Front Sprocket

Hello all, chain and sprocket time, Triumph only sell 43 rear 18 front. I already have a 19t front what the previous owner put on.
Is there a problem going back to original, will one tooth really make any difference. On a main duel carriageway I suppose I cruise 60 to 70 mph will I not be able to that with an 18 t front sprocket.
The bikes only done coming up to 9000miles but so many stiff links virtual impossible to gain correct chain adjustment.
thanks all
mallywoods

 

Thanks for that, I think given the set I may as well have a new 18t sprocket fitted, at least that's how the bikes were designed and tested.