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Now I have a 79cc Harbor Freight 4-stroke. Next step please?
- Thread starter Nehmo
- Start date
the throttle is from this thread: http://motorbicycling.com/showthread.php?t=40292
a good place for mechanical parts is www.mcmaster-carr.com, if not the best place. lucky for me their main location is only a 20 minute drive, but shipping isn't unreasonable. the online catalog is huge, they have every size and type/grade of anything a tinkerer could ever want!
try to find a bike with coaster brake wheel, it is so much better if you are using a manual clutch. this one looks decent: http://www.walmart.com/ip/Huffy-Nel-Lusso-26-Men-s-Cruiser-Bike/16775665
keep in mind that you need to reinforce the rack on a bike, it wasn't designed to hold an engine. i would attach 2 strips of 3/16x3/4 steel to the back of the rack and the wheel dropouts so the axle nuts hold it on.
a good place for mechanical parts is www.mcmaster-carr.com, if not the best place. lucky for me their main location is only a 20 minute drive, but shipping isn't unreasonable. the online catalog is huge, they have every size and type/grade of anything a tinkerer could ever want!
try to find a bike with coaster brake wheel, it is so much better if you are using a manual clutch. this one looks decent: http://www.walmart.com/ip/Huffy-Nel-Lusso-26-Men-s-Cruiser-Bike/16775665
keep in mind that you need to reinforce the rack on a bike, it wasn't designed to hold an engine. i would attach 2 strips of 3/16x3/4 steel to the back of the rack and the wheel dropouts so the axle nuts hold it on.
The Idlers I used from NAPA were 2" and 3" in diameter,and they werent as beefey looking as that one, but plenty adequate for the job. They don't mount on a shaft. They have a 3/8" hole to use a bolt to fasten them to a hinged or pivoting flatbar.
As far as a good, cheap bike with 12guage spokes and steel rims, the Huffy Cranbrook cruisers from Walmart are cheap work well with a little tweaking. That's what I used on my 2 speed Preddy build recently. you will need to re-grease all the bearings because they come very little or none. I also re-tightened and trued the wheels because they are sorta loose when new.
Maybe you can sell your current bike and buy one.
As far as a good, cheap bike with 12guage spokes and steel rims, the Huffy Cranbrook cruisers from Walmart are cheap work well with a little tweaking. That's what I used on my 2 speed Preddy build recently. you will need to re-grease all the bearings because they come very little or none. I also re-tightened and trued the wheels because they are sorta loose when new.
Maybe you can sell your current bike and buy one.
Here's a pic of how I hooked the throttle. I did nothing internaly. I removed the friction throttle, and used the original govenor spring hooked up to pull the throttle closed. I used a twisted wire to attach the end of the throttle cable to the empty hole on the bellcrank.
![IMAG0228[1].jpg](https://motorbicycling.com/data/attachments/44/44754-3b144a5b9a3aa88ca54736d135d87ee6.jpg "IMAG0228[1].jpg")
Here's the Napa pulley I used. Also Tractor Supply has them on the shelf, cheaper than NAPA too.
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=SME705203_0215391411
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=SME705203_0215391411
O'Reilly auto locally can give me one for $10. I went ahead and ordered for day after tomorrow.
While I was there, I saw an idler pulley for a surpentine car engine belt. It looked like that would work too.
What about the drive pulley on the engine? It will be a 5/8" bore, but what about the diamater? I was thinking 1.75", because I'm planning on using a 22"rim hoop (from a 26" rim). You used a smaller hoop.
One thing that's a bit disturbing: It looks like I have to go with a V-belt, but that doesn't look like the best cross-scetion for a hoop made form a rim. It seems like it will slop around (twist and move from side to side) as it drives.
BTW, your bike is beautiful.
While I was at the store, because it was tried and true, I was committed to getting wayne z's suggested part, which I ordered (but didn't yet pay for). The serpentine belt tensioner pulley would cost more new, but in the U-Pick-It junk yard, that's almost a free part. Maybe you're right.
I don't think the extra room in the wheel rim pulley will be a problem. The belt is gonna find it's sweet spot and stay there.
There is a gear calculator in the DIY thread list. I would see if a larger than 1.75 pullet would work. Smaller pullies slip more. A good overall ratio in your case would be around 12:1.
you will prolly need to fab some support pins or flat steel ect that mount close to the motor pulley to support the belt when dis-engaged to keep gravity from making the belt drag on the pulley when belt is dis-engaged. check out some mower deck clutches for ideas. Just common sense though ,once you get it going you can see what it needs to do this.
Here's a pic of my belt supports on my in-frame 2 speed friction drive. Yours will be different because your motor will have the shaft on the left side of the bike.
