Introductions and questions. I have a plan, need advice.

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dissident75

New Member
Hey everyone. I've been lurking here for a while doing a bunch of preliminary research before I start my kit.

Some background on me.
I'm new to gas powered bikes but I have been riding an electric bike for a few years as my main means of transportation. My recent move to Houston and its more lax attitudes to gas bikes has prompted me to make the switch to gas from electrics for the greater speed and range. When I say main I mean only. Having pissed of a judge a few years back I have had my privileges revoked and have a few more years of riding ahead of me and the limitations of electric have worn me a bit thin. I mean the torque and speed are great but SLA batteries are heavy and wear out quickly and good lithium iron phosphate batteries in usable capacities are freaking expensive. $900 for 48v 20AH, really?!?

I'm the kind of guy that likes to get dirty building stuff and have been for a while. I repair my own cars, do my own home repairs and rehab houses with a few buddies. I know my way around a tool box and power tools.

Generally speaking I fix and make stuff and have done so for a while.

I'm planning on building my first gas bike soon and need a bit of advise to save me some money.

I'm going to be using a Walmart Roadmaster 26" mountain bike as the base. I know it has its space limitations but since I am not going to buy another bike it will be the base. Plus it looks kinda hot.

Bike
Walmart.com: 26'' Men's Roadmaster Mountain Sport All-Terrain Bike: Bikes & Riding Toys

I'm planning on a blck finish 80/66cc grubbee skyhawk gt5 kit from gasbike.net To account for the lack of space in the frame I'm going to order the manic mechanic billet intake and a low profile air filter. I think these together will fix the carb not fiting issue I keep seeing people have on these bikes.

The engine kit
GRUBEE SkyHawk GT2B 66c/80cc Slant Head (Black Finish) Bike Engine Kit - Gas Bike Motor Kit

The intake
Ported Billet Intake

The air filter
Low Profile-Air Filter Blue

I'm also planning on swapping the brake handles for a dual pull handle to get rid of the three lever mess. The aesthetics just annoy with 3 levers. I'm also planning to use a 36 tooth sprocket from spookytoothcycles.com to get a bit more speed from the larger engine.

The dual pull brake lever
Sick Bike Parts

The sprocket
36 Tooth Engine Drive Speed Sprocket

I haven't yet decided to upgrade the exhaust to a tuned pipe setup yet, though the performance increase is nice. Basically I want it quiet and fast. Every video I've seen with the tuned pipe setups have been loud and I'm trying for a more stealth approach. Now if I could a tuned setup and somehow keep it quiet that would be ideal but that can be a future upgrade.

I also have a decent lighting scheme planned out. Dual cree flashlights mounted underslung to the handle bars. A brake light and turn signal kit and even a alarm with remote arming and vibration sensing. The alarm is a bit silly but since this is essentially going to be my car and I have yet to figure out where my big u-lock is going to mount to the bike with the engine installed it may be a necessity since I hate coiled cable locks. I can cut one of those in a minute with bolt cutters. **** vice grips and big burly dykes can do it in a pinch. The u-lock at least they'd have to take a hacksaw to.

The headlight x2
DealExtreme: $12.25 Flood-to-Throw Zooming Cree P4-WC 3-Mode LED Bike Light with Mount (3*AAA)

The brake light/turn signals
DealExtreme: $8.65 9-LED Turning Signal Lights with Electronic Horn for Bicycles (2*AA)

The alarm
DealExtreme: $9.29 Vibration Activated 120dB Anti-Theft Security Alarm with Remote Control Keychain

That in a nutshell is the grand plan.

My question is this. Will the billet intake and the low profile air filter be enough to make this fit the carb in the frame so it isn't sticking out? Also what kind of speed do you think I'll be able to reach with the 36 tooth sprocket in the setup I propose?

I look forward to what you guys have to say about the proposed plan. Any advice is appreciated.
 
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It is mainly a lot to read at once. It is very nicely organized and much easier to read than a wall o' text.
It appears that you have a good handle on your first gas bike build. I'm not sure anyone can answer your question concerning the carb/frame fit. Judging from your plans though, I think you will be able to handle things if it doesn't fit.
 
I don't know about the billet intake but I predict that after it's broken in if you give it enough room you might be able to reach a top speed of 36mph.
 
