Engine issues? Please help!

[Donavan321]

Hello, I have a 2-cycle bike motor.....I isntalled this guy last year and rode it little and then it sat, I repalced the fuel line
and filter......I cleaned the carburetor and am running seafoam through it....so anyway it still looks shiny and new but..
it wont run smoothly at WOT....it goes BRRRR BRRRR BRRR BRRRR BRRRR doesnt stall out just wont go
BRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR like it's supposed to. I've never encountered this before..I replaced the
head acorn nuts with regular nuts to allow the gasket to fully seat! I will be getting a new carburetor...... I know after awhile the
carburetors just quit. IT runs like a champ! just not on full throttle... any suggestions? I am running a 20:1 mixture.

 

[crassius]

first things I'd look at are spark plug & the boot for it

 

[HeadSmess]

dont see how the standard nuts affect the head gasket from seating.... never been an issue on any other motor.

this brr brrr brr is hard to picture. im guessing you mean its SURGING? like, power on, die, power on, die, power on, die despite holding the throttle wide open?

usually due to... a blockage/restriction in fuel line. can be from the tank cap vent to the bowl on the carb to the carb bowl vent. check.

or the mixture is just on the "too lean" side of things. check plug. if its black/brown/grey its ok, and its something else being an issue.


simple bit of gunk in the main jet?

what size motor? only one ive had that surged constantly was a 66 POS. nothing fixed that one. nothing.

 

[HeadSmess]

I will be getting a new carburetor...... I know after awhile the
carburetors just quit.

what? since when? whats in there to quit exactly?

learn how a carb works, and play with jetting the one you have.

cus you know what? youll buy a new carb and it will also need jetting to suit. carbs do not come off the shelf ready to suit an engine in all regards. racers even jet carbs to suit the day, the temperature and humidity, the track. there is no definite size jet for a given carb on any given engine. just generalisations, tweaked to suit the user.

carbs do NOT just "quit". certain parts may wear out, the cheap one might break, sure, but they dont just "quit".

im still using my first carb on my fifth or sixth engine. cus i normally buy a motor alone, i only have a few carbs. thats 20,000km+ on a carbie with no "quitting"

once again... full throttle issues is most usually too LEAN.

try a short run on 50:1 mix and see if it stops surging or at least reduces it to a degree. the less oil means a slightly richer mix. a good way of pinpointing a fault.