CB125T2 from 1980

[hairygit]

Also worth checking the wiring to and at the points and condensors in case vibration has rattled them loose again, those motors are 180 degree cranks with no balancer fitted, so do get high pitch vibration. I remember buying a brand new Cb125T2 in 1981, and after 200 miles (running in at low revs) all 4 exhaust flange nuts had vibrated off while riding, so the points etc would be subjected to similar vibes.   

[peteuk]

OK thanks. Would I still get a spark at the plugs tho if anything like that had come loose?

[peteuk]

I bet you're right about the compression cos it's all thats left. I don't have a compression tester but I know a man who has so I think that's worth a go

[hairygit]

OK thanks. Would I still get a spark at the plugs tho if anything like that had come loose?

Yes, but it may well not spark in the cylinder under compression, as it's only 2 screws to remove the points cover it's well worth checking.

[peteuk]

I've got the points cover off and there's nothing obviously  loose. I'll keep checking tho

[peteuk]

UPDATE.......SHE'S A RUNNER AGAIN
Thanks for all input. Changed the plugs and she fired right up. I can't believe it, those plugs were NOG from David Silver and they haven't lasted 2 minutes. Any ideas what could have caused them to fail so quickly....flooding maybe???

[hairygit]

Yes, as I told you before, once modern plugs have got wet, it's not worth the hassle trying to clean them, in my experience it's quicker and cheaper time wise to fit new ones. Chances are you tried to start it on choke when it wasn't cold enough to warrant it, it started, when you let the revs down it flooded, then it re started for a short time, plugs fouled up, game over! Check your jet sizes if it floods easily, many misguided spotty teenage oiks think bigger jets automatically equals more power/speed, with this kind of result, or maybe they ran K&N or similar filters for the same reason. Glad it's going again.

[K2-K6]

Ha ha, I was wrong there then. Anyway,  at least it's going again now.

This one's certainly being a little diva to to you I feel.

I didn't understand what " NOG" plugs were? Are they own brand?

[peteuk]

Sorry it's this predictive text thing, should have been NGK not NOG. Thanks hairygit and you may have hit on something. I'm certainly no boy racer (I'm 54 and ride like a vicar with a sprained wrist) but i have got K&N filters on due to ease and not wanting to spend 3 months wages on an original airbox. Could this be an issue

[hairygit]

Those things look pretty, and are fine on a race bike which is nailed full throttle all the time, but are a total pain to get jetted for general road use.

Sent from my X6pro using Tapatalk

[peteuk]

Ok thanks for the advice. I may have a problem tho now cos I've done a bit of welding and modded it for the k&Ns and a homemade battery box. I wouldn't get an original airbox to fit now. May have caused myself a bit of heartache there. Ah well you live and learn. Thanks for all the tips they really do help someone like me who has a passion but limited knowledge and experience

[K2-K6]

From the point of adaptions to the jetting with regard to running those filters then it's worth giving something of a start point to realistically assess it.

Generally by putting this type of filtration on carbs it appears to reduce the vacuum for the same type of throttle opening. This ordinarily means that as it's vacuum which pulls fuel out of the float bowl,  then you'd have to consider an increase in fuel metering to restore that balance.

If the main jets are confirmed as std,  then go with lifting the main needles by moving the circlip down one slot.

For the pilot screws, probably start at 2 turns out from fully home. These you can evaluate yourself once running and warmed up,  with choke fully out of use. When it's on tickover,  if you turn the pilot screw either way to get the fastest idle,  then turn it the opposite way very slightly until you hear the engine speed just,  only just,  start to drop. Then this should give you a reference point of how to set for your bike configuration.

If the pilot screw goes less than 1/2 turn out, or more than 3 turns out,  then it would indicate that a different sized pilot jet would be needed to get optimisation.

[peteuk]

Latest Pics.
Thanks K2, i shall put into place your tips and advice on the carbs. In the meantime here's the bike almost complete. Cheers

[MCTID]

Your bike looks brilliant. Wish I could motivate myself......I can't believe you have don all that work in two months........I'm into my second year on mine !!!!!!!!!!!

Well done anyway..........nice bike......not sure about the saddle - but it's your bike, although I really do like the paintwork.

[Nurse Julie]

Did you make the seat yourself or get it done professionally?