Introducing myself and my dual suspension BMX build!
My name is Rob. I've been a long time lurker even before I got an account. I wanted to get some knowledge on motor assisted bicycles under my belt. Growing up I was the type of kid that would take all my toys apart to mod/fix them. My dad was an auto mechanic when I was a kid. So I was always in a shop with him every chance I had. When most kids were wanting R/C cars and sports equipment for Christmas my brother and I wanted tools and tool boxes. I learned how to rebuild race motors when I was 7.
When I was 3, I would ride my tricycle down the concrete front porch steps. It doesn't look like it can be done but it can. These were the old big built in style steps. After doing that for a while I broke my trike in half where the steering tube connects to the frame. Then I tried to ride the handlebars and front wheel like a unicycle. So my parent got me an awesome little boys 16 inch batman bike. I was jumping ramps with training wheels on.
I learned how to ride my bike without training wheels when I was 4. After learning that I would ride my cousins 20 inch bmx bike that was freewheel. I was so short I had to start on a hill or a couple of steps. Then I couldn't brake because I was too weak and my hands were too small to pull the hand brake levers. I would have to jump off when I stopped and learned the old shoe on top of the back tire brake trick. I always thought of the Flintstones when I would brake like that as if that's how they brake too! When I was crawling I crawled so fast everywhere that my parents nick-named me HotRod! That name stuck with me growing up and I sure lived up to the name.
I was always riding or wrenching on something. Of course just like any young bike enthusiast I wanted to put a motor on my bike. I did the baseball card in the spoke and the crushed soda can over the back wheel(which makes it harder to pedal). I figured out as a kid how to get the most out of a bike by using the handlebars as a lever against my peddling side. Basically which ever side my legs was pushing at the time, kinda tilt the bike to the opposite side and use your arms to pull up and your whole body to really push them cranks down. Its hard to explain but you see bmxers and other cyclist doing it on videos. Especially while taking off, coming out of a turn, or up hill. Be careful if you do this though. I've had cheaper chains snap from the force and it threw me right over the handle bars. I had a dark red t-shirt on that day and there was a bright orange spot on my chest where the road ate the color off.
I loved jumping things as a kid. So I wanted to get the most speed I could. I would also race. I usually had a single speed bmx type bike growing up. When I got a little older friend where getting 10 speed mountain bikes and 21 speed road bikes. By using that little trick I could beat them every time on a single speed bike with smaller tires. In my teen years I rode my bike all over town. Usually about 25+ miles a day rain or shine. That was my only transportation until I got a car at 18.
As a teen I got a decent little digital speedo for my bmx bike at the time. I just wanted to see my stats. On a full haul basically peddling my tail off. With the gearing that bike had I could get it up to 25 mph according to that speedo. I couldn't keep it up for very long though just short burst. Its basically like sprinting but you use your whole body. I remember thinking man, if I could have a motor that would at least make a bike do 25 that would be a miracle. When my friends and I got in our teens some of them got mopeds, old dirt bikes, scooters and what not. I always rode my bike with them but having a motorized bicycle would have made our rides much better.
Even when I got a car I always had a few bikes around and rode every chance I got. My very first car (a white 4 door granny-mobile) while showing it to a friend, I jumped some elevated railroad tracks at a little faster than normal speed. We jumped it and felt like the "Dukes of Hazard". Well, in a stroke of "genius" and the fact that the jump was so fun (I am HotRod gotta live up to it lol). I decided to try the jump a little faster. It was awesome! My friend and I was flying off our seats hitting our heads on the ceiling laughing our butts off. This was on a dead road with no cars around, away from any people and late at night. So I tried it at 35 mph then 45 then 55 which was nuts! On the last pass in a cloud of ecstasy and doing my thing I went for the big bang.
