bad tickover on 500/4

[mickwinf]

Nice and sunny here in Scuthorpe so had a little ride to warm engine to do final setup. It starts easily and runs ok on higer revs but tickover is erratic, it seems to race for a few seconds when i close the throttle then after a while sometimes will settle down, if i reduce revs with the tickover screw it cuts out. So i did all the usual things, new plugs and points, timing set, checked for air leaks around rubbers etc then adjusted and ballenced carbs. There was an improvement but still not right, also carbs have been ultrasonicly cleaned and rebuilt,any ideas what else to check?

[Bryanj]

could be worth a compression check, when working  I had same problems on a C50 and comp was 110 instead of 140, turned out exhaust valve was just starting to burn

[deltarider]

Could it be something simple as (very) old gas?

[K2-K6]

I'd go with both of those.....compression check just tells you so much and it's time well spent.

Fuel can be very unstable now if it has any ethanol in the supply, so if it's not new then change it before you go any further.

Just a note about the fuel as a way of preparation to laying-up a bike....it's worth draining and using the fuel in a current vehicle when you store the bike......then using new fuel when you start again.

[mickwinf]

just filled with fresh fuel after rebuild and tank cleaned and sealed. Will check compressions but i had another thought, the only thing i didnt do when i rebuilt the carbs was take out the emulsion tubes, so will do that next.Thanks for imput guys.

[mickwinf]

well, had a couple of evenings in garage, stripped the carbs all was clean, but found one of the adjusting screws for sycronising the carbs was unscrewed from its holder so much it didnt seat properly. I also found the lifting mechanism was just catching and holding the throttle open. Put the carbs back on tonite then realised i forgot to put the return spring back on! Bugger! Very difficult to replace with carbs on bike, tried with bits of wire etc but no luck yet.

[K2-K6]

It's  real pain when you something like that as you can try all ways to get over it but may have to face up doing the bigger job to get back on track.

I've got one bike that I can't, for the sake of trying, get a throttle cable onto it without removing the carbs....it's a right pain but fortunately very rare.

Be interesting to see if you've got it ok when it's going again.

[mickwinf]

Ended up taking carbs off again to put spring back on, getting good at it now! Tried to start it but another problem occured, my starter motor started spinning even when i turned the ignition off!! had to disconnect the battery. Replaced the solonoid and a bit of dodgy wiring and seems ok now, will try starting in the morning.