New member - Install on Roadmaster from Walmart

R

ryan83

New Member
Hey everybody I'm Ryan I'm a new member from Illinois. I have a 26" Roadmaster mountain bike I got from walmart and I have an 80cc engine kit coming in the mail from boy go fast on ebay. It seems that some people have had trouble fitting this kit on the roadmaster bike. Anybody have any experience with this bike going with this engine? It's too late to return the bike at this point. Thanks in advance for any help..bld.
 
I sold my first motorized bicycle the other day and it was the
Roardmaster mountianbike from Walmart. I used the 80cc slanthead
-plug engine from zoom. This engine is a very tight fit for the bicycle.
To get your intake and carburator into the space you must take out the
studs and put carburator on intake and stock air cleaner, you will rough up
the black plastic on the air cleaner and it will fit tight against the down tube.
The clutch arm must be cut down and a hole drilled in it for the clutch cable to
go through it. The front stud for the engine mount must be cut down for the exhaust
to fit. For a $77.00 bicycle from Walmart and a not proffessional build ,it did work.
 
Charged-Reacter said:
I sold my first motorized bicycle the other day and it was the
Roardmaster mountianbike from Walmart. I used the 80cc slanthead
-plug engine from zoom. This engine is a very tight fit for the bicycle.
To get your intake and carburator into the space you must take out the
studs and put carburator on intake and stock air cleaner, you will rough up
the black plastic on the air cleaner and it will fit tight against the down tube.
The clutch arm must be cut down and a hole drilled in it for the clutch cable to
go through it. The front stud for the engine mount must be cut down for the exhaust
to fit. For a $77.00 bicycle from Walmart and a not proffessional build ,it did work.
Click to expand...

Cool man thanks. That's good news that it will fit at least and the modifications don't sound to tough...
 
Ok so I got everything put together, but there's just no way the carburetor is gonna fit. Anybody have have this problem? Is there some stuff I can get at the hardware store to mount it somewhere else on the bike and run a hose to the intake?:-||
 
Ryan,
Many guys have fabricated a custom intake manifold using copper plumbing fittings. You'll need to be good at soldering. Another alternative is this. > INTAKE
Tom
 
i use a roadmaster bike on my first build and it was not fun but it did run and look good when i was done a week later.but i bought it used like new for $20. i mounted the carb off to the side using 90% curved copper pipe fittings and the spark plug and boot will be a very tight fit.
clamps will not work for the pipes,i used jb-weld but didnt hold very well,i reccomend soldering them.or you could shorten the intake pipe and modify the air cleaner.

im now using a scwhinn del mar cruiser bike,has plenty of room for engine and bike was only $99.
 
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A 45 deg. elbow silver soldered in place. Still working great......
 

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ryan83 said:
Hey everybody I'm Ryan I'm a new member from Illinois. I have a 26" Roadmaster mountain bike I got from walmart and I have an 80cc engine kit coming in the mail from boy go fast on ebay. It seems that some people have had trouble fitting this kit on the roadmaster bike. Anybody have any experience with this bike going with this engine? It's too late to return the bike at this point. Thanks in advance for any help..bld.
Click to expand...

i have a schwinn stingray chopper, and when i bought my kit i was thinking about all the mods i would have to do, boy was i off.
1: weld plate to bike for mounting engine,
2: drill hole in to mount the bottom engine mount.
# create new muffler w/ 1/2in. pie and weld stock muffler at the end to get it to fit and make it long enough so it is know strapped to side of the rear forks.
3: drill hole for magneto and tap this for magneto to fit into.
4:adjust rear forks so it could move tire forward.
5: new clutch cable because the one that came with it snapped.
6: cut slits in the bike to mount gas tank.
7: trimmed fuel lines
and there u have it, this is all the things i did to it to fit a schwinn stingray chopper.trk.
so try something like this and be creative with it. if i can do it and im 13 i think u can do it. no lies...

i am thinking about buying a boost bootle and a 36t sprocket because it only goes 32mph now on a 20" chopper bike
 
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So I finally got it put together and running.
For the carb I ended up cutting the intake manifold in half with a hacksaw (slowly) and then running the cut ends accross a flat file till smooth and then putting a piece of heater hose around the joint and a hose clamp around it. That way you can swivel it to the side so the carb is outside the frame. The carb ends up being slanted a little bit but not a whole lot. I got this idea from another user's post on here, can't remember who... It works but the thing is when you tighten up on the hose clamp it pushes the two halves of the intake apart inevitably, and the more you tighten it the bigger the gap. I hope the rubber hose doesn't dissolve into the fuel that collects in the gap? maybe there's a different type of hose that's stiffer so it wont squeeze the two halves apart and is also oil resistant? or is heater hose already oil resistant? I wanted to do the copper pipe method but couldn't find what I needed at the hardware store.
I also had to make a mounting plate for the front motor mount due to the oversized oval tube.
The Ignition coil I just duct taped on for now
The chain guard I haven't figured out what I wanna do with that yet, the one that came with the kit definitely doesn't fit, it's too long and too wide.

So yea like you guys said putting the kit on this bike is a big hassle, It would have been alot easier if I had a welder and a milling machine... but I gotta say the black engine kit on this bike does look pretty sweet
 
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Regular heater hose is not oil resistant. Could a copper 45 or 90 deg pipe fitting work, they come in all different sizes. If it would theres all kinds of epoxies or glue to hold the pieces together once the copper piece is sleeved.
 
hey ryan - u talkin' bout me? o_O :D

The "trick" with the bit o'heater hose is to mark the perfect alignment (scribe a lil line), then pull it back off, separate the two halves and using just a touch of fuel resistant insta-gasket goop smeared inside the hose - put it back together, clamp securely but not overly tight and let it cure overnight. The goop will help "glue" the manifold together so over-torquing the clamp isn't necessary.

Any gap should now be filled with gasket goo, be careful to not use too much as a ridge will interrupt fuel flow. The beat way is ofc to have the two halves welded, its easy and/or cheap - yet I still haven't done it myself lol

As for "heater line isn't fuel resistant" - that may or may not be true, it depends entirely on the hose. Yet mine hasn't changed in any way with well over 700 miles on it, there's very little to no fuel contact anyway should it be seated well. I wouldn't worry about it, even if you find you need replace it every 1000 miles - its like 1/2" of hose lol, prolly costs .005 cents and 10 minutes of yer time :p

Mine was only supposed to be "temporary" - I really was going to weld it, but it's gettin' close to 1000 miles now and as it's still just fine... well, let's just say that's low on the priority list heh


A warning however - if yer carb is canted slightly with the primer button on the low side, the primer pin MIGHT not allow the float to reach the top completely. If (and only if) you experience carb dribble or cutting out at WOT/high RPM, trim just about 1/16" off the tip of the primer pin inside the carb's float bowl and bend the float's tabs accordingly.

THAT lil issue drove me insane till another member wondered if my float was sticking ;) (BTW - the carb in the pic is more level than it appears - I was crooked at the time heh)
 

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