Carb overflow leaks

Hi all,

I have noticed that my carb overflow is leaking when I come to a standstill at traffic lights etc. It also leaks if I donl't shut the fuel off when I turn the engine off. Is this simply a case of adjusting the float a little to shut the fuel off earlier??

Cheers
Ben

hi ben, i had alot of trouble with my carb and theres nothing too um!! I could not get it right Has your float got a pin hole init??? check it in a bowl of petrol, see if little air bubbles come from it, as for adjustment i would say no i think you just slightly bend it. But i could be wrong so just check first

regards lee

leeandaly wrote:i think you just slightly bend it.

Correct! (after a good cleaning)

My original Kehin carb(1979 and very low milage) also has a very slight leak via the overflow. Inside is cleaned thoroughly and all new rubber seals fitted. New air filter and no airleaks are obvious. The floats are sound and no leaks. Also it is impossible to get a regular idle and even throttle response. Get an even idle and then rev it hard quickly and it does not slow down for ages until it slowly lowers the revs and then stops . Re-start straight away and it idles Ok again....

Finally fixed and running normally. Big thanks to Monkey Bike UK for their advice.

It was a blockage in the main jet, the smaller of the two brass jets in the carb body. I was working on the bigger one and making sure all tiny holes were clear etc. The main or pilot jet? was also looking OK but there is a very tiny, microscopic hole through the middle which was gummed up. Used a very thin piece of copper cable strand to carefully poke through and clear it. All bits left to soak in carb cleaner and re-assemled so now it purrs like dream

A subjective question.... how fast do most peoples ST/CT 70's go? Mine is bog standard 72cc and does 35MPH flat out and screaming which is painful. At 30MPH things are better but still a little strained. I have a 16 tooth drive sprocket to try but it may be a little underpowered on anything but flat ground.Not used it for years but I am sure it was a little faster then.

I have a standard st70 and in will do 40mph at top speed, a little more with the wind on your tail . I used to get a nasty noise when I was flat out but found out it was just my engine mounts requiring a tightening. As long as everything is well fastened then it sounds great.

Thats quite a bit quicker.....I am not sure where mine is losing out then. Only done 2500 miles from new and all standard original parts. I had one in the mid 70's and that seemed a lot quicker from what I remembered, did eventually get a 90cc block which really made it go well. Not sure what to tune up on it then, maybe a new plug and points for a better spark?

I have an aftermarket air filter, but nothing fancy. My clock says its done about 4600 miles, but I know it has done a few more because it wasn't working when I got it. My engine did have a rebuild about 1000 miles ago, but all standard nos parts.

Can't remember what drive sprocket I have, but will have a look and get back to you.

Still not getting much speed out of the old girl. I changed the drive sprocket to 16 teeth (15 standard) and it has been a bit more comfortable but it is not happy at much over 30mph. It is reving cleanly and at 30mph+ it gets very rattly and noisy and feels like it is going to blow....rear sprocket is standard and everything else seems to be working well. Just no idea why it won't do more?