Approaching the hill I would usually get to speed then let off and hold that speed. This time I gunned it the whole way and my granny-mobile was flying. I looked at the speedo and the hand was on 65. I looked at my buddy and he was grinnin from ear to ear. We were going way to fast (if there is such a thing). I let off just as we approached the hill and my buddy says "PUNCH IT!" So I did and the Gmb's speed climbed to 75 as we top the crest (do not try this at home!). Holy cow, we have lift off! When the car came down this time all four shocks bottomed out. The back hit so hard that the shocks/springs didn't even come back up very much and on impact my oil pan shattered into a bajillion pieces. As smoke/steam pours from under my hood and the back of the car in low rider status, she dies right there. I had that car for a full summer and a fall(no pun intended). Totally worth the $400 I paid for that car. What they don't show us on dukes is they broke a lotta cars too.
Right before turning 19 I joined the Army as a combat medic. Kept riding bikes as much as possible. I ended up going to Iraq and injuring my back, left knee and ankle. I can still ride but no where near what I used to. When I came home I went to work as a car salesman at the local Nissan dealer. After working there almost a year the economy went down the tube in 08. No one was buying trucks or really even driving them because gas was so high at the time. To sell trucks other dealers where giving away free mopeds/scooters with the truck and giving huge discounts just to get rid of them. Even then they still wouldn't sell. On the other hand mopeds and scooters became in high demand.
I wanted to get a scooter to save money on gas. Everyone who had a moped or scooter at that time either wasn't selling it or charging an arm and a leg for one. After looking for over a month I found thru a friend of a friend a damaged 2003 Yamaha Zuma that I could afford. I got the Zuma and came home and started ordering parts. As I start to tear the bike down to be restored, I started finding other unknown issues. I ordered over $1300 in parts. I bought and installed an Athena big bore kit on the motor that was seized. Then found that it needed a lot more than I thought. It needed some kinda expensive parts and was at the point of not being worth fixing. Basically it needed way more parts than it would be worth fixed. It then sat in pieces in my shed. I had to move so I stored it all in a friends storage unit. He left the unit unlocked and my Zuma motor/rear end got stolen.
One thing I did see around that 08 time period was a guy who would fly past the dealership on a motorized bike (rack mount) everyday. Someone told me the guy would build them for others for like $375. After losing hope on the Zuma project I stayed away from bikes for a while. I moved in to a new apartment and saw a guy in the neighborhood on a schwinn occ chopper bike with a china girl on it. All I knew at that time was that was a cool bike with a good sounding two-stroke on it.
Continued on next post->
Last edited by HotRodRob; 06-06-2014 at 10:55 PM.
Introducing myself and my dual suspension BMX build! Part 2
Around that time(early 2013) my dad and I was talking about getting motorcycles. I love customizing cars and bikes. Well, anything with wheels, and a motor is a bonus. I have owned several cars that I've customized and countless bikes through the years. I was looking at doing some things to my car and a possible future motorcycle. I started doing my R&D. After looking at parts for my car, as well as motorcycles and parts for them. I realized just like the Zuma and cars I've had, cars/motorcycles and their parts are expensive to mod or customize. Remembering the two motorized bicycles I've seen around I decided to look them up.
That's when I found this place and the many gurus who have their own 2 cents to throw in. I found lots of other resources and sites but this one to me is the best. Every question that I had I found the answers by using the search bar. The many personalities here are always pleasant and very informative. I like how when things come up that may not be exactly right, They get corrected and always in a nice way. Some sites(not just motorized bicycle sites) look like a bunch of apes head butting each other. This one is like a bunch of brothers and sisters helping each other haha. I like that. Its a good learning environment.
I built a Schwinn Searcher last summer(2013). Great platform to start from. It's a cruiser style bike that comes with mountain bike style front shocks, v-brakes front and rear and it's a 7 speed. It was in the mock-up/break-in/slowly upgrading stage. The bike eventually ran and performed great. The original motor that came in my bgf kit was a nightmare to say the least. I rolled the dice and got a lemon. That's part of the fun. If I didn't want to tinker I would have bought a cheap older honda rebel and called it a day. I learned A LOT from trying to get that first black beauty going. In the end it was kinda like my zuma but an easier hit to take.
