Jump to content
Sign in to follow this  

TM 125 Spluttering at powerband possibly jetting issue?

Recommended Posts

I bought a 1998 Tm 125 about a month ago was running great up until a week ago. Now it's lost abit of low end power and splutters when it hits the powerband.

It does seem to be worse when under-load In neutral it revs ok most of the time. I've put new spark plug in, changed ht lead and cap, cleaned all electrical connections and earths, put fresh mix of fuel in, cleaned the air filter, carb, checked the reeds, checked the power valve operation tested the spark nice and blue and it had a top end rebuild the week before I bought it and has been run in correctly

It ticks over and is fine upto half throttle but splutters at full throttle in the higher rev range which makes me think the jettings out. But I'm confused as it ran perfect on it's current setting when I bought it.

Does anyone know the factory jet sizes for the 98 tm with the keihin carb?

Or does anyone have any ideas what else could cause it to splutter?

Any help appreciated

Edited by afireinsideme
Error In title

Share this post


Link to post
Share on other sites

Its not your jetting as it ran fine before. Check your compression, Make sure your coil is grounded well, check your power-valve and actuation arm / spring.

K

Share this post


Link to post
Share on other sites

I have booked it in for a compression test on Tuesday what kind of psi is acceptable? As I say the top end is quite fresh and it starts and idles fine which makes me think the compression is ok but I could be wrong. I've cleaned all terminals and the powervalve moves freely and opens fully when it should. I've been told it could be the stator, cdi or coil at fault is there anyway to test these? I have an electrical tester just unsure what wires to test and what it is I'm testing for

Share this post


Link to post
Share on other sites

sounds like you are on it and narrowed down to possible electrical issue. :bonk:

Share this post


Link to post
Share on other sites

It sounds like an electrical issue it's kind of misfiring aswell as spluttering at full throttle. I did some welding to the exhaust recently whilst it was on the bike but it seemed to run ok after. I forgot to unplug the cdi could it have damaged it? I thought cdi's tend to either work or not work. It's not something I can just borrow from a friend to test on my bike as I don't know any Tm owners and used parts are very hard to find

Share this post


Link to post
Share on other sites

coil would. Replace it, many will work. Get one off another 125 or 250 2 st

Share this post


Link to post
Share on other sites

Ok thanks i have a kx 250 87 coil that I know works I'll try it in the morning and report back. Any other suggestions welcome

Share this post


Link to post
Share on other sites
Ok thanks i have a kx 250 87 coil that I know works I'll try it in the morning and report back. Any other suggestions welcome

No problem, good luck :bonk:

Share this post


Link to post
Share on other sites

I've checked the reeds were in good shape and sealing good. I've been bedbound with flue for a few days so I've still to change the coil over with my kx one

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

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×