Dellorto 19mm Carb install - need help!
Nick Appleby
kit and a Dellorto 19mm carb - I already have a Technagas exhaust
installed. I've done only minor work on the scooter thus far, but
installing the cylinder kit proved to be no problem - pretty much a
matter of following the install instructions that came with the kit.
The carb install is proving to be trickier though. The main issue is
that having removed the original Kymco carb, I have to disconnect the
throttle cable from the original slide and attach to the Dellorto
slide... problem is the cable was connected to the original carb by a
screw-on cap, and I don't see any way to remove the cap from the brass
sleeve on the cable. I've been looking for a circlip that holds the
cap attached, but I don't see one...
My other main concern is that the jetting is right on the new carb -
the instructions mention replacing the main jet with an 80 jet, but is
this only if you are planning on using the original 50cc cylinder? As
you might be able to tell, the instructions with the Dellorto carb are
minimal, and assume a level of experience I just don't have.
I'd really appreciate getting feedback from anyone who's installed one
of these carbs before. I'm eager to get the bike back on the road, but
I'm not rushing into this - I know the potential consequences of
running with the mixture too lean. All suggestions and tips greatly
appreciated....
-- Nick
greggscooter
see bottom of your post
.................................................
"Nick Appleby" <nic...@ntplx.net> wrote in message
news:9d15ae37.02120...@posting.google.com...
Hi Nick,
I had a Malosssi 'full kit' (inc. head) a Technigas Next, DellOrto 19mm
and carbon reeds installed two years ago
. I had them drill out the #80 to a #88, put a Malossi conical airfilter in
place of the airbox.
Oh no ! it was so loud people would scowl and cover their ears. I did get
the highest top speed of any combination of parts had done so far, but
I just couldn't take the racket. That filter is for racing and boondocks.
So I went back to the stock airbox, but even removing the rubber 'horn'
and the rain trap, the engine was starving for air.
So I drilled holes in the outer face of the airbox until it ran very
strong, and though every hole increased the noise, I stopped before it got
to be too much.
The last thing was to replace the main jet with a #100. This gives very
close to the same power and speed that the conical filter allowed.
I weigh 240 lbs. and am using 4.6 gram rollers which peak out at 9,250
flat out on a slight grade, black(strongest) clutch springs in stock clutch,
and a red 'racing' rear torque spring which keeps my revs above 7,600 on the
steeper hills, which is around a true 38mph.
I had to discontinue the stock choke
at the handlegrip, and replace it with a manual choke that is secured above
the top rear of the cvt cover.
All in all I get a lot of performance from this little bugger and even
make short dashes from one ramp to the next on the interstate. Tops out at
62mph if there is no headwind.
I don't do it in mid day when everyone is doing 65 and faster.
Haven't been caught yet, ready for a bigger scooter I think.
Gregg
George
To your main concern, the jetting.
I wonder if changing only the main jet would help.
You'll have to make sure that the jetting suites the engine at any
throttle position.
For this you will probably have to tweak:
the air screw (or even the idle jet) up to about 1/4 throttle.
the needle jet, the needle and its position from about 1/8 up to 3/4
throttle.
the main jet from about 3/4 throttle to full.
I assume you don't bother replacing the slider.
The main idea is to have a correct mixture -not too lean, not too rich.
About this you can juge from the spark plug colour-brownish or grey.
The settings are tedious and involve a lot of testing so try to do them
systematically. It's a trial and error process.
The best is to get hold of a scooter repair manual where the whole
procedure is explained in detail.
And clean your air filter. -I just wonder if you don't have to change that
one too because the old one might hinder the air intake.
The reward is that after good jet settings your scooter will be really
fast.
George
Nic, Ellen, & Kelly
properly. Where do you get the different jets and needles? Who sells them
in a kit or single pieces?
Nick Appleby <nic...@ntplx.net> wrote in message
news:9d15ae37.02120...@posting.google.com...
greggscooter
"Nic, Ellen, & Kelly" <nic...@telia.com> wrote in message
news:I26I9.390$LY2....@newsc.telia.net...
> I too am having a problem getting my new 70cc and 19mm carb set to work
> properly. Where do you get the different jets and needles? Who sells
them
> in a kit or single pieces?
You haven't said what country you're in.
If the US, I'd call 'mopedhospital' and talk to Steve the mod-man.
1-866-296-1625. If he doesn't have them he'll most likely know who does.
Gregg
Kurt F
I had the same trouble upgrading to Dellorto 19 on my Cobra. I had to use a
hacksaw to saw off the upper rim of that screw-on cap in order to slide it
over the cable end. I used vice-grips to hold the cap in one hand, and
sawed around the rim with the other, until enough was left that I could
break the rim off the cap. This left me with just the brass-tipped cable
end without damage to the cable or it's sheathing.
The Dellorto kit should have a rubber boot which will fit over the cable end
and seal over the nipple in the top of the carb to keep out the elements.
JETTING!!!
George is exactly right in his reply to you. If you bought the Dellorto and
the cylinder as a kit, the jetting should be done for you by the shop that
put the kit together. If you ordered these seperately, then you must try to
start with rough-rich jettting and lean from there. If you are jetted too
lean to begin with, you can ruin your piston/cylinder on your first test run
out.
Find a rich tune while on the center stand. This will be jetting which
causes the engine to run rough (gurgling). This assumes a warmed up bike
with choke off. Performance won't be the same on the road as on your center
stand, but this way you can get your jetting into the 'safety zone' before
you hit the road to do plug readings for more exact jetting.
There's alot of good info on carb jetting in this group. I wrote my method
in here a couple of times.. search this group on 'jetting' and/or 'plug
chop'.
Start with your needle clip at the richest setting (lowest clip position),
your air screw all the way in, and your main jet may be anywhere from 80 to
115. You can order main jets in incriments of 5, as Greggscoot said, from
Steve at the moped hospital. They upgrade alot of Kymco's there. Steve can
give you an idea of where to start with your carb settings.
Test 1/4 throttle on the center stand, adjust your air screw so that it just
stops gurgling. Test 1/2 throttle on the stand, and slide your needle down
so it just stops gurgling there. Test full throttle on the stand and
decrease your main until it just stops gurgling. Use 10 second durations at
these throttles just to hear the engine. Then hit the road and do a full
plug-series as described earlier in this group.
Jets are cheap, so go ahead and order 3-5 sizes of mains to start with.
Best of luck in your tuning!
--
Yours,
Kurt F
King Cobra @ http://www.mopedhospital.com/img/70cc.jpg