Club 80-90 Forums

Mmm.. From the other thread... How have you adjusted the tappets?
if they are hydraulics then you need to preload (when each valve is closed) by 1/4 to 1/2 turn.... NOT the 2 turns stated in the Haynes etc..

Low compression will be either a ring has broke or the valve is burnt.. maybe a seat has dropped!!! or even a crack..

the carb may also be blocked faulty which wont help.. choke not stuck on etc?
You have good spark plugs in and deffo got a spark at each plug?

Looks like a head off if nothing seems to improve it.. only way to really find out then...

is it idleing too low then? does it smooth out with a little throttle?
If a tappet was stuck it would be making a hell of a knocking sound... which you havent said..

as I posted earlier regarding the tick over...the adjustment is a long screw coming from under the carb facing to the rear ..(it may have a shroud on) an electrical screwdriver will turn it (in to increase)

115 psi is borderline, and a bad cylinder so now you know the score, have to find the reason

Either rings are stuck or one broken, but until that's solved its hard to imagine you'll ever get it idling or running right. Maybe it just got too hot one day

It does sound like a head off job, to take a look... or time for a full rebuild. All dependson what you find

Some oil additives can release the carbon and free up the rings if they're just stuck, and bed them back in again to an extent, called Mono-Molecular lubricants (Magic Mystery oil in the US)... its much the same stuff that Castrol put in their Magnatec oils, I believe.