Fair enough. I know I can get a bit wordy at times but I have always found that when seeking advice, its better to give to much information rather than not enough. I was also trying to combine a introductory post with this. That may have been a mistake. Live and learn.

36 mph seems like a good solid speed. I'm no speed demon anymore (been spanked by the Man enough to beat that outta me) so much faster is unnecessary. Fun yes, necessary, no. I would like to be able to keep up with the stop and go traffic I'm going to have to face here and that seems like a good solid speed since more often than not the posted limit is 35, but more often it seems to travel well below that.

Wow, don't mind the run on sentence. It is a bit late.

Hammond. You raise an interesting thought. As far as breaking in an engine like this what is the proper way to go? I've heard that "If you want it fast then break it in fast" but is that really a standard practice? All my previous vehicles have been used so no break in was necessary. I've seen videos online where it seemed like the finished bikes were just left to idle to break in. It seems to me you would want it run the engine through the full range of speeds to properly seat everything and get the mating surfaces perfectly matched.

Any tips or tricks to breaking these 2 strokes in?
 
I agree wholeheartedly dissident - information is key... ofc I've been accused of bein' a bit "wordy" from time to time lol *shrug* Still - I don't think it was a matter of too much info, but more that yer questions aren't easily answerable. So many little things effect the speed and as usually we'd be talkin' about no more than a 5mph variance even knobby tires or a dry chain can "dramatically" effect that - add in the wildly different performance between even two identical engines... and there's no easy answer other than a ballpark guess.

Odds are that if ya can fit the engine in there at all, the billet intake & low profile air filter will help if it's tight - but be forewarned, as the billet intake isn't angled you'll need to angle the engine itself to level the carb. While I didn't have space issues w/my last build - I did have carb angle problems & that's easily fixed w/a stock steel intake as ya can cut a slot in it, bend to the proper angle for your bike & reweld... *shrug* again - depends on the bike lol

As for break in... yea, now that is completely open to debate heh, in fact it's so controversial that we've countless threads on the subject and still no one quite agrees lol As such, I'm of the opinion that with these kinda sloppy lil engines that it really doesn't matter much if at all, tho I wouldn't do the "just left to idle" method as that's begging for an overheat.


Welcome to the forum BTW ;)
 
Thanks for the welcome. Leave it to me to ask the hard questions first :). The "leave it to idle" method seemed like a really poor idea when I saw it simply based on the fact its air cooled and with no air running over it things are gonna get hot and break. I'm kinda of the opinion that to properly set the parts and mating surfaces you would want to run it hard but not thrash it. Get the wear outta the way and get the engine accustomed to running hard.

You make a good point about the carb angle. I've done a bit of research into alternate intakes and there is an offset one I've seen that looks like it would do the job nicely it there is an issue with angle and getting it to fit. That intake was at least reasonably priced at a whole seven bucks. I'd just hate to have to wait for it to be shipped once the bike is built. Perhaps ordering both just in case is the answer there.

The variance in speed also seems to make sense when all the little factors come into play. Road tires versus knobbies are going to present a different rolling resistance and probably total outer circumference will even change. Chains being lubed or dry I can see having an effect also. Even what your tires are pumped up to would have a noticeable effect. In my case getting everything perfect will help since in all likelihood I'll be switching to solid tubes since apparently littering is a problem here in Houston. I've patched and replaced more tubes in the six months here than in two years in Jersey.

The more I think about it anything you do to streamline the drive train should make a difference in top end when the power generated by the engine is so low. This gives me some food for thought.
 
I attached a photo of a rubber tube that I fastened to the manifold and a copper elbow fitting. I also added some instant gasket silicone on the copper elbow fitting before mounting the carburetor.

It might add some life to your carburetor as well. It made this one last a lot longer than I expected through humid California heat. The manifold tube and the carburetor have both lasted over 150 miles.

http://motorbicycling.com/members/wyldstallions-albums-parts-picture386-manifold-tube.jpg

wyldstallions-albums-parts-picture386-manifold-tube.jpg


I've mostly been running my motors in short bursts, through a full range of speeds. I've had a few long trips too. Pretty lucky so far.

There's a lot of good reading in here about braking in the motors.
 
