Mikuni HSR?

S

Sav63comet

Active member
The mikuni HSR, common on Harleys, seems to be a common SU replacement these days.

I ran across this chart with flow numbers....
Mikuni HSR42: 213 CFM
Mikuni HSR45: 237 CFM
Mikuni HSR48: 270 CFM

Wouldn't a pair of these work on a small six?
 
8) yep. as i recall the mikunis used on the harleys are side draft carbs, and designed for 80 ci engines, so perhaps three would be better.
 
The HSR is the one being pushed for Harleys now.

With those numbers two wouldn't be enough? Tuning would be easier. I've read that a 123-456 split is more natural than a 12-34-56 split, but I haven't figure that out as the firing order seems to make sense to me grouped either way.
 
You could in theory keep the factory head and mill off the log part keeping only the runners themselves.
Fabricate a tubular intake to mate up with the runners and put a rubber connector between the two.
Sorry, thinking too hard again.
 
8) two would be adequate, three gives you a similar combination to three 1100 autolites. as for the grouping. i would do the set up much like the triple one barrel set up. meaning i wouldnt eliminate the log itself but rather use it to help overall air/fuel distribution. let all six cylinder ultimately draw from all three carbs as it were. this helps with the tuning a bit as well. and you can run on the center carb only for putting around, and open all three up when you want to use all the power available,or you can synchronize all three carbs and run them all the time, your choice.
 
Jack Collins grouped his in the Locost as two 3-bbls. Others do it other ways.

HSR's produce a sublimely docile idle and since the early days of Pinto engined Baja races, have been the carb of choice for a hard worked Ford engine.

http://www.youtube.com/watch?v=0xXVd51tbSs

http://www.youtube.com/watch?v=JIeh3Bf_8sQ

http://www.youtube.com/watch?v=1-EVAnY7WKQ

Comparison to Weber 40.42, 45 DCOE's and 48 and 50 DCO's on a one port basis show similar CFM ratings. The advantage is that the Mikuni CV carbs are much easier to mount on a log head.

Enough information exists to tune them, and they love low preasure fuel delivery and are much easier to set up on a slow reving six.

Hook on to Horsing around with the Mustang SIx on the Classic inlines website, and see what happens when you weld just four Honda Motor Cycle carbs on. Ak Miller even considered other carbs asside from the twin SU HD8's and there was talk about the old Harley Davidson SS carbs too. Things haven't moved on from then, its taken 45 years for us 'slow' six guys to cotton onto the absolute simplicity of these carbs, whic were emission compliant on bikes right up to recently.
 
I have a manifold i am buying with three SU’s attached going on a machined off log head, as a replacement for these carbs would you recomend the Harley carbs?
 
xrwagon":3g0adyk9 said:
I have a manifold i am buying with three SU’s attached going on a machined off log head, as a replacement for these carbs would you recomend the Harley carbs?
Click to expand...


Xcstacy and some of these other guys seem to have forgotten more than I'll ever know about such things.....

Moss Motors and some of the other. LBC parts sources are now pushing the HSR as a SU replacement though. That's how I ran across them was by googling info on SU carbs.
 
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