Re: 40HP 45HP 48HP 50HP 55HP differences
Have got some info and thought it would be interesting to post.
For 1994 models (but applies to other years also) 45HP and 55HP engines differ on the carburetor bore fuel and air plug only. 45HP engine has a smaller bore carburetor than the 55HP and the same applies to the 40HP model with respect to the 48HP and 50HP.
Although the 45HP, 48HP, 50HP and 55HP models use the same reed valve stopper, their reed valve leafs and reed valve bodies have different part numbers (there could be some size difference on the slots and/or elasticity of reed leaf). The 40HP model uses a reed valve stopper which limits the leaf to open at a smaller angle than all the rest.
No other differences on the intake side, cylinder sleeve intake ports are identical on all models.
On the exhaust side the cylinder port on all but the 40HP are .048? taller, opening exhaust port slightly faster than that of the 40HP model giving the engine that more power at the high end but compromising with a loss of torque midrange. However, midrange torque on the engines with wide bore carburetors is compensated by the extra mixture fed.
Further away into the exhaust side, exhaust flutes and housing, are identical and do not differentiate on power output.
