One option for converting the carbs to TBs is the way that mlynch001 has gone: remove the slides and float bowls, and machine injector holders into the float bowl replacements. Another option that I'm giving careful consideration is the approach used for these VMax CV to EFI conversion kits
, helpfully shared by Gearheadgregg. That approach would be a bit less simple for a CBX than for a VMax, as the VMax has a perfectly round slide, while the CBX does not.
Well, gang, I've been giving this a lot of thought and done a fair bit of research, and I've decided in for a penny, in for a pound
The path I've settled on for the throttle bodies is to design my own and have them fabricated. Fabrication will be by CNC machining or maybe 3D printing (DMLS aluminum printed parts are expensive and will still require some finish machining, so just going for CNC from the start is the most likely approach).
The plan is to design them such that:
- They retain all of the OEM mounting points so that they can go in the OEM rack.
- The inlets and outlets are the same as the OEM carbs, so the whole OEM intake tract can be retained.
- OEM throttle linkage and balance/sync linkages will be used.
- Injectors will be mounted from above for ease of service.
- The two outboard TB's will be made to look similar to the OEM carbs. I'm not trying to make them exact replicas, just have them similar enough that they don't draw the eye.
- The 4 inboard TB's will probably be just the simplest design that can accommodate the necessary parts and mounting points.
The benefits of going all-new custom TB's as I see them are:
- I can get an exact fit for the OEM intake tract, which is very important to me.
- Should be close enough to the near-OEM look that I want.
- All-new parts will mean the elimination of many variables related to wear and repurposing of old OEM carbs.
- Lots of freedom in injector placement to find the best compromise of rideability/tuning, service, and packaging.
- There's definitely some bling factor.
Given that I'm not a machinist and would be paying someone else to retrofit the carbs in any case, I think that the cost of going all-custom might not be way higher than the retrofit approach. I can pull, disassemble, and clean the carbs myself, have them 3D scanned, and model the new custom ones in Fusion 360. Being able to do all of that on my own without using the time and expertise of a professional machinist should partially balance the cost of the custom CNC or DMLS fabrication. My plan is to do the models myself, have them printed in an inexpensive plastic medium so that I can do a test fit with injectors, plumbing, and wiring, and then have the finish parts made.
If I go with CNC, then I will let the fabricator handle the real expert CAM-related stuff like toolpaths - but starting from a validated model should make that not terrible. If I go with DMLS, then the detailed CAM stuff isn't required.
Now, if you'll excuse me, it's time to get back to watching Fusion 360 tutorials on YouTube.