First off sorry for not being on the site more consistently, no excuses i'm very lazy.

So the old yam is giving me problems again, hope one of you smart people can help me out.

Bike in question: 1978 Yamaha XS500D

1. I have done some winter maintenance and it seemed to go well, and I've had it out and about since mid January.

I'm having some problems when its up to operating temp, it will idle perfect. But if I give it some gas and let the revs climb to over 4k it will not come back down and hovers at 3800ish. The only way I can get it down to normal idle is to adjust the idle screw. After I have done this it appears to idle perfect again.

Until say I pull away from a set of traffic lights then stop for another set one of two things will happen:

1. it wants to stall and will if not given a little gas.

2. if I'm over that 4k rev mark it will hover at 3800ish revs again.

I'm struggling to get my head around this one, I have tried reseating the carbs. But it's not really helped.

Any advice is welcome cheers again.

Have you checked the throttle cable(s)?

Might be worth a bit of lube.

Or the slides in the carbs? sounds like a sticky one to me>

Could be the throttle cable needs lubing or very likely the linkage at the carb end, I get this on the GT at this time of year.

Or as Biker835 said but it's always a good idea to start with the simplest things!