Where's the idle adjust?

[Pwoida]

I have an '87 johno 150 with rough idle, and stalling at idle. This could be alotta things so before I fork out for repairs I thought I'd try and up the idle. Can anyone tell me where the idle adjust is cause buggered if I can find it.

[NQCairns]

Hi I dont think yours has one, it is adjusted via the spark timing ie more retarded for slower and the converse. So when in tune the standard timing will see the idle speed correct also. You could try twiddling the idle mixture screws, no harm to do there but make it worse or better?. You might have to buy tune up.nq

[Pwoida]

Thanks NQ, I think you might be right. When you say adjust the idle mixture do you mean fuel mixture, ie lean/rich? Because from my knowledge thats one thing you dont touch.

[NQCairns]

Hi PW I thin universally these 2strokes have non adjustable mid and high speed jets. To adjust these the carbie needs to be pulled apart. The low speed circuit is adjustable and whatever adjustment knobs you find will be for this (one for each carbie/cylinder. You will not blow up your #o/b with this adjustment if it were not going to explode anyway.

But you may get it to work better at idle, many times in the past just changing fuel brands saw me twiddling to get my idle smooth again or even to idle at all - once.

Try a can of John/Evin engine tuner before anything, just follow the instructions, magic stuff that, it has helped me many times from raising compression to stoping detonation to improving all performance to improving idle and starting, just cannot go past it for basic maintenance. If you have a dirty engine in the first place tuning is just a waste of time. nq

[Churbro]

I dont know if this could be any use but I have an owners manual for 1978 johnston 85 - 140 hp out boards v4 motors it show's how to adjust the idle, I also have a work shop manual some where around this house just can't put my hands on it.
if any of these are use full just post me and we can arrange to get it to you.

cheers chris.