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  1. #1
    Wonders How Big It Is piratius's Avatar
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  2. Default The Mini Pirate Bike!

    Alright!

    So, my dad called last and told me he was coming by with a surprise, and to turn on the little propane heater in the garage. He showed up about 20 minutes later, and I helped him unload whatever "it" was from the back of his little trailer. We got it inside, and I was a little surprised!





    It's an antique minibike that my uncle built around 1960. The make is "bonanza" and it was originally purchased from Coleman Powersports in Falls Church, VA (which is still there, btw!). The original engine was a 3hp Tecumseh, which was replaced by a 6hp (unverified) Briggs & Stratton. Here are some specs:

    Engine: 6hp Briggs & Stratton - Model # Unknown (doing research for rebuild parts!). Crank diameter is 5/8" keyed.
    Transmission: None. It does have a centrifugal clutch though, and a jack-shaft to provide additional reduction. Clutch & Jack-shaft are both 5/8" keyed.
    Gearing: Clutch 12T. Jackshaft input 11T. Jackshaft Output 12T. Rear Sprocket 72T.

    Rear Wheel & Tire: 2 piece rim with tube 5.3/4.6x6 tire, "hat" style drum & sprocket with drum brake.
    Front Wheel & Tire: 2 piece rim with tube 4.0x6 tire. No front brake!

    Front Suspension: Springs from a Ford Ranchero coil-over strut over sliding tubes.
    Rear Suspension: Springs from a Ford Ranchero coil-over strut over sliding tubes

    The rear tire was removed because there's no kickstand or center stand, and when we needed to store it, it made more sense to let it sit on the swingarm rather than on a flat tire! I've got what I think are most of the parts to repair it in a few buckets around. I'm going to try to start putting it back together - after taking it apart first!

    What I did last night was do an initial inspection, and write down gearing tooth counts, shaft sizes, tire sizes, etc. I went over to www.northerntool.com (since we don't have any mini-bike parts distributors!) and did a little digging of my own, and was able to come up with most of the parts I'll need to make this thing go again!

    First up was tubes and tires - I found the 5.3/4.5x6" tire for the rear at http://www.northerntool.com/shop/too...1536_200331536 and also found the corresponding tube (not going to bore you with a picture of an innertube!). I looked around for tires for the front, but decided to step the front up to a matching 5.3/4.5x6" rather than trying to find a 4.00x6. If it doesn't fit, I'll find something else to use!

    Then I went digging for a new centrifugal clutch, as mine was basically falling apart! I found the appropriate 5/8" shaft drive here: http://www.northerntool.com/shop/too...0368_200310368 . This stuff would probably be cheaper if I got it from ebay and similar places, but it doesn't matter, I just wanted everything simple and quick! I found sprockets at northern tool as well. My dad mentioned that the thing would go about 40-45mph, and that it was probably a little too fast, and that I'd have a LOT more fun with more acceleration (climbing hills, over logs, etc), so I decided to step the jack-shaft input to 13T from 11T, and then increase the jack-shaft output to 13T from 12T.

    Using http://www.sprocketcalculator.com/ , I found that this should result in a net drop of about 8% top speed, but also give me about 8% more torque! If I need to change it up even further, I can get 5/8" keyed sprockets from a lot of places online in various sizes, and step up the jackshaft input to 14T or 15T - each change in tooth count seems to be about a 8% difference!

    Gearing Table!
    XXXXXX Stock Modified
    Clutch 12T 12T
    Jack Shaft Input 11T 13T
    Jack Shaft Output 12T 13T
    Rear Wheel Sprocket 72T 72T

    When the parts come in, I'll post pictures and progress pics!

  3. #2
    Whored Hot Chili Pepper RayDog26's Avatar
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  4. Default

    That is awesome!! I want one lol

    Sent from my Nexus 4 using Tapatalk

  5. #3
    Wonders How Big It Is piratius's Avatar
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  6. Default

    Thanks Ray!

