Honda 4hp to 6hp conversion

[Boozardy]

Hi all, I’ve just bought a brand new 4hp one of the above and my question is? It’s the same dimensions, weight, CC as the 6hp, can it be converted? If you’re wondering.... why buy the 4hp if you wanted a 6hp? A.Curiosity and a £300 saving, it’ll still pootle along the canals, lakes and (coast... maybe).

[InlandAlex]

Yes, It can be converted.

It may well cost a large proportion of your saving of just buying a 6hp. Contact your local Honda dealer and they should give you a quote.

[Boozardy]

Thanks for that Alex, as I said it’s not a necessity more a curiosity.

[Livid]

probably just carb jetting, check parts diagrams to see the difference

[Fenlander]

No disrespect to Livid intended... my post just happens to follow his but...

There is a lot of urban myth about the net re power upgrades of similar HP models across all makes.

You can only work it out by going through every aspect of the parts manual as Livid says.... carb/jets, cylinder head, camshaft, exhaust tube, ign module/ecu etc... and also go through the settings for timing and advance in a service manual covering both horsepowers.

There are some models where... "just popping out a restrictor plate"... is all it takes... but more often the advised upgrade methods found online are just part of what you need to do.

With a few minutes on my hands I've had a look around at the usual USA parts store online diagrams.

Looking at a BF4 vs a BF6 the carb body is a different part number as well as the main jet assy. Also the camshaft part number is different.

[Livid]

Fantastic info Fenlander, I'm more used to 2 strokes, in hindsight a more aggressive cam profile is almost certainly a thing between hp grades. Carb body might just be a little bit of boring out or a travel limiter, but sods law dictates it isn't. It seems that upgrading between 4 strokes is pretty untenable, there's so many parts it only takes a few to make it not worth the extra expense and time, even on the little ones. Once you get into ECUs and efi you're mad if you try to upgrade an enginr

[Boozardy]

Thanks everyone for your input, I really appreciate it. Also “Fenlander” once again your sound, fact based advice made my mind up for me! The new motor is being PDI’d this week at the Honda dealership and therefore, touchwood I’ll be pootling on the Derwent this weekend using my unmolested 4hp. Cheers All. Tony