Saving Old Seagulls

Just fired up my 4.5hp non-clutch barge model after a long layup of some years. Started first pull !!! - brilliant. flushed water channels and checked for any fuel varnishing or deposits and looked OK. However although pleased that it started so well, when the throttle is opened and revs put on the the test tank, the revs vary and are not constant. she will run nice and even, then drop revs and come back up again. doesnt stall or stop, but I can hear the point at which it is supposed to run as always did, but doesnt miss, more like surging - new fresh fuel 10 to 1. Changed the plug - should I strip carb and clean? Ive read "robs" 27may12 posts on revs changing and the only other thing apart from stale fuel (isnt) could be breathing in a smallish test tank...cheers

Was it in the "smallish test tank" with the prop still attached. Better to run a non clutched seagull without the prop if you don't have a fairly large test tank

I can't tell which model you have from your description, Seagull never referred to their motors by HP, and there isn't a 'barge' model. There's what we refer to as a 'barge pusher' which had a clutch.

So could you help us out with the serial letters and numbers, found stamped on the crankcase just where it is bolted to the driveshaft casing.

Thanks

Model and serial = WS112 MM4 Silver Seagull purchased June 1975.

Yes.. tank was small ....I've decided to check the jets tomorrow anyway ... photo and serial # sent

Check your gauze filters too, they could have muck in them starving the system of fuel slightly.

Thanks Gents, feedback - Stripped carb - filters dirty , One jet blocked .... havent run it yet but am confident she will go fine. By the way another win, I found the original Jet tool / Key from 1975 !! and a spare prop spring in my shed. It looks as though I may be searching for a fuel tank cap though. (The plastic keeper mount and metal spring ? which keeps the cap from being lost or dropped - underneath the cap has broken off.