Belts, the bane of my life.
My go to reference is the Gates automotive interchange
Gates recognise 76181V09D01 as being a Honda classic wrapped V belt but do not list an alternative
According to Gates the secondary ( deck ) belt 76182V09D01 is a 1/2 x 63.375 # 6818BR
Chuck has come up with a 5/8 x 64.843 for the same belt which is weird because it is neither an imperial nor metric size.
Now here is the rub,
Both of those belts have the same effective length so it is only a case of how deep the V is in the pulley
A std Pollyester cord 5/8" belt is weaker than a kevlar 1/2" belt but the 5/8" belt will have better grip which can be accounted for by making the 1/2 kevlar belt a little tighter.
I told you belts were the bain of my life.
If the belt really is 116" then 1 or 2 inches either way will not make a great difference, you just back off or tighten up the tensioning spring.
So have a good look at your deck and see where the tension arm has been running ( paint will be worn ) .
Kevlar V belts do not stretch much, they wear thin thus sit deeper in the V groove and go slack so appear to have stretched.
Thus if you have the original belt, measure the back of the belt then round down to the nearest whole 1/2" or inch.
Honda use std section belts so can always be replaced with std A or B sections and whole inch belts are a lot cheaper than fractional sizes
When specifing a belt size , there is a simple calculation that engineers plug the pulley diameters the axel spacing and loads into then it spits out a length.
Thus you get belts like 201 & 27/32" which cost close to $ 250 down here where as a std 200" belt is $ 95.
Honda made the LX series John Deers so there should be an almost equivalent John Deer and John Deer almost never delete a part without having a reasonable replacement available.
For the 4220H I service, I fit JD belts
Now when one puts the brain into gear,
A 48" deck with 3 blades will need a belt that is near 100" long
The far left & right blade pulleys will be 32" apart and around 4" diameter so to go between them the belt needs to be 72" alone then you need to add for the front blade pulley plus tensioning pulley.
So the deck belt will be the 111" one and the PTO belt will be the 63-64" one.
I mention this because I have seen Primary & Secondary used both ways and regularly mixed up in parts listings.
The Honda owners manual my customer has lists them back to front.
If the PTo to deck belt was 111" long then the deck drive pulley would need to be 4' ( at least ) from the engine pulley .
The drive pulley which goes from the engine at the front to the tranny at the very back is only 100" long and it has to go through the clutch pulleys and be loose enough to go slack enough to not drive.
Did I say something about the bain of my life ?