Starting new build, your thoughts?

nwguy

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I bought this Rans Rocket recumbent today to base my new build on:

RansRocket.jpg


It'll be similar to this bike:

FirstBuild.jpg


which I built over 20 years ago. I'll just be using the new bike for errands around town, and climbing one long, steep hill to get to the public pool for lap swimming. I plan to locate the motor below the seat to keep the weight low and centered like so:

RansRocketWithMotor.jpg


I'll build a jackshaft where the rear idler pulley is located. A chain from the motor's gear reducer will drive that jackshaft from the left side of the bike (when sitting on it), and a chain from the cranks up front will drive it from the right side. Another right side cog will then transfer power to the rear wheel. So with BMX freewheels on adapters from Staton Inc, I'll be able to pedal or motor independently, or do both at the same time. I'll mount a rear derailleur where the front idler is to take up chain slack from the triple cranks to the jackshaft. I have a pretty clear idea on how I'll modify the frame via oxy-acetylene brazing with brass, but the 2 things I'm pondering are the engine and the primary gear reducer.

ENGINE: I got 30 mph out of a GX31 with the old bike. I think this new bike will be more efficient (lighter, hopefully better gear reducer). The motors I'm considering are:
Honda GX35
Honda GX50
Huasheng 144F-1G 53cc

The weight and price difference between these motors is pretty minimal. I understand the Hondas are governed and the Huasheng is not. Is this correct? I'm leaning towards the GX35 because it's smaller and lighter, and I don't need or really want to go 40mph on this bike. I like the reliability and parts availability of the Honda.

GEAR REDUCER:
When I built this bike, I used Staton Inc's 18.75 to 1 INSIDE DRIVE Reduction Gearbox, and with similar BMX freewheels on the jackshaft, the gear reduction was perfect. So I know it works. It's a solidly built thing and unlikely to fail (1/2" thick cast iron gears). It also bolts right up to either GX engine. However it's heavy. Bikeberry's 5:1 gear reducer looks good, and probably a few pounds lighter at only 5 pounds according to them. I like it's double chain, freewheeling cog inside and solid clutch bell. Bikeberry was unable to tell me if it'll fit a Honda GX engine, and they haven't replied to my questions about bolt spacing and clutch diameter. Anyone know these? I'm leery of Grubee's belt drive transmissions after reading too many posts about them failing. I'll need additional gear reduction with Bikeberry's or Grubee's transmissions, which might complicate things (more clearance for jackshaft cogs).

The jackshaft will use a 5/8" keyed shaft mounted on pillow block bearings bolted to a steel plate that will span the 2 lower frame tubes under the seat. I have a small pile of Staton-Inc freewheel adapters and freewheels to use with that. The Rans has an 8 speed cassette, which should be great gearing for the motor.

I plan to buy new tires. The current, old ones are 20x1.75", and for suspension's sake I'll bump them up to 20x2.25". Any tire suggestions?

Any thoughts before I break out my sawzall?
 

DieselTech

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The bikeberry double chain gear box will bolt to the gx35 or a gx50 honda. The gear box I got from them is 5.83:1 or 6:1 basically. The staton gear box is way better but like you said HEAVY! I definitely would go gx50 honda, just as light as gx35 honda. I think the new gx50 honda is rated at 2.6hp
 

nwguy

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I think it's 2 pounds difference between the gx35 and the 50. Small potatoes. Good to know about the Bikeberry trans. I wonder why their support person couldn't answer that. Their answer to my initial question was:

"we cannot guarantee compatibility since your engine is from a different manufacturer.
we do not have the exact output shaft diameter at the moment, we can coordinate with the manufacturer and get back to you once we have the info."

The "different manufacturer" comment didn't make sense to me. Maybe they just want to sell kits rather than parts.

So is the gx50 governed where the Huasheng is not according to this?


And should we be getting 53cc motors rather than 49? Is the gx35 governed too?

I do plan to have a remote gas tank.
 

Sidewinder Jerry

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Are you going to put a similar shifting system on the new bike like you had on the one you built years ago? If so have you developed a sequential non-redundant shifting system?
 