    I'm looking forward to restoring/rebuilding it. My biggest challenge is that I don't know how far I want to go right away. Do I pull the motor now (before I get it running), and wire wheel/sandblast/paint everything, or do I leave the 45-50 year old paint (not factory, it came bare metal) intact and just ignore the spots where the paint has chipped?

    If I paint it, I'm leaning towards a two-tone paint job - it would be black and XB "fluid silver". I was thinking it would look really good with all of the frame tubes and handlebars painted gloss black, with the flat headlight area and wheels done in the silver color.

    It's a lot more work, but a wire wheel will make short work of most of the paint. What it doesn't get would probably be pretty quick to hit with a sandblaster.

    Half of me wants to keep it original, the other half wants to make it my own design - black and silver is pretty classic, and the red motor won't look terribly out of place.

    Opinions?

  7. #4
    Whored Hot Chili Pepper RayDog26's Avatar
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    Well I would definitely make sure it runs before you invest a lot of time and money. Secondly check the value. If keeping it original will make it worth money down the road then don't restore it otherwise go to town and make it custom!

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  9. #5
    Wonders How Big It Is piratius's Avatar
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    Yeah...it came in bare metal, so the original paint is whatever my uncle decided to do when it was new. The motor turns over and spins freely, it was cleaned pretty well before being put into storage - the good thing about having a mechanical engineer as a relative!

    When I was a kid, I saw the motor run on WD40/starting fluid, so it should still be (relatively) good to go. Even if the motor doesn't run, it'll accept any standard B&S style mount - from 2hp all the way up to 6-8ish, and those motors can be had for a couple of hundred bucks.

    I'll do a little digging and see if I can find any ideas on how valuable it is. I'd prefer to keep it, clean it up, and then ride it, rather than have it be "original" and potentially worth slightly more money.

    -Brad

    - - - Updated - - -

    This looks surprisingly like what I've got...

    Ebay Ad!

  11. #6
    The Boss
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    Look up some racing clutches for sprint karts. I used to race B&S go-karts as a kid and there was a lot of "tuning" that went into clutch setup. If your engine makes high hp but mediaocre tq, you can set the clutch to engage later; and visa versa. We played with this a lot when switching between asphalt and clay tracks.

    Also if you make it engage later, it makes it easier to putt around on, but still maintain your speed once it's fully engaged.

    There's a world of aftermarket engine parts as well! We rebuilt our engines after every race or two (I was 13-14 y/o). We managed 17bhp out of a 5hp block. Check out http://www.apskarting.com, we used to use Noram GE Clutches.
    "It is impossible, until some crazy son of a bitch has the audacity to believe that no matter what the expert says, I can still do that shit." - C.T. Fletcher

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  13. #7
    Wonders How Big It Is piratius's Avatar
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  14. Default

    Thanks Lee! What kind of engine did you use? If I don't want to modify the stock frame, then size considerations come into play - I looked at apskarting.com, the site looks like it could have a lot of cool stuff, but it's not terribly nice to navigate (a paper catalog may be better if they have one).

    I already found the "right" clutch to replace mine - once I get it up and running I'll consider looking into modifying bits or pieces of it. Either way, both of those sites are bookmarked now.

    Thanks!

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    We used Briggs&Stratton 5hp blocks. I specify "blocks" because we ran 3hp flywheel, header, cone filter and fuel was straight methanol for the stock classes, more mods for the modified classes. We took a 5hp engine and got 7.5hp out of it instantly. Every two weeks we would bore it .010 over until we maxed out at .060 over stock, then buy another block and start again. Had pistons, cams, rods, cranks, blocks, heads - galore. It's amazing how much you hop up those little motors. Once we hit .060 over, the engine was retired to non-racing duty. If we watned to putt around the neighborhood, we popped one of those on it.

    That's a quick idea of my thumper-building history, lol. Like I've said, I was building race engine since I was 13.