Here's a pic of the Cranbrook after all the bells and whistles
There is a gear calculator in the DIY thread list. I would see if a larger than 1.75 pullet would work. Smaller pullies slip more. A good overall ratio in your case would be around 12:1.
you will prolly need to fab some support pins or flat steel ect that mount close to the motor pulley to support the belt when dis-engaged to keep gravity from making the belt drag on the pulley when belt is dis-engaged. check out some mower deck clutches for ideas. Just common sense though ,once you get it going you can see what it needs to do this.
Here's a pic of my belt supports on my in-frame 2 speed friction drive. Yours will be different because your motor will have the shaft on the left side of the bike.
Here's a pic of the Cranbrook after all the bells and whistles
I'm glad to hear you say that. I was wondering about the behavior of the belt during drive. I've decided to just use a bike rim hoop rather than the wheelchair plastic one. The plastic would be easier to work with, but it may be too narrow to satisfactorily seat the belt. Besides, I’d prefer to leave experimentation to others at this point.
But I do want to experiment with a different method of attaching the hoop to the rear wheel spokes. As I’ve already suggested, perhaps drilling radially through the inside edge or flange of the hoop (actually a spokeless 26” rim, which is 22” in d) to accommodate the spokes of the host rear wheel. I’ll have to find a drill press, but it could be done.
12:1 is the ratio I've been seeking. There appears to be a trade off on engine drive pulley size. A smaller one gives a better (lower) gear ratio, but a smaller on has less traction on the belt, thus, slips more easily.
A 1.75” motor drive pulley going to a 22” hoop gives the desired ratio on 26” bike wheels. But since I’m using 29” wheels, the overall ratio is 11.3:1.
That looks acceptable. However, I’d prefer lower. A 1.5” drive pulley seems too small for satisfactory traction.
Those pulleys are rather cheap, so I would try both and see which you like the best. You can always use a stronger spring to minimise slipping.
11.3 ratio isn't much different than 12. On my Preddy, when it was single speed, it was 9.75:1 and it had plenty of power, and a top speed of about 40 mph. Take off unassisted with pedals wasn't too much of a problem, I live in a rural area where I didn't have to do much stop and go.
One thing great about belt drive it that it's easy to walk the belt off by hand, with no tools or mess, when you want to pedal without the motor. Just stuff the most of the belt in the frame somewhere out of the way and go.
11.3 ratio isn't much different than 12. On my Preddy, when it was single speed, it was 9.75:1 and it had plenty of power, and a top speed of about 40 mph. Take off unassisted with pedals wasn't too much of a problem, I live in a rural area where I didn't have to do much stop and go.
One thing great about belt drive it that it's easy to walk the belt off by hand, with no tools or mess, when you want to pedal without the motor. Just stuff the most of the belt in the frame somewhere out of the way and go.
[For those of you starting your read at this point, I'm OP, and I'm the one everybody is helping.]
As I said before, one of item I need for to make the bike motorized is a new rear wheel. (The original one, having quick-release skewers, was quick-stolen. Someone probably took the whole rear wheel for the tire. But it is a 29" wheel, and it's unlikely that's the size they wanted. My wheel is probably in the bush somewhere now.) I'm currently using an old 26" wheel that doesn't accept disc brakes.
Buying a wheel by itself is reasonable for high-end bikes, but for the Pacific Cycle ones sold by Walmart, it doesn't make much sense economically, particularly when whole bikes are discounted occasionally if you watch carefully. The Walmarts around Kansas City, again and again, put bikes outside unprotected from the rain. They get rained upon, and then you can bargain for a discount. If there is yet more problems, you may get even more discounted. The managers will initially tell you 10% off, but they can go beyond that.
Anyway, I didn't get a cruiser. I got what Pacific Cycle calls a Stat. It's a 29" with front and back disc brakes and a springed fork. It's not much different from the Deception.
Yes, I realize some of you frown on this choice, but considering the price, $135 using tax exempt card, I had to buy it. (The only damage was cosmetic or fixable.)
At least I'm starting this project with a new bike.
As I said before, one of item I need for to make the bike motorized is a new rear wheel. (The original one, having quick-release skewers, was quick-stolen. Someone probably took the whole rear wheel for the tire. But it is a 29" wheel, and it's unlikely that's the size they wanted. My wheel is probably in the bush somewhere now.) I'm currently using an old 26" wheel that doesn't accept disc brakes.
Buying a wheel by itself is reasonable for high-end bikes, but for the Pacific Cycle ones sold by Walmart, it doesn't make much sense economically, particularly when whole bikes are discounted occasionally if you watch carefully. The Walmarts around Kansas City, again and again, put bikes outside unprotected from the rain. They get rained upon, and then you can bargain for a discount. If there is yet more problems, you may get even more discounted. The managers will initially tell you 10% off, but they can go beyond that.
