break-in period on 48cc , not sure if my engine is running correctly.....

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greggasbike

New Member
Nov 23, 2010
59
0
0
north carolina
Hello out there, just a question about the breaking period of my new 48cc motor....


I have read and heard about the "break in " period for the engine. But not exactly sure what the motor acts like in this time..... does this sound right?

So , I finished my MB last weekend. Rode it twice this week , about 30-40 miles. I used the 16:1 ratio for the break in of the motor. Just riding it very easy at a school parking lot ( schools out of session , so no one to bother me and big area to ride, and some streets around the school ).

The engine starts right up , very easy. The engine will idle just fine, smooth actually , not much vibration at idle. The throttle will rev okay.

Now when I start riding it....

1) It takes a while to build up any speed. I will peddle for a good 50-100 ft then give it some gas. It will go but then lose power almost right away.

2) If I go downhill , it will get going just fine, but when I hit full speed , the motor will backfire, or make some kind of popping sound... Notice I am not giving it full throttle , just a slight turn, b/c already picking up speed from the hill. If I try to give it more gas , it will almost choke out the engine.

3) There is no power whatsoever ... It will not go up any hill , even 15degree incline on the motors own power.


The only thing I can do , start on flat area, get the bike going , release clutch /give a little gas, then slowly ( i mean slow) get it to about 15mph and it will cruise for a bit. If I try to go any faster the engine dies out...


Does this sound right , that the engine is just "breaking in" and will get its power and everything sorted out once it ride more??? or do I need to adjust the carb or something ? ( I have checked for exhaust and intake leaks and everything seems fine ??? )


Thanks everyone for your help , this forum rules !
 

Elitefr

New Member
Sep 12, 2010
22
0
0
Pittsburgh
Sounds like an air-leak to me. Make sure your carb is securely fastened. If it is try applying some high heat silicon or just adjust the carb to have a very low air/fuel ratio
 

anothen

New Member
Dec 31, 2010
31
0
0
Austin Texas
ditto to the above,
also double check electrical.
The popping and backfiring
could be from wire shorting.
Check the spark plug cable
for looseness and spark plug
itself.
Uncover the magneto plate
and check to make sure
all four screws mounting the
magneto is secure.
If you are using a kill
button, disconnect the
kill button to see if it
cures the problem.
Make sure all wires
are clear from the exhaust.

If all else fails, take a large
club and beat the ****
out of it. It don't help
but it's a sure fire way
to vent frustration.
 

Black_Moons

New Member
Oct 25, 2010
205
2
0
Canada, Bc
Yea basicly you got a carb air leak, or some other fuel problem, like a non vented tank cap (try and ride with it loose?), Or similar.

the engine should work fine from day 1 when setup properly, it just goes from reasonable power to fun power after break-in, And then up to dangerious power once you start modifying it and add an expansion exhaust etc :)

Critical break in is the first 1 gallon of gas, Idealy you want lots of oil, and to run it hard, but intermitantly. (ie got WOT now and then and get some high rpms, just not continiously) and then it seems to gain a little more power over the next 4 gallons, then its broken in.
 

biknut

Well-Known Member
Sep 28, 2010
6,631
409
83
Dallas
What kind of motor do you have?
What kind of carb?

If I were you I'd go with 24:1 too , and maybe change the spark plug to a NGK BP6HS and buy an extra plug and change it after you go to 32:1

If you are buying synthetic probably go to 40:1
 

greggasbike

New Member
Nov 23, 2010
59
0
0
north carolina
Okay , so I worked on it last night and rode it again today....

Here's what I did checked.

1) checked wires ( at magneto etc) ... all connections are good.
2) took off the muffler and intake , checked gaskets and replaced.
3) changed the gas oil ratio 32:1
4) put high temp-silicon on the intake around carb , stop up any possible air leaks there.
5) checked the choke for functionality.
6) l oosened the gas cap.
7) checked spark plug gap and secure fit

prbly a few more things... can't think of them all , it was late last night.

So , when I rode it today , I am still having same problems. It will start fine / idle fine. But it will barely ride. Downhill it will get up to about 20 , but if you pull the throttle it will either backfire or die out. Flat ground , it acts like it wants to go , then dies out. Also , when I first started the engine (for the first time when the kit was built) I did have a lot of white smoke come out , from muffler , around it and near where it bolts on. The smoke went away after a few minutes and never came back ...

What is the possibility that its the head gasket ? The other new thing it does now , when at a stopped position if you try to rev it , it will not rev all the way , it will die out when i you pull throttle near full.

Still missing all the fun of riding this thing , been a fun journey so far.

Its a 48cc skyhawk gt2b , its really bothering me now . Wish I bought another kit. This one has had a few problems now ( that would have been really easy for the manufacturer to solve)
 

scottmanesis

New Member
Dec 30, 2010
107
0
0
Austin, TX
Just curious what the altitude is where you are at? Possibly wrong jetting for the atmospheric pressure? Just guessing because I don't know.
 

Allen_Wrench

Resident Mad Scientist
Feb 6, 2010
2,784
26
36
Indianapolis
Just out of curiousity: what notch is the C-clip on the carb needle at? You may want to check. Most people set it at the second notch from the top, but you'll want to see what works for you. Also make sure your choke isn't creeping closed on you as you ride. I've had that happen so often that I put a nylock nut on it. When that wasn't working as well as I liked (I have no idea why not) I used locktite on it. That fixed it.
Just my two cents, but you may want to check those things.
 

anothen

New Member
Dec 31, 2010
31
0
0
Austin Texas
If it was head gasket there would
be noticeable leaks.

It's sounding more like a carb
problem.
Inspect the carb for trash.
If the float is too tight, it
would cause this symptom.

Also check the muffler make
sure it's not blocked.