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Old 06-04-2014, 11:49 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 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. Reason: formatting
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