Let's talk about the Dellorto15mm and the 16mm SHA. Do you have a preference? Does it matter? I mean... 1 millimeter diffrence!? But alas, they exist so there has to be pros and cons.
So lets talk about it.
i hear the 16 is more finicky somehow.....at least the new ones.
154mm^2 vs 177mm^2 inlet area
I personally havent been able to tell the difference between the two, but each one was on a different bike.
honestly I always went with 15's.
Almost all the intakes are sized to 15 anyway. As a result I've got no real experience with the 16's except having run a 16 on a 15 intake, which unsurprisingly was not as good as a 15 on a 15 intake...
probably where the "finicky" reports come from too.
"just running undersized intakes and it's not behaving as i'd like so i'll call it finicky."
This is where we need CW or a couple of other guys to chime in with theory.
I like the 15mm sha way better than 16mm especially on piston port kits for the bigger the bore size is in a carburetor the smaller diameter atomizer needs to be for a finer spray mist to fill the whole bore in the carburetor and a sha doesn’t have normal replaceable atomizer and needles like a normal carburetor does.
For easier starting and easier jetting for me the 15mm gets the nod but on some French bikes the 16 mm sha seems to work OK,
I like the the 14mm bing over a larger15mm bing on pp kits (due to easier to start and and jet) too though on reed kits the 15mm bing rules
I've not tried either...I always just bore out my 14.12's to 15.15's using Graham's tutorial, so I haven't needed to buy one.
I had a theory about the lack of slide cut angle on the stock 16.16s causing havoc at mid throttle and creating a lean condition, i never investigated but it could be a cause of problematic tuning.
edit: it may relate to mismatched intakes as well, again causing havoc on mixture flow. (edited)
i have a 15mm on a stock moby(15mm intake), and a stock pug (15mm intake) and a 16mm on another pug...they are all about the same but the 16mm on the one pug has amazing throttle response...of course it also has a 15mm intake, 70cc kit, mbk cdi, performance pipe, tuned vario...so there's that...
probably about the same
> Woolfardisworthy bullfardisworthy Wrote:
> I had a theory about the lack of slide cut angle on the stock 16.16s
> causing havoc at mid throttle and creating a lean condition, i never
> investigated but it could be a cause of problematic tuning.
> edit: it may relate to mismatched intakes as well, again causing havoc
> on mixture flow.
I ALWAYS have to tune the slide on SHAs. Lots of good info out there on this.
I've had pretty good luck 16.16, I personally hate SHA's but I bought a bunch when they were on sale and put them on a variety of bikes with no issue.
A carb is a carb is a carb, they all need tuning and some are easier to tune then others but they can all be tuned.
time is money, as sizes go up, it's harder and harder to tune across the entire throttle range with limited tuning options.
add a needle, or idle jet, boom, options open up.
comparative expense maybe.
!5/15 Dellorto has always worked perfectly on my StreetMate,a 64cc kitted bike.Idles great and starts always. Gets 100 mpgs so I have no complaints in the last 15,000 miles or so. don-ohio (:^)
I ran a 16/16 on my old tomos blue bullet with great results. Of course i custom made a shorty intake for it that was flowing a true 16mm.
People that put 15/15's on Tomos puzzle me. Most buy a bigger carb and put it on a stock intake. Even the aftermarket "L" intake that claims to be 15mm only flows at 13.5mm.
13/13 forever. :)
> Jimmy Cincinnati Wrote:
> I ran a 16/16 on my old tomos blue bullet with great results. Of course
> i custom made a shorty intake for it that was flowing a true 16mm.
> People that put 15/15's on Tomos puzzle me. Most buy a bigger carb and
> put it on a stock intake. Even the aftermarket "L" intake that claims to
> be 15mm only flows at 13.5mm.
Good point,Jimmy! The intake should be matched up. I've had to grind out a few of them. When a 15mm opening suddenly closes to 13 or so, smooth flow suffers.
Doesn't hurt anything, but crimps the effect the larger intake would've had.
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