Pk et3 engine difference

Anyone know what differences there are between a pk125 engine and an et3 engine?



The early pk engines are virtually identical to the et3 with a few subtle improvements.Electronic ignition is alway going to be an advantage over the old primmy engine points system with et3 and pk motors utilising extra transfer ports in the casings.


How’s the new engine coming along?[:lickout:]

I have seen a primmy for sale, with a pk125 engine in it, wondered if this was an improvement, on an et3 engine.

I know et3s are supposed to be better than primmy engines, but not how the et3 engine and the pk compare.

pks are not that well regarded, but I’m not sure whether that’s just the shape of the panels etc that people don’t like…?



Cheers Avenger, that’s what I wanted to hear, although I’m not liking the sound of all the health talk!!!


For good smallframe info relating to engines then clik trhis somewhat long link

Eh Jim ? Pk engines in Primmies ? 1968 Primmies ?

Now theres a coincidence !



Thats uncanny !

Check the „engines“ section on that link I sent and it backs up what i have told you (even though it is a badly tranlated version you can still get the info required) is a very useful site also.

don’t confuse the shape of a pk scooter having any bearing on th motor build and performance. Pk weighing a bit more as a scoot would obviously affect performance on the power delivery. But then so does dieting and losing an ale gut !

I have an early (2stud carb manifold mount) PK125 engine and also have an et3 engine. The immediate differences are - different flywheel, a circular gear selctor on the PK and slighly improved outer clutch cable boss on the casings. Ive used the same exhaust on both engines with no mounting problems.Rear hub and brakes are different

Later pk’s have 3 stud carb manifolds, large cone cranks , 12 volt as standard, different specs in compression ratio’s etc blah blah blah .

Why do you need to know?

I wouldn’t be seeking impartial advice from an interested party there would I?

…the whole of the world wide web and…



Very slowly, got all the bits but need to pick up the casings which are in a mates garage. Gonna get alloy added to the casings to enable huge transfer ports and rework the malossi barrel to make a very temperaMENTAL twist no go eater. You’ll kow when its done cos I’ll start posting obscure tuning questions that probably won’t get answered.

Anyone know the optimal squish clearance for the 136 cylinder head, is it 1.2mm for safety or do I go lower ?

(there small but I ****in luv em) no predicatable genatalia responses please[:smile:]