The original black rb80 that I got in my bgf kit was gorgeous. The fins were all fat and perfectly caste. That black motor looked so good. Especially on my blue bike with black fenders and tank. The only problem with the looks of my original rb80bk was it looked like it had a tool scratch on the output sprocket cover that was repainted/painted over without being sanded out. Still looked pretty good though. But I had to send that one back because it was really bad on the inside.
That whole kit was a big let down. The throttle housing/kill switch broke within a couple days because of cheap thin/brittle plastic. The original throttle and clutch cables where pretty much useless. Even after lubing them up they were still very hard to pull. The grease inside the clutch cable guide/grease bung was dry. The carb leaked where the fuel line connects to the carb. It's really hard to tighten that barb/connection on the old style NT like I had. No matter how tight I got it she still leaked. The petcock leaked from the input threads. Then the rubber gasket in the petcock would get spun around and cover the holes. The carbs guide pin that keeps the slide in line was pushed out and cause all kinds of problems that was very hard to track down. That was the first time I had put hands on a CG and had to trouble shoot everything. The tank cap didn't vent. So I would get the vapor lock issue and starve my carb. That was also kinda hard to track down. The stock chain jammed up in the output housing because the inside of the output sprocket cover was rubbing on the chain.
That first motor and kit pretty much had every possible problem. There were so many more problems but you get the picture. The only thing that actually worked as it should was the rear sprocket/rag joint and the gas tank(besides the cap and petcock). Everything else had to be upgraded right off the bat. Didn't save money getting the cheapest since I had to replace all the broke stock parts and ship the first motor back($40).
The new motor I got wasn't black like I originally ordered. And the castings looked like they didn't use enough aluminum to fill the fins on the jug. They are super thin at the edge and missing in some spots. However, I went through the new motor upon receiving it and it looked great on the inside like really really good.
My dad said "I've never seen a motor that you have to tear apart and rebuild when its brand new." Well, I had never seen one either but upon reading I learned its a good idea. The other black beauty could still be around if I would have tore it down when I first got it. It makes since though. The only reason the factory is putting it together is because it makes it easier to package. They do not torque every nut, bolt, stud and screw down to the proper specs. They probably put them together with the least tools possible. Its a kit and part of the fun is going through/rebuilding the motor the right way and doing the finishing clean up when you get it. That's just my opinion. YMMV
The new silver motor has the nice 360 degree balanced crankshaft. The only weird thing is the rb80 was supposed to have the "wide intake". Well, the new motor has an even wider intake and intake mount studs(40mm). Once I mounted the new motor this thing was a whole different monster than the rb80. This new motor has almost no vibes and easily took my stock 44t setup to 32 mph. Even my dad who is ~200# got it to 32 mph. That's not gps but my pretty accurate wired bike speedo. These are pretty common results but the reason I was so surprised was because the short time that the black motor ran it was a dog. It could barely do more than 20 in perfect flat and no wind. Also, the black one had horrible vibes even though it was mounted metal to metal with a SBP front motor mount adapter.
The silver motor was nice and broke in(~650 miles) with a banana pipe, shorty intake, jnm velocity stack, performance air filter, speed carb, ngk plug, good plug wire and a shift kit. Nothing internal yet. I had the carb dialed in just right using Lucas semi-synthetic @ 50:1. I never got that bike/motor up to top speed (I've gotten a little more cautious than I was when I was younger). According to my (probably not very accurate) vintage style cable speedo I would be going between 40 and 45(was probably going slower than the speddo shows, not sure though) and she wanted to keep climbing. I only weigh 125 lbs. So it doesn't take many horsepuppies to get me flying. I don't care who you are, going above 35 mph or so on a motorized bicycle is pretty exhilarating to say the least!
