bike spluttering when i try to go fast

[sniper]

I just got a 125cc off ebay and when i fully open up the throttle in fourth it starts spluttering and i have no power unless i take the throttle off.
I have seen people talking about this before but cant find it on the search.There must be an easier way to fix this without spending money at a dirtbike shop to do it for me.

 

[Dabomb]

what about when u open it up in all other gears?

id say the fuel mixture is off time for adjusting!

 

[sniper]

Heres the thing.i got it out of the box and put fuel and oil in and done everything i have to do before starting.Ihave ought a couple of these bikes before and none of them started with out me having to screw the idle screw clockwise a few turns to get it started or it just wont start.

I ran it in with three tanks only going slow through all the gears.After the third tank i opend it up and it just bogs out.I think its only in third and fourth.But in forth it bogs out and i have to let throttle go or will just die.

I want to sell this bike as i got it and now made my mind up that i dont like this particular bike.
So im worried if someone that wants to test ride it,it will bog out and they will not want to buy it from me.

I need to know how to make it not do this without spending much or any money.

 

[Dabomb]

ADJUST THE AIR/FUEL MIXTURE SCREW!

does it pop a lot?
does exhaust smell like raw fuel?
is it hard to start?

running the motor in easy or 'slow' isn't a good idea either.

 

[sniper]

I would adjust the fuel screw but not sure which way and how much to turn.I adjusted the idle/air screw just so it idles smoothly.The exhaust does pop a bit when i rev the bike hard when in neutral but dont know about when riding as it bogs out before it has a chance.

Its not hard to start except on two occations when engine was hot i couldnt kick start it.But i usually just use the elec start.
And it just smells like normal exhaust fumes but mabee a little fuel smell but its hard to tell.

I dont understand why running it in slow would be bad because thats what everyone says to do and its even in the manual.Something like dont go over 20km in 1st and 2nd and not over 40km in 3rd and fourth for the first three to four tanks.

 

[Dabomb]

hmmm excessive popping would be running lean and a tasty smell of raw fuel would be rich.
change it up, screw in for more fuel, out for less.

brand new rings don't contact all the way around the 360 degrees of their circumference.
exhaust from hard acceleration pushes the rings out against the cylinder around the whole entire cylinder giving a tight seal and wears into the shape of your cylinder.

the manuals are wrong, they want you not to push your bike hard so that YOU wont break it.

Speed is a poor judgment when wearing in motors.

the load on the engine and throttle position are the best measures.

 

[rotn50]

My pitpro 125 did the same, the clip on the needle in the carb slide was in the middle position i moved it to the lowest position and have never had a problem since, but it ran like a pig until i did this mainly in 3rd and 4th at higher revs.

 

[Dabomb]

yes, you can do that too, the rules with the clip on the needle in the carby/piston is as follows:

clip at the TOP = runs more lean
clip at the BOTTOM = runs more rich

 

[TMY]

Quick question. Are you going through all gears quickly then into fourth? or are you coming into a corner in fourth then pulling full throttle striaght out of the corner? Sounds like the revs are too low so its about to stall.

 

[Andrew Aslan]

Quick question. Are you going through all gears quickly then into fourth? or are you coming into a corner in fourth then pulling full throttle striaght out of the corner? Sounds like the revs are too low so its about to stall.

Thats the same thing i was thinking when i read the start.
Coz thats what heppens if your not going fast enough for 4th gear... Not high enough revs.

 

[Dabomb]

yer its called a lack of torque!

 

[aaron.blake]

check tyhe spark plug it may have water in it thats what i had troble in all gears but now its clean and runs good!

 

[sniper]

Im not talking about going into a corner but i assume it would happen then too.Its when im traveling in a straight line and i usually go through the gears fastish then when it gets to a certain point in mainly fourth,around 55km/h it starts bogging.

I know these bikes go faster than that as i have owned a few of them before.Ill have a play with it tomorrow and get back and let you`s know the outcome.If i have buggerd up the piston rings by going too slow should i get new rings and go hard from the get-go?Thanks for the help fellas.

 

[rosie]

is ur choke on hahaha

 

[sniper]

well this i have never really been sure of.People say different things,If i try to start it with the chike lever down it starts then dies.So i start it with the choke up to warm the bike up and the engine is louder then after 5min then i turn the choke down and it goes quieter and idles fine.Is this the correct procedure?

I didnt have time to fiddle around with it today but will have a look tomorrow hehe.