Crossfire mbx racer build
 

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well, it's looking like we will be having 4 more race events on the schedule starting january- april.....
and the wife wants in so i need to build a buggy for her. lucky i happen to have a really rough version of her favorite 150, a crossfire, sitting in the heap pile.....and i mean rough.
evrey build has to have an aspect of newness for me to get motivated, so this will basically be a track buggy. the plan is to roll as many tricks into this as i can to make this thing as good as possible on an mx track to compete.
so here is what i have to work with and let the adventure begin!

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spent a couple hours tonight on the swingarm. really took my time to get everything squared up a possible. i used a yerf swingarm for reference but other than that there really was no reference point. at the end of the night everything seemed pretty darn square and level.

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busy night w/ customers so i didn't get much done. most of the finish welding and started to plate the swingarm

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swingarm is about done.

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swing arm is done, basically re enforced everything we've either broken on a yerf or crossfire rear end and addressed it.
rear hoop braced, bottom of the rear hoop gusseted, stiffened the axle hangers, notched the top bar for room for the carb and intake, widened the shock mounts and gussets on both sides of the front legs. just needs some good sanding and paint.

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well thought about it a bit and talked it over with the wife and she told me to go for it so this just went single seat!

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well got the remainder of the floor all peeled off of the tubing but not w/out slicing my wrist pretty good, nothing like a paper towel and electrical tape to keep the evening going.
once i got that all done i started measuring, cutting , bending and nitching and tacked it together to see what i had. i'm trying to rush through this so i'm eye balling alot of it. it looked good enough to weld so tomorrow i'll flip it and finish. once that is done i'll get it back on the cart and level it up to start the cage.

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once you go single seater you never go back to a double lol.

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had an idea for this one to make aluminum side panels and floor so here is the 1st taste. hopefully i'll get the rest done tomorrow.

Nice.. game me idea maybe how change out the floor pan on the dog.
How you connecting to the tabs?

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one side finished

Nice, adding a lot of chassis stiffness by running the flat stock fully along the tubing. looks easier than making a gazillion little metal tabs like i've done. Are you going to grind pattern or paint the panels? (you know what i'm a fan of by now LOL)

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that was the plan w/ the flat, less tube and the flat would keep the frame rigid. the plan is to polish the panels, paint is the backup plan if they don't look good.

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fit the other panels in and started working on the cage. i decided to cut and modify the a-pillar bars for a few reasons. i was down to my last stick of tube, why not save the money and bend time if i did have more tubing and i did want to keep some crossfire cues to it. i bent a main hoop and notched it at an angle because i like the look of the forward lean to add a little tension to the look of everything lean front to back like most buggy cages do. i also cut 2 inches off the bottoms of the a-pillars to give it a lower chopped look then added a bend to bring them in where they meet the new main hoop i bent. i tacked everything into place and decided to let it sit and sleep on the next move.

What's the best way to shine up aluminum? Does it need to be sanded then polished? Or will sanding be not a good thing? Just polish, and you get what you Get?
Looks awesome by the way. Really wanting to drop the steel floor plate in the yerf dog, and go back this route. Really think will drop some pounds off buggy.

sanding will give you swirl marks, with th e"roughness" based on the grit. aluminum polish and a buffing pads will give you smooth shine.

really looking good john ! when does the line production start lol.

Not meaning to detract from JD's thread here but there's all sorts of things you can do with aluminum. Polishing is the most labor intensive and requires a lot of maintenance to keep it that way. These panels were made by simply using a 2" scotchbrite disc in a drill press. position the panel then bring down the disc with slight pressure. Shoot on some clear coat and it will last for a long time.

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nice!

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well got to put in a good long day in on it. the cage is done!.....i believe?
decided to try a roof. my first intent was to go between the bars like the side panels but that proved to be too complicated between the corner welds and too much trial and error , lack of aluminum, and an over abundance of lack of patience. so the plan is....because whatever template i made was never perfect, to get it close , bolt it in and grind/sand the excess to the cage.....
her's where i got so far.

Ok. Got ya, on polish. Travis .... best thing I've found for your fenders. And great btw on anyyyy metal polish, is this. But like idea of clear coat over it. Haven't tried. But will. Just polished all fenders and rims. Will let set for 24hrs, before Appling clear coat.
Btw. After you apply, best to get a big soft towl. Rub off fill no more black. Double, triple up on towel. Gets around the diamond plate issue on the fenders.

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well i had to go and do it.......i had to take a good chunk of a week and clean my shop!
i just couldnt take it any more, but it was well worth it. it's amazing the things you find!
started up again and knocked out a few things.
1st, test fit a motor and had to make an alteration to one of the legs. the plastic shroud was hitting on the right side. other than that everything seems to eyeball up pretty well.
2nd got the motor built about 85%, basically just need to install the clutching and build an exhaust for it.
3rd , cut and ground some more stuff off of the frame like the keyswitch box and grab bar on the dash and cleaned up the lines of the roof.

my camera took a dump so i had to demote one of my others to "shop camera", and use my phone , so i have other pics i'll have to post later.

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here are the phone pics of the swingarm leg. unfortunately i didnt take an immediate "before" pic.

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so now i am catching this thread up.
worked on the back deck, which most of that was coming up with an idea of what i wanted to do.
got the tank mounts done, made 2 large gussets for the cage and then cut the old tank in 1/2 because i needed a template.

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the original plan was to use my tsc brake for the back panel but i bent the handles trying to bend it so i ended up using some alum angle i had in the shop.

