Gokart MZ 250

[karte_m0lim]

few more pics ..

finished axle sprocket mount and chain ..

added heel support on pedals..

chain is touching chain cover so some cutting is coming ..

need to bend exhaust pipe a bit ...

and yes, carburetor leaking started ..

left to do: find seat , new throttle cable , fix carburetor and test ride ..

 

[2SlickNick]

Keep up the good work. Also your new exhaust looks much better, than the aluminum foil one used in your vid.

 

[karte_m0lim]

ok , so almost everything is don except seat...

so I decided to make it one by my own ..

I made my *** shaped mold of stiropor (Styrofoam, somebody confirm that is correct translation)...

over it I apply plastic coating... and found on hard way that it melt down styrofoam...

anyway, I am not really happy with final results as there is a lot of bumps..

today I flatend it and added sealant....

just to mention, this is first time I work with this stuff...

 

[landuse]

Good job you are doing there

 

[karte_m0lim]

added valve on fuel line ...

added bearing on steering column (was pipe in pipe) ...

front bumper in progress...

edit: this how it should like...

edit2: almost forgot, a bit of revving ...

https://www.youtube.com/watch?v=9oFQPWr9OIA

https://www.youtube.com/watch?v=NIUO_-J_jDw

 

[karte_m0lim]

not much work over weekend ..

a bit of Styrofoam modeling ..

I play a bit too much and instead front wing I have Loggerhead Sea Turtle ..

 

[karte_m0lim]

so, it is finally moving ..

still some tweaking and fine tuning on engine and clutch ..

sorry for poor video quality..

now, painting left ..


https://youtu.be/qRg5QWkoq4E

 

[itsid]

I play a bit too much and instead front wing I have Loggerhead Sea Turtle ..

I actually like the sea turtle... personally.. I'd even paint it as a sea turtle when done!

'sid

 

[Desertduler]

Hey it moves! May I suggest something to you? Ditch that tiny air filter and upgrade it to a larger foam air filter and see if your air fuel ratio cleans up a bit, your engine is running too rich and a lot more power can be had with the correct jetting, just remember two stroke engines draw in lot's of air and that tiny K&N type air filter (which I never use on any of my engines and never would because they indeed let dust through them) along with the filters short length will create a air restriction along with your engine being a piston port inducted the short filter length can cause the fuel standoff to condense and the air fuel ratio will be too rich. Here is an example of fuel stand off which occurs in both two and four cycle engines most certainly two stroke piston ported engines.
https://www.youtube.com/watch?v=zs8mnaouP8U

 

[karte_m0lim]

Thanks..I noticed fog when I remove air filter...

Engine and clutch still need some work as I never had this type of engine before, everything is new to me.

@sid, already destroy whole wing/turtle
..

 

[NewbCarter]

Hey it moves! May I suggest something to you? Ditch that tiny air filter and upgrade it to a larger foam air filter and see if your air fuel ratio cleans up a bit, your engine is running too rich and a lot more power can be had with the correct jetting, just remember two stroke engines draw in lot's of air and that tiny K&N type air filter (which I never use on any of my engines and never would because they indeed let dust through them) along with the filters short length will create a air restriction along with your engine being a piston port inducted the short filter length can cause the fuel standoff to condense and the air fuel ratio will be too rich. Here is an example of fuel stand off which occurs in both two and four cycle engines most certainly two stroke piston ported engines.
https://www.youtube.com/watch?v=zs8mnaouP8U

Sorry for bugging but , could you explain the signs of the engine running rich ?

I did talk with karte , and it seems that the idle adjustment screw is off , which would explain the thing running rich on low RPM ( also mentioned that the engine is sluggish if sitting in idle too long )

 

[Desertduler]

Sorry for bugging but , could you explain the signs of the engine running rich ?

I did talk with karte , and it seems that the idle adjustment screw is off , which would explain the thing running rich on low RPM ( also mentioned that the engine is sluggish if sitting in idle too long )

Yes I can, his engine is blubbering as he opens the throttle and not revving quickly as is should, before he makes any carburetor adjustments that air cleaner should be changed as it will not provide enough air to that two stroke so all the jetting will be wrong as a baseline to start with, I can post some pictures explaining the circuits and what they do and where they come into play should he need guidance if he wishes.

