ETZ251 tickover settings

[Emzedder]

I am trying to achieve a reliable tickover on my ETZ251 which has only 1500 miles to its credit so should not have a worn out carb. The Haynes manual says 4 turns out on the air screw and one and a half turns on the pilot jet screw but I understand from comments on this forum that these figures are incorrect. It isn't very clear from the Haynes manual which is which but the big one is the air and the small one the jet I think. So, how do I set it up? I've tried all sorts but nothing works.

[Blurredman]

The idle/pilot screw should be the one at an angle pointing towards the top of the carburettor. The practice is, this screw keeps against a step in the slide, thus stopping the slide from going down any further than the screw provides. I believe mine is about 10 turns from in.

The mixture screw could be anywhere between 1.5 and 2.5 turns from in, depending on carb wear etc. Try 2 and take it from there.

[Emzedder]

[quote="Blurredman"]The idle/pilot screw should be the one at an angle pointing towards the top of the carburettor.

My carburettor does not have a throttle stop screw. It has the pilot jet screw and an air screw. It isn't possible to stop the slide going right to the bottom except by adjusting the throttle cable but that should have 1/8 inch of slack. The air screw controls a volume of air which bypasses the slide thus controlling tickover speed. I am thinking now that there may be a blockage to the pilot jet. Thanks for taking the trouble.

[breakwellmz]

No throttle stop screw?

[Blurredman]

What carburettor is on your bike?

[etz251tr]

This pilot jet screw adjustment 1,5 is wrong but for Etz 125-150.
On 30N 3-1 carburator Etz 251 model pilot screw adjust: 2,5 .

[Emzedder]

Yes it's the 30N 3-1 carb. I'll try with 2.5 on the jet screw. I haven't touched it for about a week and still think maybe there's a blockage there but at least I now have some idea. Thanks.

[Blurredman]

Take the screws out all together and check that they're not icky with old petrol.