Got Bob?

Finally started this bobber thing that's been kicking around my head for awhile out of leftover parts and scrap metal , pipe etc. Dumped my original version with the modified stepthrough frame and went full tube .

Wheelbase is 54" . Will run a fairly stock Tomos A3 engine with the Puch 22 cylinder and piston , just port matched and a Dellorto homemade expansion chamber .

Front fork is General 5-Star hydraulic with a relocated brake tab welded so I can use the A3 hubs and custom spacers. The hubs have sealed bearings front and rear (standard size - electric high speed motor ) 12mm YZ80 front axle front and rear. The wheels themselves are Motobecane 17" rims laced to Tomos A3 hubs for a 17" wheel that I won't have to down tooth (stock rear sprocket with 17" rim !! ) Triple tree is from a Suzuki XR75 and shimmed to fit the 26mm 5-Star fork tubes and the top tree bracket modified to fit the screw down forks (that was tough). I originally put the YZ80 forks and disk on there but that will be on the second frame out of my jig , so this one will be all low buck whatever I find . Front frame half is Suzuki SP100 dirtbike (had the right angles, sort of ) Funny , I found a set of tapered roler bearings at Walmart on clearance and they fit the headtube perfectly Back half is standard 1/2" mild steel tubing 0.95" wall bent and plated for the rear wheel. Handle bar shown is Yamaha ??? I think it was off my 550 Maxim . I think I might have found a way to make an internal throttle for about $10 , super simple design - no throttle cable !! We'll see. Brake will be single lever controlling both brakes ala BMX dually . Headtube angle/rake is 31 degrees for a trail of 3 - 4 inches hence the dirtbike frame . My next frame will use a standard streetbike frame for a 35 degree rake. I'm going to try to run a 12volt battery and GM electronic ignition (no kidding Honda/Yamaha guys do it all the time ) Don't really know if the GM ignition will allow 2-stroke RPMs but I have it setup and it's free so......

No front fender(maybe a small one to be legal) , bobbed rear fender off the Bullet A3. Frame is setup to use a 3.5" rear tire in the future , right now lil bitty 2.5's . Seat will be that modified bike seat from Walmart (bolted to bracket and top fender mount) with a pair of chevy valve springs for suspension. Engine will have left pedal arm unpinned and clipped to frame (removeable and pin can be reinserted in case I need to have the pedals actually work) Right pedal arm will be live to start it , then it too will pivot forward and clip into a mount , both pedals will face forward for foot pegs . There will be a fake oil tank below the seat for the battery and electronics . I need to figure out what to do with all the empty space below the tank . Possibly wind the expansion chamber up and back , I don't know depends on what else I find in my garage. Anyways - Feedback , both good /bad . Funny I just saw that 200cc Kikker Hardknock bike and thought crap I'm reinventing the wheel !! I have a Lifan 150cc engine with the upright cylinder that will go in bike number two that someone gave me , anyways I'd like to see if I missed any design cues from you crazies ! Suggestions ?? Let's hear them ..........


Re: Got Bob?

Different view


Re: Got Bob?

I like it although i would have liked to see the stretched silver bullet done. I've got drawings for a similar bike, but I want to use external pedals so I can put them really far forward.

Re: Got Bob?

Yes I know the downtube , to duals has a funny jog in it (not very smooth looking) BUT I machined a metal insert that fit in the down tube before it connects to the dual frame stays , it's mechanically rigid in both planes . It will be slightly hidden with the horn bolted on .

Re: Got Bob?

hi Grey , The tube frame was a whole lot lighter and I had a choice of a removable tanks , plastic even , the design choices were too endless. I also thought of sprocketing another crank in front of the engine to the original crank axle but thought Why am I spending so much time on this thing? After awhile you have this over engineered machine that is unrideable and starts looking funny . After I'm done I'm moving on to the 150cc 4-stroke version. It'll be the tweener bike that isn't quite a scooter and not quite a full sized bike that I can ride in the local scooter club other than my MadAss clone . The Local scooter club guys already talked me into building 5 frames for them so it'll be interesting to see what they come up with . One guy stuck a GY6 engine in his, using a modified rear wheel . He machined the alloy wheel down to the hub and connected a sprocket to the hub. The rear wheel is chain drive BUT no visible brake because the rear brake is in the rear hub and braking is via the chain. The best part is that it's a CVT and twist and go operation. Should be a screamer .

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