RCF Micro

Addicted 2 Minis

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#4
I've decided on a theme for this build, it's going to be "Old Skool" cool!. The frame will be a satin or semi-gloss grey powdercoat, the same grey as the new jeeps (Sting Grey). I will be using black Hunt Wilde grips and foot peg covers. For brake and throttle, I will be using Diacompe MX122 BMX levers with clutch brake. Gas tank is from BAM Manufacturing, .39 gallon 4"x8" end fill with 1/8" NPT outlet on opposite end. For the seat, I'm going with a 7"x10" black/white diamond stitch kick-up, sorry Karen, I figured you would be too busy with running this event. The engine will be a stock 79cc predator as intended but I will be installing a Coleman CT100 air filter kit from Monster Scooter Parts and straight header with header wrap. As an aditional touch, I will have a black exhaust plug with an oversized "Remove Before Flight" flag to emphasize just how small the bike is. For the clutch/chain, I will be going with an 11 tooth Comet for 5/8" shaft and RLV Gold chain. The only thing I haven't decided on is the wheel and tire setup, I have two ideas but haven't decided on which one to use. My first idea is having a 4" Tri-Star up front with sawtooth tire and 5" Tri-Star in the rear with slick tire. If I were to go with this setup, I would be using a CND split sprocket adapter and 66 tooth WMS skip tooth sprocket. My second idea is to have 4" Azusalite wheels front and rear with whitewall sawtooth tires and RCF's split sprocket adapter. Below are pictures of what I will probably be using, I may go with a 2" thick foam 8"x10" black/white diamond stitch seat with no kick-up, different sprocket and wheel/tire combo.

Hunt Wilde grips.jpg Hunt Wilde foot peg covers.jpg Diacompe MX122 brake levers.jpg BAM 4x8 spun aluminum tank.png CT100 air filter kit.jpg Black exhaust plug.jpg Remove Before Flight flag.JPG 79cc straight header.jpg 7x10 black-white diamond stitch seat.jpg Azusalite with RCF sprocket adapter.jpeg WMS 66T skip tooth sprocket.jpg CND Tri-Star sprocket adapter.jpg 8x12 black-white diamond stitch seat.jpg
 

Addicted 2 Minis

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#5
Well, I got all my parts, doesn't look like I'll be able to ship it here in Afghanistan as my contract is ending in May. I'm thinking of cutting out a little sooner anyhow, that should give me time to get it all together before the deadline. I was going to use the engine from my Coleman CT100U that is a brand new take-off but my wife said "Get another, this ones mine, it makes a great door stop!", WOW!, my wife is actually encouraging me to buy another mini bike part?, Hahahaha. The one thing I like about the Coleman engine is, the throttle was designed like the larger clones and is mini bike ready, unlike the 79cc Predator which if you're not using an aftermarket intake and Mikuni clone, options are slim. I'm going to stock up on some Coleman CT100U throttle mechanisms as they will bolt right on and don't look like an afterthought like the aftermarket non-Mikuni setups. I'm still deciding on which wheel/tire combo to go with, there's only 6" between the axle hangers and I have an addiction to fat slicks, looks like that options out the window. My custom 10"x8" seat turned out nice, I just hope I guesstimated the holes right, my wife was supposed to bolt it on and send me some pictures, I'm not griping, I'm happy that she cares enough to send me what she did, she's really tired of my mini bike "junk" as she calls it!. Here's a picture of the 10"x8" seat. I think the square 8"x8" ones are pretty cool, not a big fan of the 12"x8" on a bike this small, I wanted something to separate it from all the others so I met in the middle, not too long, not too short, hopefully just right!.

10x8 seat_top.JPG 10x8 seat_side.JPG
 

Addicted 2 Minis

Well-Known Member
#6
So I woke up to find a bunch of pictures that my wife had sent me, what a wonderful surprise. The one thing that bugs me when I see someones bike I like is they never tell you anything, like the dimensions of the seat they used or the size of the tank. I like to post all the details so if someone wants to do the same thing, they don't have to guess like I did. The seat is 10"x8" with 2" thick foam, two bolt holes 4" apart from the center of the seat, I bought it from eBay seller Panther 70760. My biggest worry was if I chose the right location for the bolt holes, seeing how I'm not there to measure it for myself, everything is a guesstimate. I was afraid that the seat would not match the bends in the frame towards the front or hang over too much in the back but it lined up great!. The tank is 4"x8" .39 gal. spun aluminum from BAM manufacturing, it has a 1/8" NPT outlet on the opposite end of the fill neck, located 1/2" in from the end. I figure with the kickstand on the left, it would be best to have the fill neck on the right so it isn't spilling fuel while parked, plus with the exhaust on the left it doesn't make sense to have the fill neck right above it. These are the things I think of when doing a build, not just how it looks but functionality as well.

