Whats wrong with Mikuni I bodies?

[te4250]

I thought I had seen somewhere why people don't generally use them, but cant seem to find it again. I now have 3 sets from three gp800s I picked up for parts. Is there something I need to modify to use them in a stand up? I read the groupk page that says they generally suffer from a lean midrange despite jetting richer once the choke shafts are removed and a freer flowing airbox fitted. They say Novi modifies them to be more responsive to inlet signal but don't go into specifics as to how, or why they deliver less fuel than a regular sbn in the first place.

Also, Anyone here have experience boring carbs? Can I just punch these I bodies out to 48-50mm and laser cut a new throttle plate for a cheap set of big carbs?

 

[kevbo]

The aftermarket never modified them nor did they ever make manifolds for them. I-body carbs have larger venturis than SBN. They flow more air and require larger main jets. This also makes them less tolerant of being too big for a small engine. Some custom modified SBNs incorporate a vortex generator on the fuel nozzle allowing them to work well when oversized. Nobody knows much about carbs beyond a name and number. I-bodies would be vastly popular if someone bored them and charged $1500 for a pair.