Sidewinder Jerry

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I think it's 2 pounds difference between the gx35 and the 50. Small potatoes. Good to know about the Bikeberry trans. I wonder why their support person couldn't answer that. Their answer to my initial question was:

"we cannot guarantee compatibility since your engine is from a different manufacturer.
we do not have the exact output shaft diameter at the moment, we can coordinate with the manufacturer and get back to you once we have the info."

The "different manufacturer" comment didn't make sense to me. Maybe they just want to sell kits rather than parts.

So is the gx50 governed where the Huasheng is no't according to this?


And should we be getting 53cc motors rather than 49? Is the gx35 governed too?

I do plan to have a remote gas tank.
The Honda 50's governor can be removed. I've used a Robin Subaru 35 for 12 years and all I've ever replaced is the spark plug and fuel filter. I did change out the non-adjustable carburetor for an adjustable one.
 

DieselTech

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I think it's 2 pounds difference between the gx35 and the 50. Small potatoes. Good to know about the Bikeberry trans. I wonder why their support person couldn't answer that. Their answer to my initial question was:

"we cannot guarantee compatibility since your engine is from a different manufacturer.
we do not have the exact output shaft diameter at the moment, we can coordinate with the manufacturer and get back to you once we have the info."

The "different manufacturer" comment didn't make sense to me. Maybe they just want to sell kits rather than parts.

So is the gx50 governed where the Huasheng is not according to this?


And should we be getting 53cc motors rather than 49? Is the gx35 governed too?

I do plan to have a remote gas tank.
I think the hausheng 144f 53cc is governored too, they just get you a extra 800-1000 rpm over the hausheng 142f 49cc engine. I'm not sure what the new honda gx50 is governored at. The hausheng 142f 49cc is governored electronically thru the ignition coil. Yes bikeberry just wants to sell you a complete kit.
 

nwguy

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Jerry, the rear cassette gearing will be sequential and non-redundant for the motor since it's 8 cogs of different and increasing/decreasing sizes. I haven't calculated all the gear inches resulting from the front chainrings in combination with that cassette. That would only relate to me pedaling though. Interestingly, the biggest chainring has 63 teeth to compensate for the 20" wheel size. It's a monster.

OK, I think I'm going with the GX35 and Staton-Inc's gear reducer. I used a Robin Subaru 35 on my Super Grocery Getter. I did replace its carb once. I think I let gas sit in it for too long. The carb was only 20 something bucks though.
 

Sidewinder Jerry

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Jerry, the rear cassette gearing will be sequential and non-redundant for the motor since it's 8 cogs of different and increasing/decreasing sizes. I haven't calculated all the gear inches resulting from the front chainrings in combination with that cassette. That would only relate to me pedaling though. Interestingly, the biggest chainring has 63 teeth to compensate for the 20" wheel size. It's a monster.

OK, I think I'm going with the GX35 and Staton-Inc's gear reducer. I used a Robin Subaru 35 on my Super Grocery Getter. I did replace its carb once. I think I let gas sit in it for too long. The carb was only 20 something bucks though.
Here's my sequential non-redundant shifting system for a 3x8: 1(1-5), 2(3-6), 3(5-8) for 13 sequential non-redundant ratios. Take off gears are 1(1) for starts up hill and 2(2) for all other starts. I also use color coding of the shifters.
 

nwguy

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To my knowledge, the only mounting bolt holes on the Honda GX35 or 50 are the 4 holes around the clutch. With a Honda GX50 or 35 bolted to a Bikeberry dual chain transmission, what are the mounting points for securely attaching the motor/transmission combo to the bike frame? Staton-Inc's heavy gear reducer has 2 bolt holes on the side of the case for this, so you bolt the reducer to the bike and the engine just hangs off the reducer. BikeBerry's transmission has the 4 holes to bolt it to the motor (blue arrows below) and 2 other holes that bolt the case halves together (red arrows below). I can fabricate mounting points on the frame of my bike, but how would the transmission or motor attach?

bikeBerryReducer.jpg
 
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