FR651 hp upgrade

[Mad_mat222]

Greetings,
I have the fr651 engine in my hustler and just looking for a bit more grunt as I run a mulch plug full time and need to keep the tip speed up. I have done a lot of research and from everything I found the block and running gear are identical to the fr730. The only difference being the carbs. The fr651 runs a walbro lmf 23 the fr730 a walbro lmf 22. Every other detail is the same except the 730 is a kilo heavier. Possibly for an oil cooler would be my guess.

Does anyone know if it’s as simple as just swapping carbs?

I’m aware other models share blocks and just run limiters in the lower hp models.

Any advice on the difference between the two models would be much appreciated.

Cheers
Mat

 

[Mad_mat222]

Bump

in addition, has anyone modded these engines? I’ve seen what they are doing with some of similar displacement engines. Eg https://www.performance670.com/category/detail-product/predator-670-engine-parts

they are supercharging etc. I wouldn’t want to go that extreme but a little extra grunt out of these is not unreasonable.

any suggestions or experience?

 

[7394]

I currently have two 651V engines. & to take it from 21.5hp to 23hp is a carb mod.

Yes Bore & storke are same for 651V & 730V.