Jump to content
Sign in to follow this  

125 problems

Recommended Posts

hi everyone , i went to go out on my bike today and as soon as i started it it was revving really high to the point where i thought it was going to blow up or something lol , i tried to mess around with the carb to see if it was an issue with the jets etc ... ive ordered a new throttle cable does anyone know if this is what would cause it , or if not what is the cause ?

Share this post


Link to post
Share on other sites

Yea, the throttle cable can get stuck open at the carb side. The cable sheath gets stuck on the outside of the mount for the cable. Usually you can feel it in the throttle though, it will be stiff and only turn a tiny bit. You can check for this by simply pulling the boot that protects the cable on the carb back a bit and making sure its seated right. Same goes for up at the throttle tube. If you pop the air filter off, you can clearly see the throttle plate as well, it should be all the way down with a small crack at the bottom.

Sometimes high revving is caused by an air leak in one of the boots to or from the carb, so look for that as well. :smirk:

Share this post


Link to post
Share on other sites

If it's cooler out now than it was the last time you rode, you might just need to turn the air screw in a little.That's typical of 125's and 200's when the temps drop a little.Try leaning your bike over before you start it until gas comes out the overflow. This will flood it some before start up, and helps keep it from screaming.I keep my thumb on the kill switch in case I have to hit it if it starts the scream.

Share this post


Link to post
Share on other sites

ive been into the carb like 10 times in the past day to make sure its clean , blew out the jets , i was out on the bike on friday after putting the needle position to 3 from 4 , it was running good , not great but good think i need a new spark too but then i went out on saturday and as soon as i kicked it it was really high over rev to the point where i wasnt wanting to let it sit idleing , i have checked the carb with the throttle assembled and the slide isnt actually all the way down there is a slight crack but i think this is bigger than its supposed to be

by the way i dont mean there is actually a crack on anything a mean it is sitting open slightly

Share this post


Link to post
Share on other sites

i also noticed that the carb boot DOES have a crack in it but its had it for a while and a while ago i stuck a patch from a puncture repair kit over it and it was running fine

Share this post


Link to post
Share on other sites

does any one know if my powervalve may be jammed open clogged up ? and if i was going to clean the powervalve would i need to take the top end off the bike or could i just take the pv off ?

Share this post


Link to post
Share on other sites

Take the inspection cover off the right side of the motor on the head and see if the lever is more towards you or back towards the exhaust port.

Its pretty straight forward, the motor needs; spark, air and fuel to run. If you were getting incorrect spark, it wouldn't run right. If you were getting too much fuel, it would fall flat on its face. The only way for it to go crazy rev is if its getting too much air. When it gets a lot of air, it sucks on the carb ports more, which gives it more fuel and its a chain reaction.

It can't get air from the exhaust port (unless there is a major leak, but it wouldn't run right either), it can't get air from bad reeds. It can only get air from the carb throttle plate being too high OR from a leak somewhere.

Since you've been in the carb a few times, the throttle cable seems less of a problem I guess... But it might still be an issue because you might notice the right position for the throttle plate when closed.

Edited by tye1138

Share this post


Link to post
Share on other sites

the Kehin carbs have very tiny holes in the choke system, these are known to clog and cause the high revs on start up when the bike is cold and choke is on. So, if it is only with the choke on then it is a normal wear with time thing as the carb ages. It will stop revving if you turn the choke off. If not only with the choke on then you are doing the right thing and the other suggestions are worthy.

Share this post


Link to post
Share on other sites

hi it happens when the choke is on and off , i have ordered a jetting kit to see if this solves my problem , does anyone else have any other thoughts on this ?

Share this post


Link to post
Share on other sites

i had this issue with the first start on my 125 scared the hell outta me cause it started takin off. it was the throttle cable on top of the carb not bein in right. it got jammed up in the rubber boot on top of the cap to take the slide out. what i do everytime before i start it is to twist full throttle then let go of the throttle. when it springs back shut you should hear the slide hit the carb idle screw. make sure the hitting sound comes from the carb not the throttle. its amazing how sensitive the bikes are to the slide bein slightly too open.

Share this post


Link to post
Share on other sites

hi it happens when the choke is on and off , i have ordered a jetting kit to see if this solves my problem , does anyone else have any other thoughts on this ?

Trust me, its a leak somewhere or the throttle body is stuck open, it has absolutely nothing to do with jetting, your just wasting money sadly.

Edited by tye1138

Share this post


Link to post
Share on other sites

i was going to do the jetting anyway because i want to learn how and ive heard your bike is better if you get it right , i sorted this today , had a feeling it was the throttle cable but wasnt 100% as the bike was perfectly fine the day before yet when i changed it today i couldnt believe the difference , really dont understand what happend

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...