Hi, fellas I have a Keihin butterfly carby off of my 1988 FXR  which I replaced with a Mikuni flat slide years ago assuming the Keihin was the original factory carb. The last couple of years I've been enjoying trying to squeeze a little more out of a 650 cc single motor & having exhausted the possibilities of the standard 40mm cv & a Mikuni Roundslide I dug out the old Harley Keihin which when I measured it up is a 44mm throat with a beautiful 65m bell mouth & clamp both ends..the throttle action is also quite quick compared to the other carbies & its compact..no slide chamber & with an adjustable pumper. The motor is now out to 680 with more compression & head work & is of similar bore & stroke to my FXR (which I love riding) so with some creative thinking it was on & with fire extinguisher in hand it fired up first stab like it was meant to be there...the motor loved it..its pulling well into the 6's now but there are a few rough patches. My problem is Im struggling to find any information on it, most people say throw these in the bin but a few guys have persevered & like them ..  it seems its late 1970s ...80s..Ive found many similar but they are 40 or 42mm with similar intermediate jetting but not the same & none with a clamp on filter of this size bellmouth. the no's stamped on it are  PA-40-E  &   BG16 with Harley Davidson stamped on the cable drum...Gratefull for any leads ..Regards sparky

sparky the one that came stock on my old Shovel was 38mm, don't know where you would get info. I changed mine out, was no warranty in those days

Thanks Speedzter! ..yeah the no's suggest 40mm but the throat measures 44 & next to a mikuni 40mm cv its a big hole with very little to block air flow & the motor seems to like it..so thanks very much..thats just what I was after...Cheers mate

Thanks again Speedy..Ive found quite a bit of useful info from your leads..reading between the lines it seems they are not EASILY tunable & people soon moved onto the more user friendly & economical carbs which became available but some guys loved em! & with a bit of patience I think they can be made to work as Im really only interested in performance & the pluses are Ive already got it..most other 44mm pumper carbs just wouldn't fit the in space I have & they'r not cheap to buy! 

There was an SE 44mm CV at one stage, had one on my 01fxdx, dyno bloke reckoned it was an underated carb when I asked if I would be better with something else and to leave it be, I took his advice on that, would one of them fit in there? They are a bit light on the ground nowdays but you can still get kits for them.

Thanks Greasy, the CV's are a bit taller..Im keen to have a go at this one now that Ive got a bit of info on it but cheers ill keep that in mind

Its a Suzuki savage.. & 18 months ago I would have never have thought of fitting such a big carby but I've experimented with a couple of different types as the motor has evolved & its just a big learning experience.  It seems its just about getting the right air/fuel ratio into the motor at the right time & getting it lit & to a certain extent the more the better! & everyone has a different opinion about that..air velocity..atomization ect & certainly I agree there must be a point where big is too big but it depends on the motor & the carby.   2 stroke cabies for example have much longer hoods over the venturies in the throats to compensate for the lower airflow..slide cutaways & shapes...all difficult things to get right hence fuel injection I guess.. get a computer to deal with it! now that I think of it my Buell XB has a 49 mm throttle body & thats feeding 2 x 600cc cylinders. I dont think a 44m would  have been  suitable for my standard suzuki motor but its changed a lot, ported head, altered valves, higher compression, bigger bore, altered cam timing, more lift, different exhaust & at the end of the day it pulls harder & revs higher with this carby than I could with the others, which makes me smile....& aint that why we do this stuff

Grin factor is definitely a big part of it

Cheers Speedy..yeah I've seen some of their stuff, haven't gone down the cafe racer route yet, still like riding like it is..took the forward pegs off my fxr but on this I like em..because its so small I guess but if I can get the motor to where I want it I have lingering thoughts of buying a Suzuki 600 gsxr wreck & using the forks, wheels & maybe swing-arm..everyone thinks Im crazy.... but if being nuts keeps ur sane...so be it