Thottle cable ST70

Any one got any tips on installing a new throttle cable on a Honda ST70 6 volt 1972 ????

It's the model where the cable runs through the inside of the handlebars....

Pulling my hair out on this one...... I bought a new cable as the twistgrip / old cable cable was a bit sticky. Installed new one and the inner cable to outer cable length is obviously too short as I can't stop the engine racing. .... Thought it was dodgy new cable so I bought another !!! That one does the same..... Even the old one causes the engine to race now !!! Spent hours tinkering and just looking at it !!..... Seems after countless times that I have tried and tried again, can't stop the engine from racing.
I've measured the outer cable to inner cable (base of outer cable to top side of carb nipple)..... Old one measured 79mm...... David Silver Spares new one 77mm...... Monkey Bike UK new one 78mm.

The few mm's of difference shouldn't be a problem, as you can adjust the length of the cable using the adjustment screw on top of the carb.

Because you still have the problem when re-using the old cable, the problem will be somewhere else.
Please check if you mounted the valve tube (don't remember the right word, it's the ropund tube where the cable stops) in the carb in the right position.
If you haven't, it won't get to the bottom of the carb, resulting in full throttle at all times.
You can easily recognice this by the high tension on the spring above it.
Search for a little 'nipple' inside, and turn the tube.

PS: Try to start the engine with the cable unfitted.

Thanks Waynus.....

The problem did lie somewhere else !...... and I did use your tip of running the engine without the cable attached to the twistgrip..... Doing this, the engine started and ran reasonably slow. I then pulled on the cable to rev the engine, which it did...... But then the engine started reing fast and slow all by itself !.... It was then that I thought that there must be an air leak.

So the cable was not the cause....... What had happened was that whilst I was waiting for the first new cable to arrive, I took the carb off to sort something out. What I didn't realise was that the rubber o ring between the carb and the inlet manifold had fallen out..... All along it was sitting on top of the engine barrel looking at me !

Appreciate your input.

Glad to hear you found and solved the problem!