View Single Post
Old 06-04-2014, 11:56 PM
HotRodRob HotRodRob is offline
Motorized Bicycle Senior Member
Join Date: Apr 2013
Location: Western KY
Posts: 77
Default 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. Reason: spelling/formatting
Reply With Quote