RCF seat side.JPG
RCF seat bottom.JPG
RCF BAM tank.JPG
 

Addicted 2 Minis

Well-Known Member
#7
Just ordered my engine, I decided to go with the 79cc engine from gasbike.net and I'll tell you why. The Predator 79cc doesn't come with any sort of throttle linkage that is minibike friendly, they leave it up to you to figure that one out. The Coleman CT100U does have a minibike friendly throttle linkage but they don't sell just the engine. I went on Colemans site and they want $19.99 for just the throttle linkage and $18.75 to ship it!, REALLY!, a little piece of metal the size of my thumb and index finger that could fit in a bubble envelope, $18.75!!!, what a joke!. So I searched for 79cc engines with throttle linkage and found that the gasbike.net engine fit the bill, $119.00 and free shipping!, now we're talking. Yeah, you can run down to Harbor Freight and get a Predator most of the time for $80, then there's the $15 in gas there and back and I would still have to rig up my own throttle?. So the little bit more the gasbike.net engine cost is worth the peace of mind to me anyhow, below is a picture of the 79cc gasbike.net engine with throttle linkage, The stock Coleman CT100U and an aftermarket add-on, you can clearly see the throttle linkage and how much cleaner it looks than those aftermarket or add-on jobs. Now my only worry is what size crank it has, some of these engines have a 16mm crank, even the Predator says 5/8" (16mm) in the specifications but they are not the same size, a 16mm clutch fits loose on a 5/8" shaft and a 5/8" clutch won't fit easily on the 16mm shaft as many people found out with the first run of Doodlebug DB30's, not to mention the standard and metric keyway differences. 5/8" as a decimal is .625 in. and is 15.875mm. For the return spring, you just run the cable trough a standard compression spring between the adjuster and the cable stop like on the Coleman engine (second picture).

Gas Bike 79cc.jpg

Coleman CT100U Engine.jpg

99cc-Throt-Link_1024x1024.gif
 

Addicted 2 Minis

Well-Known Member
#9
The 79cc predator does have a 5/8 crank.
Yep, I just thought it was odd that they also say it's 16mm in the specs. They don't mention what size the crank is on gas bike.net which makes me wonder if it's 16mm for real. I guess I could have asked but seeing how OldMiniBikes does have the 16mm clutches, if it ends up being 16mm, I'll just order one up from there. Here's the Spec sheet from Harbor Freight showing the 5/8 (16mm) crank diameter.

Predator 79cc specs.png
 
#11
The 99cc predator was 16mm. I'm not sure they make those anymore.
Yeah, I have an old 99cc that was on a Doodlebug when I bought it. I guess they had issues with the head cracking between the valves. You would think they would use the same head as the 79cc but I guess not. Usually when they leave out a detail such as the crank diameter it means your stuck with limited options, they list the crank length, why not the diameter?. I looked to see what clutches they sell for it on their site and they don't list just the clutch, you have to buy the whole kit and even then, they don't tell you what size the clutch is, seems kinda suspicious to me. I guess I'll find out when it shows up at my door. I'll make sure to post my findings so others aren't plagued with the guesswork, once again, I feel like a guinea pig.
 
#12
I have decided to go with different throttle/brake levers. Since I'm going with an aviation style theme, I figure what would be better than colored levers, kind of like nav lights. The colored levers will serve a dual purpose too, the left lever will be for the brake which will be red for stop and the right lever will be for the throttle which will be green for go, It just so happens that's how nav lights are too.

MX122_Red.jpg MX122_Green.jpg
 

Addicted 2 Minis

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#13
Changing gears a bit, since I work in army aviation, I wanted to go with a theme from something that work around. I wanted it to be "Old Skool" cool as well, What's cooler than Fighter jets?, not much so I decided to make a few changes. The frame color is still going to be grey but I am going with a lighter Air Force fighter grey. This helped me decide on tires and wheels too. I am going with plain white steel wheels with Cheng Shin 3.00-4 C154 tires, I figure they would look more aviation like than the rear slick and sawtooth front that I originally planned. I am going with a 10x7 Black-Grey diamond stitch kick-up seat, it just looks more "Old Skool" mini bike than the flat seat. Below are some pictures of the color I'm going with, the wheels, tires and the seat along with a picture of an F-16 to give you an idea.

LIGHT-COMPASS-GHOST-GRAY-FS-36375-2-oz-Tru-Color-Paint.jpg Rotary 8983 Side.jpg Cheng Shin 3.00x4 C154.jpg 10x7 Grey-Black diamond stitch.jpg

F-16.jpg
 
#14
Thanks to the corona virus, I have no idea when I'll be able to leave Afghanistan. I would have my wife run it down to have it powder coated but there's some things I wanted to do to it first. I guess if I don't make it, I'll just move over to the projects and rides section, fingers crossed.
 

Addicted 2 Minis

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#15
I know I've been hanging out at the bottom of the list for some time, being 8,000 miles from my build kind of puts a damper on things, not to mention the latest and greatest goings on back stateside. Getting home to finish before the deadline is looking promising though so that's good. My wife understands that when I do finally get back, it's nothing but mini bike building until it's done!, then, unfortunately at some point and time, there's the "Honey do's".
 
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