Newest Build

[boomarkert]

So I got into these things by buying a used motor and bike that I saw on the side of the road a while back.. Since then I decided to build a new bike with a new motor.
I bought the motor kit on KingsMotorBikes.com, which I heard wasn't a great idea but I think I got a pretty good deal..
Anyway, I got the 66cc 2011 GT5, which came with the CNS carb (crappy, I know). I do like the fact that I have a choke lever instead of having to reach down to the carb when I start riding. I put the motor onto a Trek (a crossover road/mountain bike), couldn't decide if I wanted to put it onto my Fuji mountain bike, that may be the next project.
The install was pretty straight forward, didn't run into any real issues. Luckily the kit came with the Z tube for the intake, the carburetor wouldn't have fit in the frame without it.
Now I'm breaking the engine in with a 16:1 fuel ratio and not going any faster than about 15mph... Even without pulling the throttle all the way you can tell this bike wants to FLY! I can't wait to really give it a go and see what it can do

So that's where I'm at, I want to make some modifications but as of right now I am broke haha. So we'll see what the future holds for the bike

PS, I appreciate everything I've learned from the people on this site.. I've been reading this forum since I first picked up the original motorbike and have learned so much about everything that has to do with motors and pedal bikes. So Thank You Everyone!

 

[Artificer161]

Looks nice, what modifications are you looking at doing when you have the cash?

 

[boomarkert]

I would like to either purchase or build an expansion chamber first and foremost. From what I've understood, those give the biggest boost to your engine out of any upgrade you can get. I'd like to change out the CNS Carb possibly, though I've actually had no problems with it so far.
Other than that really, just simple small modifications, like sprocket sizing, new throttle possibly.. Stuff like that

 

[boomarkert]

So I took the bike out today for a nice long ride through the park.. BEAUTIFUL ride, with the fall colors and all..
Best of all, the bike ran GREAT!!!

It took a minute to warm up, and I gave it a while before I got close to pushing it since I am still breaking the engine in, but once it was going it was wonderful. Eventually I got a top speed of 32.5, which wasn't even that hard to achieve honestly. I expect to get a higher top speed once the engine is run in a bit and I run up the fuel/oil ratio a bit.

Super smooth ride, I took a road through the park that's pretty much completely smooth. So it was great, and even though the roads I took to get there were pretty crappy, it rode very well on those too. I had a slower cruising speed between 25-27mph most of the ride, and even at the slower throttle it ran/sounded great.

Once I finally got back home and looked at the motor, kind of expecting to see some gas/oil drips here n there or something, the motor is still COMPLETELY clean!! It's sealed up great! I can't wait to see what this thing can do once it's been ridden in more! I'll update when there's more to update

 

[JonnyR]

if you want a realy good carb get a thatdax RT but if the cns is working leave it for now arrow makes a good exhaust one that gets the pipe up and away from your peddles http://www.arrowmotorizedcycles.com/shop-now---exhaust-pipes.html

 

[boomarkert]

I like the exhaust.. I just don't know if there's room for it to go through the frame like it does. It's such a tight squeeze in that Trek frame, barely fit the motor as it is lol.

As for the carb, yah I've heard about the RT.. I'm looking into it, though like you said, as long as the CNS is working, I'm going to leave it.

 

[boomarkert]

So I've been riding, all's good, but it still 4-cycles all the time . And today it felt super sluggish, wouldn't go any faster than 25mph, I think it's cuz I'm not gettin enough air but the cns carb doesn't allow adjusting. I even noticed that the pin for the float bowl doesn't have any slots to adjust to..
What do I do??? Would a smaller rear sprocket make it work better? If I can't get more air into the engine, I figure I need to find a way to make the engine need more gasoline lol. Maybe the exhaust? Idk, any ideas would be much appreciated, other than "throw out your carb" kinda stuff... I know, the cns sucks, but it's what I got right now. I'm looking into the RT, but not sure yet. Plus I need more money first haha

 

[boomarkert]

I pulled the brass plug out of the carburetor to get to the fuel/air screw.. It doesn't seem to be helping too much, the bike still wont go faster than 21mph, and won't stop "4-cycling".. I don't know what else to do, possibly my fuel/oil mix? I did switch from 16:1 to 24:1 right before it started acting up a bit, idk if that had anything to do with it or what.

