Cb125td superdream poor running

Hey guys,

After snooping around for a few months, I thought i'd finally register up and join in.

Its my first of probably many posts here, so i thought i'd start with a question.

I have a 1981 honda cb125td superdream i'm looking to mess around with.

However, before making it what i want, i need to get the engine running properly.

The bike will run lovely for about 20 minutes, then after it'll bog down, get sluggish and eventually die. She also vibrates like something from the dark end of the internet.

I've had the carbs rebuilt and balanced, done the valve clearances but to no avail.


Please if anyone knows whats going on or even has a suggestion, let me know

Cheers
fordy

check your timing?

and what colour do the spark plugs have? pictures maybe?

125td are the double mikuni carbs aren't they?

fun little bike though!

The timing is fine, it was set not too long ago.
The plugs are black so its running pretty rich.

Yeah thats the one, with the mikuni's. Apparantly someone who had before me (friend of a friend) tuned it up a bit. So i think its over jetted.


Along side this, after a bit of probing, there's no current reading from one of the wires from the pick-up for the right hand coil when the bike is hot

I only have experience with the keihin's. don't know if there is much jetting to do with the mikuni's as there are also airjets inside i wouldn't fiddle too much with it and just rejet it to bare stock...

also are your sparkplugs the right ones? maybe they are too cold for the engine. and is the black on the sparkplugs dry or greasy?

I've managed to trace the dropping cylinder to a faulty pick up. It shorts out when the bike gets hot, i've replaced it and thats sorted that.
However it is still running rich.

I spoke to fella i bought has confirmed it has had a larger jet put in (10 up from standard) so i'll pull it out and try a standard size

10 up is a bit much indeed, considering it's a 125 twin... i went from 85 to 90 so 5 up (main jet). firs i had tried 95 but was way too rich also...
again, this is on the keihin's... but you'll figure it out