Tdr 125 idles VERY high!

[Tomjoske]

sorry for late reply! finally have been able to give it a go.
I did what you said and I got it to a nice idle speed and went a lot better but still had the same problem where it would randomly idle high again and rev hang. I checked for air leaks too and when I spray directly on the idle speed screw area the revs increase... i think I didn't notice is before because it was already reving quite high

 

[Tomjoske]

could it be in my wiring as well?? I read on here a guy had the exact same problem with his bike and he got it working again by re connecting a wire? my kills switch just magically stopped working aswell

 

[my67xr]

the kill switch shouldn't effect the high idle.

what sort of kill switch do you have ?
most types can be carefully pulled apart, take note of what goes where etc
and you may find a loose soldered joint, dirty contacts or a broken wire
check your connection too, where it plugs to the socket from the loom.

when the revs increase as you spray it,
it could be from an air leak at the thread for the idle speed screw,
or it might be because the spray runs down the carby an into the fuel bowl to base join too.

try to isolate the area, by removing the idle speed screw take note how many full turns to undo it.
when it is out, smear some grease on the threads, then refit it, turning it back in the same amount of turns it took to remove it.
start it up and see if the idle speed has increased (to the higher rpms when you were spraying it)

if it doesn't, then i would say that your fuel bowl mounting surface is warped, or the carby base mounting face is warped
this would most likely be the cause of your problem imo

 

[Tomjoske]

it's definently the idle screw cause when I spray it directly around the fuel bowl it's fine

 

[Tomjoske]

and it's the 2nd kill switch with just the button

 

[my67xr]

when spraying the screw, was it the idle speed screw with the big spring, or the brass mixture screw ?

 

[Tomjoske]

Yea the idle speed screw with the spring

 

[my67xr]

try some thick bearing grease on the threads.
if that doesn't work, the threads in the carby , or the threads on the must be very worn out
otherwise you'll need to replace the carby

 

[my67xr]

can you get another photo for me, i think i have noticed something ?

take the idle speed screw right out of the carby,
slip the spring off and take a pic of the screw for me and post it up here

 

[Tomjoske]

I'm finally back!!! had no internet and got called away for work! but I'm back now! here's the update: I found a local pit bike supplier and got a new mikuni carby for $50***8230; I put that one and with no tuning at all it's running 100000% better! the only problem I have with it now is that in top gear and full throttle after about 5 seconds of the bike at top speed it starts to pop and lose power***8230; but it's completely rideable and a lot of fun.. does my main jet need to be adjusted to help with this problem???

 

[my67xr]

you might get away with just tuning it ?
adjusting the mixture screw, see post 37 , but your mixture screw may be underneath the carby at the front if the new carby is a china copy Mikuni 22/26mm

and maybe the needle clip needs adjusting too with the popping?
try taking the slide out, then the needle, and drop the clip to the bottom one, then assemble it and take it for a test ride.
if it is better, you need to go up a size on the Main jet

 

[Tomjoske]

you might get away with just tuning it ?
adjusting the mixture screw, see post 37 , but your mixture screw may be underneath the carby at the front if the new carby is a china copy Mikuni 22/26mm

and maybe the needle clip needs adjusting too with the popping?
try taking the slide out, then the needle, and drop the clip to the bottom one, then assemble it and take it for a test ride.
if it is better, you need to go up a size on the Main jet

Does it sound like its running lean? The plug reading doesn't seem too bad... It's a dark brown color... It's not sooty black

 

[Blender]

what size pilot jet do u have? the china mikuni 26.22's usually come with a 95 main, and a 15 pilot. a 20 pilot is the best possible thing you can do with them, makes a huge difference. But it sounds like your running lean up top, wich a slight;ly larger main jet will most liely fix.

 

[Tomjoske]

what size pilot jet do u have? the china mikuni 26.22's usually come with a 95 main, and a 15 pilot. a 20 pilot is the best possible thing you can do with them, makes a huge difference. But it sounds like your running lean up top, wich a slight;ly larger main jet will most liely fix.

so I have to buy a new jet?? or do I just move the jet???

 

[Blender]

no, to remove the jet and change it, all you have to do is unscrew the fuel bowl on the carb, take the pilot jet out, and put the #20 in. the pilot only affects idle and 1/4 throttle, so it wont fix your problem up top, but it will make the revs down low a hell of a lot snappier. perhaps try running a 97 main jet may fix that ?

 

[Tomjoske]

no, to remove the jet and change it, all you have to do is unscrew the fuel bowl on the carb, take the pilot jet out, and put the #20 in. the pilot only affects idle and 1/4 throttle, so it wont fix your problem up top, but it will make the revs down low a hell of a lot snappier. perhaps try running a 97 main jet may fix that ?

ok cool I'll look into getting a #20 pilot. and for the main jet would adjusting it help it??

 

[Blender]

adjusting the mixture screw also only affects the idle to around 1/4 throttle. jets are around 5 bucks for a pack of 3 different sizes (you specify upon order) so its fairly cheap

 

[Tomjoske]

yeah but isn't the main jet for 3/4 to full throttle??? can't you adjust it by moving the nneedle up and down?

 

[my67xr]

yeah the needle clip is a fine adjustment of the main jet.

try it out with the clip on the bottom notch, and see if it improves it at all.

then try the clip on the top notch, just to make sure

if it runs better on the top then you need a smaller jet, and if it runs better on the bottom notch then you need a bigger jet.


i'm pretty sure Dhz sells the jets for $5 ea