I'm trying to get the Honda CB125 I bought off Voltaire running and have struck a bit of a conundrum. The electrical side seems tickety-boo. But the carb has me scratching my head. The bike starts and runs but it 8 strokes. It will rev but it takes a fair while to wind up. It's running very rich and my efforts to lean it out have made no difference. Then petrol starts pissing out of the overflow tube so I shut it down and shut off the fuel. Can anyone give me a diagnosis for that? Also - the throttle is nice and smooth, turns nicely. But when I bolt the carb to the engine. it gets so tight I can't even turn the throttle. If I back off the nuts, the throttle gets lighter again. WTF am I going to do about that because I am lost on that one? Is the carb rooted?
Return to sender....
Warranty?
return to sender....Warranty What about the BFTP mission statement " we know ...blah blah...bikes go" needle jet: raised for richer...lowered for poorer...er leaner Float Needle: may not be shutting off...flooding. is main jet correct size...? The flange may need to be dressed on a bit o glass with wet and dry and crc to make it level... failing that could you try one of the carbs off the other 100/125's? ....as we say at work: " How would I know...I only sell the bloody things...." Ask on the main forum as there are really clever guys like Dangerous Bastard there....
Nah, carbs just old. Quite typical with old stuff. Just seems rooted, but in reality probably good for years yet. Like me, in fact. Rich and pissing out the overflow. Options are 1. The float is jamming on something 2. The float needle is missing, deranged, in upside down , worn out 3. The float jet is worn , loose, deranged, missing. 4. Sometimes there is a wee oring in the float jet area gets left out. Had me scratching my head on my TC125 5. The float height is wrong (most likely Remove crab. Remove bowl. Inspect, peer, probe and pry. Lap in needle with Brasso if necessary. replace , reinstate as required. Also , the mounts are deranged., so that bolting the crab down distorts it. Is the big O ring there? Should there be a Tufnol block. Wise men wonder. Check the flange for truth with a lie dector - uh , straight edge.
Some good tips there (return to sender one excepted)...
Re the float height, how do I measure it and change it. I can do all the other stuff but I don't know about floats.
try this.... http://honda-cg.ifrance.com/Honda-CG-125-1976-1991.pdf
I'm chuckling here - I've got a Scientific Publications Manual and a Haynes manual and on the topic of float adjustment, say it's 24mm but you need a special Honda developed tool to do it; as well as saying that Honda spent a lot of money developing the carburettor settings and you will not be able to better them yourself. Translation: Our technical writer got pissed at this stage and his notes were illegible after he spilled rum on them. So we just chucked that bit in to throw you off the scent. Ixion - all the bits are there for the carb mounting set-up and I'll check the face with a straight edge. I have a couple of other carbs so will throw one of those on today to test whether they also distort when tightened against the engine - then I'll know whether its the carb or the mounting. This one has blind-sided me.
Disconnect the carb and leave the fuel line on, whip the bowl off and hold the float up, chuck some gas down the fuel line and see if minimal pressure on the float stops the fuel from running down your arm. Then while your at it do the float measurement as per the manual setting because Honda knows best
In the absence of a correct float level (that worked) for my TLR200 - I run it and turn the tap off....if it revs up before stopping the level is too high,if it just dies it's too low.You are looking for it to just start to run cleanly before it dies.The TLR200 is hard to set up as it runs at very low speeds,and then has to take full throttle suddenly....it's still not without problems,but I've been running it like this for some time.''Works For Me''.
I've done all of that. Setting the float level has stopped it pissing fuel out the overflow but the bike runs just the same - eight stroking and bogging on the throttle. I can only concur that the thing has been assembled with the valve timing out. The carb is fucking perfect, the points are fucking perfect, the timing is fucking perfect, it can only be what happens between the two things.
Id still suss that crab. Did you fix the slide jamming thing? Left field question, but is it the correct crab for that engine ? I think ive got a Honda CB125 somewhere in a shed. Dumno ehat nick its in i think spmeone tried tp bucket it but i could pull the crab off if you want to try another one
ahhh...have you checked the advance/ retard spring weighs ....I think they are behind the points plate. Might not be working properly... I had issues on my sons XR 80 once where the key in the flywheel was flogged and the timing changed when you reved it. Being a Honda I'd be guessing the timing would be easy enough to check...line up some dots or summit...
Chapter 5 - it is not the advance retard nor the valve timing. What about the condenser? Coil breaking down under compression? Fecked if I know - there aren't many things left, really.