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Ok, for the life of me can't figure out how to start a new thread, so replying here to ask my question. I put 66 cc china engine on a thrift store bike. Went together quicker and easier than I imagined, but can't get it to start. I have good spark, compression seems, good, will start with 'easy start spray' when sprayed directly into the cylinder, but only for 10 or 15 seconds or so. throttle cable and body seem to be functioning. I have 16:1 Gas/two cycle synthetic oil ratio (too much oil?) Plug looks dry and unused when I check it. I have played around with the choke, idle set screw and float level to no avail. An help would be greatly appreciated:-||:-||
 
Sounds a lot like you're not getting any fuel entekaese, pull the line from the carb and open the petcock, draining some fuel into a clean container - if yer getting good flow, the problem is prolly in the carby... it may be a clogged jet or simply maladjusted floats.


To post a new thread, click on the subforum you wish to post in, then click "Forum Tools" at the top right of the list of threads in that subforum - a drop down menu will appear and the first choice is "Post a New Thread" :)
 
Thanks. Fuel flow from tank seems good, doesn't gush out, but not a trickle either. Took carb apart, casting is fair, but machining is really rough I could see how a bit of metal might block something but everything I can see looks alright. Maladjusted float seems most likely from what I hear you saying. I can continue playing with it but I don't really know where it is supposed to be.

Awesome forum by the way, Helpful, informative, and entertaining.
 
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Welp, the first revision of the bike is built and I couldn't be happier. Used a different engine than I intended, used a zk2-80 black slant head form boygofast. It fit in the frame just fine with only a minor clearance issue on the carb and aircleaner. The carb I have tilted slightly, and the aircleaner I simply chopped the tubes off the bottom to get the required clearance. I havent added the spiffy lights I specced out yet but they will be added soon enough after I get around to ordering them but for now I am more than pleased with the result.

Damn thing is fast as **** and stomps the electric I rode for the last 2 years in terms of range speed and just being all around more bad a$$.

Now I just need a name for her.

34159d1299713261-stuck-clutch-over-revving-engine-not-2011-03-05-15.56.44-2-.jpg
 
Use caution with that frame- I built one on that platform, not sure if it was a lemon or not- but it gave me plenty trouble. first to go was the Crank, -pedal just fell off during a ride, I look down to see the threads stripped.
I do have to say, I really like the stance of that frame, kinda moto-X looking. Nice build!
 
I keep reading about people with bad experiences with this bike but I have a lot of trouble believing it. I mean yes, cheap walmart pos, being subjected to more stress than it was designed for but I have put some cheap bikes through some serious he11 and I've yet to break one in a way that was permanent.

But thanks for the advice. I'll keep a eye out for potential issues. Though truthfully, so long as the frame stays in one piece I can fix or replace most anything else that goes wrong with it. And once I get my welder, then the frame may not even be a big deal. I think a large part of the reliability issues with this model of bike boils down to the initial assembly by the minimum wage guys at wally world to be honest. Some folks just have no pride in their work.

I have to say riding this bike so far has been an experience. I get looks constantly. Smiles, thumbs up, and people waving me over to ask about it and talk about it. Seeing the kinds of responses I get from this it puts me in an entrepreneurial state of mind.

The way peoples eyes bug out when the hear about its speed and range is too funny.

Thanks for the kind words, it really is a sharp looking bike once its built. I didn't buy it with the intention of building this. Truthfully it was bought as a parts/replacement bike but when the other bikes controller 5h1t the bed I decided to just ride this one as is. Never gave me a problem at all.

I'm very pleased with the result so far.
 
One thing I can agree with, is to learn for yourself. what works for one doesn't work for all- sounds like you have the initiative to work through the small problems.
Also have to agree with you about replacing the bad parts- my current build started life as a huffy newport, another wal-mart bike. It is so far one of the nicer of my builds- stripped it down bare, Paint and all the little tricks I learned along the way, relocated seatpost, modified front fork, etc.


I have only respect for someone who can take input, and still blaze their own trail. Kinda like building that first bike..... Think my whole family thought I was nuts!
 
I think pride has little to do with depatment store cheapies.These guys are told they can make $16.00/hour but then have to assemble 4 bikes an hour, I'm not sure I could do a good job at that pace. Again you get what you pay for and a lot of the sloppy assembly work can be corrected by doing it yourself. Good luck. P.S. nice looking bike.
 
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No your probably right but the mentality of faster quicker shoddier just irks me. Like when you get your car back from the garage and there's a tool under the hood or the gear shifter is reinstalled crooked.Both of which has happened to myself and several friends.

Just working isn't good enough sometimes.
 
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