 

[karte_m0lim]

I have user manual but I do not have all screws and adjusments as in manual....

I am not sure did I use air filter or it was run without it.

Also, as I said to @newb, I play with fuel pipeing and I put fuel filter in opposite direction than it was before so it is podsible that all dirt is in carb now..

Anyway, any help or advice will be appreciated..

 

[Desertduler]

I have user manual but I do not have all screws and adjusments as in manual....

I am not sure did I use air filter or it was run without it.

Also, as I said to @newb, I play with fuel pipeing and I put fuel filter in opposite direction than it was before so it is podsible that all dirt is in carb now..

Anyway, any help or advice will be appreciated..

Ok then, I would take the carburetor apart and clean it out and check for debris in carburetor, I am going to take you through the components of your carburetor let us start with the idle mixture circuit, the air screw adjusts the air flowing to the pilot jet not fuel in your carburetor and the air for that circuit enters in the hole that I have pointed out, the air screw should be adjusted to obtain a steady engine idle speed without the engine loading up with fuel and dying or running lean and revving up after the throttle has been opened, you should be able to turn the air screw in (rich) or out (lean) and the perimeters for the adjustment screw is 1 to 2.5 turns out and if the idle mixture cannot be changed within those perimeters the pilot jet would have to be changed either with a smaller or larger size depending on the engines needs, this circuit also controls the air fuel mixture with the throttle opening out to about 1/4 throttle, I don't suspect this circuit should be to far off if your carburetor is the original one for your engine so it may just need some turning of the adjustment screw.
Think of this adjustment like if you were sucking a drink out of a cup with a straw and the straw had a small hole in it and if you plugged hole in the straw off with your finger slightly as you were trying to drink you would get either more or less of the drink mixed with air depending how much of the hole you blocked off with you finger, the same applies with the adjustment of the air screw on your carburetor but the opposite applies for a idle fuel mixture screw on other carburetors.
With me so far?

 

[Desertduler]

Here are other components of your type of carburetor, starting from the top, throttle valve, jet needle, needle jet, and main jet.

 

[Desertduler]

The throttle valve has a number stamped on it underneath, on this one is is marked 1.5 which means that the cutaway on the slide is 1.5mm or .060 the larger the number the larger the cutaway and the more air that will flow into the carburetor so a 1.5 cutaway will produce a richer air fuel mixture than say a 3.0 cutaway. The throttle valve has an effect on the air fuel mixture from off idle to about 3/8 of a throttle opening.

 

[Desertduler]

The needle jet has specific sizes and they have a combination of letters and numbers to designate their size either rich or lean and this component controls the air fuel mixture from about 1/8 to 3/8 of the throttle opening.

 

[NewbCarter]

Yes I can, his engine is blubbering as he opens the throttle and not revving quickly as is should, before he makes any carburetor adjustments that air cleaner should be changed as it will not provide enough air to that two stroke so all the jetting will be wrong as a baseline to start with, I can post some pictures explaining the circuits and what they do and where they come into play should he need guidance if he wishes.

Ahh ok , thank you for the explanation . I do have some experience with small 2strokes but big ones are a new thing to both me and karte

p.s - this applies to reed-valve induction 2strokes as well ?

 

[Desertduler]

The jet needle has an effect on the air fuel mixture with the throttle opening from about 1/8 to 7/8 of the throttle opening and it can be adjusted by moving the " E " up or down in the five positions, up with the clip creates a leaner mixture and the opposite is true when the clip is moved down and they too have size differences and taper differences and have letter and number designations for their sizes, (rich or lean)

 

[karte_m0lim]

Huh dude, you wrote too much for my current state of mind..

I go to sleep now, but in the morning will add few picts of carb I have and some picts from manual as well so maybe you can give me some more advices.

But still, thanks for yours replays...