motor
6. Make custom exhaust
7. Make a DIY throttle.
8. Be content and not attempt this again.

It's just that easy.

[mdlee1958]

Max,
Do you have your MaxTorque clutch yet, if not I have a brand new one that has only been taken out of the package and slid onto the drive shaft only to find out that it wasn't going to work for what I had in mind. It is an 11t 5/8" shaft cent. clutch. Would part with it cheap if you are interested.

[MaxPower]

Originally Posted by mdlee1958

Max,
Do you have your MaxTorque clutch yet, if not I have a brand new one that has only been taken out of the package and slid onto the drive shaft only to find out that it wasn't going to work for what I had in mind. It is an 11t 5/8" shaft cent. clutch. Would part with it cheap if you are interested.

that sounds great. Is it the HTD clutch (http://www.maxtorque.com/html/htd_clutch.html)? I need to think through this project before I dive into it.

I'm estimating $400-$500 to get the job done. Right now I'm having problems locating a 12" O.D. timing belt pulley (or any pulley that big) with a 5/8" shaft. It's sounding like it'll have to be custom made. I'm trying to avoid using a EZM or Firebelly gearbox. Just trying my own thing. there is a reason those boxes are so expensive.

[Youngbird]

MP....I'll give away one of my ideas. Go to max-torque and get a driver and a driven....then you have a torque convertor that is in fact capable of changing ratios for you....check it out. Total cost about $180.-$200. including the belt.

[tyrslider]

Looks like the smaller pitch one is about 1.5" in diameter (don't know doesn't say). If you put a 9" pully and a 10 tooth sprocket on the shaft you'd have about the right ratio. On a typical shift set up for the Hondas is 32:1 ish, so w/ the HF around 16:1 will do. It is tough to see when your reduction is all at once, but let's compare it to the typical 2 stroke set up.

Off of the output shaft at the motor it is reduced on the same side w a 20t sprocket (I think, Have only done one 2 stroke shift kit) so frome 4:1 to 8:1. Then on the other end another reduction is made from a 10t to a 40, 44, or 48t chainring depending on your preferences giving you ratios 32:1, 35.2:1, and 38.4:1. you then drive your rear cog w a 32tish chainring giving you a top speed in mid gear of 32.5mph, 29.3, and 26.8 respectively. My ratio estimate of the 2 stroke may be off but o/a reductions are accurate.

in your setup your trying to make one reduction before you drive the rear instead of the standard 3 used on a standard 2 stroke and 4 stroke set up. so by reducing the rear drive sprocket as much as you can you help make this possible w/o having a huge pulley motor drive side.

[tyrslider]

A quick cursery check yeilded no specs on the MaxTorque converter set up but looks to be in the range of 2:1 to 1:1 o/a ratio band and would require more reduction for a single speed and still more for a shifter.

[MaxPower]

Originally Posted by Youngbird

MP....I'll give away one of my ideas. Go to max-torque and get a driver and a driven....then you have a torque convertor that is in fact capable of changing ratios for you....check it out. Total cost about $180.-$200. including the belt.

Is this what your are refering to (http://www.maxtorque.com/html/torq_convert.html)? If so, I don't think it will give me a big enough ratio. Just looking at the picture the jackshaft input looks to be about 6". My calculation show with a 13" OD pulley I'll get about 19:1 on the high side and 7:1 on the low side. I believe the max torque variable speed drive is not tall enough for my needs.

anyone know where to get large timing pulleys? or any large pulleys?

[Felton]

Its not for a timing belt but its a pulley around 13 in. and its for a 5/8 shaft. might have to paint it so it won't rust. 14A X 5/8 Die Cast One Groove Sheave

I would stick with the pulley not the timing belt. I have been doing similar research but do not want to talk too much about it in public for fear of taking away customers from someone elses product. I too have been drooling over tysliders gear reducer. Two things keep me from buying it one is I want a little more reduction because I plan on pulling a heavy trailer and I want to have my bike ready for March.

[MaxPower]

Originally Posted by tyrslider

If you put a 9" pully and a 10 tooth sprocket on the shaft you'd have about the right ratio.

A 9" pulley would be much better than a 12" but I think it'll give a ratio thats to low. I'm probably wrong

some math:

For the high side
1.5" drive pulley and a 9" jackshaft input pulley = 5.6:1
18 tooth cog to 32 tooth cog = 1.78:1
Final Drive ratio= 10:1
Speed at 3600 RPM = 28 mph

For the low side
1.5" drive pulley and a 9" jackshaft input pulley = 5.6:1
18 tooth cog to 14 tooth cog = 0.8:1
Final Drive ratio= 4.4:1
Speed at 3600 RPM = 64 mph

I'm looking for a top speed (no wind and I loose 50 pounds) of 40 mph on the bike. So I think the mathematical top speed should be about 50 mph. I have no experience with this engine but I think 9" is to small because it yields a speed of mathematical speed of 64 mph. I could be completely wrong.

[MaxPower]

Originally Posted by Felton

Its not for a timing belt but its a pulley around 13 in. and its for a 5/8 shaft. might have to paint it so it won't rust. 14A X 5/8 Die Cast One Groove Sheave

thank you so much. This may be my ticket. good bye timing belt.