johnson 70hp

[caterman]

got a 1978 johnson 70hp, starts and runs really well untill you accelerate, engine then feels and acts like its choked but after 30 seconds ish it accelerates fine. could i of mixed too much oil into the petrol? any advice would help please.
thank you
mike

 

[guido2]

Not likely your problem....what was your mixing ratio?

 

[caterman]

50:1 i was told

 

[joereeves]

If compression and spark is as it should be, the usual cause of that problem is:

Timer base under flywheel (spark advance) sticking somewhat. Use slight bit of grease on brass bushing BUT only oil on nylon retaining ring.

Carburetor throttle butterflies opening too soon. Should just start to open when scribe mark on cam aligns dead center with throttle roller.

Carburetors fouled. If so, clean and rebuild.