Hope someone can help me out here, I'm goin crazy trying to get this thing running correctly

 

[Buzzerbiker]

Just read your plight, don't know if your fixed yet. When solving single cylinder driveability issues I ALWAYS replace the spark plug first, then look at air/fuel issues. The 16:1 does foul the plug more easily, are you using a good synthetic blend oil? If the plug doesn't help, pull the float bowl, check that the jets are in place, and check float level. Good luck!

 

[a_dam]

This thread is kinda old, but I hope my reply can be of some help.
I only have experience with the two "wacker" motors I used on my homemade builds. Both are small 2-cycles, a 25cc and 28cc. They are pretty sensitive to load and temperature. I couldn't imagine running a motorized bike without expecting to adjust the choke/carb mixture.

Off the bat, I can think of a few things that will make a motor run rich and "4-cycle".
Naturally, if the carb mixture screw (especially the one on the intake side) is opened too much, the fuel mix will be too rich.

If the choke is closed at all.

Riding downhill or with the wind will make a motor more likely to 4-cycle.

A motor runs richer when warmed up - that's why you choke a cold motor, then go no-choke when it warms up.

But, my little 2-strokes need carb screw adjustment when the weather changes. They run richer when the outside temp is colder. I soldered/glued external tabs to my carb screws so I can easily adjust them while riding, and with the screw and choke I can get it well tuned for all conditions.

Oh, the other thing that will make a motor run rich is if the air filter is dirty (it acts like a choke). If your motor is 4-cycling a lot, it is probably flooding the air filter with fuel and oil.

Clean your air filter and your spark plug. Make sure your choke is not staying partially closed.

Can't give advise on much else since I don't know about the china kits.

 

[Buzzerbiker]

Hi "a" ya I was responding to "boomarkert's" issue. My Sthil is running like a champ though. You are right on with your pumper carb insights. I always have a screwdriver along for the ride. Last time I was out though, it was 34deg, so I opened the Hi screw 1/8 turn before I even started the engine. Just right! It is tuned pretty HOT and is sensitive to "air", but 1/8 T back and forth on the Hi screw covers it on any given day. Thanks, I'm parked for the winter now unless we get a chinook. Good biking to you.

 

[a_dam]

Hi buzzerbike,

It is depressing that riding weather is pretty much gone for this year. Highs in the 40s with wind speed about 40 as well (getting some effect from the hurricane).

My reply was directed at boomarkert as well. I've never had a china motor, but I read that instead of a carb screw they have a needle that you adjust in/out by notches. In that case I would move that needle in a notch to lean the mix. And make sure you have a clean air filter and proper choke function.

I wouldn't think that going lighter on the oil mix (16:1 to 24:1) would cause 4-stroking.

 

[Buzzerbiker]

Hi again "a", I think my season is about done too, but if I can't ride I'll do more scheming. Got wood heat in my garage, so it's a good place to spend the worst days. Ya, reducing the oil mix won't make an engine blubber, I'm curious though if even 24:1 is needed. I use 50:1 on all my two strokes, BUT, only with a premium fuel, AND, synthetic blend oil,like Husqvarna, or Echo. Not sure if the china motors have the internal quality for that lean a mixture. I have an ancient 3.7 cube Homelite saw that specified 24:1 OE, but does run sooooo much better on 50:1 prem/synth. The newer oil technology is what makes the difference. This Homelite may get rodded up for a ride someday, $5 at a yard sale, but I am really looking more toward a 4 cycle next, or, two 29cc 4stroke mated. Oh, I did see nice upgrade carbs for the china mills for about $25. Probably worthwhile. These china kits seem like a good way to go for the average builder, as for me, I have more time than money, and gobs of bike parts, shafts, bearings,etc. My next one, Lord willing, will be a little more elaborate, hopefully more retro. You have a great winter, post some pics next time you got something cooking, take care.

 

[geoffmaree]

4 stroking tells me to adjust the e clip on the carb slider for a leaner mixture.

 

[geoffmaree]

sounds like its flooding