Anyway, I didn't get a cruiser. I got what Pacific Cycle calls a Stat. It's a 29" with front and back disc brakes and a springed fork. It's not much different from the Deception.
Yes, I realize some of you frown on this choice, but considering the price, $135 using tax exempt card, I had to buy it. (The only damage was cosmetic or fixable.)
At least I'm starting this project with a new bike.
Hey, I'm a believer of workin' with what you have on hand. I built a rack mount once with a vert. shaft Briggs with a cone shaped friction wheel and a cone back up wheel. The only time I noticed the weight was when it was parked. When riding it , it was fine. The cone friction wheel wore out the tire rather quickly though.
Go for it! Rack mount eliminates a lot of problems. You don't have to deal with gas tank and exhaust mods. Just hafta lean the bike against something instead of using the kickstand.
Go for it! Rack mount eliminates a lot of problems. You don't have to deal with gas tank and exhaust mods. Just hafta lean the bike against something instead of using the kickstand.
Using the new bike, the Stat pictured above, which has a 29" rim, a hoop made from a 26" rim won't fit. The hoop is barely "visible" from directly above because it sits on the spokes where the spokes attach to the bike rim, roughly near the center plane of the wheel. But before I get to possible remedies, listen to this idea.
The 79cc engine is mounted with PTO facing left on a 20” × 6” × ¼” plate (or smaller) which is hinged on the seat post and extends back over the rear wheel. Under the plate near the back is a shaft on which is mounted a 3”roller and a 4” pulley. A belt goes from the engine-pulley to pulley on the shaft connected to the roller. The plate is spring loaded downward with gravity, but the plate has a long extension arm (lever) that goes forward, between the riders legs, on the side of the top (horizontal) tube. This is the clutch. Pushing down on the lever moves the engine & roller up and disengaged it from the rear wheel.
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That's a great design, but the PTO will have to be on the right side to propel the bike foreward.Using the new bike, the Stat pictured above, which has a 29" rim, a hoop made from a 26" rim won't fit. The hoop is barely "visible" from directly above because it sits on the spokes where the spokes attach to the bike rim, roughly near the center plane of the wheel. But before I get to possible remedies, listen to this idea.
The 79cc engine is mounted with PTO facing left on a 20” × 6” × ¼” plate (or smaller) which is hinged on the seat post and extends back over the rear wheel. Under the plate near the back is a shaft on which is mounted a 3”roller and a 4” pulley. A belt goes from the engine-pulley to pulley on the shaft connected to the roller. The plate is spring loaded downward with gravity, but the plate has a long extension arm (lever) that goes forward, between the riders legs, on the side of the top (horizontal) tube. This is the clutch. Pushing down on the lever moves the engine & roller up and disengaged it from the rear wheel.
I was refering to left as right. ;-)
Anyway, if you approve, that means I should go for it. I'm headed to a hardware store to see what fits.
I'm thinking I don't need an additional plate at all. I can just use the engine mounting plate and attach everything to that. I can use a U-shaped strip of steel to support the shaft, roller, and pulley. And I can come up with something to go from the plate to the seat tube. (In this bike there's a rectangular-cross-section brace from the seat tube to the top tube. That looks like a decent place to make the pivot for the hinge.)
I have to do some searching to see what builders use for rollers. I welcome suggestions.
Also, this arrangement places the muffler very close to the rider's ass...I'm going out now.
Here's a thread started by Cannonball 2. He built several FD bikes, and one was a rack mount with the Preddy i think. He mounted the jackshaft and motor on the rack, with the roller/jackshaft between the seat and motor, and the rack hinge was behind the seatpost.
This might give you more muffler clearance. You may try removing the muffler assy and re-mounting it upside down to see what that does.
I think he ended up with the oak roller giving the best service and ease of construction.
http://motorbicycling.com/showthread.php?t=29961&highlight=cheap+easy+drive+roller
This might give you more muffler clearance. You may try removing the muffler assy and re-mounting it upside down to see what that does.
I think he ended up with the oak roller giving the best service and ease of construction.
http://motorbicycling.com/showthread.php?t=29961&highlight=cheap+easy+drive+roller
I respect Cannonball2's industry and wisdom, but wood? I though that stuff was obsolete.
I'm trying to find some bearing mounts and get the materials for the roller-shaft.
I settled on a 1.75" diameter V-belt pulley to go on the motor crankshaft.
I bought it, but the store I was in didn't have bearing mounting hardware. I'm going out again today.
I'm toying with the idea of using only 2 (one on each side) straight piece of perforated angle-steel
[This is almost an irrelevant comment to the construction, but I'm limited to buses and bikes for transportation to get parts. So, although I'm in an industrial part of the world, and access to materials locally should be adequate, it's a pain just to bring home a piece of steel.]