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in the meantime i had my father in law priming and painting the swingarm

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i had to build some exhausts so i figured i'd knock this one out while i was at it

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well this should be the last hump with the cage si i can jump to the front end, the pedals. had a busy day so this was about all i could squeeze out.

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working on the pedal setup

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i bought to sticks of 1/4" rod thinking to bake both a brake rod and throttle rod but only ended up making the throttle rod and using the original brake rod to save myself a little time. i had to center the pedals but i wanted the rods as outboard as possible so here's what i came up with.

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well got a few nibbles done tonight.
trying to get the chassis done so i can move to the front end which i am still pondering how much fab i want to do vs using stock. i know i am using a different rack which means different tie rods so i'll have to think about it. in the meantime i bent and added a piece of tubing to be used to mount the shoulder harness tab and a coupe of other pieces to the bottom rear of the cage which will serve as the lap belt tabs. i got a little sidetracked helping a friend get his yerf race ready by welding up his spiderbox.
tomorrow is my anniversary so i will anticipate a night off.

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couple of nights ago i had a free minute so i cut out the floor

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pulled out my crosshammer 250 project and knocked one side of the front end off along w/ the stock crossfire arms to get a point of reference and find that happy medium of where i wanted to be.
today i start on the spindles

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well it pays to keep stuff laying around, like this partial crossfire front end clip.
this helped so my father n law could grind on the frame. got the spindles done, just need to get some heims in for the tie rods and the front should be done. the spindles started out as joyner 250 spindles.

Nice build so far. Cant wait to see it when its done

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well i havent had a chance to post in a while, been a little busy. new units being delivered to the shop for christmas and just got back from a cruise with the wife.
in the meantime been whittling away at the project. remounted the rack to get a more correct steering geometry, finished the tie rods and tabs for the spindles and completed the shock mounts for the front. while i was gone on the cruise my father in law started the painting process on all of the fabbed hard parts and the finishing work on the chassis

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That really looks great Jersey

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got back from the cruise and it was paint time. my father in law did all the prep work and paint while i was busy with customers most of that time.
christmas eve i started assembly and basically finished at the track and fired it up on the trailer. ran into a couple of hicups along the way. chain alignment was tough until we found the output shaft was bent. replacing it made life easier. the brake pedal was bending and binding up the return so i cut and moved that at the track.needless to say we got it loaded and i bolted the panels and the roof up in the trailer . all said and done the chassis feels great , in the little time i sat in it, but i still have an issue which i believe is the motor getting hot. i blame the seat and panels blocking the air to cool the motor. after 3 laps the motor starts to lose power. i have some ideas to help cure this so when i get a chance , i'll need to remedy this and make a shifter bracket so i can hook up the reverse.

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That looks awesome.

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That does look awesome.
Question, where did you get the Diamond plated aluminum?
I've looked around, but only can find 12" or 24" inches squares. Like to place aluminum for bottom plate as well. (don't half to be diamond plated)
That said, how did you attach to frame? sheet metal screws? or did you make tabs for it, and bolt them in?

BTW who came up with the color scheme?
Different, but could grow on me.

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the alum i buy by the sheet. it comes 10'x4', the same w/ the alum i got for the panels. i have a friend next door who has a welding/ fab business so i order it through him along w/ my sq tubing, flat stock and angle.
i attached the florr w/ rivets and the panels and roofed are bolted.

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took the wife to the paint store and she picked. just happened to be 2 mopar colors.

I'll half to ask my buddy. He runs a machine/fab shop for heavy operations. He orders metal all the time, bet he can help me out. Can I ask what that 10x4 sheet would roughly run?
As far as over heating, wondering if placing an air flow fin, going straight to the Fan, something like the Honda FL 350 or 400. ???
But might look weird compared to what how the Honda did it since the fan is further back.
Just a thought.
Looks great. Looks like you got some good travel on your front shocks.
Bet it rides pretty good.
coddoes on wife color combo. :)

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ive had that sheet a while but i want to say it was about $200.
from what little video ive seen it looks like it handles the bumps pretty well and i know it turns on a dime. i test drove it a few times on flat ground and it takes a lot less input at the wheel to turn it then my yerf. turn the wheel hard and it whips the rear end right around.

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found a little time to work on this machine again in between customer work.
found that after the 1st event that the trailmaster tank i used was hitting the swingarm pretty close to the petcock,because i already had it in mind to move the lower shock mounts back a bit to level out the swingarm i needed to find another tank or rethink how i had it mounted. i found another tank in my junk room. i t had a leak so i patched that up and we repainted it. this tank was alot shallower and the petcock was mounted far left so that killed two problems. i cut the shock mounts and moved them both back an inch. now we are in the process of rebuilding the motor, apparently the new oil pump we put in was failing explaining the overheating problem. i will be rewiring it soon enough just because it was done in a rush the night before the race and is not up to par as far as what i do, but it got us by.

That looks great! Following this build

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well we got races coming up so been working on the honeydew list
new motor is in , new exhaust built and mounted and reverse handle mount built and installed.

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well, last fall was the I4MX/MBX triple crown series and the wife and her machine won it....then we just got done running our 1st full series (6 races)
, it ran from feb til june.....and now she's a 2 time champ.

you can catch a bunch or race vids and a build walk around vid of this one on the jd's custom buggies youtube channel
https://www.youtube.com/channel/UCji..._as=subscriber

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round 3 , moto 1 one probably the most fun for me all season, when me and the wife battled it out til the 3rd lap when i broke my axle. awesome go pro vid of the showdown

https://www.youtube.com/watch?v=6S9degHFww4&t=382s