Last winter when it started getting too cold for the gear I have. I was gonna go on one last ride. It was a chilly night in the low 30's. I got my bike out of the basement, fired her up and let her sit a couple minutes to warm up. After she got warm I headed down the road. About 3 blocks away I'm cruisin at around 15-20 mph when all of a sudden bang, then dead engine. I tried to fire it back up but couldn't. I could tell the motor was still free and not seized up. After trying what I could I start to pedal it home. Now, when I pedal the rear freewheel turns and the wheel doesn't! While trying to kickstart it a couple times after it died, I ended up striping the threads on my freewheel hub. I guess the cold made the threads(aluminum) brittle or something. Was so bummed at the time I just pushed it home, put it in the basement and didn't mess with it for a while.
Continued on next post->
Last edited by HotRodRob; 06-06-2014 at 11:00 PM.
Introducing myself and my dual suspension BMX build! Part 3
Recently as its getting warmer I got the Schwinn out to see what was wrong. I remember the way it sounded when trying to start it. She sounded like I blew a seal or gasket. It just wouldn't build much compression. I pulled the clutch and mag covers to check the seals but they where good. When I opened the mag cover I noticed that the top right bolt hole(on the cover) is broke in half and that piece of pot metal was sitting under the mag! That means that little piece of metal got in my mag and made my motor temporarily seize up causing my wrist pin to blow. I'm guessing the cover was also brittle because of the cold. It was probably on an exhaust cycle. When the piston started coming down from firing the plug, then that piece of metal got in there and jammed my crank up. The piston wanted to keep going down because of the exhaust stroke and blew the weakest link which is the wrist pin bearing. So I took the head off and there are needle bearings smashed into the top of my piston(probably from trying to start it after the bearing blew). My carb was fine and my gas/oil mix was good. When I rebuild that motor I will do a mild port match/clean up on the inside of the ports on a new top-end. It was already plenty fast for me. I mainly cruise back roads at normal bicycle speeds.
Being a short dude (5'6") I prefer lower seat heights. On my Searcher with a lay-back seat post and a nice thick gel cruiser seat I can barely have both feet flat comfortably. I was thinking of getting a 24 inch cranbrook and doing a springer fork and banana seat with springer sissy bar. I think it would look cool and fit my size better. However on the night I was gonna order the cranny I was looking around the net for bikes that might work. I stumbled upon this bmx bike(which has always been my favorite type) that I had never seen before. It looked like a CG might fit in the frame. It has dual suspension, So a shift kit or heavy duty/spring loaded tensioner would be needed. It's only a single speed and if going with a shift kit would need to be converted to a multi-speed(which can be a challenge.) I have the shift kit, so I could go with that. I did some measuring/guesstimating and it looked like the motor/shift kit would(hopefully) squeeze in there but it would be close. It has a nice triple tree up front and beefy shocks in the back. The bike is the Greenline DS-20 BMX. I fell in love on first sight. It almost seemed too good to be true. I crossed my fingers and rolled the dice(ordered one from Amazon). With the DS-20 I won't need to buy extra brakes, forks, and suspension sissy bar, that I would have had to get for the cranny because its comes with all that.
As always I started doing my R&D. Seems the DS-20 is kinda new because I couldn't find any reviews. Also couldn't find anyone who had motorized one. Its a gamble but I figured if a china girl didn't fit I will motorized it somehow. Another thing is its a single speed and I would need to convert to 7 speed which can come with some headaches. Luckily the rear chain stays only need a 1/4 - 1/2 inch spread. Which looked possible.
I get the bike in and its beautiful. I got the flat black one which matches my helmet and is what I was gonna paint my Searcher anyways. It also comes in lime green and steel grey which both look very good as well. The suspension is nice and firm in the rear. The front triple tree forks are heavy duty and have a softer yet still firm spring rate. Non-motorized the DS-20 feels great over all bumps and jumps. I gave it a nice shake down. It felt great and is the perfect size for me. It almost looks like this bike was made for the china girl. At first I kinda thought it was, as you probably know most bmx bikes usually have no room in the frame (without heavy modification) for even the smallest of motors, and Greenline bikes are known in the motorized bicycle world.
