The short story – I think it works. The Honda carb fits on my Toro 20684 (Suzuki 47P 2-stroke) in place of the Mikuni with a few modifications to the Honda carb, but with the 5 minutes of run time I had on the mower I could only get it to run on choke. More about that later, I’m going to assume I can fix that & describe what I did.
Why this is potentially great:
The Honda Carb costs $14, the Mikuni costs $140 and potentially this can be done on other Mikuni-carb’d engines (Kawi FC150/180, Wisconsin Robin, Lawn Boy M, ??). The Mikuni develop wear between their throttle shafts and the carb body, leak unfiltered air & run lean.
Got all the real info from PERR (http://www.perr.com/phpBB3/viewtopic...&t=7952#p59550
) and discussed it another thread here (https://www.mytractorforum.com/showth...=237483&page=2
Install went as described on PERR with one BIG difference. I did not have to change the carb mounting studs on the engine (I did this, and then the air box would not fit, easily a wasted hour.) Honda carb fits almost like the Mikuni, it is just slightly thicker.
As you can see in the pictures, the carbs are very similar in size and linkages. The process was roughly:
1. Remove mikuni & clean up old gaskets if you’re going to reuse. All gaskets on the engine side of the carb can be reused.
2. Tape up all the places on the Honda Carb you don’t want aluminum shavings, and enlarge the mounting holes towards the center of the carb body. I couldn’t get a dremel in the holes, so I used a regular round file. Probably took 10 minutes – not a big deal.
3. Maybe omit this step? I took the PERR guys’ advice and drilled the main jet to .78 mm or wire gauge 68. Duraforce folks should know this size well. Except I couldn’t get the jet to actually fall out of the carb body, it unscrewed and then hung up at the bottom of the ‘tube.’ Does anyone have Honda carb experience with this? I think this is the GCV mowers if that helps (I will search more too). Since I don’t have to mower running right, although it seems I’m fuel starved, I can’t say if I should have done this. I don’t know if this caused the issue, or if the mower wouldn’t have run without it at all. Anyhow…
4. Attach the stock linkages to the Honda carb, and mount the carb to the stock studs. Here is where everyone gets to play their games for getting the carb on/off the studs. I was able to get the carb on/off with linkages attached, but it was a squuuueeze.
5. Start practice fitting the airbox, you’ll have to do 2 things:
a. Cut the gasket listed below to be very close to the carb body, or the airbox won’t fit flush, and
b. Grind away/cut away a lot of the plastic on the choke lever. Just lots of trial & error. The parts:
1 each Carb=16100-Z0Y-013 (now 16100-Z0Y-813)
1 each filter plate gasket=17228-ZL8-000
Problem as of now: (hopefully to be edited out once I fix it…)
Have only had few minutes to play with it…but I could only get it to run on full choke and when the mower was loaded with the BBC engaged. It does run, and sounds pretty good, given that it’s on choke! So, clearly there’s a problem. I completely forgot this carb has an adjustable idle circuit (looks like it at least), so maybe that’s my savior. I’ll try to get home while the sun is still up tomorrow and try—and search for a huge air leak that maybe I created with all my gasket pulling & stud pulling…I want this to work badly for me and everyone else…and all my Mikuni mowers!
Had one other odd problem, I think the float hung up on me while I was fitting the Honda Carb, so I had big puddles of gas on my first try. (my excuse for not working on this more) I disassembled the carb, saw no problems, and pressure tested the needle/seat (10psi). No problems on reassembly, just odd.