    We actually got in trouble for being too modified...in the super modified class!
    Last edited by Jet-Lee; 01-29-2014 at 09:57 PM.
    "It is impossible, until some crazy son of a bitch has the audacity to believe that no matter what the expert says, I can still do that shit." - C.T. Fletcher

    Click here to enlarge
    Left to Right:
    2003 Blast (Blue), 2001 XBlast (Rex), 2007 XB9R Firebolt (Bolt)

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  17. #9
    Wonders How Big It Is piratius's Avatar
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    So I think I'm going to paint it - the frame will be black, with silver accents (front/number plates, springs, engine plate), and I'm probably going to leave the motor red. I may paint the flywheel cover buell silver as well, but that'd be for another day.

    I meant to get out in the shop and really get at it last night (pull the motor, etc), but I laid down on the couch and fell asleep - I guess I needed that more than I thought! I'll try to start the disassembly sometime in the next few days!

    -Brad

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    Wonders How Big It Is piratius's Avatar
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    Ok guys! So, I got the media blasting (sand blasting) Cabinet almost all put together. Going to do a little more sealing on the edges, but hopefully by Thursday (probable Snow Day, 8" expected!) I should be ready to blast these silly wheels!

    Cabinet is Harbor Freight #68893, found here: http://www.harborfreight.com/40-lb-c...net-68893.html



    So, this is the infamous "Harbor Freight $209 Media Blasting Cabinet" that you can usually get for around $160 with a 20% off coupon they generously provide for free on their website, or in print via coupons they send out every couple of weeks.

    It comes flat-pack style, a-la Ikea, but with metal and about 1,200,543 screws, washers, and nuts - none of which use an allen wrench (they require two sizes of philips and three different metric wrenches to assemble). You'll need a medium-small phillips screwdriver, a medium large phillips screw driver, and a 7mm, 8mm, and 10mm wrench or socket.

    The biggest complaint about this cabinet is that it leaks. A lot. One person online claimed he lost about 10lbs of blasting media during a short session. Clearly, unacceptable. How do we fix it? Check the next picture to see what I did!



    So the answer to the previous question, "How do we solve the leaking problem?" is simple. RTV Gasket Maker.

    Put a bead of this stuff EVERYWHERE you join two panels. At the top edge of the cabinet, you can see where the gasket sealant has squeezed out. On the sides, you can't see it - they include foam strips on several of the panels, and if you remove the foam, then some of the holes don't line up! Argh! In those cases, I took the bead down the inside edges, and filled in the corners as best I could - as you can see on the inside back corner (middle of the picture), and along the inside edges of the funnel (you can see it through the left glove hole).

    I even put a bead of RTV around the rings where the gloves will mount - and they already came with a rubber gasket! I figure, if I'm doing it right, I should do it right. Sure, it'll take longer to assemble, but who cares? It shouldn't leak!


    This is the view of the inside of the cabinet. You can see the nice bead drawn down the edges of the funnel, and a portion of the bead that runs up the back inside corners.

    The grey foam tape is visible along the sides and back - the last thing I have to do before putting the gloves and window on is to draw a bead along the four bottom walls around that grate - a heavy screen will go on top of it, and allow the parts to sit above the sand hopper (below).

    All in all, I think I have about 3.5 hours (not included drying time!) into putting this together. Without bothering with the RTV, I probably could have one together in about two hours, but it would leak and be miserable to use! The extra time is well worth it - it'll keep the dust contained as well as the blasting media, and will make cleaning up suck a lot less!

    EDIT: If you're going to assemble this thing, do yourself a favor and find someone who'll loan you an electric ratchet. I did the whole thing by hand (almost) and there are seriously about 140-150 machine screws, and some of them are hard to spin a ratchet or wrench while holding the other side steady with a screwdriver. I did the bottom (attaching the funnel, etc) with the an electric ratchet, and it sped up the process tremendously. If I were going to build another one of these, I think I could cut 30 minutes off of the assembly time by having the auto-ratchet.
    -Brad
    Last edited by piratius; 02-12-2014 at 05:53 PM.

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