A couple days after I get her I'm thinking about a banana seat for the bmx(the stock seat is hard as a rock, which is cool for bmx but not cruising in comfort) and was lookin on ebay when I stumble upon a bike that looks very similar to mine in the thumbnail. So I pull it up. Sure enough it was a Yamaha "Moto-bike" (made from 74-76) for sale. These things are awesome.
I did some research on them and found that kawasaki and honda(couldn't find a pic or much info on the honda) also made very similar bikes. As well as a few other bicycle brands in that time period. They are all a little different, yet look a lot alike. Basically the Greenline DS-20 is all the good aspects of those bikes in one with a few modern touches like the modern bmx stem, three-piece cranks and the modern brakes.
The DS-20 is a heavy beast of a machine but that kinda comes with having dual suspension on a bmx haha. It's really not super heavy but feels nice and substantial. The original bikes were made for dirt jumping/bmx. The Greenline version would fit right in on the trail as well as the street. The welds, paint, frame, hardware, brakes, rear suspension, triple-trees as well as the fit and finish of this bike is (IMO) way above and beyond what I expected at the ~$245(shipped) price tag.
I have a new black 66cc CG mounted to my jackshaft mount sitting in the frame. It has roughly 1-2 mm of space above the head to the middle frame rails. I also have a cool new old stock moped tank with NOS flip up gas cap, some chrome fenders, front headlight/fairing(I'll have pics when I do the build thread soon probably in the rat-rod section), fender mount tail/brake light, mini-gen setup with charger and battery, some solid rubber moped pedals(I can't stand pedals with sharp points that can grind your shin if your feet slip off the pedals), another bike(for the 7 speed hub/wheels and it has other parts like another set of triple trees and other parts for future builds, plus the bike was cheaper than just a new set of wheels like I needed), SBP expansion chamber, new Shimano HyperGlide 7 speed freewheel, KMC chain, and a Shimano derailleur with mount. I also have a nice comfy moped seat. My huge gel seat and lay back seat post doesn't look right on it IMO. I also have some Maxxis Ringworm tires with slime tubes which look nice. They are kinda like the hookworms but with a different pattern. I have more parts/stuff I'll go over more in the build tread.
I have some pics(of mock-up) I will post once I have enough posts, and I'll start a build thread in the Rat-Rod section here soon. My bike doesn't really fit any other sections. Since I'm using parts from other vehicles with somewhat of a 70's vibe and my frame is flat black I think it will fit right in. Plus that section has been slow going here lately.
My Schwinn Searcher is gonna stay as a pedal bike for a while. I offered it to my dad to build a motorized bicycle but he is a procrastinator(wonder where I get it from!?) Once I get the BMX going I plan to get a Micargi Hero or some other 20" bike to motorized. I'll get a new top-end for the silver 66cc CG and use it on whatever new bike I get. Once the other bike is going I will do the final paint and finishing touches to the bmx(it will never be truly "finished"). When I have two bikes going I will let my (responsible) friends and family ride the other bike if they wanna go for a ride with me.
I just got done going through the new motor. I mildly ramped the exhaust and transfer port area on the piston top. I cut the piston skirt that was blocking the intake. I also smoothed the intake/exhaust and transfer ports. My head came looking nice. It has the squish band machined in and It was milled at the factory to be flat. The top of the cylinder was also milled flat. I still used sandpaper on glass to make them both even smoother/level, as well as a tiny boost in compression(maybe). I didn't take off much. Once all the inside work was done I cleaned and lubed everything up. Then I put it all together with new gaskets I made and coated with copper gasket spray. Along with a thinner head gasket from Sick bike parts. Still waiting on a few parts and will need to order a couple more once I get further along. There is a lot more that I have done and plan to do. I will cover it all when I start my build thread.
I quit smoking cigarettes and started using e-cigs a couple years ago. I save over $100 a month so I decided to use that money to build a fun bike to get a little exercise and be able to go the distances I used to be able to go. Since I am on a tight budget my builds are more a slow upgrade what I can when I can. Money is better spent(IMO) on getting safety things like a helmet, lights, mirrors, blinkers, gloves, and other gear. Rather than all on speed upgrades. Its nice to go fast you just wanna make sure you and your bike can safely do that. And stopping is at the top of the list.
Sorry to write a book of my life story haha. I felt I knew so much about some of you guys I would share a little about myself. Wish I lived on the west coast so it would be easier to get to a racing event. I would be all on that. Maybe I should start something around here. We do have a dirt oval track with a smaller oval in the middle, an 1/8th mile dragstrip(!?) and a couple gokart tracks hmmm.....
Hello, I'm Rob. My current build is a Greenline DS-20 dual-suspension BMX with a 66cc CG and a SBP shift kit. Nice to meet you. Lets talk bikes!
Last edited by HotRodRob; 06-07-2014 at 12:29 AM.
Re: Introducing myself and my dual suspension BMX build!
Here are some pics. I will have more when I do the build thread. These pics are of the bike in mock up. The fairing isn't fully on. The tank is sitting on some shop towels. Nothing is hooked up and everything is just kinda sitting there, besides the seat.
As you can see the stock SBP outside bottom bracket sprocket is too close to the motor to run the chain in a straight line. I ordered a couple smaller sprockets to play around with. They should be here in a day or two. Everything so far has barely fit and/or need modifications to make work. This build isn't going together like a normal build would. I have nothing to go off of. So there is a lot of trial and error as well as putting parts on and pulling them off to modify. I am extremely lucky it's got this far! Lots of fun so far though.
I wasn't even outside 5 minutes to take these pics. The second car that drove passed pulled over and ask if he could buy it! I told him it's not done yet and it's my dream bike. But I told him I would build him one. He said he will be getting back to me!
My goal with this build is to make my bike look like it came from the factory that way, if ya know what I mean? Stock looking yet slightly modified. I also want people to ask "What is that!?"
What do you guys think?
Last edited by HotRodRob; 06-06-2014 at 11:05 PM.
Re: Introducing myself and my dual suspension BMX build!
The DS-20 isn't my first motorized bicycle build. I would NOT recommend the DS-20 or any unknown/unused bike to a first timer. There are way too many unknowns and modification. To be honest I'm not even 100% sure I'm gonna be able to make it work. It's kinda an odd size and takes a lot of patience and parts on and off to make them fit. Not much has gone on in the normal order or way a normal build would go. If I was still new to china girls and shift kits, then this build would be intense to say the least and IMO too much to just jump right into as a first timer. Like I said I have been extremely lucky that its made it this far.
My first one was a Schwinn Searcher that I later put a SBP shift kit on. As well as several other mods. I went over it a bit in my second post, but I don't blame you for not reading ALL of that wall of text above haha! The more important one is my third post anyways.
My, next step while waiting for parts is I'm gonna make a gas tank mount which will raise the tank a little more to hopefully look a little more level with the seat. If it stays nice outside maybe paint a few little things. After that I'll put my hand controls on. Eventually I will cut my stem down an inch or so. That way my handlebars will be a little lower and tuck behind the fairing better.
When I get the parts I need to get her on the road I'm gonna take more pics and video. Once she is "done" and I get another motorized bicycle going I will do the finishing paint/body work. So far the plan is to black out most bolts/mounts, cranks and chain guard. Then, the fairing, gas tank, and BB sprockets will be VHT Fire red metallic. Lots of other parts and plans to go over. So, Pull up a chair and a nice cold drink and hang on for the ride.
Last edited by HotRodRob; 06-06-2014 at 11:06 PM.
Re: Introducing myself and my dual suspension BMX build!
This has certainly given me some inspiration, I have been searching for a full suspension bike to mount a china girl. My Goat is a lot of fun, but a little rough on the tracks with the hard tail.
Been thinking to find something I can modify and change the swingarm pivot point?